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Bioindicators of climate and trophic state in lowland and highland aquatic ecosystems of the Northern Neotropics.

Natural and anthropogenic factors influence physical and chemical lake variables and aquatic biota, especially environmentally sensitive phytoplankton, phytobenthos, zooplankton and zoobenthos communities. Such factors include water extraction, pollution, eutrophication, flow modification, changes in water level, habitat degradation, climate warming, and changes in evaporation and precipitation (Dudgeon et al. 2006). Continental waterbodies are some of the most endangered ecosystems in the world (Sala et al. 2000), especially those in developing countries (Perez et al. 2011a). Waterbodies in the Northern Neotropics are important resources for local inhabitants. They provide drinking water, sites for recreation, navigation, and habitat for both aquatic and terrestrial fauna and flora (Dudgeon et al. 2006). Despite their importance, there have been few limnological or ecological studies of these ecosystems, especially in Guatemala and Belize (Perez et al. 2011a). Many local inhabitants around the largest lakes in Guatemala, Lakes Izabal, Peten Itza, Amatitlan and Atitlan, rely on local fisheries for subsistence and to generate income in local markets. Such activities have affected the trophic state of these lakes. Lake Peten Itza, located in the Maya Biosphere Reserve in Northern Guatemala still displays high diversity of aquatic bioindicators, but cultural eutrophication in the lake has increased during the last few decades (Rosenmeier et al. 2004, Perez et al. 2010a), putting many species at risk. Lake Amatitlan is highly productive and has suffered from cultural eutrophication for decades (Perez et al. 2011a). Aquatic bio-indicator diversities in the lake are probably low because of the hypereutrophic conditions. Cyanobacteria dominate the phytoplankton community in the lake, and high rates of decomposition lead to hypoxic or anoxic conditions in deep waters. Cyanobacteria blooms in the lake produce toxins that can be dangerous to humans if present in high concentrations (Perez et al. 2011a).

Aquatic organisms that are sensitive to changes in water chemical composition, pollution and trophic state, i.e. aquatic bioindicators such as diatoms, chironomids and microcrustaceans, are frequently used to track environmental change. Diatoms are generally a dominant group in the phytoplankton, whereas cladocerans, copepods and ostracodes are typically the main zooplankters in fresh waters (Dole-Olivier et al. 2000, Walseng et al. 2006). Diatoms are unicellular golden-brown algae (Bacillariophyta) characterized by silica shells (frustules) that are well preserved in lake sediments. Diatoms live in planktonic and benthic habitats (Battarbee et al. 2001). Chironomids are non-biting midges (Insecta: Diptera) and are frequently the most abundant group of aquatic insects in fresh waters. Chironomids are true flies, but they spend most of their life cycle (egg, larva, pupa) in aquatic habitats (Armitage et al. 1995). They are ubiquitous inhabitants of Neotropical aquatic ecosystems. Nevertheless, there have been few studies in the region concerning their taxonomy and aut-ecology (Perez et al. 2010a). Microcrustaceans such as ostracodes, cladocerans and copepods are important organisms in limnological and paleolimnological studies. Ostracodes are typically <3mm long. The two valves that enclose the body are composed of low-Mg calcite (Meisch 2000). Similar to ostracodes, cladocerans are small (0.2-2.5mm). Limbs and a postabdomen extend from a ventral opening in the carapace, facilitating locomotion and feeding (Dole-Olivier et al. 2000). Ostracode valves and cladoceran exoskeletons preserve well in lake sediments. Body parts of freshwater copepods (<2.0mm long), however, are poorly preserved. Nevertheless, sacs with resting eggs of some copepod species are robust and well preserved in late Quaternary lake sediments (Bennike 1998). Microcrustaceans, diatoms and chironomids are the main food sources for many aquatic macroinvertebrates and for vertebrates such as fish. They are key components of the food web in lake ecosystems and therefore of great ecological and economic value (Cohen 2003, O'Sullivan & Reynolds 2004). Impacts on these communities from pollution, changes in lake trophic state or climate, can have dramatic consequences for fish populations (Moss et al. 2003). Microcrustaceans, diatoms and chironomids are widely distributed, can rapidly colonize new habitats (Cohen 2003, Hausmann & Pienitz 2007) and share characteristics that make them useful as bioindicators and paleo-indicators: (1) their well preserved remains in lake sediments can be identified to genus, and sometimes to species level, (2) they are often abundant, (3) they are highly sensitive to environmental changes, (4) they have short life cycles and communities thus respond quickly to environmental changes.

Consistent taxonomy, along with information on species autecology and the factors that affect species distributions and diversity, are indispensable to ensure that inferences from bioindicators, whether in modern or paleoenvironmental contexts, are valid. There have been few paleolimnological studies using bio-indicators in remote tropical areas, in large part because of the paucity of autecological data. Detailed bioindicator analysis, coupled with information on physical and chemical attributes of aquatic ecosystems, is required to fully exploit the utility of such bioindicator taxa. These taxonomic groups are highly sensitive to environmental changes, such as shifts in salinity, conductivity or ionic concentration (Fritz et al. 1991, Smith 1993, Perez et al. 2011b), total phosphorus concentration (Hausmann & Kienast 2006), lake level (Sylvestre 2002), air temperature (Walker et al. 1997, Brooks & Birks 2001), pH and organic matter concentration (Rosen et al. 2000), and changes in precipitation and trophic state (Massaferro et al. 2004, Perez et al. 2010a).

There has been little research on the aut-ecology of lacustrine organisms in the Northern Neotropics. Most studies have focused on taxonomy and biogeography. Studied groups include cladocerans (Elias-Gutierrez et al. 2006, 2008) and copepods (Suarez-Morales & Elias-Gutierrez 2000, Suarez-Morales & Reid 2003). Perez et al. (2010a,b,c, 2011b) recently conducted studies on the freshwater ostracode fauna of the Yucatan Peninsula and surrounding areas. There are, however, few studies on diatoms and chironomids. This study presents information on chironomid, diatom, cladoceran, copepod and ostracode taxa from 63 waterbodies in the Northern Neotropics, along with associated environmental data. Our objective was to determine the factors that govern the distributions of these bioindicators so they could be used to infer late Quaternary environmental conditions and climate on the Yucatan Peninsula, Guatemala and Belize. In this study, we (1) present an inventory of the main species that inhabit aquatic ecosystems of the Northern Neotropics, (2) display ecological information from the studied waterbodies, (3) evaluate relationships between bioindicator relative abundances and environmental variables, (4) identify areas with high species richness and diversity that could be of conservation interest in this zoogeographic province and (5) develop a basis for transfer functions that can be applied in paleolimnological studies to infer past environmental variables such as water chemical composition and lake level. Ultimately, these transfer functions will be applied to fossil assemblages in long sediment cores retrieved from Lago Peten Itza, Guatemala and other waterbodies in the Northern Neotropics to infer past environmental variables.

MATERIALS AND METHODS

Study site: The Yucatan Peninsula (Mexico, Guatemala and Belize, Fig. 1) and surrounding areas are rich in aquatic ecosystems that have different origins (tectonic, volcanic, karstic) and possess diverse water chemical composition. Chemical characteristics of waterbodies are mainly influenced by bedrock geology, climate and saltwater intrusion at coastal sites (Perez et al. 2011a). The Yucatan Peninsula (Fig. 1) is a marine carbonate platform. The region is of interest to ecologists and paleoecologists alike, because it displays steep, increasing NW-S precipitation (~400-3 200mm/y) and altitude (~0-1 560m.a.s.l.) gradients (Perez et al. 2011a). A dry season (January-May) and a rainy season (June-October) characterize the Yucatan Peninsula and surrounding areas. Short-duration showers usually occur from November to December (Schmitter-Soto et al. 2002). Most of the study area is located in a dry tropical climate zone that is rich in aquatic ecosystems and displays high aquatic biodiversity (Lutz et al. 2000, Perez et al. 2011a).

Sampling and habitat characterization:

Two fieldtrips were carried out in the Yucatan Peninsula (Mexico), Guatemala and Belize (14[degrees]13'00"-21[degrees]25'00" N and 87[degrees]20'00"91[degrees]03'00" W) in 2005-2006 and 2008. A single sampling was carried out for each lake. Chironomids, diatoms and microcrustaceans (cladocerans, copepods, ostracodes) were collected from 63 aquatic ecosystems (Fig. 1, Table 1a, b). These ecosystems included deep (10-340m) and shallow (<10m) lakes (Table 1a), "cenotes" (sinkholes), coastal lagoons, ponds, rivers, and wetlands (Table 1b). Surface sediment samples (lake deepest point, littoral zones, other water depths) were retrieved using an Ekman grab. Ostracodes and cladocerans that live in macrophyte-rich littoral zones were collected with 250[micro]m and 100[micro]m-mesh hand nets, respectively. Physical and chemical variables and the chemical and isotopic composition of lake waters were studied to better characterize the habitat. Water samples were collected from at least three depths above the lake's deepest point (surface, mid-depth and bottom). Only surface waters near the shore were collected in smaller water bodies (ponds, rivers and wetlands). Water temperature, dissolved oxygen, pH and conductivity in surface waters were measured in situ using a WTW Multi Set 350i. Most measurements were done at midday. Water samples were collected in duplicate for laboratory analysis of Ca, Na, Mg, K, Cl, HCO3 SO4, and for [delta][sup.18]O and [delta][sup.13][C.sub.DIC] analysis. [delta][sup.18]O values were used as an indicator of the balance between evaporation and precipitation and [[delta].sub.13]C values as a productivity proxy (Schwalb 2003). Cations were measured using an ICP-OES Jobin Yvon JY 50 P Spectrometer. Bicarbonate was determined by titration with 0.1N HCl. Anions were measured using a 761 Compact IC Methrom at the Institut fur Umweltgeologie, Technische Universitat Braunschweig, Germany. Carbon and oxygen isotopes in waters were analyzed on a VG/ Micromass PRISM Series II isotope ratio mass spectrometer and a Finnigan-MAT DeltaPlus XL isotope ratio mass spectrometer with a GasBench II universal on-line gas preparation device at the University of Florida, USA.

Bioindicator analysis: Surface sediments (~3g wet sediment) for chironomid analysis were (1) deflocculated in 10% KOH, (2) heated to 70[degrees]C for 10 minutes, (3) heated in water to 90[degrees]C for 20 minutes, and (4) sieved using 212Lim and 95Lim-mesh sieves. Chironomid head capsules were extracted from samples using a Bogorov sorting tray and fine forceps. Head capsules were slide-mounted in Euparal, identified, counted and photographed. Identification followed Perez et al. (2010a). We identified taxa to the morphospecies level because taxonomic data are generally lacking for the Northern Neotropics.

Sediment samples for diatom analysis were treated with hot concentrated HN[O.sub.3], then with 33% [H.sub.2][O.sub.2], followed by successive rinsing and decanting with distilled water. Sub-samples of the homogenized solution were diluted by adding distilled water and were left to settle onto coverslips until dry. The coverslips were fixed onto glass slides with Naphrax[R] mountant (refraction index=1.73). Counting was performed generally on three slides using a Nikon NS600 microscope at 1000x magnification. The total number of valves counted per sample varied from 50 in nearly sterile samples to >1000 in rich samples. Diatom identification and taxonomy followed Krammer & LangeBertalot (1986, 1988, 1991a, 1991b) revised by the nomenclature of E. Fourtanier & J.P. Kociolek (on-line version of the Catalog of Diatom Names: http://research.calacademy.org).

Surface sediments were initially analyzed for cladocerans using low magnification on a light microscope. Remains were isolated, identified, and counted and specimens were kept in small vials filled with 3-4% formaldehyde solution. Several drops of glycerin were added to all vials to prevent desiccation. Permanent preparations of peculiar species were prepared for detailed microscopic observation to facilitate identification. We used polyvinyl lactophenol or Hydro-Matrix[R] as mounting media. Species were identified using the works of Korovchinsky (1992), Smirnov (1992, 1996), Lieder (1996), Flossner (2000), Kotov & Stifler (2006), Elias-Gutierrez et al. (2008) and Van Damme et al. (2011). Calanoid copepods that live in open waters and littoral zones were sampled with a plankton net (100-Lm mesh), preserved with 10% formalin, and identified and counted under a dissecting microscope. Literature used for taxonomic identification included Bowman (1996), Gutierrez-Aguirre & Suarez-Morales (2000), Suarez-Morales & Elias-Gutierrez (2000, 2001), and Elias-Gutierrez et al. (2008). The details of the method used for ostracode analysis is in Perez et al. (2011b). At least 100 adult ostracode valves were extracted from 50mL of wet surface sediment. Samples were wet-sieved using stacked sieves (630-, 250-, 63Lm mesh). Both hard and soft parts were analyzed and used for identification to species level when possible. Identification followed Furtos (1933, 1936a, b), Brehm (1939), Keyser (1976), and Perez et al. (2010a, b, c, 2011 b). Samples are stored at the Institut fur Geosysteme und Bioindikation, Braunschweig, Germany. All bioindicator data are presented as relative abundances.

Species richness (S), i.e. the total number of species, and biodiversity, i.e. the Shannon Wiener Index (H) (Krebs 1989), were determined for each taxonomic group (chironomids, diatoms, cladocerans, copepods and ostracodes) in all waterbodies. Multivariate analysis was used to characterize species aut-ecology by relating species relative abundances to water variables. Prior to statistical analysis, 14 environmental variables (water depth, water temperature, conductivity, dissolved oxygen (DO), pH, [delta][sup.18]O, [delta][sup.13][C.sub.DIC], Ca, K, Mg, Na, Cl, HC[O.sub.3], [SO.sub.4]) from all waterbodies were standardized (x-mean/st dev) and species relative abundances were log-transformed. Rare species, i.e. those present in <3 waterbodies, and samples containing few or no specimens, were excluded from analysis. Species included in the multivariate analysis are shown in bold in tables 2, 3 and 4. Thirty-eight chironomid, 97 diatom, 32 cladoceran, 3 copepod and 17 ostra-code species were included in the statistical analysis. Correlations between environmental factors and the relative abundance of organisms were explored using Pearson correlation, which allowed up to seven environmental variables to be included in statistical analysis. Seven environmental variables were forward selected for statistical analysis of chironomids (DO, pH, temperature, conductivity, HC[O.sub.3], [delta][sup.13]C, water depth) and diatoms (DO, pH, temperature, conductivity, [[delta].sub.13]C, [[delta].sub.18]O, water depth), four for cladocera (DO, temperature, HC[O.sub.3], conductivity), and six for copepods (temperature, HC[O.sub.3], Na, Cl, [delta][sup.18]O, water depth) and ostracodes (temperature, pH, HCO3, Na, conductivity, water depth). Forward selection of the environmental variables followed Hausmann & Kienast (2006) and Mischke et al. (2007).

Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) were used to relate counts (relative abundance) of chironomids, diatoms, cladocerans and ostracodes to environmental variables, whereas Redundancy Analysis (RDA) was used for copepod counts. This was accomplished using Canoco for Windows 4.55 (Ter Braak & Smilauer 2002). We first estimated the length of environmental gradients using a DCA and then used a CCA and RDA to discern the environmental factors that control bioindicator distributions in the study area. Generally, if a gradient is short (<3 SD), a linear model should be used, whereas with larger gradients (>4 SD), a unimodal model is recommended, because the approximation using the linear function is poor (Leps & Smilauer 2003).

RESULTS

We collected 66 chironomid species and morphospecies belonging to the subfamilies Chironominae, Orthocladiinae and Tanypodinae (Table 2), 282 diatom species that belong to the orders Centrales and Pennales (Table 3), 51 cladoceran species belonging to the orders Anompoda and Ctenopoda, six copepod species (Calanoida), and 29 ostracode species (Podocopina, Table 4). Photographs of selected species are shown in figure 2. Figures 3, 4, 5 and 6 display the relative abundances and altitude ranges of the aquatic bioindicators.

