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Comunidade de algas perifiticas em substrato artificial e natural em um tributario do reservatorio de Rosana (Ribeirao do Corvo, Estado do Parana, Brasil).

Periphytic algal community in artificial and natural substratum in a tributary of the Rosana reservoir (Corvo Stream, Parana State, Brazil)

Introduction

The species diversity plays an important role in the processes of production, consumption, respiration and decaying, mainly at littoral regions, since the aquatic vegetation is generally associated to different communities. The high availability of habitats provided by the diversity of aquatic vegetation favors the establishment and development of several organisms, mostly the periphyton (WETZEL, 1981; WETZEL; LIKENS, 1991).

The periphyton is a sessile community that responds punctually to environmental conditions. This community presents short life cycle (3 - 10 days) which allows quick answers to environmental changes (HAMBROOK, 2002; RODRIGUES et al., 2003; WU et al., 2009). The heterogeneity in the structure of phycoperiphytic community may be understood through the species composition in different successional stages. The studies about the distribution and mobility of algae from this community, when analyzed in short time scale, are more suitable due to population changes (WETZEL, 1983). This distribution extremely homogeneous of periphyton and its interaction with natural substrata, coupled to the need to standardize the community development time and the substratum nature, have motivated the use of artificial substrata. The review made by Cattaneo and Amireault (1992) indicated that 60% from published papers had used different types of artificial substrata.

In Brazil, among the published researches with artificial substratum reproducing a natural one are those using glass tubes (MOSCHINI-CARLOS et al., 2000), glass slides (RODRIGUES; BICUDO, 2001, 2004) and plastic tubes (FERNANDES; ESTEVES, 2003) to compare with petioles of emerging macrophytes, whereas other studies had used polyamide strings (OLIVEIRA et al., 2001) and glass slides (VERCELLINO; BICUDO, 2006) to analyze the structure and dynamic of periphytic algae community. Although Brazil presents one of the major hydroelectric parks of the world, the knowledge about periphyton in these environments is still scarce.

This study hypothesized that the composition of periphytic algae varies in function to the type of substratum (artificial and natural) and/or due to abiotic conditions of the system. The prediction is that in the course of time the phycoperiphytic community from an artificial substratum will be similar to that found in natural one, considering the species composition, and that both communities will be mainly influenced by nutrient concentrations. Therefore, we analyzed (a) the floristic composition from the community of periphytic algae in both substrata of one tributary of Rosana reservoir, Corvo Stream, during a warm and rainy period; (b) the algae similarity, between artificial and natural substratum; and (c) the principal abiotic factors influencing the species composition and richness of phycoperiphytic community, in both substrata.

Material and methods

Study area

The samplings location is one tributary that flows into the lacustrine region from Rosana reservoir (Corvo Stream, 22[degrees]39'S; 052[degrees]46'W, Figure 1), near the dam. This river is situated in Parana State, between the counties of Diamante do Norte and Terra Rica. The sampling station was 4.95 km far from the lacustrine region of the reservoir.

[FIGURE 1 OMITTED]

Corvo Stream presents, in the sampling local, approximately 250 m of width and 5.8 m of depth. The banks practically did not present arborous vegetation, and the littoral region present several ecological types of aquatic macrophytes: emerged (Typha sp., Sagittaria sp. and Eichhornia azurea Kunth), floating (Eichhornia crassipes (Mart.) Solms, Nymphaea sp. and Salvinia sp.) and rootedsubmersed (Cabomba furcata (Schult.) Schult., Egeria densa Planchon, Egeria najas Planchon, Miriophyllum sp. and Utricularia foliosa Lineau).

Samplings and analyses

Periphyton samplings were performed from November 21st to December 12nd, 2003, a period characterized as warm and rainy. Two types of substrata were chosen for the samplings: Egeria najas (natural substratum) and a plastic plant (artificial substratum), similar to natural substratum (Figure 2).

For the natural substratum, a fragment of Egeria najas was removed from the environment, and a median part was detached (about 7 to 8 cm of length), excluding the apex and base. Afterwards, this median part was transfered to previously moistened flasks, and kept in ice, and later the periphyton was removed for analysis. The samplings of both substrata were carried out in the lacustrine region of the environment. For the artificial substratum, each one was washed in running water and after this; each branch was attached to a weight (pebbles wrapped in plastic) using a nylon line, and Styrofoam pieces as buoys. These sets were put in Corvo Stream, close to the left bank, about 60 cm of depth, in November 21st.

[FIGURE 2 OMITTED]

Samplings of artificial substratum occurred every three days, between November 24th (1st sampling and 3rd successional days) and December 12nd, 2003 (last sampling and 21st day), while for the natural substratum, the samplings began at the first day of installation of artificial substratum (11/21), and during alternate days (11/26; 01, 06, 09 and 12/12), totaling 13 samples (six for the natural substratum, and seven for the artificial one). The periphyton was washed from the substrata using brush and distilled water, and then transferred to transparent flasks. The samples were preserved with Transeau solution (BICUDO; MENEZES, 2006).

Abiotic data evaluated in the study were furnished by Limnology Laboratory, from Nucleo de Pesquisas em Limnologia, Ictiologia e Aquicultura -- Nupelia. Water temperature (YSI 55 portable oximeter), turbidity (LaMotte portable turbidimeter) and wind (anemometer) were measured during the samplings. The concentrations of total nitrogen, total phosphorus and total dissolved phosphorus were determined based on Valderrama (1981), nitrate, ammonium and orthophosphate were estimated according to Mackereth et al. (1978), Solorzano (1969) and Golterman et al. (1978), respectively.

The taxonomical study of periphytic algae was accomplished using approximately 15 temporary slides, by sample. For this procedure, we used optical microscope with micrometric ocular. Some genera of green filamentous algae, as Bulbochaete, Oedogonium, Mougeotia and Spirogyra, were distinguished only in vegetative groups, based on the cells diameter and length, due to the absence of reproductive structures in the analyzed individuals.

The algae identification was based on classical literature, as Croasdale and Flint (1986, 1988), Dillard (1990, 1991), Forster (1982), Komarek and Anagnostidis (1999, 2005), Krammer and LangeBertalot (1986, 1988, 1991), Patrick and Reimer (1966, 1975), Prescott (1982), Prescott et al. (1981, 1982) among others. Regarding the classification system of algae, we adopted Round (1965, 1971), following the recommendation made by Bicudo and Menezes (2006).

The species richness, expressed in number of taxa for both substrata, was obtained from qualitative samples complemented with quantitative samples.

The similarity of periphytic algae from artificial and natural substratum, between the sampled periods, was analyzed using the Jaccard similarity index (species presence/absence data), using NTSYS software, version 2.1 (ROHLF, 2000) and unweighted average (UPGMA).

The values of total richness of algae classes from both substrata were correlated with the abiotic variables, through Pearson correlation analysis, using Statistica software, version 7.1 (STATSOFT, 2005).

Results

Floristic composition

The community of periphytic algae comprised 495 taxa distributed in 133 genera and 11 classes, considering both substrata (natural and artificial) (Table 1). Among these taxa, 403 occurred in the natural substratum, and 401 in the artificial one. In the table 1, the complete list of species is presented, and, from this total, 86 taxa occurred exclusively in the natural substratum, and 98 in the artificial. The most representative classes in the natural and artificial substratum were Zygnemaphyceae (37.2 and 36.4%, respectively) Bacillariophyceae (21.6 and 24.7%, respectively), Chlorophyceae (17.4 and 17.2%, respectively) and Cyanophyceae (13.2 and 12%, respectively).

Amongst Zygnemaphyceae, Staurodesmus, Closterium, Staurastrum and Cosmarium (66.5% from the total of Desmidiales) were the best represented genera, in both substrata. Bacillariophyceae, Order Pennales, presented Gomphonema and Eunotia as the most representative genera regarding the number of taxa. Among Chlorophyceae, Characium, Desmodesmus and Scenedesmus were the best represented (Table 1).

Therefore, independently of substratum type, we verified the predominance of Zygnemaphyceae (desmids), followed by Bacillariophyceae (diatoms), Chlorophyceae and Cyanophyceae (Table 1, Figure 4).

The number of species, in natural substratum, ranged from 156, in December 12nd (final of the experiment, 6th sampling) to 261 taxa, in November 26th (beginning of the experiment, 2nd sampling), thus, we observed a sudden decrease in the number of species during the final phase (Figure 3). In relation to artificial substratum, this number varied between 169, in December 9th (18th day), and 259 taxa, in December 6th (15th day).

[FIGURE 3 OMITTED]

In the natural substratum, there was a change in the number of desmids taxa, in December 6th (4th sampling), when we registered an expressive contribution of diatoms. The same was observed for the artificial substratum, however, in the last two samplings (December 9th and 12th, 18th and 21st successional days, Figure 4).

[FIGURE 4 OMITTED]

Taxonomic similarity in periphytic community

In the diagram from the grouping analysis performed with periphytic algae from both substrata, there was a separation of groups, for the distinct substrata. Two groups were distinguished for artificial and natural substratum (Figure 5). For the artificial substratum, the assemblages of species referring to 3rd and 6th successional days (1st and 2nd samplings) were distinguished amongst themselves, and from the other days; a second group was formed, between the 9th and 12nd days (3rd and 4th samplings). The 15th successional day (5th sampling) was distinct from the others, however presented higher similarity with the final phase of the experiment, between the 18th and 21st days (Figure 5).

For the natural substratum, the results pointed higher similarity among the samples from the three last samplings (December 6th, 9th and 12th), otherwise, the sample of the beginning of the experiment (November, 21st) was grouped with intermediary experimental phase (November 26th, and December 1st; Figure 5).

[FIGURE 5 OMITTED]

The values referring to physical and chemical parameters of the water, electric conductivity, dissolved oxygen, water temperature and pH presented more constant values, while the other variables as nutrient concentrations and turbidity presented higher variation (Table 2).

Relationship between abiotic variables and phycoperiphytic community

In Paranapanema river watershed, as well as in Corvo Stream (lateral arm from Rosana reservoir), here is a precipitation regime, with concentration of rainfall between November to February, period characterized as warm and rainy. In the study period (November-December), there was higher volume of precipitation at the end of November (11/28, 1st study week) and beginning of December (12/01, Figure 6), two days before the 4th sampling, 12nd successional day at artificial substratum.

[FIGURE 6 OMITTED]

This high precipitation along with the strong winds during the study period was responsible for the high quantity of material carried into the reservoir, contributing to increase the turbidity and nutrients concentration, which influenced the species composition of periphytic algae. In this way, the number of taxa recorded in the natural substratum was positively correlated to NT (r = 0.95), PT (r = 0.88), P[O.sub.4.sup.-3] (r = 0.93), PDT (r = 0.84) during the 1st week. This community attribute was also positively correlated to P[O.sub.4.sup.-3] (r = 0.92) during the 2nd week, and also with the turbidity (r = 0.93) in the 3rd week.

Considering the artificial substratum, during the 1st week, the species richness of phycoperiphitic species was positively correlated to PT (r = 0.93), N[H.sub.4.sup.+] (r = 0.97), turbidity (r = 0.91), and wind (r = 0.99).

During the 2nd week, positive correlations were observed between the species richness and N[O.sub.3.sup.-] (r = 0.95), and wind (r = 0.88), whereas negative correlations were verified with PDT (r = -0.97), and turbidity (r = -0.93). In the 3rd week, a negative correlation was registered with the turbidity (r = -0.98).

Discussion

The increase in species richness observed during the first days of colonization in the artificial substratum, was possibly due to the propagules present in the environment, since the habitat was not yet colonized, the migration processes favor the colonization and succession of species, allowing the composition of not only colonizing and opportunistic species of diatoms, as well as Chlorococcales, Desmidiales and filamentous algae, as Bulbochaete and Oedogonium. The immigration is an important process in the composition, colonization and increase of periphytic algae in artificial substratum (HILLEBRAND; SOMMER, 2000; PETERSON, 1996; STEVENSON; PETERSON, 1989).