Chironomids: Figures 3 a, b, c display the relative abundances of the most common chironomid morphospecies, i.e. >10 individuals per waterbody and present in >2 aquatic ecosystems. The dominant tribe was Chironomini and consisted of 32 morphospecies (Table 2). Widely distributed taxa, i.e. present in >15 aquatic environments, included Cladotanytarsus sp.1, Chironomus anthracinus, Cladopelma sp., Dicrotendipes sp., Goeldochironomus sp., Micropsectra sp., Parachironomus sp., Paratanytarsus sp.1, Polypedilum sp. and Polypedilum sp. 2. Chironomus anthracinus, Dicrotendipes sp., Goeldochironomus sp. and Labrundina sp. had the highest relative abundances in most aquatic environments. Most chironomid species were collected at lower elevations (<450m a.s.l.). Only 15 species were collected in aquatic ecosystems in the Guatemalan highlands. Dominant species in highland lakes were Apedilum sp., Apsectrotanypus sp. and Chironomus anthracinus. Chironomus anthracinus dominated the chironomid community in hypereutrophic Lake Amatitlan, Southern Guatemala. Chironomids inhabiting mainly the Peten lowlands were Stempellina sp. and Coelotanypus/Clinotanypus. Chironomus plumosus was the dominant species in Progreso Lagoon, Belize, and Cladopelma sp. was collected in all studied aquatic ecosystems in the Belizean lowlands. Species typical of the Yucatan lowlands were Cladotanytarsus sp. 1, Goeldochironomus sp. and Polypedilum sp.1 and sp. 2.

Diatoms: Diatoms were the most abundant and diverse taxonomic group studied. Figures 4 a, b show the most abundant diatom species ([greater than or equal to]2 waterbodies). Pennate diatoms displayed the highest number of families and species. In contrast, centric diatoms were only represented by four families (Tables 3 a-e). Naviculaceae represents 162 of the 282 diatom species and were mainly distributed in lowland waterbodies on the Yucatan Peninsula. Widely distributed diatom species, i.e. those found in >20 waterbodies, include Brachysira procera, Cyclotella meneghiniana, Denticula kuetzingii, Encyonema densistriata, Mastogloia smithii and Nitzschia amphibia. Nitzschia amphibia and Ulnaria delicatissima var. angustissima were found in all highland lakes. Aulacoseira granulata, Fragilaria crotonensis, Ulnaria acus and Ulnaria ulna were present in three of four sampled highland lakes. The dominant species in hypereutrophic Lake Amatitlan were Cyclotella meneghiniana and Discostella aff. pseudostelligera. Fragilaria crotonensis is a species restricted to the highlands and the Eastern lowlands in Guatemala, whereas Staurosirella pinnata was only collected in Lake Izabal, in the Eastern lowlands of Guatemala. Interestingly, few waterbodies have a predominantly monospecific diatom flora, e.g. Lake Rosario (93.6% Nitzschia amphibioides), Lake Atitlan (86.2% Fragilaria crotonensis), Almond Hill Lagoon 81.2% N. amphibia) and the pond called Belize 2 (72.6% Encyonema densistriata).

Microcrustaceans: Cladocera were the most diverse group of microcrustacea, with 51 species belonging to seven families. Ostracodes were next, with 29 species distributed in 10 families. Calanoid copepods followed, with six species belonging to two families (Tables 4 a, b). Figures 5 a, b and figure 6 show the relative abundances of the most widespread cladoceran, copepod and ostracode species, i.e. those present in >2 aquatic environments.

Cladocerans: Most collected cladoceran species belong to the order Anomopoda, family Chydoridae (Table 4 a). The greatest numbers of species were collected in lakes, ponds, and coastal waterbodies, whereas few species were collected in "cenotes" and rivers, where shells without soft parts were generally found. Assemblages in the highlands were dominated by Bosmina huaronensis, Ceriodaphnia dubia, Daphnia mendotae, Daphnia pulicaria, Moinodaphnia minuta and Simocephalus congener. Daphnia pulicaria and Simocephalus congener are restricted to highland lakes. Daphnia mendotae was the only species collected in highly productive Lake Amatitlan. Ceriodaphnia cf. rigaudi and Bosmina huaronensis displayed high relative abundance (>35%) in the Eastern lowlands of Guatemala. Dunhevedia odontoplax was the only species restricted to the Peten and Belize lowlands, and like Ceriodaphnia dubia, was absent in the Yucatan lowlands. The greatest numbers of cladoceran species were collected in the Mexican lowlands (n=41), followed by the Belizean lowlands (n=36), and the Guatemalan lowlands (n=25). Cladoceran communities in the lowlands were dominated by Diaphanosoma brevireme, Simocephalus serrulatus, Bosmina tubicen, Ilyocryptus spinifer, Macrothrix elegans, Macrothrix cf. spinosa, Anthalona verrucosa, Chydorus brevilabris and Chydorus eurynotus. Rare cladoceran species collected in only one waterbody of the lowlands include Coronatella circumfimbriata (Loche), Dadaya macrops (Jamolun), Karualona karua (Cenote), Kurzia longirostris (Chacan-Bata) and Oxyurella ciliata (Cayucon).

Copepods: Only calanoid copepods were studied, and only six species belonging to the families Diaptomidae and Pseudodiaptomidae were identified (Table 4 b, Fig. 6). Copepod species found in highland lakes include Arctodiaptomus dorsalis, Leptodiaptomus siciloides and Prionodiaptomus colombiensis. Arctodiaptomus dorsalis was the only species collected in hypereutrophic Lake Amatitlan. Leptodiaptomus siciloides and P. colombiensis are rare species that live in the highlands and were collected in the oligotrophic Laguna de Ayarza and in Lake Guija. Arctodiaptomus dorsalis was widely distributed in the lowlands, but mostly dominated aquatic ecosystems in the Peten lowlands. Mastigodiaptomus nesus is restricted to the Belize and Yucatan lowlands, whereas Pseudodiaptomus marshi inhabits the Peten and Belize lowlands. Except for Mastigodiaptomus nesus, which was found in Cenote Juarez, no calanoid copepods were collected from "cenotes" and rivers.

Ostracodes: Partial results on ostracode distribution in the Yucatan Peninsula and surrounding areas were published by Perez et al. (2011b) and therefore only the most important results are presented here. Ostracoda was the group of microcrustaceans that displayed the highest number of families (Table 4 b, Fig. 6). Families with highest numbers of species included Cyprididae (n=11), Candonidae (n=6) and Limnocytheridae (n=5). The genera Limnocythere and Physocypria had the highest numbers of species (n=3). Ubiquitous species include Cypridopsis okeechobei, Cytheridella ilosvayi, Darwinula stevensoni and Pseudocandona sp. (Fig. 6). There is a clear difference between highland and lowland assemblages and between fresh and brackish water assemblages. Species typical of the highlands are Candona sp., Chlamydotheca colombiensis, Ilyocypris cf. gibba, Limnocythere sp. and Trajancypris sp. Physocypria denticulata inhabits aquatic ecosystems of the lowlands in Belize and Yucatan, whereas Physocypria globula is restricted to the Peten lowlands. Lowland rare species Cytherura sandbergi, Elpidium bromeliarum, Eucypris sp., and Physocypria xanabanica, were collected in Celestun, Rio Dulce, Laguna Rosario, and in the small pond Belize 1, respectively. Cypretta brevisaepta was abundant in Lake Oquevix and in a small pond nearby.

Species richness and diversity in aquatic ecosystems: The species richness (S) and the Shannon Wiener diversity index (H) of diatoms, chironomids and microcrustaceans for the 63 studied aquatic ecosystems are shown in figures 7 a, b. Ostracodes were collected in 59 waterbodies, chironomids in 53 and cladocerans in 46. Copepods were found in only 30 aquatic environments. Lowland waterbodies (<450m.a.s.l.) displayed highest diversity values, up to H=2.6 (diatoms), and greatest species richness, as many as 33 species (cladocerans). Lowland waterbodies Crooked Tree Lagoon, Lake Peten Itza and Almond Hill Lagoon, followed by Lakes Yaxha, Macanche, San Jose Aguilar, Cayucon, San Francisco Mateos, Coba, Yalahau, Ocom, Nohbec, Milagros and Bacalar, yielded the highest overall species richness (up to S=77) on the Yucatan Peninsula and in surrounding areas.

Chironomids and ostracodes were present in all waterbody types (Fig. 7 a). Sampled rivers lacked diatoms and cladocerans. Copepods were scarce in rivers, "cenotes" and coastal waterbodies. The Jamolun wetland was dominated by chironomids and cladocerans. Cladocerans and ostracodes were present in all the highland lakes. Lakes Amatitlan, Gloria, Petexbatun, Celestun and Laguna Rosada displayed H values of 0 for chironomids, cladocerans and calanoid copepods. Ostracodes yielded H values >0, in TUM, a pond near Lake Oquevix, in the Subin river and in Laguna Rosada. Cenote San Ignacio Chochola displayed an H=0 for all bioindicators. Sabanita yielded an H>0 only for chironomids (H=1.8).

Chironomids were prominent mainly in lowland lakes. Up to 18 morphospecies were collected in Lake Yaxha and in the pond Belize 2, and 16 species were collected in Lakes Oquevix, Almond Hill Lagoon, Chacan-Bata, Bacalar and highland Guatemala Lake Atitlan (Fig. 7 a). Hypereutrophic Lake Amatitlan had a monospecific chironomid assemblage of Chironomus anthracinus. Dicrotendipes sp. was the only species collected in Lake Petexbatun, southern Peten. Highest diversity was reported in Lakes Oquevix (H=2.50) and Yaxha (H=2.54). Relatively low diversities (H [less than or equal to] 0.7) were determined in Cenotes Peten de Monos and Timul, Northern Yucatan Peninsula.

Diatoms were generally more diverse than other bioindicators in each waterbody. The number of diatom species per lake, if present, ranged from 7 to 28. Highest numbers of species (S>20) were reported in Lakes Peten Itza, Yaxha, Coba, Yalahau, Milagros, San Jose Aguilar, San Francisco Mateos, Cenote and Crooked Tree Lagoon. Among sampled ponds, only Belize 1 and 2 possessed diatoms. In oligotrophic Crater Lake Ayarza, no diatoms were found. High diatom diversities (H [greater than or equal to] 2.0) were determined in Lakes Yaxha, Macanche, Peten Itza, San Jose Aguilar, San Francisco Mateos, Coba, Yalahau, Milagros, Bacalar, Crooked Tree Lagoon, Cenote Xlacah and in coastal waterbody Celestun. In contrast, Lakes Atitlan, Rosario, Almond Hill Lagoon and Cenote Timul were characterized by low diversities (H<1.0).

Highest cladoceran species richness was found in Crooked Tree Lagoon (33), Almond Hill Lagoon (21), Lakes Peten Itza and Ocom, and in the Jamolun wetland (17). Few cladocerans were found in "cenotes" and coastal environments. The highest diversity index (H=2.4) was also found in Crooked Tree Lagoon. Male specimens were rare and reported for the cladoceran species Ceriodaphnia cf. rigauda, Diaphanosoma brevireme, Ephemeroporus barroisi, Macrothrix elegans and Macrothrix paulensis.

Highest numbers of ostracode species ([less than or equal to] 10) were collected in Lakes Bacalar and Milagros in Eastern Yucatan and in Ixlu River, Northern Guatemala (Fig. 7 a). The largest and deepest lake, Peten Itza, possessed nine ostracode species. Only a few waterbodies on the Yucatan Peninsula lacked ostracodes: Chacan Lara, Sabanita and Silvituc. Ostracodes were abundant on the Yucatan Peninsula, especially in the lowlands of Peten (S [greater than or equal to] 5). Rivers were characterized by relatively high numbers of species (S=5-10). Ostracodes in "cenotes" and in the Jamolun wetland were not as abundant as in other aquatic ecosystems. Ostracodes were highly diverse in rivers, and lowland lakes (H [less than or equal to] 1.8). Ponds displayed low diversities (H [less than or equal to] 0.5) except for a pond near Lake Oquevix (TUM, H=1.0). Brackish waterbodies were characterized by diversity indices [less than or equal to] 1.29.

Copepods were less abundant and diverse than chironomids, diatoms, cladocerans and ostracodes. Few calanoid copepod species (S [less than or equal to] 2) were collected and were rarely found in rivers, "cenotes" or coastal waterbodies. Copepod diversity in the study area was [less than or equal to] 0.69. Highest diversities were reported in Lakes Bacalar and San Francisco Mateos, followed by Lakes Izabal (H=0.65), Crooked Tree Lagoon (H=0.60) and Almond Hill Lagoon (H=0.33).

Calibration of bioindicators on the Yucatan Peninsula: We assessed relationships between the various studied biological groups and environmental variables. Quantitative relations between chironomids, diatoms, cladocerans and ostracodes and environmental variables were assessed using a unimodal model with 14 explanatory variables, because gradient lengths were [greater than or equal to] 3 standard deviations (SDs). The first two axes in the DCA explained 17.7% of chironomid variability, 16.3% of diatom variability, 21.5% of cladoceran variability, and 27.8% of the ostracode species data. The sum of eigenvalues was 2.8 for chironomids, 4.3 for cladocerans, 6.1 for diatoms and 3.1 for ostracodes.

To improve the performance of the CCA model, the number of environmental variables was reduced to include only those that best explain the bioindicator distributions. Forward-selected variables displayed low inflation factors (<5). Seven variables were related to chironomid (HC[O.sub.3], [delta][sup.13]C, pH, temperature, conductivity, dissolved oxygen, water depth) and diatom relative abundances (conductivity, [[delta]sup.18]O, dissolved oxygen, temperature, pH, [delta][sup.13]C, water depth), four to cladoceran (conductivity, HC[O.sub.3], temperature, dissolved oxygen) and six to ostracode abundances (conductivity, HC[O.sub.3], Na, water depth, temperature, pH) (Fig. 8). For copepods, a linear model was chosen because the gradient length was only 2.15 SD units. The first two axes in the DCA explained 72.9% of the variability in the copepod species data. The sum of eigenvalues was 1.6. Six forward-selected variables (HC[O.sub.3], Cl, Na, temperature, water depth, [delta][sup.18]O) were included in the final RDA. In the final CCAs and RDA, HC[O.sub.3] was the main factor controlling chironomid and copepod assemblages on the Yucatan Peninsula (Fig. 8). Diatom, cladoceran and ostracode communities are more influenced by conductivity. [delta][sup.13][C.sub.DIC], a lake productivity proxy, and lakewater [delta][sup.18]O, a proxy for changes in the balance between evaporation and precipitation and perhaps conductivity, were the second most important factors affecting chironomid and diatom distributions, respectively (Fig. 8). The final CCA for chi-ronomids explained 4.8% ([lambda]1=0.14, [lambda]2=0.11), 6.8% for diatoms ([lambda]1=0.42, [lambda]2=0.33), 6.4% for cladocerans ([lambda]1=0.27, [lambda]2=0.15), 9.9% for ostracodes ([lambda]1=0.31, [lambda]2=0.13) of the variability in species data, and the final RDA for copepods explained 24.9% ([lambda]1=0.25, [lambda]2=0.11) of the variability in species data (Table 5).