The decrease in the number of species in the natural substratum over the experiment occurred during the days with higher pluviometric intensity. On the other hand, in artificial substratum, there was a different result, possibly, because this substratum is under succession process, since the increase in the number of species was gradate until November 30th (9th successional day and 3rd sampling), with a decrease in December 3rd (12nd day and 4th sampling). This reduction during the 4th sampling for both substrata may be related to the high precipitation that occurred in November 28th and mainly during the night of December 1st, i.e., two days before the sampling. From this period, the environmental conditions stabilized and hence, the number of species reached the maximum values during the 5th sampling (December 6th, 15th successional day), decreasing drastically again from the 6th sampling (December 9th, 18th day).

The oscillation in the species heterogeneity may be explained by the predominance of resilient species in phycoperiphytic community. These species can recover from disturbing events, as fluctuations in water level and large movement of the water column, caused by rainfall and constant winds. Based on studies about the succession of periphytic algae, the assemblages would be more resilient in more heterogeneous environments (more diversified environmental conditions in face of disturbing events, e.g., rainfall, wind), than in homogeneous ones, because the species diversity in one habitat, would increase the efficient use of available resources (STEVENSON, 1997). The high resistance of many diatoms to wave's effect, even flooding, shows competitive advantages (BIGGS; THOMSEN, 1995; PETERSON, 1996; SABATER et al., 1998; STEVENSON, 1996b), and allows greater representativeness in rivers with high frequency of flooding. A. minutissimum, e.g., (species present in all samplings from both substrata), is widely recorded as intermediary colonizer, and highly resistant to disturbances (BIGGS; THOMSEN, 1995; PETERSON, 1996).

The differentiation of phycoperiphytic community in artificial substratum, was evidenced by the grouping analysis, in three phases: the initial, mainly formed when the community receives a gradate increase of species; the intermediate, when there is still an increase in the number of species, reaching a maximum; and the final phase, when there is a severe decrease in number of species, probably due to the replacement and addition of species in different successional stages. The exposure time necessary to periphyton community reaches the maturity stage (maximum in the number and density of species) may vary from two weeks to longer periods, depending on the type of environment, water temperature and the type substratum (LOBO; BUSELATO-TONIOLL, 1985; PATRICK; REIMER, 1975; SABATER et al., 1998). In Corvo Stream, this phase was achieved until the 15th colonization day, as also verified in other studies (CATTANEO et al., 1975; LAM; LEI, 1999; RODRIGUES; BICUDO, 2001).

Moreover, the environmental processes of each habitat, exert a direct influence on the development, composition, and distribution of phycoperiphytic community, specifically concerning the algal flora of each location (CASCO; TOJA, 1994; STEVENSON, 1996a,). Consequently, the high variation in nutrient concentrations (especially phosphorus and nitrogen), mainly from rainfall and constant winds that cause greater displacement of allochthonous material into the environment, besides the resuspension of sediment for the water column, elevating the turbidity, indicate a possible influence on the number and composition of species. On the one hand, when these events are more intense (high precipitation, strong winds) there may be a negative influence, as seen during the 4th sampling, both in natural and artificial substrata, when a sharp decrease in species number was detected. Otherwise, the positive effects of environmental variables previously mentioned may be corroborated by the correlations between the species richness with nutrients (especially phosphorus and nitrogen), turbidity, wind and rainfall.

The highest number of Zygnemaphyceae species, followed by Bacillariophyceae, in both substrata, leads to a greater representativeness of these unicellular algae. Unicellular organisms are fast colonizers, due to their high reproductive rate; while the colonial or filamentous organisms are slower in propagation process (HILLEBRAND; SOMMER, 2000). These traits should influence the phycoperiphytic communities in the upper Parana river floodplain, considering the high predominance of these non-flagellate unicellular forms, in the studied environments (RODRIGUES; BICUDO, 2004).

The contribution of diatoms, with several species of Eunotia (higher number of species in Penales), forming large filaments of cells aggregate in chains (E. pectinalis, E. sudetica and E. camelus), or composing extensive 'arborescent colonies' connected by the edges (E. flexuosa and E. lineolata), among others, may be associated to morphological and adaptive traits from each taxa, since these algae are better adapted to periphytic habit, besides being grouped and involved in mucilage sheaths that favor the better attachment to the substrata.

The great representativeness of Zygnemaphyceae (desmids) may be related in part to the amount of available substratum for colonization (diversity of aquatic vegetation), and the high values of nutrients and to the water temperature; and also due to the unicellular condition with mucilage sheaths around the cells. In a study of colonization by periphytic algae in glass slides close to macrophyte stands, Rodrigues and Bicudo (2001) related the high richness of desmids in the periphytic community to the presence of macrophyte stands. Diversified flora of desmids presents faster growth at warmer temperatures, with optimum ranging from 25[degrees]C to 30[degrees]C (COESEL, 1996; COESEL; WARDENAAR, 1990; FELISBERTO; RODRIGUES, 2005a and b). In this way, Corvo Stream, tropical environment, with temperatures varying between 26 and 28[degrees]C, with high nutrient concentrations and diversity of aquatic vegetation, is a favorable local to the development of this algal flora.

Regarding the Chlorococcales, Desmodesmus and Scenedesmus are exceptionally common in any environment, oligo, meso or eutrophic (BICUDO; MENEZES, 2006; LURLING, 2003), and are among the first to colonize the environment (BICUDO; MENEZES, 2006). The high variation in nutrient concentrations of the studied environment allowed the development of species from this Order. Additionally, Characium species, possibly due to the development stage of periphytic biofilm, were favored by the increase of filamentous green algae (as Oedogonium and Bulbochaete) and also by the quantity of species from the Eunotia genus, to which they were fixed through attaching discs.

In summary, the results of taxonomical composition of periphytic algae in natural (Egeria najas Planchon) and artificial (plastic plant) substratum were similar, revealing that the development of these algae were also related to environmental conditions, over time. The grouping analysis enabled to register three growth phases of the community, with a maximum peak at 15[degrees] successional day, which allow suggesting that the community achieved the maturity stage. Thus, we may state that the heterogeneity in the structure of phycoperiphytic community may be understood through species composition in different succession stages. Furthermore, the number of species, regardless the substratum type, was positively related to the higher nutrient availability, higher values of turbidity, especially during the first week; and negatively related to the turbidity, during the second and third weeks.

DOI: 10.4025/actascibiolsci.v32i4.4627

Acknowledgements

We wish to thank the Nucleo de Pesquisas em Limnologia, Ictiologia e Aquicultura--Nupelia, and PEA (Programa de Pos-Graduacao em Ambientes Aquaticos Continentais) from the State University of Maringa, for the logistic, technical and scientific support during the accomplishment of this study; to Capes for the scholarship. We also thank to Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) for productivity scholarship to LR. This research is inserted in PRONEX Project 'Produtividade em Reservatorio: relacoes com o estado trofico e predacao', developed by Nupelia.

Received on July 28, 2008.

Accepted on July 15, 2009.

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Sirlene Aparecida Felisberto (1) * and Liliana Rodrigues (2)

(1) Universidade Federal de Goias, Campus Samambaia, Cx. Postal 131, 74001-970, Goiania Goias, Brazil. (2) Universidade Estadual de Maringa, Maringa, Parana, Brazil. *Author for correspondence. Email: sirfe@hotmail.com
Table 1. Taxa of periphytic algae surveyed in Corvo Stream
(tributary of Rosana reservoir), in the study period.

Bacillariophyceae

Achnanthidium exiguum (Grun.)        Gomphonema augur Ehr. **
  Czarn.
A. minutissimum (Kutz.) Czarn.       Gomphonema augur Ehr. var. turris
                                       (Ehr.) Lang.-Bert.
Amphipleura lindheimerii Grun.       Gomphonema cf. auritum Braun ex
                                       Kutz.
Amphora copulata (Kutz.) Schoem.     Gomphonema brasiliense Grun.
  & Arch.
Amphora cf. oualis (Kutz.)           Gomphonema gracile Ehr.
  Kutz. **
Amphora sp.                          Gomphonema paruulum Kutz.
Aulacoseira granulata (Ehr.) Sim     Gomphonema subtile Ehr. **
Aulacoseira granulata (Ehr.) Sim.    Gomphonema cf. truncatum Ehr. *
  var. angustissima (O. Mull.)
  Sim. **
Aulacoseira sp. *                    Gomphonema sp.
Brachysira neoxilis Hor.             Gomphonema sp.1 *
  Lang.-Bert. & Mos.
Capartogramma crucicula              Hantzschia amphioxys (Ehr.) Grun.
  (Grun. & Cleve) **
Cyclotella stelligera (Cleve &       Nauicula aikenensis Patr.
  Grun.) V. Heur.
Cymbella acuta (A. Schm.) Cleve      Nauicula constans Hust.
Cymbella afinis Kutz.                Nauicula cryptocephalla Kutz.
Cymbella cuspidata Kutz.             Nauicula cryptotonella Lang.-Bert.
Cymbella cf. moreirae (Rod.) Ludw.   Nauicula cf. drouetiana Patr. **
Cymbella cf. mycrocephala Grun. *    Nauicula cf. menisculus Schum. **
C. nauiculiformes Auer. ex Heib.     Nauicula cf. tenera *
Diatoma sp.                          Nauicula sp. *
Diploneis cf. suboualis Cleve        Nitzschia amphibia Grun.
Encyonema lunatum (Smith) V.         Nitzschia frustulum Grun. **
  Heur. *
Encyonema mesianum (Chol.) Mann *    Nitzschia cf. intermedia Hantz.
                                       ex Cleve & Grun.
Encyonema minutum (Hil.) Mann *      Nitzschia cf. linearis Grun.
Encyonema cf. perpusillum Cleve      Nitzschia palea (Kutz.) Smith
  & Mann *
Encyonema silesiacum (Bleis.)        Nitzschia sp. *
  Mann *
Encyonema sp.                        Penales unidentified 1
Encyonema sp.1                       Penales unidentified 2 *
Eunotia bilunaris Ehr.               Pinnularia cf. braunii Grun. *
Eunotia camelus Ehr.                 Pinnularia diuergens Smith
Eunotia curuata (Kutz.) Lagerst.     Pinnularia gibba Ehr.
Eunotia didyma Hust.                 Pinnularia interrupta Smith
Eunotia cf. faba (Ehr.) Grun. *      Pinnularia luculenta A. Schm.
Eunotiafexuosa Breb.                 Pinnularia maior (Kutz.) Rab.
Eunotia formica Ehr.                 Pinnularia mesolepta (Ehr.) Smith
Eunotia indica Grun.                 Pinnularia cf. microstauron
                                       (Ehr.) Cleve *
Eunotia lineolata Hust.              Pinnularia subcapitata Greg. *
Eunotia maior (Smith) Rab.           Pinnularia uiridis (Nitz.) Ehr.
Eunotia cf. minor (Kutz) Grun. *     Pinnularia sp.
Eunotia monodon Ehr. *               Placoneis disparilis (Hust.)
                                       Lang.-Bert.
Eunotia pectinalis (Dillw.) Rab.     Planothidium lanceolatum (Breb.)
                                       Round & Bukh. *
Eunotia pectinalis (Dillw.) Rab.     Pleurosira laeuis (Ehr.) Comp.
  var. ventricosa Grun.
Eunotia sudetica O. Mull.            Rhopalodia cf. brebissoni Kram. *
Eunotia zygodon Ehr. *               Rhopalodia gibberula (Ehr.) O.
                                       Mull. **
Fragilaria capucina Desm.            Sellaphora pupulla Kutz.
Fragilaria capucina Desm. var.       Stauroneis phoenicenteron (Nitz.)
  gracilis (Oestrup) Hust.             Ehr.
Fragilaria delicatissima (Smith)     Stenopterobia delicatissima