Chironomid species such as Stempellina sp., Goeldochironomus sp., Coelotanypus/Clinotanypus, Paratanytarsus sp. 2, Tanytarsini A and Tanytarsini J were positioned in the lower left quadrant of the CCA ordination biplot (Fig. 8 a). These species are typical of lowland waterbodies, especially those located on the Eastern part of the Yucatan Peninsula, Belize, and the central and Eastern areas of the Peten Lake District. Species located in the upper left quadrant inhabit mainly lowland aquatic ecosystems, except for Apedilum sp. This species was collected at both high and low elevations, but was more abundant in highland Lake Atitlan. Apsectrotanypus sp., Cricotopus spp., Tanytarsini C and Stenochironomus sp. inhabit highland lakes and were positioned in the right upper quadrant of the biplot. The chironomid species Glyptotendipes sp. 2 in the upper part of the right quadrant of the biplot was mainly collected in "cenotes," Lake Oquevix, Rio Dulce and Loche pond. Chironomus anthracinus, located in the lower right quadrant, was the only species present in hypereutrophic Lake Amatitlan. Labrundina sp., Beardius sp. and Paratanytarsus sp.1 were widely distributed in the lowlands of the Yucatan Peninsula and surrounding areas.

Diatom species Halamphora coffeaeformis, Campylostylus normannianus, Nitzschia frustulum, Navicula palestinae, Tabularia fasciculata, Navicula salinarum, Amphora securicula and Cocconeis placentula are located in the lower quadrant of the biplot (Fig. 8 b) and are characteristic of lakes with high conductivities, up to 38.2mS/cm. Species characteristic of lower conductivities and most diatom species typical of fresh waters are located near the central part of the biplot.

The CCA biplot for cladocerans indicates that water conductivity influences species distribution on the Yucatan Peninsula (Fig. 8 c). Simocephalus mixtus and Karualona muelleri were positioned in the upper right and left quadrant of the CCA biplot, respectively, because they dominated lakes with high conductivities (up to ~6 000LiS/cm) such as Cenote, Almond Hill Lagoon, Chichancanab, Punta Laguna, Yalahau, among others. Kurzia polyspina was located in the upper right quadrant because it prefers waters with dissolved oxygen concentrations between 7.3 and 8.3mg/L. Streblocerus pygmaeus, located in the lower left quadrant of the CCA biplot, is a species typical of warm lake waters (>25[degrees]C) with lower conductivities (<350[micro]S/cm) such as Oquevix, Crooked Tree Lagoon and Cayucon. The dominant cladocerans in highland Lakes Atitlan, Amatitlan, Ayarza and Guija were Ceriodaphnia dubia and Bosmina huaronensis, located in the upper and lower right quadrants, respectively. Moina minuta was typical of Lake Atescatempa, Izabal, Chacan-Bata, pond Belize 1 and the Jamolun wetland. Daphnia mendotae was the only species identified in surface sediments from Lake Amatitlan.

Similar to the findings for chironomids, bicarbonate determined calanoid copepod distribution in the study area (Fig. 8 d). Few specimens were collected in the highlands of Southern Guatemala, thus all species on the biplot are typical of the lowlands. Arctodiaptomus dorsalis, in the lower left quadrant of the ordination diagram, dominated lakes with fresh waters, and was absent in "cenotes" and coastal waterbodies. Mastigodiaptomus nesus, in the lower right quadrant, is typical of HCO3rich waters (125-710mg/L), such as San Jose Aguilar, Loche, Juarez, Coba, Punta Laguna, Chichancanab and Yalahau. Pseudodiaptomus marshi, in the upper right quadrant, is typical of lakes at low altitudes (<5m.a.s.l.), such as Lake Izabal, Guatemala and Lagoons Progreso and Almond Hill, Belize. This species was also collected in waterbodies displaying slightly higher conductivities, such as Bacalar and Lagoons Progreso and Almond Hill.

The CCA biplot for ostracodes suggests that conductivity, followed by HC[O.sub.3], are the main factors controlling species distribution (Fig. 8 e). Perissocytheridea cribosa, Cyprideis sp. and Thalassocypria sp. are situated in the positive part of axis 1, indicating their preference for high-conductivity waters (750[micro]S/cm-55.3mS/cm). Ostracode species that prefer freshwaters are situated in the center of the CCA biplot. Cypridopsis vidua, in the upper right quadrant of the CCA biplot, was more abundant in highland Lake Ayarza, Guatemala. Species tolerating the hypereutrophic water of Lake Amatitlan include Candona sp., Cypridopsis vidua and Darwinula stevensoni. Ostracodes displaying high abundances in highland and lowland lakes included Cypridopsis okeechobei, Cytheridella ilosvayi and Darwinula stevensoni. Potamocypris sp., in the upper left quadrant, was collected in Lakes Rosario, Yalahau, Loche pond and Cenote Timul, suggesting its preference for warm waters (up to 32[degrees]C) and waters with HC[O.sub.3] concentrations as high as 707mg/L.

DISCUSSION

Neotropical aquatic bioindicators across broad trophic and climatic gradients: We have provided a first comprehensive list of modern diatom (282) and chironomid (66) species for the region, along with species distributions, relative abundances in each lake, and quantitative ecological information. CCA ordination biplots, relating bioindicator species and forward selected variables, distinguish between taxa typical of highland vs. lowland lakes, brackish vs. fresh waters, alkaline vs. acidic waters, and lakes of different trophic states. Most bioindicator species live at low elevations (<450m.a.s.l.), with fewer species and individuals in highland lakes. In general, diatom, cladoceran and ostracode communities are most affected by conductivity, reflecting lake water chemical composition, marine influence (Perry et al. 1995) and the N-S precipitation gradient in the Yucatan Peninsula. Species of these taxonomic groups presented characteristic faunas of fresh and brackish waters. Bicarbonate controls chironomid and copepod distribution in the study area. Concentration of bicarbonate in lake waters is an important variable in the study area because most of the studied lakes lie in karst terrain. Another related factor could be the greater abundance of edible algae in hard water lakes (Ghadouani et al. 1998). The second determinant variable for chironomid distribution was [delta][sup.13][C.sub.DIC], an indicator of lake water productivity (McKenzie 1985), indicating the potential of some chironomid species as indicators of lake trophic state. Our results demonstrate that aquatic bioindicators on the Yucatan Peninsula are highly sensitive to changes in water column conductivity, alkalinity and trophic state.

Sanchez et al. (2002) identified 75 diatom species in "cenotes" and anchialine caves on the Eastern Yucatan Peninsula. Similar to our findings, they reported that pennate diatoms were the dominant group. Few diatoms were of marine origin. Similar results were also found in aquatic ecosystems of Costa Rica (Haberyan et al. 1997), El Salvador (Rivas Flores et al. 2010) and Nicaragua (Swain 1966). All studies indicated that Naviculaceae is a dominant family in waterbodies of the Northern Neotropics. Six species belonging to Naviculaceae, Thalassiosiraceae and Bacillariaceae were hydrochemically tolerant and displayed wide distributions: Brachysira procera, Encyonema densistriata, Mastogloia smithii, Denticula kuetzingii, Cyclotella meneghiniana and Nitzschia amphibia. Nitzschia amphibia tolerates broad trophic state and conductivity ranges. Cyclotella meneghiniana and Discostella aff. pseudostelligera dominated the hypereutrophic waters of Lake Amatitlan, Guatemala. Velez et al. (2011) used diatoms and other variables to infer environmental and cultural changes in and around this highland lake. They suggested that C. meneghiniana is an indicator of low lake levels, whereas N. amphibia indicates eutrophic waters. Highland and lowland lakes differ in their bioindicator communities, as some species are highly sensitive and restricted to specific areas. Fragilaria crotonensis is a species typical of the highlands and Eastern lowlands in Guatemala. Fragilaria species indicate oligotrophic to mesotrophic conditions (Castellanos & Dix 2009). This species dominated (86.2%) in Lake Atitlan, a lake that experienced extensive cyanobacteria (Lyngbya hieronymusii/birgei/robusta) blooms in October 2009 (Rejmankova et al. 2011). When we visited Lake Atitlan in March 2008, the lake still displayed oligo- to mesotrophic conditions, indicated by the dominance of F. crotonensis, shortly before the first cyanobacteria bloom, which occurred in December 2008.

Vinogradova & Riss (2007) reported 84 chironomid taxa, mainly morphospecies, from 18 lakes on the Yucatan Peninsula. In their study, the dominant chironomid species were Cladopelma lateralis and species belonging to the genus Tanytarsus. Our dataset included a larger number of aquatic ecosystems (n=63), however results from both studies are similar. Few chironomid taxa are restricted to specific areas. Rather, the dipterans seem to tolerate a broad range of environmental conditions. Chironomus anthracinus displayed high relative abundance in most sampled waterbodies and the larvae have been to shown to be among the dominant food items of fish (Armitage et al. 1995). This species was very abundant in many of our surface sediment samples. It tolerates eutrophic waters (Porinchu & MacDonald 2003), which characterize many lowland and some highland lakes in the study area. For instance, C. anthracinus was the only dipteran species collected in hypereutrophic Lake Amatitlan, Guatemala. For decades, this highly productive lake has received wastewater, delivered by its main inflow river, the Rio Villalobos. This species was also collected in Cenote Timul, which displayed high [delta][sup.13][C.sub.DIC] values of +13.6%o (Perez et al. 2011a). These results illustrate that C. anthracinus can be used as an indicator of highly productive waters in the Northern Neotropics. A larger number of species (n=51) inhabit the lowlands. Fewer species were identified in the highlands (n=15), suggesting that chironomids are very abundant in low-elevation neotropical regions, similar to findings in Africa (Eggermont et al. 2010), where 81 chironomid taxa were collected across an altitude gradient (489-4 575m.a.s.l.) and in Brazil (de Oliveira Roque & Trivinho-Strixino 2007), where 191 morphospecies were collected.

Cladocerans dominated the microcrustacean communities in the study area. Fifty-one species were collected in the waterbodies and the greatest number of species belonged to the family Chydoridae. Many species of Chydoridae have great value as water-quality indicators because they are highly sensitive to changes in lake trophic state (de Eyto et al. 2002). Cladocerans and copepods are the two taxonomic groups most studied on the Yucatan Peninsula and in surrounding areas (Elias-Gutierrez et al. 2008). Mexico has been actively involved in studying the systematics of Cladocera (Elias-Gutierrez et al. 2006). Therefore, identification of collected cladocerans and copepods to species level was possible. Elias-Gutierrez (2006) reported a total of 162 cladoceran species for two regions of Mexico (Morelos and southeast Mexico), four being endemic species of Southeast Mexico. Some of the cladoceran species we collected are widely distributed in the Northern Neotropics and South America. These include Diaphanosoma brevireme, Pseudosida ramosa, Macrothrix spinosa, M. elegans, Chydorus nitidilus, Ephemeroporus tridentatus, Alona ossiani, Oxyurella ciliata and O. longicaudis (Elias-Gutierrez 2006). One interesting finding of our study was the presence of Anthalona brandorffi, described as Alona brandorffi (Sinev & Hollwedel 2002) in the waterbodies Crooked Tree Lagoon, Silvituc Lagoon and Loche, because this species was found for the first time in Boa Vista, Brazil, and its distribution in the Northern Neotropics was unknown. Cladocerans were not as abundant in highland lakes of Guatemala. Laguna de Ayarza and Lake Atitlan still display oligo-mesotrophic conditions. Macrophytes, the typical habitat of cladocerans, are scarce in these lakes. In contrast, Lake Amatitlan is hypereutrophic, and only a single cladoceran species, Daphnia mendotae, was collected in such extreme conditions. Species restricted to the highlands include D. pulicaria and S. congener, even though they apparently have wide distributions (Cerny & Hebert 1993, Illyova & Nemethova 2005, Marrone et al. 2005). For instance, D. pulicaria seems to prefer cool waters, typical of highland Lake Atitlan ([less than or equal to] 21.8[degrees]C). Occupying cooler, deep waters may be a strategy to reduce risk of predation (Stich & Maier 2007). Species restricted to aquatic ecosystems of Guatemala and Belize include: Dunhevedia odontoplax and Ceriodaphnia dubia. Dunhevedia odontoplax has been collected in Morelos, Veracruz (Elias-Gutierrez 2006). Mainly cladoceran carapaces were collected in "cenotes" and rivers, but there were few live specimens. Most "cenotes" we sampled lacked aquatic vegetation, the main habitat of most cladoceran species. Distribution of zooplankton in rivers is very heterogenous (Vadadi-Fulop 2009) and we might simply have collected samples from sites where densities were low. Scarcity of cladocerans in rivers, however, is common because they are not as well adapted to lotic aquatic environments as ostracodes and chironomid larvae. Another explanation for the low species richness and numbers could be that adults of some species are more typical of the rainy season, and we collected surface sediments in the dry season. Future sampling should be conducted across the seasons.

Only six calanoid copepod species were collected from the sampled waterbodies. Recent studies in Mexico (Elias-Gutierrez et al. 2008, Brandorff 2012) report up to 100 freshwater copepod species, of which 20 species belong to the order Calanoida. SuarezMorales & Reid (2003) suggest that the fauna of the Yucatan Peninsula has affinities with Cuba and the insular Caribbean, and differs from that of Central Mexico, which is closer to the fauna of upper Central America. Prionodiaptomus colombiensis mainly inhabits altitudes from 10 to 100m.a.s.l and it has been previously reported in Tabasco, Mexico while Leptodiaptomus siciloides is widely distributed in Mexico (Elias-Gutierrez et al. 2008). Arctodiaptomus dorsalis tolerates a broad range of environmental conditions and was collected in waterbodies with different origins and trophic states. For instance, it inhabits hypereutrophic volcanic Lake Amatitlan in the highlands, and meso-oligotrophic, karst Lake Peten Itza in the lowlands. According to Suarez-Morales (2003), this nearctic species is the most widespread diaptomid in the Yucatan Peninsula and has also been collected in Southeastern USA, central and Eastern Mexico, Central America and the Caribbean islands. Dispersal of this species is relatively recent (post-Pliocene) and it colonized the Yucatan Peninsula during past marine regressions, during times of emergence of areas on the peninsula. This could explain why this species is now highly tolerant and widely distributed.

Of the six copepod species found, M. reidae is endemic to Campeche (Elias-Gutierrez et al. 2008, Suarez-Morales & Elias-Gutierrez 2000) and Northern Guatemala (this study). All species belonging to the genus Mastigodiaptomus found in the Yucatan Peninsula are neotropical. Suarez-Morales (2003) report another endemic species for the area, Mastigodiaptomus maya. Unfortunately, we did not collect this species, but it seems to coexist with M. reidae in Chicana pond, near the Biosphere Reserve of Calakmul, Yucatan Peninsula, and probably speciated for ecological reasons. Our results indicate that M. nesus inhabits waterbodies in Belize, Campeche, Quintana Roo and Yucatan, as reported by Elias-Gutierrez et al. (2008). The present distribution of this taxon could be a remnant of the original Mastigodiaptomus fauna in the Yucatan Peninsula and may reflect recent, post-Pliocene dispersal and Holocene climatic fluctuations (Suarez-Morales 2003). We identified P. marshi in aquatic ecosystems in the lowlands of Belize (Lagoons Progreso and Almond Hill) in the Eastern lowlands of Guatemala (Lake Izabal) and Southern Yucatan (Bacalar). Pseudodiaptomid copepods mainly inhabit marine and brackish water environments, although recent studies (Suarez-Morales 2003) suggest that P. marshi is a species that is starting to colonize freshwater environments. Canonical Correspondence Analysis indicated that the ions sodium and chloride affect the distribution of this species. But the fact that we collected this copepod species in freshwater Lake Izabal supports the idea that is starting to colonize freshwater environments. Lake Izabal is connected with the Caribbean Sea via the Rio Dulce and El Golfete. Similar to cladocerans, few copepods were found in rivers, probably because they are not well adapted to inhabit running waters, avoiding such environments and preferring the littoral zones of lakes (Casanova & Henry 2004).