  Lang.-Bert.                         (Lew.) Breb. ex V. Heur.
Fragilaria jauanica Hust. *          Stenopterobia intermedia (Lew.)
                                       V. Heur.
Frgilaria pinnata Ehr. *             Surirella bisseriata Breb.
Frustulia rhomboides (Ehr.)          Surirella linearis Smith
  De Toni var. rhomboides
Frustulia rhomboides (Ehr.)          Surirella cf. robusta Hust. **
  De Toni var. crassineruia
  (Breb. ex Smith) Ross
Frustulia rhomboides (Ehr.)          Surirella sublinearis Hust.
  De Toni var. saxonica (Rab.)
  De Toni
Frustulia cf. uitrea Oestrup *       Surirella sp.
Frustulia uulgaris (Thwait.)         Synedra acus Kutz. var.
  De Toni *                            angustissima Grun. *
Frustulia sp. *                      Synedra goulardii Breb. *
Gomphonema afine Kutz.               Ulnaria ulna (Nitz.) Ehr.
Gomphonema cf. apicatum Ehr. *       Talassiosira sp. **
Ankistrodesmus falcatus (Corda)      Dimorphococcus lunatus Braun *
  Ralfs
Ankistrodesmusfusformis Corda        Drepanochloris uherkouichii
                                       Marvan
Ankistrodesmus spiralis (Turn.)      Gloeocystis cf. gigas (Kutz.)
  Lemm.                                Lagerh. **
Aphanochaete repens Braun            Golenkinia radiata (Chod.)
                                       Wille **
Bicuspidela cf. incus Pasch.         Kirchneriella lunaris (Kirch.) *
Botryococcus sp.                     Kirchneriella obesa (West) West
                                       & G.S.West *
Chaetosphaeridium globosum           Monoraphidium arcuatum (Korsh.)
  (Nord.) Kleb.                        Hind.
Chaetosphaeridium sp. *              Monoraphidium caribeum Hind.
Characiellopsis skujae (Fott)        Monoraphidium circinale (Nyg.)
  Kom.                                 Nyg.
Characium cf. acuminatum Braun **    Monoraphidium contortum (Thur.)
                                       Kom.-Legn.
Characium ambiguum Herm.             Monoraphidium griffithii (Berk.)
                                       Kom.-Legn. **
Characium cf. cucurbitinum           Monoraphidium sp. *
  (Biss.) Teil. *
Characium ensiforme Herm.            Oocystis lacustris Chod. *
Characium guttula Play.              Pediastrum duplex Meyen
Characium ornithocephalum            Pediastrum duplex Meyen var.
  (Braun) var. ornithocephalum         subgranulatum Racib.
Characium ornithocephalum (Braun)    Pediastrum tetras (Ehr.) Ralfs
  var. hapochytriiforme Prin.
Characium ornithocephalum (Braun)    Planktosphaeria gelatinosa Smith
  var. pringsheimii (Braun) Kom.
Characium sp. **                     Radiococcus sp. *
Chlamydomonas cf. globosa Snow       Scenedesmus antennatus Breb.
Chlamydomonas sp.                    Scenedesmus acuminatus (Lagerh.)
                                       Chod.
Closteriopsis acicularis (Smith)     Scenedesmus cf. acunae Comas **
  Belc. & Swale
Coelastrum indicum Turner            Scenedesmus acutus (Meyen) Chod.
Coleochaete cf. irregularis          Scenedesmus acutus (Meyen) Chod.
  Prings. **                           var. alternans Hortob.
Coleochaete orbicularis              Scenedesmus acutus (Meyen) Chod.
  Prings. **                           var. globosus Hortob.
Coleochaete sp.                      Scenedesmus bijugus (Turp.) Kutz.
Crucigenia sp.                       Scenedesmus jauanensis Chod. *
Desmodesmus cf. abundans (Kirch.)    Scenedesmus linearis Kom. *
  Hegew.
Desmodesmus armatus (Chod.)          Scenedesmus cf. regularis Svir. *
  Hegew.
Desmodesmus armatus (Chod.) var.     Scenedesmus wisconsinensis
  bicaudatus (Gugl.) Hegew.            (Smith) Chod. **
Desmodesmus cf. armatus (Chod.)      Scenedesmus sp.
  var. spinosus (Frit. & Rich)
  Hegew. **
Desmodesmus communis (Hegew.)        Selenastrum gracile (Rein.)
  Hegew.
Desmodesmus denticulatus             Selenastrum rinoi Kom. et Com. *
  (Lagerh.) Friedl & Hegew.
Desmodesmus denticulatus
  (Lagerh.) Friedl & Hegew. var.
  linearis (Hansg.) Hegew.
  Sphaerocystis schroeteri
  Chod. **
Desmodesmus dispar Breb.             Stigeoclonium sp.
Desmodesmus maximus (W. &. G.S.      Tetraedron caudatum (Corda)
  West) Hegew.                         Hans. **
Desmodesmus opoliensis (Rich.)       Tetraedron minimum (Braun) Hans. *
  Hegew. var. carinatus (Lemm.)      Tetraedron regulare Kutz. **
  Hegew. *
Desmodesmus perforatus (Lemm.)       Tetrastrum sp. **
  Hegew.
Desmodesmus quadricauda (Turp.)      Westella sp.
  Hegew.
Desmodesmus serratus (Corda)         Chlorococcales unidentified
  Friedl & Hegew.
Desmodesmus spinosus (Chod.)         Chlorococcales unidentified 1
  Hegew.
Dictyosphaerium pulchellum Wood *    Chlorococcales unidentified 2
Dictyosphaerium sp. *

Cyanophyceae

Anabaena cf. affinis Lemm. **        Lyngbya maior Men.
Anabaena cf. circinalis Rab. **      Merismopedia glauca (Ehr.)
                                       Kutz. **
Anabaena spiroides Kleb.             Merismopedia tenuissima Lemm.
Anabaena sp.                         Merismopedia sp. *
Anabaena sp.1 **                     Microcrocis cf. irregularis
                                       (Lagerh.) Geitler
Aphanocapsa elachista W. & G.S.      Microcrocis cf. pulchella (Buell)
  West                                 Geitler **
Aphanocapsa delicatissima W. &       Microcystis aeruginosa (Kutz.)
  G.S. West **                         Lemm.
Aphanocapsa greuillei Raben.         Microcystis firma (Breb. et Len.)
                                       Schm.
Aphanocapsa cf. pulchra (Kutz.)      Oscillatoria cf. curuiceps
  Raben. *                             Agardh. **
Aphanocapsa sp.                      Oscillatoria principes Vaucher
Calothrix sp. *                      Oscillatoria sancta (Kutz.) Gom.
Chamaesiphon incrustans Grun.        Planktolyngbya limnetica (Lemm.)
                                       Kom.-Legn.
Chamaesiphon sp.                     Planktolyngbya sp.
Chroococcus minor (Kutz.) Nag.       Phormidium cf. chlorinum (Kutz.)
                                       Umez. & Wat.
Chroococcus minimus (Keis.) Lemm.    Phormidium irriguum (Kutz. Ex
                                       Gom.) Anag. & Kom.
Chroococcus sp.                      Planktothrix agardhii Anag. &
                                       Kom. *
Coelosphaerium aerugineum Lemm. *    Pseudanabaena catenata Laut.
Geitleribactron periphyticum         Pseudanabaena lonchoides Anag.
  Kom. **
Geitlerinema jasoruense (Vouk)       Pseudanabaena moniliformes Kom.
  Anag. **                             & Kling
Geitlerinema splendidum (Grev.)      Pseudanabaena mucicula
  Anag.                                (Hub.-Pest. & Naum.) Schw.
Gloeocapsa cf. rupestris             Radiocystis fernandoi Kom. &
  Kutz. **                             Kom.-Legn.
Gloeocapsa sp.                       Rhabdoderma irregulare (Naum.)
                                       Geitler **
Gloeocapsopsis sp. **                Rhabdoderma lineare Schm. & Laut.
Jaaginema quadripunctulatum          Rhabdoderma uermiculare Fott
  (Bruhl. & Bisw.) Anag. & Kom.
Komuophoron crassum (Voz.) Anag.     Rhabdoderma sp. **
  & Kom.
Komuophoron minutum (Skuja) Anag.    Snowella sp.
  & Kom. *
Komuophoron schmidlei (Jaag)         Spirulina laxa Smith
  Anag. & Kom.
Leptolyngbya fragilis (Gom.)         Synechocystis sp. *
  Anag. & Kom. **
Leptolyngbya lagerheimii (Gom.)      Woronichinia elorantae Kom. &
  Anag. & Kom.                         Kom.-Legn. *
Leptolyngbya perelegans (Lemm.)      Chroococcales unidentified *
  Anag. & Kom.
Lyngbya comperei Senna

Chrysophyceae

Bicoeca cf. synoica Skuja            Salpingoeca serpettei Bourr. **
Dinobryon diuergens Imhof            Salpingoeca urceolata Kent
Dinobryon sertularia Ehr.            Salpingoeca sp.
Mallomonas sp.                       Synura sp. *
Salpingoeca marsonii Lemm. *

Cryptophyceae

Cryptomonas ouata Ehr. **            Cryptomonas sp.

Dinophyceae

Peridinium cf. cinctum O. Mull. *    Peridinium sp. *
Peridinium cf. uolzii Lemm.

Euglenophyceae

Colacium sp.                         Phacus cf. pusillus Lemm. **
Euglena cf. acus Ehr. **             Phacus cf. raciborskii Drez. **
Euglena cf. gracilis Klebs           Phacus sp. **
Euglena cf. spirogyra Ehr. *         Strombomonas sp. **
Euglena uiridis Ehr. **              Trachelomonas cf. bernardi
                                       Wolos. **
Euglena sp.                          Trachelomonas crispa Balech
Lepocinclis sp.                      Trachelomonas hispida (Perty)
                                       Stein. *
Phacus acuminatus Stokes             Trachelomonas intermedia Dang.
Phacus curuicauda Swir. *            Trachelomonas klebsii Ehr. **
Phacus cf. polytrophos Poch. *       Trachelomonas sp.

Oedogoniophyceae

Bulbochaete sp. *                    Oedogonium sp.
Bulbochaete sp.1                     Oedogonium sp.1
Bulbochaete sp.2                     Oedogonium sp.2
Bulbochaete sp.3 *                   Oedogonium sp.3
Bulbochaete sp.4                     Oedogonium sp.4

Ulothricophyceae

Ulothrix sp.                         Uronema sp. **
Uronema elongatum Hodg.

Xanthophyceae

Characiopsis acuta (Braun)           Characiopsis sphagnicola
  Borzi **                             Pascher **
Characiopsis aquilonaris Skuja       Isthmochhoron lobulatum (Nag.)
                                       Skuja **
Characiopsis elegans Ettl            Stipitococcus uasiformis Tiff.
Characiopsis minuta (Braun)
  Lemm. **