Effects of altitude and related variables precipitation and trophic state, on ostracode species distribution and assemblage composition in the study area are clear. The taxonomy, ecology and distribution of non-marine ostracodes from the Northern Neotropics (Mexico, Guatemala and Belize) was investigated by Perez et al. (2010b, 2010c, 2011b), Darwinula stevensoni has a worldwide distribution and Cytheridella ilosvayi is abundant throughout the entire continental Neotropics. Cypridopsis okeechobei displays a narrower distribution, extending from the United States to the Peten Lake District, Northern Guatemala. Pseudocandona sp. was also abundant and we suggest this species is endemic to the Yucatan Peninsula, but further taxonomic and molecular analysis is needed to test this assertion. We were unable to identify some ostracodes collected in the highlands to species level. They may be endemic to the region or be distributed throughout higher-elevation areas of Central America and Mexico that have not been studied yet. These species include Candona sp., Limnocythere sp. and Trajancypris sp. A conductivity gradient is well marked on the Yucatan Peninsula. Ostracodes were mainly typical of freshwaters, but some, like Cyprideis sp., Loxoconcha sp., Paracytheroma stephensoni, Perissocytheridea cribosa and Thalassocypria sp. were typical of waterbodies with high conductivities, up to 55.3mS/cm. Cypretta brevisaepta had been reported only from Southern Florida and the West Indies, but we found it in Lakes Oquevix, Macanche, and a pond near Lake Oquevix in Peten, Guatemala and in San Jose Aguilar, Mexico.

A broad trophic state gradient characterizes the study area, ranging from hypereutrophic Lake Amatitlan to oligotrophic Laguna Ayarza. Hypereutrophic Lake Amatitlan displayed species characteristic of highly productive waters, including Chironomus anthracinus, Discostella aff. pseudostelligera, Daphnia mendotae, Candona sp., Cypridopsis vidua and Darwinula stevensoni. Our results demonstrate that few zooplankton and zoobenthos species inhabit higher elevations (>450m.a.s.l.) in Guatemala. Cladocerans, copepods and ostracodes were more diverse and abundant in lowland aquatic ecosystems, suggesting that environmental conditions in those waterbodies are optimal for zooplankton and zoobenthos development and reproduction. The Yucatan Peninsula and surrounding areas (Guatemala and Belize) are rich in aquatic ecosystems, therefore it will be important to collect samples from additional sites to expand our training set. Aquatic bio-indicators should also be collected at different seasons to provide information on species life cycles. Despite the utility of the collected data, additional sampling campaigns in aquatic ecosystems throughout Mexico, Guatemala, Belize and Central America are required. We also recommend return visits to previously studied ecosystems to capture seasonal variability. Central Mexico is rich in aquatic ecosystems and there have been few studies on bioindicators in that region. We are developing a calibration dataset for central Mexico that will provide new autecological information for bioindicators that will expand our original Yucatan training set.

Importance of species richness and diversity of bioindicators in neotropical aquatic ecosystems: Diversity and species richness data from waterbodies provide information on modern environmental conditions, e.g., trophic state, anthropogenic impact and urban development and the degree of degradation. Our findings provide information for identifying conservation hotspots on the Yucatan Peninsula, Guatemala and Belize. Highest species diversities were reported at lower elevations (<450m.a.s.l.). The highest number of species and diversities per waterbody were usually reported for lowland lakes, where precipitation is high, up to 3 050mm/y. Crooked Tree Lagoon, Belize displayed the highest diversity (H[less than or equal to]2.4, diatoms). The lagoon is protected and recognized as a wetland of international importance under the Ramsar Convention of Wetlands (http://www.ramsar.wetlands.org). Lakes Bacalar and Chichancanab, on the Yucatan Peninsula, were declared protected areas in April 2011 (SIPSE 2011). Most aquatic ecosystems in the study area, however, lack such environmental protection. Government agencies, universities and NGOs should collaborate to guarantee that aquatic ecosystems in the region are protected. Highland lakes, despite their lower diversities, deserve special attention because they often possess rare or unidentified taxa and may be home to new or endemic species. Chironomids and ostracodes were highly diverse (H[less than or equal to]2.54) in sampled aquatic ecosystems. Lakes Chacan Lara, Sabanita and Silvituc were small waterbodies that lacked ostracodes, probably due to low lake water conductivities ([less than or equal to]183LiS/cm). Diatoms, cladocerans and copepods were scarce or lacking in rivers, "cenotes" and coastal waterbodies. Further sampling campaigns are needed to corroborate these observations and improve on methods for collection of bioindicators that were present in low abundances. Rivers deserve special attention because they frequently receive domestic and industrial waste, affecting species distributions and diversity.

This study on the waterbodies on and around the Yucatan Peninsula found that microcrustacea, insect larvae and diatoms in neotropical lakes are abundant, diverse and highly sensitive to environmental variables. Such organisms therefore have great potential as modern and late Quaternary bioindicators. This investigation generated the first training sets for chironomids, diatoms, ostracodes, cladocerans and copepods in the region and is a pre-requisite for future quantitative paleolimnological reconstruction of late Quaternary environments in the Northern Neotropics. Our results highlight the exceptional potential of the studied taxonomic groups as bioindicators of climate and trophic state.

Analysis of the distribution and ecological preferences of the five studied groups (diatoms, chironomids, cladocerans, copepods and ostracodes) generated new information that is required to make better use of these aquatic bioindicators in the neotropical region. Clear differences emerged in the chemistry and biology of highland versus lowland water bodies. Volcanic highland lakes display origin and water chemical composition different from those of karst lowland lakes. Biodiversity in the highlands is lower than in the lowlands. The highland aquatic fauna is dominated by chironomids Apsectrotanypus sp., Cricotopus spp., Tanytarsini C, Stenochironomus sp., diatoms Ulnaria acus, cladocerans Ceriodaphnia dubia and Bosmina huaronensis, ostracodes Candona sp., Chlamydotheca colombiensis, Cypridopsis vidua, Cytheridella ilosvayi, Darwinula stevensoni, Limnocythere sp., Physocypria globula, Stenocypris major and Trajancypris sp, cladocerans D. pulicaria and S. congener and the copepods Leptodiaptomus siciloides and Prionodiaptomus colombiensis.

This study covered a wide range of trophic state, which allowed us to differentiate between species that are tolerant and intolerant of highly eutrophic waters. Bioindicator species inhabiting highly productive waters and tolerating extreme conditions include Chironomus anthracinus, Cyclotella meneghiniana, Discostella aff. pseudostelligera, Daphnia mendotae, Arctodiaptomus dorsalis, Candona sp., Cypridopsis vidua and Darwinula stevensoni. A broad conductivity gradient also characterizes the Yucatan Peninsula and surrounding areas. Most collected species inhabit freshwaters, but a few tolerate high conductivities, making them potential indicators of such conditions. They include diatoms such as Halamphora coffeaeformis, Campylostylus normannianus, Nitzschia frustulum, Navicula palestinae, Tabularia fasciculata, Navicula salinarum, Amphora securicula, and Cocconeis placentula, cladocerans Simocephalus mixtus and Karualona muelleri, the copepod species P. marshi, as well as ostracodes Cyprideis sp., Perissocytheridea cribosa and Thalassocypria sp. Good indicators of alkaline waters are Paratanytarsus sp.1, Djalmabatista sp., Endotribelos sp., and Mastigodiaptomus nesus, whereas waters with HCO3<275mg/L were dominated by Stempellina sp., Tanytarsini J, K, Apedilum sp and Arctodiaptomus dorsalis.

Transfer functions that express quantitative relations between bioindicator species and environmental variables will ultimately be developed using results from this study. These transfer functions will be used to make quantitative paleoenvironmental inferences, by applying them to fossil assemblages in sediment cores retrieved from lakes in the region. Despite the utility of the collected data, additional sampling campaigns in aquatic ecosystems throughout Mexico, Guatemala, Belize and other parts of Central America are required. We also recommend return visits to previously studied ecosystems to capture seasonal variability.

ACKNOWLEDGMENTS

We are grateful to the agencies and people who helped us with field and laboratory work, including the University of Belize, Forestry and Fisheries Departments (Belize), Universidad del Valle de Guatemala, CONAP, AMSCLAE, AMPI, FINABECE, Trifinio (Guatemala), SRE, CONAPESCA, ECOSUR-Chetumal (Mexico),

Institut fur Geosysteme und Bioindikation (Germany), TU-Braunschweig (Germany), Dietmar Keyser, Dustin Grzesik, Jason Curtis, David Klassen, Jose Harders, Carmen Herold, Bessie Oliva, Roberto Moreno, Eleonor de Tott, Margaret Dix, Margarita Palmieri, Alma Quilo, Gabriela Alfaro, Jacobo Blijdenstein, Melisa Orozco, Silja Ramirez, Wolfgang Riss, Evgenia Vinogradova, Luis Toruno, Mario Cruz, Rita Bugja, Luciana Mitsue, Susanne Krueger, Javier Perez y Perez, and Carolina Alvarado de Perez. Special thanks to anonymous reviewers for detailed suggestions and comments. We are grateful for financial support provided by the Deutsche Forschungsgemeinschaft (DFG, grant Schw 671/3) and start-up money to A.S. provided by the TU Braunschweig.

REFERENCES

Armitage, P.D., P.S. Cranston & L.C.V. Pinder. 1995. The Chironomidae: biology and ecology of nonbiting midges. Chapman and Hall, London, England.

Battarbee, R.W., V.J. Jones, R.J. Flower, N.G. Cameron, H. Bennion, L. Cavalho & S. Juggins. 2001. Diatoms, p. 155-202. In J.P. Smol, H.J.B. Birks & W.M (eds.). Last. Tracking environmental change using lake sediments, vol 3. Kluwer Academic, Dordrecht, Netherlands.

Bennike, O. 1998. Fossil egg sacs of Diaptomus (Crustaceae: Copepoda) in Late Quaternary lake sediments. J. Paleolimnol. 19: 77-79.

Bowman, T.E. 1996. Freshwater calanoid copepods of the West Indies. Syllogeus 58: 237-246.

Brandorff, G.O. 2012. Distribution of some Calanoida (Crustacea, Copepoda) from the Yucatan Peninsula, Belize and Guatemala. Rev. Biol. Trop. 60: 187-202.

Brehm, V. 1939. La Fauna microscopica del Lago Peten, Guatemala. An. Esc. Nac. Cienc. Biol. 1: 173-203.

Brooks, S.J. & H.J.B. Birks. 2001. Chironomid-inferred air temperatures from Lateglacial and Holocene sites in north-west Europe: progress and problems. Quat. Sci. Rev. 20: 1723-1741.

Casanova, S.M.C. & R. Henry. 2004. Longitudial distribution of Copepoda populations in the transition zone of Paranapanema river and Jurumirim Reservoir (Sao Paulo, Brazil) and interchange with two later lakes. Braz. J. Biol. 64: 11-26.

Castellanos, E. & M. Dix. 2009. Informe final, UVG, Levantamiento de la Linea Base del Lago de Atitlan Presentado al Ministerio de Ambiente y Recursos Naturales, Universidad del Valle de Guatemala, Guatemala.

Cerny, M. & P.D.N. Hebert. 1993. Genetic diversity and breeding system variation in Daphnia pulicaria from North American lakes. Heredity 71: 497-507.

Cohen, A. 2003. Paleolimnology. Oxford University, New York, USA.

De Eyto, E., K. Irvine & G. Free. 2002. The use of Members of the Family Chydoridae (Anomopoda, Branchiopoda) as an Indicator of Lake Ecological Quality in Ireland. Biology and Environment. Proc. Roy. Ir. Acad. 102: 81-91.

De Oliveira Roque, F. & S. Trivinho-Strixino. 2007. Chi ronomid species richness in low-order streams in the Brazilian Atlantic Forest: a first approximation through a Bayesian approach. J. N. Am. Benthol. Soc. 26: 221-231.

Dole-Olivier, M.J., D.M.P. Galassi, P. Marmonier & M. Creuze des Chatelliers. 2000. The biology and ecology of lotic microcrustaceans. Freshwater Biol. 44: 63-91.

Dudgeon, D., A.H. Arthington, M.O. Gessner, Z.I. Kawabata, D.J. Knowler, C. Leveque, R.J. Naiman, A.H. Prieur-Richard, D. Soto & M.L.J. Stiassny. 2006.

Freshwater biodiversity: importance, threats, status and conservation challenges. Biol. Rev. 81: 163-182.

Eggermont, H., O. Heiri, J. Russell, M. Vuille M., L. Audenaert & D. Verschuren. 2010. Paleotemperature reconstruction in tropical Africa using fossil Chironomidae (Insecta: Diptera). J. Paleolimnol. 43: 413-435.

Elias-Gutierrez, M. 2006. Estudio comparativo del zooplancton en dos regiones de Mexico. Informe final SNIB-CONABIO proyecto No. AS019. El Colegio de la Frontera Sur, Distrito Federal, Mexico.

Elias-Gutierrez, M., A.A. Kotov & T. Garfias-Espejo. 2006. Cladocera (Crustacea: Ctenopoda, Anomopoda) from southern Mexico, Belize and Northern Guatemala. Zootaxa 119: 1-27.

Elias-Gutierrez, M., E. Suarez-Morales, M.A. Gutierrez-Aguirre, M. Silva-Briano, J.G. Granados-Ramirez & T. Garfias-Espejo. 2008. Cladocera y Copepoda de las aguas continentales de Mexico. Universidad Nacional Autonoma de Mexico, Mexico.

Flossner, D. 2000. Die Haplopoda und Cladocera (ohne Bosminidae) Mitteleuropas. Backhuys, Leiden, Netherlands.

Fritz, S.C., S. Juggins, R.W. Battarbee & D.R. Engstrom. 1991. Reconstruction of past changes in salinity and climate using a diatom-based transfer function. Nature 352: 706-708.

Furtos, N. 1933. The Ostracoda of Ohio. Ohio Biological Survey. The Ohio State University, Columbus, USA.

Furtos, N. 1936a. Fresh-water Ostracoda from Florida and North Carolina. Am. Mid. Nat. 17: 491-522.

Furtos, N. 1936b. On the Ostracoda from the cenotes of Yucatan and vicinity. The cenotes of Yucatan, a zoological and hydrographic survey. Carnegie Institution of Washington, Washington, USA.

Ghadouani, A., B.P. Alloul, Y. Zhang & A.E.E. Prepas. 1998. Relationships between zooplankton community structure and phytoplankton in two lime treated eutrophic hardwater lakes. Freshwater Biol. 39: 775-790.

Gutierrez-Aguirre, M.A. & E. Suarez-Morales. 2000. New extension range of the diaptomid copepod Prionodiaptomus colombiensis Thiebaud, 1912 (Copepoda, Calanoida) with complementary description of this species. Zoosystema 22: 507-516.

Haberyan, K.A., S.P. Horn & B.F. Cumming. 1997. Diatom assemblages from Costa Rican lakes: an initial ecological assessment. J. Paleolimnol. 17: 263-274.

Hausmann, S. & F. Kienast. 2006. A diatom-inference model for nutrients screened to reduce the influence of background variables: Application to varved sediments of Greifensee and evaluation with measured data. Paleogeogr. Palaeoclimateol. Palaeoecol. 233: 96-112.

Hausmann, S. & R. Pienitz. 2007. Seasonal climate inferences from high-resolution modern diatom data along a climate gradient: a case study. J. Paleolimnol. 38: 73-96.

Illyova, M. & D. Nemethova. 2005. Long-term changes in cladoceran assemblages in the Danube floodplain area (Slovak-Hungarian stretch). Limnologica-Ecol. Manag. Inland Waters 35: 274-282.

Keyser, D. 1976. Zur Kenntnis der brackigen mangrovebewachsenen Weichboden Sudwest-Floridas unter besonderer Berucksitchtigung ihrer Ostracodenfauna. Ph.D. Thesis, Universitat Hamburg, Hamburg, Germany.

Korovchinsky, N.M. 1992. Sididae and Holopediidae (Crustacea: Daphniiformes). SPB Academic, The Hague, Netherlands.