Zygnemaphyceae

Actinotaenium diplosporum (Lund.)    Haplotaenium minutum (Ralfs)
  Teil. **                             Bando **
Actinotaenium globosum (Bulnh.)      H. minutum (Ralfs) Bando var.
  Teil.                                attenuatum (W. West) Bando **
Actinotaenium lagenarioides (Roy)    Hyalotheca dissiliens (Smith)
  Teil. *                              Breb. ex Ralfs
Closterium acutum Ehr. *             Micrasterias abrupta West & G.S.
                                       West *
C. acutum Ehr. var. uariabile        Micrasteriasfurcata Ralfs
  (Lemm.) W. Krieg.
Closterium closterioides (Ralfs)     Micrasterias laticeps Nordst.
  Louis & Peet. *                      var. acuminata W. Krieg. **
Closterium closterioides (Ralfs)     Micrasterias laticeps Nordst.
  Louis & Peet. var. intermedium       var. laticeps
  (Roy & Biss.) Ruz. *
Closterium cornu Ehr. ex Ralfs       Micrasterias mahabuleshwarensis
                                       Hobs.
Closterium cynthia de Not.           Micrasterias radiosa Ralfs var.
                                       radiosa
Closterium dianae Ehr. ex Ralfs      Micrasterias radiosa Ralfs var.
  var. minus Hieron.                   elegantior (G.S. West) Croasd.
Closterium ehrenbergii Menegh.       Micrasterias rotata (Grev.) Ralfs
  ex Ralfs **                          ex Ralfs **
Closterium exiguum West & G.S.       Micrasterias truncata (Corda)
  West *                               Breb. ex Ralfs var. pusilla
                                       G.S. West
Closterium gracile Breb.             Mougeotia sp.
Closterium incuruum Breb.            Mougeotia sp.1
Closterium jenneri Ralfs             Mougeotia sp.2
Closterium laterale Nordst. **       Mougeotia sp.3
Closterium leibleinii Kutz.          Mougeotia sp.4
  ex Ralfs
Closterium moniliferum (Bory)        Mougeotia sp.5 **
  Ehr. ex Ralfs
Closterium nauicula (Breb.) Lutk.    Netrium digitus (Ehr.) Itzigs.
                                       & Rothe
Closterium nematodes Josh. var.      Netrium digitus (Ehr.) Itzigs.
  proboscideum Turn. **                & Rothe var. paruum (Borge)
                                       Krieg. **
Closterium pusillum Hantzsch **      Netrium oblongum (De Bary)
                                       Lutk. *
Closterium setaceum Ehr. ex Ralfs    Octacanthium mucronulatus
                                       (Nordst.) Comp.
Closterium tortum B.M.               Onychonema laeue Nordst.
  Griffiths **
Closterium toxon W. West             Penium exiguum West *
Closterium tumidum Johns.            Penium margaritaceum (Ehr.)
                                       ex Breb.
Closterium tumidum Johns. var.       Pleurotaenium ehrenbergii (Breb.)
  nylandicum Gronbl.                   de Bary
Closterium uenus Kutz. ex Ralfs *    Pleurotaenium nodosum (Bail.)
                                       Lund. **
Closterium sp.                       Sphaerozosma aubertianum W.
                                       West *
Cosmarium abbreuiatum Racib. var.
  minus (West & G. S. West) W.
  Krieg. & Gerl. Spirogyra sp.
Cosmarium cf. abruptum Lund. *       Spirogyra sp.1
Cosmarium anisochondrum Nordst.      Spirogyra sp.2 *
  var. tetrachondrum Scott &
  Gronbl. *
Cosmarium bayleyi Wolle *            Spirogyra sp.3 **
Cosmarium bitriangulum Gronbl.       Spirogyra sp.4 **
  var. groenbladii Gronbl.
Cosmarium blytty Wille               Spondylosium moniliforme Lund.
                                     Spondylosium panduriforme
                                       (Heimerl) Teil. var. limneticum
                                       (West & G. S. West)
Cosmarium brasiliense (Wille)        Forst.
  Nordst.
Cosmarium cf. cleuei (Lund.)         Spondylosium planum (Wolle) West
  Lutk. **                             & G.S. West
Cosmarium comissurale (Breb.)        Spondylosium pulchelum Arch. **
  Ralfs var. crassum Nordst.
Cosmarium contractum Kirch.          Spondylosium pulchrum Bail.
Cosmarium excauatum Nordst.          Spondylosium pygmaeum (Cooke)
                                       W. & G.S. West *
Cosmarium galeritum Nordst. var.     Staurastrum ambiguum Turner
  borgei Krieg. & Gerl.
Cosmarium granatum Breb. ex Ralfs    Staurastrum anatinum Cooke &
                                       Wills
Cosmarium impressulum Elfv.          Staurastrum bineanum Rabenh. **
Cosmarium laeue Rabenh. var.         Staurastrum boreale West & G.S.
  laeue                                West
Cosmarium laeue Rabenh. var.         Staurastrum brasiliense
  westii Krieg. & Gerl. *              Nordst. **
Cosmarium lagoense (Nordst.)         Staurastrum brebissonii Arch.
  Nordst. var. amoebum Forst. &        var. brasiliense Gronbl.
  Eck. **
Cosmarium mamiliferum Nordst. **     Staurastrum clauiferum West &
                                       G.S. West
Cosmarium margaritatum (Lund.)       Staurastrum cyclacanthum West &
  Roy & Biss. var. margaritatum        G.S. West
  f. minor (Boldt)
  West & G.S. West
Cosmarium minimum var.               Staurastrum dilatatum (Ehr.)
  subrotundatum W. & G.S. West         Ralfs
Cosmarium moerlianum Lutk. var.      Staurastrum hagmannii Gronbl.
  brasiliense Borge
Cosmarium naegelianum Breb.          Staurastrum hantzschii Reinsch
Cosmarium norimbergense Reinsch      Staurastrum leptacanthum Nordst.
  var. depressum (West & G. S.         var. borgei Forst. *
  West) W. Krieg. & Gerl.
Cosmarium panamense Presc. *         Staurastrum leptocladum Nordst.
                                       var. leptocladum
Cosmarium phaseolus var.             Staurastrum leptocladum Nordst.
  phaseolus Breb. ex Ralfs f.          var. cornutum Wille **
  minus Boldt.
Cosmarium portianum Arch.            Staurastrum margaritaceum (Ehr.)
                                       Ralfs
Cosmarium protractum (Nag.) de       Staurastrum muticum (Breb.) Ralfs
  Bary
Cosmarium pseudobroomei Wolle        Staurastrum nudibrachiatum Borge
Cosmarium pseudoconnatum Nordst.     Staurastrum orbiculare (Ehr.)
                                       Ralfs var. orbiculare
Cosmarium pseudoexiguum Racib.       Staurastrum orbiculare (Ehr.)
                                       Ralfs var. depressum Roy &
                                       Biss.
Cosmarium cf. pseudopyramidatum      Staurastrum cf. polymorphum
  Lund. **                             Breb. *
Cosmarium punctulatum Breb.          Staurastrum cf. pseudotetracerum
                                       (Nordst.) West & G. S. West
Cosmarium cf. pyramidatum Breb.      Staurastrum quadrangulare Breb.
  (Ralfs) *                            ex Ralfs var. quadrangulare
Cosmarium quadrum Lund. var.         Staurastrum quadrangulare Breb.
  minus Nordst.                        ex Ralfs var. contectum
                                       (Turn.) *
Cosmarium quadrum Lund. var.         Staurastrum quadricornnutum Roy
  sublatum (Nordst.) West & G.S.       & Biss.
  West
Cosmarium quinarium Lund. *          Staurastrum rotula Nordst. **
Cosmarium regnellii Wille **         Staurastrum sebaldi Reinsch var.
                                       ornatum Nordst.
Cosmarium regnesii Reinsch           Staurastrum minesotense Wolle
Cosmarium regnesii Reinsch var.      Staurastrum setigerum Cleve var.
  montanum Schm.                       pectinatum West & G.S. West
Cosmarium reniforme (Ralfs) Arch.    Staurastrum subauicula West &
  var. reniforme                       G.S. West
Cosmarium reniforme (Ralfs) Arch.    Staurastrum tetracerum (Kutz.)
  var. compressum Nordst.              Ralfs
Cosmarium sublobatum (Breb.)         Staurastrum trifidum Nordst. var.
  Arch. var. brasiliense Borge         inflexum West & G.S. West
Cosmarium subspeciosum Nordst.       Staurastrum sp. *
  var. subspeciosum
Cosmarium subspeciosum Nordst.       Staurodesmus breuispina (Breb.)
  var. ualidius Nordst. *              Croas.
Cosmarium subtumidum Nordst.         Staurodesmus clepsydra (Nordst.)
                                       Teil.
Cosmarium trilobulatum Reinsch       Staurodesmus corniculatus (Lund.)
                                       Teil. var. spinigerum W. West
Cosmarium uexatum W. West            Staurodesmus cuspidatus
                                       (Breb. ex Ralfs) Teil.
Cosmarium sp. *                      Staurodesmus dejectus (Breb.)
                                       Teil. var. dejectus
Cosmarium sp.1                       Staurodesmus dejectus (Breb.)
                                       Teil. var. apiculatus (Breb.)
                                       Teil.
Cylindrocystis brebisonnii           Staurodesmus dejectus (Breb.)
  (Menegh. ex Ralfs) de Bary           Teil. var. breuispinus (Nygaa.)
                                       Coesel *
Desmidium aptogonium Breb. *         Staurodesmus dickiei (Ralfs)
                                       S. Lill.
Desmidium baileyi (Ralfs)            Staurodesmus glaber (Ehr. Ex
  Nordst. **                           Ralfs) S. Lill. *
Desmidium greuillii (Kutz.) de       Staurodesmus grandis Teil. var.
  Bary **                              paruus W. & G.S. West **
Desmidium pseudostreptonema West     Staurodesmus lobatus (Borges.)
  & G.S. West **                       Bourr. **
Desmidium swartzii Agardh **         Staurodesmus mamillatus (Nordst.)
                                       Teil.
Euastrum abruptrum Nordst.           Staurodesmus patens (Nordst.)
                                       Croas.
Eaustrum denticulatum (Kirchn.)      Staurodesmus cf. spencerianus
  Gay                                  (Mask.) Teil. *
Euastrum euolutum (Nordst.) W. &     Staurodesmus sp.
  G.S. West **
Euastrum monocylum (Nordst.)         Teilingia granulata (Roy et
  Racib. var. borgei Gronbl.           Biss.) Bourr.
Groenbladia undulata Nordst. *       Teilingia quadrispinata (Scott et
                                       Gronbl.) Bourr. *
Gonatozygon aculeatum Hast.          Zygnema sp.
Gonatozygon monotaenium de Bary      Zygnema sp.1
Gonatozygon pilosum Wolle *          Desmidiaceae unidentified