Kotov, A.A. & P. Stifler. 2006. Cladocera family Ilyo cryptidae (Branchiopoda: Cladocera: Anomopoda). Guide to the identification of the microinvertebrates of the Continental Waters of the World. Kenobi Productions, Ghent, Belgium and Backhuys, Leiden, Netherlands.

Krammer, K. & H. Lange-Bertalot. 1986. Susswasserflora von Mitteleuropa. Bd. 2/1. Bacillariophyceae: Naviculaceae. Gustav Fischer, Stuttgart, Germany.

Krammer, K. & H. Lange-Bertalot. 1988. Susswasserflora von Mitteleuropa. Bd. 2/2. Bacillariophyceae: Bacillariaceae, Epithmiaceae, Surirellaceae. Gustav Fischer, Stuttgart, Germany.

Krammer, K. & H. Lange-Bertalot. 1991a. Susswasserflora von Mitteleuropa. Bd. 2/3. Bacillariophyceae: Centrales, Fragilariaceae, Eunotiaceae. Gustav Fischer, Stuttgart, Germany.

Krammer, K. & H. Lange-Bertalot. 1991b. Susswasserflora von Mitteleuropa. Bd. 2/4. Bacillariophyceae: Achnanthaceae. Gustav Fischer, Stuttgart, Germany.

Krebs, C.J. 1989. Ecological Methodology. Harper and Row, New York, USA.

Leps, J. & P. Smilauer. 2003. Multivariate analysis of ecological data using CANOCO. Cambridge University, Cambridge, England.

Lieder, U. 1996. Crustacea, Cladocera/Bosminidae. In J. Schworbel, P. Zwick. SuBwasserfauna von Mitteleuropa 8/2-3. Gustav Fischer Verlag, Germany.

Lutz, W., L. Prieto & W. Sanderson. 2000. Population, Development, and Environment on the Yucatan Peninsula: From Ancient Maya to 2030. International Institute for Applied Systems Analysis, Laxenburg, Austria.

Marrone, F., R. Barone & L. Naselli-Flores. 2005. Clado cera (Branchiopoda: Anomopoda, Ctenopoda, and Onychopoda) from Sicilian Inland Waters: An Updated Inventory. Crustaceana 78: 1025-1039.

Massaferro, J., S. Ribeiro Guevara, A. Rizzo & M. Arribere. 2004. Short-term environmental changes in Lake Morenito (41[degrees]S, 71[degrees]W, Patagonia, Argentina) from analysis of sub-fossil chironomids. Aquat. Conserv. Mar. Freshwat. Ecosyst. 15: 23-30.

McKenzie, J.A. 1985. Carbon isotopes and productivity in the lacustrine and marine environment, p. 99-118. In W. Stumm. Chemical Processes in Lakes. John Wiley & Sons, New York, USA.

Meisch, C. 2000. Freshwater Ostracoda of western and central Europe, In J. Schworbel & P. Zwick. SuBwasserfauna von Mitteleuropa. (8/1) Spektrum Akademischer GmbH, Germany.

Mischke, S., U. Herzschuh, G. Massmann & C. Zhang. 2007. An ostracode conductivity transfer function for Tibetan lakes. J. Paleolimnol. 38: 509-524.

Moss, B., D. McKee, D. Atkinson, S.E. Collings, J.W. Eaton, A.B. Gill, I. Harvey, K. Hatton, T. Heyes & D. Wilson. 2003. How important is climate? Effects of warming, nutrient addition and fish on phytoplankton in shallow lake microcosms. J. Appl. Ecol. 40: 782-792.

O'Sullivan, P.E. & C.S. Reynolds. 2004. The lakes handbook. Limnology and limnetic ecology, vol 1. Blackwell, Cornwall, England.

Perez, L., R. Bugja, J. Massaferro, P. Steeb, R. van Geldern, P. Frenzel, M. Brenner, B. Scharf & A. Schwalb. 2010a. Post-Columbian environmental history of Lago Peten Itza, Guatemala. Rev. Mex. Cienc. Geol. 27: 490-507.

Perez, L., J. Lorenschat, M. Brenner, B. Scharf & A. Schwalb. 2010b. Extant freshwater ostracodes (Crustacea: Ostracoda) from Lago Peten Itza, Guatemala. Rev. Biol. Trop. 58: 871-895.

Perez, L., J. Lorenschat, R. Bugja, M. Brenner, B. Scharf & A. Schwalb. 2010c. Distribution, diversity and ecology of modern freshwater ostracodes (Crustacea), and hydrochemical characteristics of Lago Peten Itza, Guatemala. J. Limnol. 69: 146-159.

Perez, L., J. Lorenschat, R. Bugja, M. Brenner, P. Hoelzmann, G. Islebe, B. Scharf & A. Schwalb. 2011a. Aquatic ecosystems of the Yucatan Peninsula and surrounding areas. Hydrobiologia 661: 407-433.

Perez, L., P. Frenzel, M. Brenner, E. Escobar, P. Hoelzmann, B. Scharf & A. Schwalb. 2011b. Late Quaternary (24-10 ka BP) environmental history of the Neotropical lowlands inferred from ostracodes in sediments of Lago Peten Itza, Guatemala. J. Paleo limnol. 46: 59-74.

Perry, E.C., L. Marin, J. McClain & G. Velazquez. 1995. Ring of cenotes (sinkholes), northwest Yucatan, Mexico: its hydrogeologic characteristics and possible association with the Chicxulub impact crater. Geology 23: 17-20.

Porinchu, D.F. & G.M. MacDonald. 2003. The use and application of freshwater midges (Chironomidae: Insecta: Diptera) in geographical research. Prog. Phys. Geogr. 27: 378-422.

Rejmankova, E., J. Komarek, M. Dix, J. Komarkova & N. Giron. 2011. Cyanobacterial blooms in Lake Atitlan, Guatemala. Limnologica -Ecol. Manag. Inland Waters 41: 296-302.

Rivas Flores, A.W., R.E. Gomez Orellana & A.J. Monterrosa Urias. 2010. Consideraciones generales para el estudio y monitoreo de diatomeas en los principales rios de El Salvador. Formulacion de una guia metodologica estandarizada para determinar la calidad ambiental de las aguas de los rios de El Salvador, utilizando insectos acuaticos. Proyecto Universidad El Salvador (UES). Organizacion de los Estados Americanos (OEA), San Salvador, El Salvador.

Rosen, P., R. Hall, T. Korsman & E. Renberg. 2000. Diatom transfer-functions for quantifying past air temperature, pH and total organic concentration from lakes in Northern Sweden. J. Paleolimnol. 24: 109-123.

Rosenmeier, M.F., M. Brenner, W.F. Kenney, T.J. Whitmore & C.M. Taylor. 2004. Recent eutrophication in the southern basin of Lake Peten Itza, Guatemala: human impact on a large tropical lake. Hydrobiologia 511:161-172.

Sala, O.E., F.S. III Chapin, J.J. Armesto, E. Berlow, J. Bloomfield, R. Dirzo, E. Huber-Sanwald, L.F. Huenneke, R.B. Jackson, A. Kinzig, R. Leemans, D.M.

Lodge, H.A. Mooney, M. Oesterheld, N.L. Poff, M.T. Sykes, B.H. Walker, M. Walker & D.H. Wall. 2000.

Global biodiversity scenarios for the year 2100. Science 287: 1770-1774.

Sanchez, M., J. Alcocer, E. Escobar & A. Lugo. 2002. Phytoplankton of cenotes and anchialine caves along a distance gradient from the northeastern coast of Quintana Roo, Yucatan Peninsula. Hydrobiologia 467: 79-89.

Schmitter-Soto, J.J., F.A. Comin, E. Escobar-Briones, J. Herrera-Silveira, J. Alcocer, E. Suarez-Morales, M. Elias-Gutierrez, V. Diaz-Arce, L.E. Marin & B. Steinich. 2002. Hydrogeochemical and biological characteristics of cenotes in the Yucatan Peninsula (SE Mexico). Hydrobiologia 467: 215-228.

Schwalb, A. 2003. Lacustrine ostracodes as stable isotope recorders of late-glacial and Holocene environmental dynamics and climate. J. Paleolimnol. 29: 256-351.

Servicios Informativos y Publicitarios del Sureste (SIPSE). 2011. Se decretan tres areas protegidas en Quintana Roo. SIPSE.COM, Campeche, Quintana Roo, Yucatan, Mexico (Downloaded: November 10, 2011, http://www.sipse.com/noticias/96930--decretan-tresareas-protegidas-quintana-.html). Sinev, A.Y. & W. Hollwedel. 2002. Alona brandorffi sp. n. (Crustacea: Anomopoda: Chydoridae) a new species from Brazil, related to A. verrucosa Sars 1901. Hydrobiologia 472: 131-140.

Smirnov, N.N. 1992. Macrothricidae of the World. Guides to the Identification of the Macroinvertebrates of the Continental Waters of the World, vol. 1. SPB Acad. Publ., The Hague, Amsterdam, Netherlands.

Smirnov, N.N. 1996. Cladocera: the Chydorinae and Sayciinae (Chydoridae) of the World. Guides to the identification of the macroinvertebrates of the Continental Waters of the World, vol 11. SPB Acad. Publ., The Hague, Amsterdam, Netherlands.

Smith, A.J. 1993. Lacustrine ostracodes as hydrochemical indicators in lakes of the north-central United States. J. Paleolimnol. 8: 121-134.

Stich, H.B. & G. Maier. 2007. Distribution and abundance of Daphnia pulicaria, a large Daphnia of the "pulex group", in Lake Constance (Lower Lake). Limnologi ca-Ecol. Manag. Inland Waters 37: 303-310.

Suarez-Morales, E. & M. Elias-Gutierrez. 2000. Two new Mastigodiaptomus (Copepoda, Diaptomidae) from southeastern Mexico, with a key for the identification of the known species of the genus. J. Nat. Hist. 34: 693-708.

Suarez-Morales, E. & M. Elias-Gutierrez. 2001. On the taxonomical status of Arctodiaptomus dampfi Brehm (Crustacea: Copepoda: Diaptomidae) with comments on A. dorsalis (Marsh). J. Limnol. 60: 11-18.

Suarez-Morales, E. 2003. Historical biogeography and distribution of the freshwater calanoid copepods (Crustacea: Copepoda) of the Yucatan Peninsula, Mexico. J. Biogeogr. 30: 1851-1859.

Suarez-Morales, E. & J. Reid. 2003. An updated checklist of the continental copepod fauna of the Yucatan Peninsula, Mexico, with notes on its regional associations. Crustaceana 76: 977-991.

Swain, F.M. 1966. Bottom sediments of lake Nicaragua and Managua, western Nicaragua. J. Sediment. Petrol. 36: 522-540.

Sylvestre, F. 2002. A high-resolution diatom reconstruction between 21,000 and 17,000 14C yr BP from the southern Bolivian Altiplano (18-23[degrees]). J. Paleolimnol. 27: 45-57.

Ter Braak, C.J.F. & P. Smilauer. 2002. CANOCO 4.5. Microcomputer Power. Ithaca, New York, USA.

Vadadi-Fulop, C. 2009. Zooplankton (Cladocera, Copepoda) dynamics in the River Danube upstream and downstream of Budapest, Hungary. Opusc. Zool. Budapest 40: 87-98.

Van Damme, K., A.Y. Sinev & H.J. Dumont. 2011. Separation of Anthalona gen. n. from Alona Baird, 1843 (Branchiopoda: Cladocera: Anomopoda): morphology and evolution of scraping stenothermic alonines. Zootaxa 2875: 1-64.

Velez, M.I., J.H. Curtis, M. Brenner, J. Escobar, B.W. Leyden & M. Popenoe de Hatch. 2011. Environmental and cultural changes in highland Guatemala inferred from Lake Amatitlan sediments. Geoarchaeol. 26: 346-364.

Vinogradova, E.M. & H.W. Riss. 2007. Chironomids of the Yucatan Peninsula. Chironomus 20: 32-35.

Walker, I.R., A.J. Levesque, L.C. Cwynar & A.F. Lotter. 1997. An expanded surface-water palaeotemperature inference model for use with fossil midges from eastern Canada. J. Paleolimnol. 18: 165-178.

Walseng, B., D.O. Hessen, G. Halvorsen & A.K. Schartau. 2006. Major contribution from littoral crustaceans to zooplankton species richness in lakes. Limnol. Oceanogr. 51: 2600-2606.

Liseth Perez * (1,2), Julia Lorenschat (1), Julieta Massaferro (3), Christine Pailles (4), Florence Sylvestre (4), Werner Hollwedel (5), Gerd-Oltmann Brandorff (6), Mark Brenner (7), Gerald Islebe (8), Maria del Socorro Lozano (2), Burkhard Scharf (1) & Antje Schwalb (1)

(1.) Institut fur Geosysteme und Bioindikation, Technische Universitat Braunschweig, Langer Kamp 19c, 38106 Braunschweig, Germany; l.perez@tu-bs.de, j.lorenschat@tu-bs.de, burkhard.w.scharf@t-online.de, antje.schwalb@tu-bs.de

(2.) Instituto de Geologia, Universidad Nacional Autonoma de Mexico (UNAM), Ciudad Universitaria, 04510, Distrito Federal, Mexico; lcpereza@geologia.unam.mx, mslozano@unam.mx

(3.) CENAC-APN, CONICET, San Martin 24, 8400, Bariloche, Argentina; julimassaferro@hotmail.com

(4.) CEREGE, Universite Aix-Marseille, CNRS, IRD, Europole mediterraneen de l'Arbois, BP 80, 13545 Aix-enProvence cedex 4, France; pailles@cerege.fr, sylvestre@cerege.fr

(5.) Oldenburger Strasse 16A, 26316, Varel, Germany; whollwedel@freenet.de

(6.) Georg-Groning-Str. 29A, 28209, Bremen, Germany; gobrandorf@aol.com

(7.) Department of Geological Sciences & Land Use and Environmental Change Institute, University of Florida, Gainesville, 32611, Florida, USA; brenner@ufl.edu

(8.) Herbario, El Colegio de la Frontera Sur (ECOSUR), Unidad Chetumal, Av. del Centenario 424, 77000, Chetumal, Quintana Roo, Mexico; gislebe@ecosur.mx

* Corresponding author

Received 29-V-2012. Corrected 02-IX-2012. Accepted 04-X-2012.

TABLE 1A

Location, morphometry and selected limnological variables of
surface waters (single measurements) for sampled waterbodies on the
Yucatan Peninsula (modified from Perez et al. 2011b). ID indicates
the abbreviations used for the studied waterbodies in figures 3-7.
ID-Nr. indicates the location of all sampled aquatic ecosystems
across a NW-S precipitation gradient in figure 1

Area           ID    ID-       Name of
                     Nr.       aquatic
                              ecosystem

Guatemalan    AMA    19    Amatitlan
Highlands     ATI    20    Atitlan
              AYA    23    Ayarza
              GUI    21    Guija
              ATE    22    Atescatempa

Guatemalan    IZA     1    Izabal
Eastern
Lowlands

Peten         OQU    25    Oquevix
  Lowlands    SAL    26    Salpeten
              MAC     4    Macanche
              YAX     5    Yaxha
              ITZ     2    Peten Itza
              SAC    28    Sacpuy
              PER     3    Perdida
              GLO    29    La Gloria
              DIE    30    San Diego
              POZ    32    Las Pozas
              PET    33    Petexbatun
              ROS    34    El Rosario

Yucatan       MIL    12    Milagros
Lowlands      BAC    13    Bacalar
              NOH    14    Nohbec
              OCO    15    Ocom
              CHI    16    Chichancanab
              PUN    17    Punta Laguna
              JOS    36    San Jose Aguilar
              SAB    37    Sabanita
              BAT    38    Chacan-Bata
              LAR    39    Chacan-Lara
              JOB    41    Jobal
              FRA    42    San Francisco
                             Mateos
              MIS    43    La Misteriosa
              CAY    45    Cayucon
              YAL    18    Yalahau
              COBA   61    Coba

Belizean      ALM     8    Almond Hill
Lowlands                     Lagoon
              CRO     9    Crooked Tree
                             Lagoon
              HON    10    Honey Camp
                             Lagoon

Area                             Coordinates              Altitude
                                 NW                       [m.a.s.l]

Guatemalan    14[degrees]26'03.7"   90[degrees]32'58.6"     1200
Highlands     14[degrees]42'34.8"   90[degrees]15'59.4"     1560
              14[degrees]25'39.3"   90[degrees]08'11.6"     1414
              14[degrees]15'43.7"   89[degrees]32'11.3"      433
              14[degrees]13'01.1"   89[degrees]41'39.2"      587

Guatemalan    15[degrees]29'24.5"   89[degrees] 8'32.7"       4
Eastern
Lowlands

Peten         16[degrees]39'14.2"   89[degrees]44'26.1"      148
  Lowlands    16[degrees]58'38.2"   89[degrees]40'30.9"      114
              16[degrees]57'60.0"   89[degrees]38'06.5"      165
              17[degrees]03'48.9"   89[degrees]24'27.1"      219
              17[degrees]00'02.0"   89[degrees]51'16.4"      115
              16[degrees]58'46.4"   90[degrees]00'52.2"      122
              17[degrees]04'00.7"   90[degrees]12'41.7"      75
              16[degrees]57'07.5"   90[degrees]22'36.1"      132
              16[degrees]55'59.5"   90[degrees]24'54.5"      134
              16[degrees]21'02.4"   90[degrees]10'28.9"      146
              16[degrees]26'11.8"   90[degrees]11'46.0"      115
              16[degrees]31'31.4"   90[degrees]09'36.2"      117

Yucatan       18[degrees]30'41.5"   88[degrees]25'35.8"       1
Lowlands      18[degrees]39'54.0"   88[degrees]23'27.0"       1
              19[degrees]08'8.54"   88[degrees]10'46.6"       1
              19[degrees]28'28.6"   88[degrees]03'17.9"       1
              19[degrees]52'43.2"   88[degrees]46'06.5"       2
              20[degrees]39'00.6"   87[degrees]38'28.2"       3
              18[degrees]22'04.5"   89[degrees]00'41.2"      107
              18[degrees]24'03.2"   88[degrees]34'20.6"      38
              18[degrees]28'42.1"   89[degrees]05'13.9"      91
              19[degrees]11'21.8"   88[degrees]10'17.0"      90
              18[degrees]41'40.7"   90[degrees]06'45.4"      74
              17[degrees]53'55.9"   90[degrees]39'22.8"      52

              18[degrees]02'40.3"   90[degrees]29'14.0"      57
              18[degrees]02'34.3"   90[degrees]58'33.0"      69
              20[degrees]39'25.9"   89[degrees]13'02.0"       2
              20[degrees]29'40.2"   87[degrees]44'19.2"       7

Belizean      17[degrees]27'49.0"   88[degrees]18'31.6"       1
Lowlands
              17[degrees]46'42.8"   88[degrees]31'37.4"       2

              18[degrees]02'44.5"   88[degrees]26'20.5"       1

Area          Depth *     Surface         Temp.       Diss.    pH
                [m]         area       [[degrees]C]   oxygen
                        [[km.sup.2]]                  [mg/L]

Guatemalan      23          15.2           22.8        18.7    9.3
Highlands       340         126            21.8        7.3     8.4
                250          14            21.6        7.2     8.4
               21.5          45            26.2        7.7     8.4
                 2          1.1            27.3        6.7     8.0

Guatemalan     14.8         645            26.4        7.6     8.3
Eastern
Lowlands

Peten           10          1.6            31.4        6.9     7.7
  Lowlands      38          2.9            29.7        8.4     8.2
                80          2.5            26.8        5.0     8.0
                22           7             29.0        7.3     8.7
                165         100            27.6        8.9     8.5
                 6          3.5            28.8        8.0     8.4
                 4           11            28.8        9.8     8.8
                65          3.6            29.2        8.8     8.6
                8.1         3.8            28.6        8.2     8.6
                35          2.0            29.8        9.0     8.4
                40          5.6            30.9        9.7     8.0
                 3          0.02           28.3        7.6     7.1

Yucatan          4          3.1            27.9        12.4    8.1
Lowlands        16           51            27.0        7.9     7.8
                0.6         8.5            29.2        9.4     8.5
                10          0.25           27.9        7.2     8.0
                14          5.1            28.5        7.7     8.0
                20          0.9            26.8        7.2     8.0
                 3          2.0             -          4.8     8.0
                2.5         0.02           27.5        8.1     8.0
                --          2.9            26.3        2.2     7.0
                 3          1.2            28.1        6.0     7.5
                 3                         31.7        10.9    8.3
                 5          0.1            24.8        0.9     7.3

                5.8         5.0            26.7        7.7     8.0
                 8          2.0            25.3        3.3     7.4
                11          0.25           28.8        8.7     8.9
                --          0.35           28.9        8.7     8.5

Belizean        1.9         1.5            27.5        6.4     7.1
Lowlands
                3.3          23            28.5        6.9     7.8

                 8          3.9            25.9        9.1     8.5

Area           Cond.     Secchi
              [[micro]     [m]
               S/cm]

Guatemalan      630      0.1-0.8
Highlands       465        6.6
                1772      11.4
                206        1.4
                283        0.1

Guatemalan      215        --
Eastern
Lowlands

Peten           238        0.4
  Lowlands      4310       0.8
                850        --
                232        1.8
                533        7.5
                285        0.5
                232        0.7
                187        0.6
                179        0.6
                292        1.8
                568        0.6
                1019       --

Yucatan         2720       1.0
Lowlands        1221      10.3
                1231       0.6
                774        5.5
                2060       2.8
                754        4.7
                488        0.6
                139        0.5
                146        --
                174        0.7
                241        --
                474        --

                1411       2.1
                127         ?
                2350       1.1
                1213       0.9

Belizean        1715       1.7
Lowlands
                330        2.0

                1481       1.8

* Maximum sampled water depth and/or maximum lake depth.

TABLE 1B

Location, morphometry and selected limnological variables
of surface waters (single measurements) for sampled "cenotes"
(sinkholes), coastal waterbodies, rivers, wetlands and
ponds on the Yucatan Peninsula (modified from Perez et al. 2011b).
ID indicates the abbreviations used for the studied waterbodies
in figures 3-7. ID-Nr. indicates the location of all sampled
aquatic ecosystems across a NW-S precipitation gradient in figure 1

Type of        ID     ID-Nr.   Name
aquatic
ecosystem

Cenotes         XLA     50     Xlacah
                MON     52     Peten de Monos
                IGN     55     San Ignacio Chochola
                CHE     56     Chenha
                TIM     57     Timul
                YOK     58     Yokdzonot
                JUA     60     Juarez
                YAA     63     Ya'ax'ex
                KAN     54     San Francisco Kana
                TEK     62     Tekom
Coastal         PRO     35     Progreso
water bodies    CEN     11     Cenote Little Belize
               ROSA     49     Rosada
                CEL     51     Celestun
Rivers          SUB     31     Subin
                IXL     27     Ixlu
                DUL     24     Rio Dulce
                CUB     44     Cuba
                CAN     46     Candelaria
                GUE     47     Guerrero
Wetland         JAM     48     Jamolun
Ponds           TUM     53     Near Oquevix
                LOC     59     Loche
                SIL     40     Silvituc
                BZ1     6      Belize 1
                BZ2     7      Belize 2

Type of                       Coordinates                   Altitude
aquatic                           N W                       [m.a.s.l]
ecosystem

Cenotes        21[degrees]05'27.6"   89[degrees]35'53.3"        6
               20[degrees]50'59.6"   90[degrees]19'13.8"       25
               20[degrees]45'00.9"   89[degrees]50'03.2"        7
               20[degrees]41'23.0"   89[degrees]52'34.5"        3
               20[degrees]35'38.8"   89[degrees]21'23.7"        9
               20[degrees]42'24.6"   88[degrees]43'52.0"       13
               20[degrees]48'09.6"   87[degrees]20'23.8"       14
               20[degrees]37'15.4"   88[degrees]24'56.0"       27
               20[degrees]51'22.2"   90[degrees]07'04.5"        3
               20[degrees]36'08.1"   88[degrees]15'52.5"       18
Coastal        18[degrees]13'05.2"   88[degrees]24'35.2"        5
water bodies   18[degrees]13'36.9"   88[degrees]22'55.57"       7
               21[degrees]20'11.3"   89[degrees]18'01.9"        4
               20[degrees]51'20.8"   90[degrees]22'39.2"       14
Rivers         16[degrees]38'11.6"   90[degrees]11'00.3"       141
               16[degrees]58'27.3"   89[degrees]53'27.8"       110
               15[degrees]40'25.3"   88[degrees]57'49.3''       4
               17[degrees]56'55.4"   90[degrees]28'39.1"       80
               18[degrees]11'02.4"   91[degrees]02'59.6"       44
               19[degrees]12'41.6"   90[degrees]43'47.6"        5
Wetland        19[degrees]27'58.3"   89[degrees]29'45.1"       115
Ponds          16[degrees]40'31.7"   89[degrees]44'18.1"       179
               21[degrees]25'04.3"   88[degrees]08'30.8"       20
               18[degrees]38'23.2"   90[degrees]17'35.2"       59
               17[degrees]14'33.5"   88[degrees]58'19.7"       77
               17[degrees]18'17.9"   88[degrees]29'18.9"       33

Type of        Depth *     Surface         Temp.       Diss. oxygen
aquatic          [m]         area       [[degrees]C]      [mg/L]
ecosystem                [[km.sup.2]]

Cenotes          45         <0.01           27.9            4.0
                 1.5        <0.01           26.6            1.4
                  4         <0.01           27.4            2.7
                  2         <0.01           28.3           10.4
                  -          0.03           30.4           11.4
                 45         <0.01           25.2            5.3
                 25          0.03           27.9            8.7
                 47         <0.01           26.4           10.6
                  -          0.01           30.7            9.7
                 1.5        <0.01           25.5            6.7
Coastal          3.2         7.2            26.4            7.0
water bodies    11.1         0.06           25.8            8.3
                 0.5         2.3            28.1           10.5
                 1.5          28            24.9            5.2
Rivers            1           --            26.2            4.2
                  1           --            25.9            6.7
                  7           --            27.6            6.5
                 0.5          --            24.9            7.3
                 1.5          --            26.9            1.9
                  1           --            26.2            3.6
Wetland          1.5          --            25.7            2.9
Ponds             1         <0.01           25.9            9.4
                  1         <0.01           32.0           14.4
                 2.5        <0.01           30.2            7.7
                 1.5        <0.01           28.2            5.8
                  1         <0.01           27.4            7.5

Type of        pH     Cond.    Secchi
aquatic              [mS/cm]    [m]
ecosystem

Cenotes        7.0    1452       5
               6.9    3670      1.5
               6.9    2110       4
               7.6    2520      3.5
               9.1    1465      0.2
               7.4     949       7
               8.1     643      1.6
               8.0     793      0.8
               8.2    1751      0.3
               7.3     958      1.5
Coastal        8.2    2040      1.3
water bodies   8.2    5960      5.5
               8.7    55300     0.5
               7.8    38200     0.5
Rivers         7.4     720      0.5
               7.5    1025       1
               7.6     192      0.5
               7.8    2040      0.5
               7.7    1564      1.0
               7.7    2700      0.5
Wetland        7.3    2520      0.5
Ponds          9.3     168       --
               9.4    4340      0.2
               8.2    183.2      --
               7.3     192       --
               8.0     244       --

* Maximum sampled water depth and/or maximum lake depth.

TABLE 2

Chironomids (family Chironomidae; n=66) found in aquatic
ecosystems in the Northern Neotropics. Species are ordered
alphabetically within subfamilies and tribes. Species codes
in bold (n=38) were taxa included in multivariate analysis.
Code indicates the species abbreviations used in Figures 3a,b,c
and 8. A number or letter was designated along with the genus to
identify different morphospecies. For the ecosystem studies see
tables 1A, B

Taxa                                           Code

Subfamily Chironominae
Tribe Chironomini

Apedilum sp.                                   APED
Axarus sp.                                     AXAR
Beardius sp.                                   BEAR
Brundinella sp.                                BRUN
Chironomus anthracinus Zetterstedt 1860        CHAN
Chironomus plumosus Linnaeus 1758              CHPL
Cladopelma sp.                                 CLAD
Corynocera ambigua Zetterstedt 1838            CORC
Corynocera olivieri type                       CORO
Cryptochironomus sp.                           CRYP
Dicrotendipes sp.                              DICR
Einfeldia sp.                                  EINF
Endochironomus sp.                             ENDO
Endotribelos sp.                               ENTR
Glyptotendipes sp.1                            GLEN
Glyptotendipes sp.2                            GLYP
Goeldochironomus sp.                           GOEL
Harrisius sp.                                  HARR
Kiefferulus sp.                                KIEF
Lauternborniella sp.                           LAUT
Paracladopelma sp.                             PCLA
Paratendipes sp.                               PART
Parachironomus sp.                             PCHI
Phaenopsectra sp.                              PHAE
Polypedilum sp.                                POLY
Polypedilum sp.2                               PO16
Sergentia sp.                                  SERG
Stempellina sp.                                STEM
Saetheria sp.                                  SAET
Stenochironomus sp.                            STEN
Sublettea sp.                                  SUBL
Xenochironomus sp.                             XENO

Tribe Tanytarsini

Cladotanytarsus sp.1                           CLA1
Cladotanytarsus sp.2                           CLA2
Micropsectra sp.                               MICR
Tanytarsini A                                  TANA
Tanytarsini C                                  TANC
Tanytarsini D                                  TAND
Tanytarsini F                                  TANF
Tanytarsini J                                  TANJ
Tanytarsini K                                  TANK
Paratanytarsus sp.1                            PAR1
Paratanytarsus sp.2                            PAR2

Tribe Pseudochironomini

Pseudochironomus sp.                           PSEU

Subfamily Orthocladiinae

Corynoneura sp.                                CORY
Cricotopus spp.                                CRIC
Eukiefferiella sp.                             EUKI
Limnophies sp.                                 LIMN
Mesosmittia sp.                                MESS
Parakiefferiella fennica Tuiskunen 1986        PAFE
Parapsectrocladius sp.                         PAPS
Pseudosmittia sp.                              PSSM
Psectrocladius sp.                             PSEC

Subfamily Tanypodinae

Ablabesmya sp.                                 ABLA
Alotanypus sp.                                 ALOT
Apsectrotanypus sp.                            APSE
Coelotanypus/Clinotanypus                      COEL
Djalmabatista sp.                              DJAL
Fittkauimyia sp.                               FITT
Labrundina sp.                                 LABR
Larsia sp.                                     LARS
Macropelopia/Apsectrotanypus                   MACR
Monopelopia sp.                                MONO
Procladius sp.                                 PROC
Tanypodinae indet.                             TAID
Zavrelymia sp.                                 ZAVR

TABLE 3

Diatom species (n=282) found in aquatic ecosystems in the
Northern Neotropics. Species are ordered alphabetically
within classes, orders, suborders and families. Species
codes in bold (n=97) were included in multivariate analysis
Code indicates the species abbreviations used in figures 4a,b
and 8. A number was designated along with the genus to identify
different morphospecies. For the ecosystem studies see tables 1a,b

Taxa                                                     Code

Class Bacillariophyceae

Order Centrales

Sub-Order Coscinodiscineae

Hemidiscaceae

Actinocyclus sp.                                         ACTI

Melosiraceae

Hyalodiscus scoticus (Kutzing) Grunow 1879               HYSC

Paraliaceae

Paralia sulcata (Ehrenberg) Cleve 1873                   PARA

Thalassiosiraceae

Aulacoseira ambigua (Grunow) Simonsen 1979                MA
Aulacoseira crenulata (Ehrenberg) Thwaites 1848           AUC
Aulacoseira distans (Ehrenberg) Simonsen 1979             MD
Aulacoseira granulata (Ehrenberg) Simonsen 1979           MG
Aulacoseira granulata var. angustissima (Otto Muller)     MGA
  Simonsen 1979
Aulacoseira granulata f. curvata (Hustedt)                MGC
  Simonsen 1979
Cyclotella atomus Hustedt 1937                           CYAT
Cyclotella caspia Grunow 1878                            CCAS
Cyclotella comensis Grunow in Van Heurck 1882            CYCO
Cyclotella cyclopuncta Hakansson & Carter 1990           CYCL
Cyclotella meneghiniana Kutzing 1844                     CYMG
Cyclotella striata (Kutzing) Grunow in Cleve             CYST
  & Grunow 1880
Cyclotella aff. petensis                                 CYEN
Cyclotella aff. striata                                  CAST
Cyclotella sp.                                            CPS
Cyclotella sp. 22                                        CP22
Discostella pseudostelligera (Hustedt)                    CCP
  Houk & Klee 2004
Discostella aff. pseudostelligera                        CYAP
Discostella stelligera (Cleve et Grunow)                 CYCS
  Houk & Klee 2004
Stephanodiscus hantzschii Grunow in Cleve                STHA
  & Grunow 1880
Stephanodiscus minutulus (Kutzing) Cleve                 STME
  & Moller 1882
Stephanodiscus medius H. Hakansson 1986                  STNU
Stephanodiscus parvus Stoermer & Hakansson 1984          STPA
Thalassiosira sp.                                        THAS

Sub-Order Rhizosoleniineae

Biddulphiaceae

Terpsinoe musica Ehrenberg 1843                          TERM

Order Pennales

Sub-Order Araphidineae

Fragilariaceae

Campylostylus normannianus (Greville) Gerloff,           CAPS
  Natour & Rivera 1978
Cymatosira lorenziana Grunow 1862                        CLOZ
Fragilaria bidens Heiberg 1863                           FRBI
Fragilaria capucina Desmazieres emend Lange-              FCA
  Bertalot 1980
Fragilaria capucina var. vaucheriae (Kutzing) Lange-     FCAV
  Bertalot 1980
Fragilaria crotonensis Kitton 1869                        FCR
Fragilaria famelica (Kutzing) Lange-Bertalot 1980         FF
Fragilaria tenera (W. Smith) Lange-Bertalot 1980          FT
Fragilaria ulna var. goulardi (Brebisson) Lange-         FRGO
  Bertalot 1980
Opephora marina (Gregory) Petit 1888                     OMAR
Pseudostaurosira brevistriata (Grunow in Van Heurck)      FBR
  Williams & Round 1987
Staurosira construens Ehrenberg 1843                     FRAC
Staurosirella pinnata (Ehrenberg)                         FP
  Williams & Round 1987
Synedra hartii Cholnoky 1963                              FHA
Tabularia tabulata (C.A.Agradh)                          TABA
  Snoeijs 1992
Tabularia fasciculata (C.A.Agradh)                       TAFA
Williams & Round 1986
Ulnaria acus (Kutzing) Aboal in Aboal,                   SYNA
  Alvarez-Cobelas, Cambra & Ector 2003
Ulnaria delicatissima var. angustissima                  FAAU
  (Grunow in Van Heurck) Aboal in Aboal,
  Alvarez Cobelas, Cambra & Ector 2003
Ulnaria delicatissima var. angustissima                  FARD
  (Grunow in Van Heurck) Aboal in Aboal,
  Alvarez-Cobelas, Cambra & Ector 2003
Ulnaria ulna (Nitzsch) Compere 2001                      SYNU

Sub-Order Raphidineae

Eunotiaceae

Eunotia camelus Ehrenberg 1841                           EUCM
Eunotia bilunaris (Ehrenberg) Mills 1933-1935             EUL
Eunotia monodon Ehrenberg 1841(1843)                     EUMO
Eunotia praerupta Ehrenberg 1841(1843)                   EUPR
Eunotia sp.                                              EUSP
Peronia fibula (Brebisson in Kutzing) Ross 1956          PERF

Achnanthaceae

Achnanthes minutissima var. scotica (Carter)             AMSC
  Lange-Bertalot in Lange-Bertalot
  & Krammer 1989
Achnanthidium brevipes (Agardh) Heiberg 1863              ABR
Achnanthidium exiguum (Grunow) Czarnecki 1994             AEX
Achnanthidium hungaricum Grunow 1863                      AHU
Achnanthidium minutissimum (Kutzing)                      AMI
  Czarnecki 1994
Cocconeis neodiminuta Krammer 1990                        CD
Cocconeis placentula Ehrenberg 1838                       CP
Karayevia submarina (Hustedt) Bukhtiyarova 2006          ASUB
Psammothidium marginulatum (Grunow)                       AUM
  Bukhtiyarova et Round 1996

Naviculaceae

Amphipleura pellucida (Kutzing) Kutzing 1844             APLL
Amphora arenaria Donkin 1858                             AMRE
Amphora arenicola Grunow in Cleve 1895                   AMER
Amphora copulata (Kutzing) Schoeman                      AMPU
  & Archibald 1986
Amphora cymbifera Gregory 1857                           AMCY
Amphora graeffeana Hendey 1973                           AMGR
Amphora granulata Gregory 1857                           APTA
Amphora holsaticoides Nagumo & Kobayasi 1990             AMHS
Amphora lybica Ehrenberg 1840                             AY
Amphora marina W. Smith 1857                             AMAR
Amphora pediculus (Kutzing)                              AMPE
  Grunow in Schmidt et al. 1875
Amphora proteus Gregory 1857                              AMP
Amphora securicula Peragallo & Peragallo 1899            AMSE
Anomoeoneis sphaerophora Pfitzer 1871                     ANS
Anomoeoneis sphaerophora f. costata (Kutzing)            ANSC
  A.-M. Schmid 1977
Anomoeoneis sphaerophora f. sculpta (Ehrenberg)          ANSS
  Krammer in Krammer & Lange-Bertalot 1985
Anomoeoneis vitrea (Grunow) Ross in Patrick &             ANV
  Reimer 1966
Brachysira australofollis H. Lange-Bertalot &            BRAL
  G. Moser 1994
Brachysira hofmanniae H. Lange-Bertalot in               BROF
  H. Lange-Bertalot & G. Moser 1994
Brachysira neoexilis H. Lange-Bertalot                   BREX
  in H. Lange-Bertalot & G. Moser 1994
Brachysira procera H. Lange-Bertalot                     BRPR
  & G. Moser 1994
Brachysira vitrea (Grunow) R. Ross in Hartley 1986       BRVI
Brachysira sp.                                           BRSP
Caloneis alpestris (Grunow) Cleve 1894                    CAL
Caloneis bacillum (Grunow) Cleve 1894                     CAB
Caloneis fontinalis (Grunow) Lange-Bertalot &            CAFO
  Reichardt in Lange-Bertalot & Metzeltin 1996
Capartogramma paradisiaca Novelo,                        CAPA
  Tavera & Ibarra 2007
Climaconeis colemaniae A.K.S.K. Prasad in Prasad,        CLIM
  A.K.S.K., Riddle, K.A. & J.A. Nienow 2000
Craticula ambigua (Ehrenberg) Mann in Round,             CRAA
  Crawford & Mann 1990
Craticula cuspidata (Kutzing) Mann in Round,              NCU
  Crawford & Mann 1990
Craticula halophila (Grunow ex Van Heurck)               NAHA
  Mann in Round, Crawford & Mann 1990
Craticula perrotettii Grunow 1867                        CRPE
Cymbella mexicana (Ehrenberg) Cleve 1984                 CYMX
Cymbella rhomboidea Boyer 1916                           CYRH
Cymbella sp. 25                                          CY25
Diadesmis confervacea Kutzing 1844                       NACF
Diadesmis contenta (Grunow ex Van Heurck)                 NCN
  Mann in Round, Crawford & Mann 1990
Encyonema densistriata Novelo, Tavera & Ibarra 2007      ENDE
Encyonema gracile Rabenhorst 1853                         CYL
Encyonema mesianum (Cholnoky) Mann in Round,             CYME
  Crawford & Mann 1990
Encyonema minutum (Hilse in Rabenhorst) Mann in          CYMT
  Round, Crawford & Mann 1990
Encyonema muelleri (Hustedt) Mann in Round,              CYMU
  Crawford & Mann 1990
Encyonema perpusillum (A. Cleve) Mann in Round,          CYPE
  Crawford & Mann 1990
Encyonema silesiacum (Bleisch in Rabenhorst) Mann        CYML
  in Round, Crawford & Mann 1990
Encyonema turgidum (Gregory) Grunow                      CYTI
  in Schmidt et al. 1875
Encyonopsis angusta Krammer et Lange-Bertalot            CYAM
  in Krammer 1997
Encyonopsis cesatii (Rabenhorst) Krammer 1997             CYC
Encyonopsis falaisensis (Grunow) Krammer 1997             CYF
Encyonopsis microcephala (Grunow) Krammer 1997           CYMI
Encyonopsis naviculacea (Grunow) Krammer 1997            CYNV
Diploneis caffra (Giffen) A. Witkowski,                  DICA
  H. Lange-Bertalot & D. Metzeltin 2000
Diploneis fusca (Gregory) Cleve 1894                     DFUS
Diploneis litoralis (Donkin) Cleve 1894                  DILI
Diploneis oblongella (Naegeli in Kutzing) Cleve-Euler     DOB
  in Cleve-Euler (& Osvald) 1922
Diploneis ovalis (Hilse in Rabenhorst) Cleve 1891         DO
Entomoneis paludosa (W. Smith) Reimer in Patrick         ENTO
  & Reimer 1975
Eolimna minima (Grunow in Van Heurck)                     NAI
  H. Lange-Bertalot in G. Moser, H. Lange-Bertalot
  & D. Metzeltin 1998
Eolimna submuralis (Hustedt) Lange-Bertalot               NAS
  & Kulikovskiy in Kulikovskiy et al. 2010
Eolimna aff. submuralis (Hustedt) Lange-Bertalot &       NUSI
  Kulikovskiy in Kulikovskiy et al. 2010
Fallacia pygmaea (Kutzing) Stickle & Mann in Round,      NPYG
  Crawford & Mann 1990
Fistulifera pelliculosa (Brebisson) Lange-Bertalot 1997   NPE
Gomphonema affine Kutzing 1844                           GAFF
Gomphonema amoenum Lange-Bertalot in Krammer              GOE
  & Lange-Bertalot 1985
Gomphonema angustum Agardh 1831                          GOIM
Gomphonema clevei Fricke in Schmidt et al. 1902           GC
Gomphonema gracile Ehrenberg 1854                         GG
Gomphonema hebridense Gregory 1854                        GOH
Gomphonema insigne Gregory 1856                          GOIN
Gomphonema parvulum (Kutzing) Kutzing 1849                GP
Gomphonema pseudoaugur Lange-Bertalot 1979                GPA
Gomphonema pseudotenellum Lange-Bertalot in              GPST
  Krammer & Lange-Bertalot 1985
Gomphonema truncatum Ehrenberg 1832                       GT
Gomphonema vibrioides Reichardt &                        GOVI
  Lange-Bertalot 1991
Gomphonema aff. bozenae Lange-Bertalot et                GOBE
  Reichardt in Lange-Bertalot & Metzeltin 1996
Gomphonema sp.                                           GOSP
Gyrosigma baltica (Ehrenberg) Rabenhorst 1853            GBAL
Halamphora acutiuscula (Kutzing) Z. Levkov 2009          AMCU
Halamphora coffeaeformis (Agardh) Z. Levkov 2009         AMCO
Halamphora montana (Krasske) Z. Levkov 2009              AMMO
Halamphora normanii (Rabenhorst) Z. Levkov 2009          AMNI
Halamphora veneta (Kutzing) Z. Levkov 2009               AMVN
Hippodonta capitata (Ehrenberg) Lange-Bertalot,          NACA
  Metzeltin & Witkowski 1996
Hippodonta hungarica (Grunow) Lange-Bertalot,            NCHU
  Metzeltin & Witkowski 1996
Luticola mutica (Kutzing) Mann in Round, Crawford        NAMM
  & Mann 1990
Mastogloia asperuloides Hustedt 1933                     MAAS
Mastogloia braunii Grunow 1863                           MABR
Mastogloia constricta Cleve 1892                         MACO
Mastogloia cyclops Voigt 1942                            MACY
Mastogloia elliptica (Agardh) Cleve in                   MASE
  Schmidt et al. 1893
Mastogloia elliptica var. dansei (Thwaites) Cleve 1895   MDAN
Mastogloia lanceolata Thwaites in W. Smith 1856          MLAN
Mastogloia malayensis Hustedt 1942                       MALY
Mastogloia pseudoelegans Hustedt 1955                    MELP
Mastogloia pusilla Grunow 1878                           MAPP
Mastogloia recta Hustedt 1942                            MREC
Mastogloia smithii Thwaites in lit. ex W. Smith 1856     MASM
Mastogloia smithii var. lacustris Grunow 1878            MASL
Mastogloia aff. gracilis Hustedt 1933                    MAAG
Mastogloia aff. recta Hustedt 1942                       MARC
Mastogloia sp.                                           MASP
Navicula apta Hustedt 1955                               NAPT
Navicula concentrica Carter & Bailey-Watts 1981          NCCA
Navicula cryptotenella Lange-Bertalot in Krammer &        NRT
  Lange-Bertalot 1985
Navicula eidrigiana Carter 1979                          NEDR
Navicula flanatica Grunow 1860                           NAFN
Navicula gregaria Donkin 1861                             NGG
Navicula hasta Pantocsek 1892                            NHAS
Navicula leptostriata Jorgensen 1948                     NLEP
Navicula palestinae Gerloff, Natour & Rivera 1984        NPAE
Navicula perminuta Grunow in Van Heurck 1880             NAPR
Navicula phyllepta Kutzing 1844                          NAPH
Navicula pseudoarvensis Hustedt 1942                      NPS
Navicula pseudocrassirostris Hustedt 1961                NPCO
Navicula radiosa Kutzing 1844                             NRA
Navicula salinarum Grunow 1880                           NRUM
Navicula salinicola Hustedt 1939                         NASA
Navicula schroeteri Meister 1932                         NACH
Navicula subrhynchocephala Hustedt 1935                  NCHO
Navicula subrostellata Hustedt 1955                      NSRO
Navicula subrotundata Hustedt 1945                        NSO
Navicula veneta Kutzing 1844                             NAVE
Navicula sp.                                              NS
Neidium ampliatum (Ehrenberg) Krammer in Krammer         NEAP
  & Lange-Bertalot 1985
Neidium iridis (Ehrenberg) Cleve 1894                     NEI
Oestrupia powelli (Lewis) Heiden ex Hustedt 1935         NPOW
Parlibellus panduriformis John 1991                      PARP
Parlibellus aff. crucicula (W. Smith) A. Witkowski,      NCRU
  H. Lange-Bertalot & D. Metzeltin 2000
Parlibellus sp.                                          PARL
Petroneis sp.                                            PETRO
Pinnularia acrosphaeria Rabenhorst 1853                   PA
Pinnularia alpina Mereschkowsky 1906                     PIAL
Pinnularia appendiculata (Agardh) Cleve 1895             PIAP
Pinnularia borealis Ehrenberg 1843                        PIB
Pinnularia braunii (Grunow in Van Heurck)                 PBR
  Cleve 1895
Pinnularia cuneatiformis Krammer et Metzeltin            PICU
  in Metzeltin & Lange-Bertalot 1998
Pinnularia divergens W. Smith 1853                       PIDI
Pinnularia interrupta W. Smith 1853                      PIIT
Pinnularia major (maior) (Kutzing) Rabenhorst 1853       PIMA
Pinnularia mesolepta (Ehrenberg) W. Smith 1853           PIME
Pinnularia microstauron (Ehrenberg) Cleve 1891           PIMI
Pinnularia subcapitata Gregory 1856                      PISU
Pinnularia tabellaria Ehrenberg 1843                     PITB
Pinnularia stomatophora (Grunow in Schmidt et al.)       PITO
  Cleve 1895
Pinnularia streptoraphe Cleve 1891                       PITR
Placoneis clementioides (Hustedt) Cox 1987               PLCI
Placoneis porifera (Hustedt) E.J. Cox 2003               NPOR
Plagiotropis neovitrea Paddock 1988                      PLVI
Pleurosigma sp.                                          PLSP
Rhoicosphenia abbreviata (C. Agardh)                      GAB
  Lange-Bertalot 1980
Sellaphora densistriata (H. Lange-Bertalot &             SEDE
  D. Metzeltin) H. Lange-Bertalot & D. Metzeltin
  in D. Metzeltin & H. Lange-Bertalot 2002
Sellaphora laevissima (Kutzing) D.G. Mann 1989            NAV
Sellaphora pupula (Kutzing) Mereschkowsky 1902           NAPP
Sellaphora seminulum (Grunow) D.G. Mann 1989              NSM
Sellaphora stroemii (Hustedt) H. Kobayasi in Mayama,     NSTR
  S., Idei, M., Osada, K. & T. Nagumo 2002
Seminavis strigosa (Hustedt) D.G. Mann &                 AMST
  A. Economou-Amilii in D.B. Danielidis
  & D.G. Mann 2003
Seminavis robusta Danielidis & D.G. Mann 2002            SEMI
Seminavis pusilla (Grunow) E.J. Cox & G. Reid 2004       CYMP
Stauroneis anceps Ehrenberg 1843                          SA
Stauroneis nana Hustedt 1957                             STNA
Stauroneis phoenicenteron (Nitzsch) Ehrenberg 1843        SPH
Stauroneis schimanskii Krammer in Krammer                STSH
  & Lange-Bertalot 1985
Stauroneis aff.schimanskii Krammer in Krammer            STAH
  & Lange-Bertalot 1985

Epithemiaceae

Epithemia adnata (Kutzing) Brebisson 1838                 EZ
Epithemia turgida (Ehrenberg) Kutzing 1844                ET
Epithemia sp.                                            EPSP
Rhopalodia acuminata Krammer in Lange-Bertalot           RHAC
  & Krammer 1987
Rhopalodia gibba (C.G. Ehrenberg 1830)                    RG
  O. Muller 1895

Bacillariaceae

Bacillaria paxillifera (O. F. Muller) Hendey 1951        BACX
Denticula elegans Kutzing 1844                            DE
Denticula kuetzingii Grunow 1862                          DKU
Denticula neritica Holmes & Croll 1984                   DNER
Denticula subtilis Grunow 1862                            DSB
Hantzschia amphioxys (Ehrenberg) Grunow in Cleve          HA
  & Grunow 1880
Hantzschia virgata (Roper) Grunow in Cleve &             HAVR
  Grunow 1880
Nitzschia acidoclinata Lange-Bertalot 1976               NIAC
Nitzschia amphibia Grunow 1862                           NIAM
Nitzschia amphibia f. frauenfeldii (Grunow)              NIFE
  Lange-Bertalot in Lange-Bertalot & Krammer 1987
Nitzschia amphibioides Hustedt 1942                       ND
Nitzschia bacillum Hustedt 1922                          NIBU
Nitzschia commutata Grunow in Cleve & Grunow 1880        NTCM
Nitzschia constricta (Kutzing) Ralfs in Pritchard 1861   NICO
Nitzschia distans Gregory 1857                           NDIN
Nitzschia frustulum (Kutzing) Grunow in Cleve            NFRU
  & Grunow 1880
Nitzschia frustulum var. bulnheimiana (Rabenhorst;       NBUL
  Rabenhorst) Grunow in Van Heurck 1881
Nitzschia gessneri Hustedt 1953                          NGSS
Nitzschia gracilis Hantzsch 1860                         NTGR
Nitzschia granulata Grunow 1880                          NGRA
Nitzschia grossestriata Hustedt 1955                     NIGR
Nitzschia hantzschiana Rabenhorst 1860                    NIH
Nitzschia homburgiensis Lange-Bertalot 1978              NIHO
Nitzschia inconspicua Grunow 1862                         NI
Nitzschia lacuum Lange-Bertalot 1980                     NILA
Nitzschia liebethruthii Rabenhorst 1864                  NILI
Nitzschia linearis (Agardh) W. Smith 1853                NILN
Nitzschia littorea Grunow in Van Heurck 1881              NIL
Nitzschia microcephala Grunow 1880                       NIMI
Nitzschia miserabilis Cholnoky 1963                      NBIS
Nitzschia nana Grunow in Van Heurck 1881                 NINA
Nitzschia palea (Kutzing) W. Smith 1856                   NPA
Nitzschia pararostrata (Lange-Bertalot)                  NIPR
  Lange-Bertalot 1996
Nitzschia perminuta (Grunow in Van Heurck)               NIPE
  M. Peragallo 1903
Nitzschia pseudofonticola Hustedt 1942                   NIPF
Nitzschia sigma (Kutzing) W. Smith 1853                  NSIG
Nitzschia sp. 1                                          NISP1
Nitzschia subacicularis Hustedt in Schmidt et al. 1922   NISU
Nitzschia thermaloides Hustedt 1955                      NTOI
Nitzschia vitrea Norman 1861                             NIVT
Tryblionella acuminata W. Smith 1853                     NICU
Tryblionella hungarica (Grunow) Mann in Round,           NIHU
  Crawford & Mann 1990
Tryblionella levidensis W. Smith 1856                    NILE
Tryblionella panduriformis (Gregory) Pelletan 1889       NPAN
Tryblionella scalaris (Ehrenberg) P. Siver               NSCI
  & P.B. Hamilton 2005

Surirellaceae

Campylodiscus echeneis Ehrenberg ex Kutzing 1844         CAEC
Campylodiscus clypeus (Ehrenberg) Kutzing 1844           CAMPY
Stenopterobia delicatissima (Lewis) Van Heurck 1896       SUE
Surirella (Suriraya) elegans Ehrenberg 1843              SUEL
Surirella ovalis Brebisson 1838                           SUO
Surirella sp.                                             SUR
Surirella striatula Turpin 1816-1829                     SUTR

TABLE 4

Microcrustaceans found in aquatic ecosystems in the Northern
Neotropics. Species are ordered alphabetically within
orders and families. Species codes in bold (cladocerans= 32;
copepods= 3; ostracodes=17) were included in multivariate
analysis. Code indicates the species abbreviations used in
figures 6 and 8. For the ecosystem studies see tables 1a,b

Taxa                                                 Code

Cladocerans (n=51)
Order Ctenopoda
Family Sididae
Diaphanosoma brevireme Sars 1901                     DBR
Latonopsis australis group                           LAU
Pseudosida ramosa Daday 1904                         PRA

Order Anomopoda

Family Daphniidae

Ceriodaphnia dubia Richard 1894                      CDU
Ceriodaphnia cf. rigaudi Richard 1894                CRI
Daphnia mendotae Birge 1918                          DME
Daphnia pulicaria Forbes 1893                        DPU
Scapholeberis armata freyi Dumont & Pensaert 1983    SAR
Simocephalus congener (Koch 1841)                    SCO
Simocephalus mixtus Sars 1903                        SMI
Simocephalus serrulatus (Koch 1841)                  SSE

Family Moinidae

Moina minuta Hansen 1899                             MMI
Moinodaphnia macleayi (King 1953)                    MMA

Family Bosminidae

Bosmina huaronensis Delachaux 1918                   BHU
Bosmina tubicen Brehm 1953                           BTU
Bosminopsis deitersi Richard 1895                    BDE

Family Ilyocryptidae

Ilyocryptus spinifer Herrick 1882                    ISP

Family Macrothricidae

Macrothrix elegans Sars 1901                         MEL
Macrothrix paulensis (Sars 1900)                     MPA
Macrothrix cf. spinosa King 1853                     MSP
Streblocerus pygmaeus Sars 1901                      SPY

Family Chydoridae

Alona dentifera (Sars 1901)                          ADE
Alona guttata group                                  AGU
Alona ossiani Sinev 1998                             AOS
Alonella cf. excisa (Fischer, 1854)                  AEX
Anthalona brandorffi (Sinev & Hollwedel 2002)        ABR
Anthalona verrucosa (Sars 1901)                      AVE
Camptocercus dadayi Stingelin 1900                   CDA
Chydorus brevilabris Frey 1980                       CHB
Chydorus eurynotus Sars 1901                         CHE
Chydorus nitidulus Sars 1901                         CHN
Coronatella circumfimbriata (Megard 1967)            CCI
Coronatella monacantha (Sars 1901)                   CMO
Dadaya macrops (Daday 1888)                          DMA
Dunhevedia odontoplax Sars 1901                      DOD
Ephemeroporus barroisi (Richard 1894)                EBA
Ephemeroporus hybridus (Daday 1905)                  EHY
Ephemeroporus tridentatus (Bergamin 1939)            ETR
Euryalona orientalis (Daday 1898)                    EOR
Graptoleberis testudinaria (Fischer 1848)            GTE
Karualona muelleri (Richard 1897)                    KMU
Kurzia longirostris Daday 1888                       KLO
Kurzia polyspina Hudec 2000                          KPO
Leberis davidi (Richard 1895)                        LDA
Leydigia striata Biraben 1939                        LST
Notoalona globulosa (Daday 1898)                     NGL
Oxyurella ciliata Bergamin 1939                      OCI
Oxyuella longicaudis Birge 1910                      OLO
Pleuroxus quasidenticulatus Smirnov 1996             PQU
Pseudochydorus globosus (Baird 1843)                 PSG

Copepods (n=6)

Class Maxillopoda
Subclass Copepoda
Order Calanoida
Family Diaptomidae
Arctodiaptomus dorsalis (Marsh 1907)                 ADO
Leptodiaptomus siciloides (Lilljeborg 1889)          LSI
Mastigodiaptomus nesus Bowman 1986                   MNE
Mastigodiaptomus reidae Suarez-Morales               MRE
& Elias- Gutierrez 2000
Prionodiaptomus colombiensis (Thiebaud 1912)         PCO

Family Pseudodiaptomidae

Pseudodiaptomus marshi Wright 1936                   PMA

Ostracodes (n=29) *

Class Ostracoda

Order Podocopida

Family Darwinulidae

Darwinula stevensoni (Brady & Robertson 1870)        DST

Family Candonidae

Candona sp.                                          CAN
Physocypria cf. denticulata (Daday 1905)             PDE
Physocypria globula Furtos 1933                      PGL
Physocypria xanabanica (Furtos 1936)                 PXA
Pseudocandona sp.                                    PSE
Thalassocypria sp.                                   THA

Family Cyprididae

Candonocypris cf. serratomarginata (Furtos 1936)     CSE
Chlamydotheca colombiensis Roessler 1985             CCO
Cypretta cf. brevisaepta Furtos 1934                 CBR
Cypridopsis okeechobei Furtos 1936                   COK
Cypridopsis vidua (Muller 1776)                      CVI
Eucypris sp.                                         EUC
Heterocypris punctata Keyser 1975                    HPU
Potamocypris sp.                                     POT
Stenocypris major (Baird 1859)                       SMA
Strandesia intrepida Furtos 1936                     SIN
Trajancypris sp.                                     TRA

Family Cytheridae

Perissocytheridea cribosa (Klie 1933)                PCR

Family Cytherideidae

Cyprideis sp.                                        CIS

Family Cytheromatidae

Paracytheroma stephensoni Puri 1954                  PST

Family Cytheruridae

Cytherura sandbergi Morales 1966                     CSA

Family Ilyocyprididae

Ilyocypris cf. gibba Ramdohr 1808                    IGI

Family Limnocytheridae

Cytheridella ilosvayi Daday 1905                     CIL
Elpidium bromeliarum Muller 1880                     EBR
Limnocythere floridensis Keyser 1976                 LFL
Limnocythere opesta Brehm 1939                       LOP
Limnocythere sp.                                     LIM

Family Loxoconchidae

Loxoconcha sp.                                       LOX

* Perez et al. (2011a).

TABLE 5

Results of the Canonical Correspondence Analysis (CCA) and
Redundancy Analysis (RDA) using chironomid,
diatom, cladoceran, ostracode and copepod species data and
forward selected variables (FSV)

                                                 CCA

Axes                                  1       2       3        4

Chironomids; FSV=7
Eigenvalues                         0.141   0.110   0.087    0.080
Species-environment correlations    0.792   0.781   0.864    0.738
Cumulative percentage variance
of species data                      4.8     8.6     11.6    14.4
of species-environment relation     24.8    44.3     59.6    73.6
Sum of all canonical eigenvalues

Diatoms; FSV=7

Eigenvalues                         0.416   0.329   0.260    0.184
Species-environment correlations    0.890   0.947   0.834    0.831
Cumulative percentage variance
of species data                      6.8    12.2     16.4    19.4
of species-environment relation     26.9    48.2     65.0    76.9
Sum of all canonical eigenvalues

Cladocerans, FSV=4

Eigenvalues                         0.273   0.147   0.085    0.069
Species-environment correlations    0.771   0.677   0.635    0.611
Cumulative percentage variance
of species data                      6.4     9.9     11.9    13.5
of species-environment relation     47.5    73.1     87.9    100.0
Sum of all canonical eigenvalues

Ostracodes; FSV=6

Eigenvalues                         0.312   0.133   0.103    0.047
Species-environment correlations    0.792   0.611   0.561    0.398
Cumulative percentage variance
of species data                      9.9    14.2     17.4    18.9
of species-environment relation     49.7    70.9     87.3    94.8
Sum of all canonical eigenvalues
RDA

Calanoid copepodes, FSV=4

Eigenvalues                         0.249   0.106   0.039    0.382
Species-environment correlations    0.637   0.670   0.510    0.000
Cumulative percentage variance
of species data                     24.9    35.5     39.4    77.6
of species-environment relation     63.1    90.1    100.00    0.0
Sum of all canonical eigenvalues

                                      CCA

Axes                                 Total
                                    inertia

Chironomids; FSV=7

Eigenvalues                          2.909
Species-environment correlations
Cumulative percentage variance
of species data
of species-environment relation
Sum of all canonical eigenvalues     0.567

Diatoms; FSV=7

Eigenvalues                          6.111
Species-environment correlations
Cumulative percentage variance
of species data
of species-environment relation
Sum of all canonical eigenvalues     1.545

Cladocerans, FSV=4

Eigenvalues                          4.247
Species-environment correlations
Cumulative percentage variance
of species data
of species-environment relation
Sum of all canonical eigenvalues     0.574

Ostracodes; FSV=6

Eigenvalues                          3.140
Species-environment correlations
Cumulative percentage variance
of species data
of species-environment relation
Sum of all canonical eigenvalues     0.627
RDA

Calanoid copepodes, FSV=4

Eigenvalues                          1.000
Species-environment correlations
Cumulative percentage variance
of species data
of species-environment relation
Sum of all canonical eigenvalues     0.394
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Title Annotation:articulo en ingles
Author:Perez, Liseth; Lorenschat, Julia; Massaferro, Julieta; Pailles, Christine; Sylvestre, Florence; Holl
Publication:Revista de Biologia Tropical
Date:Jun 1, 2013
Words:16523
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