* taxa exclusive to artificial substratum; ** taxa exclusive to
natural substratum.

Table 2. Values of abiotic variables in Corvo Stream (Rosana
reservoir), during the period of 11-21 to 12-12-03. (DO =
dissolved oxygen, PT = total phosphorus, PDT = total dissolved
phosphorus, P[O.sub.4.sup.-3] = orthophosphate, NT = total
nitrogen, N[O.sub.3.sup.-]-= nitrate, N[H.sub.4.sup.+] =
ammonium).

Weeks                                               1st week

Variable                                  11-21   11-24   11-26   11-27

Wind (m [s.sup.-1])                         2.8     3.1     1.5     1.0
Conductivity ([micron]S [cm.sup.-1])       36.1    40.0    44.8    43.9
Water temperature ([grados]C)              26.0    28.2    27.5    26.8
DO (mg [L.sup.-1])                          7.0     7.6     6.4     6.6
pH                                          6.9     7.0     7.0     6.7
Turbidity (NTU)                             2.9     2.8     2.5     3.0
PT ([micron]g [L.sup.-1])                   5.7     9.6    13.1    11.1
PDT ([micron]g [L.sup.-1])                  3.1     3.2     5.2     4.4
P[O.sub4.sup.-3] ([micron]g [L.sup.-1])     2.3     3.3     4.3     4.2
NT ([micron]g [L.sup.-1])                 322.1   409.0   392.6   346.8
N[O.sub.3.sup.-] ([micron]g [L.sup.-1])   185.3   215.1   206.3   176.6
N[H.sub.4.sup.+] ([micron]g [L.sup.-1])    18.0    20.9    31.7    65.1

Weeks                                               2nd week

Variable                                    11-30    12-01    12-03

Wind (m [s.sup.-1])                           5.6      1.0      3.4
Conductivity ([micron]S [cm.sup.-1])         37.0     37.6     34.8
Water temperature ([grados]C)                26.7     26.5     27.0
DO (mg [L.sup.-1])                            6.4      6.6      6.0
pH                                            6.7      6.5      6.3
Turbidity (NTU)                               4.2      6.6     11.9
PT ([micron]g [L.sup.-1])                    18.0     17.8     22.4
PDT ([micron]g [L.sup.-1])                    9.0      8.8      9.2
P[O.sub4.sup.-3] ([micron]g [L.sup.-1])       7.0      6.9      3.7
NT ([micron]g [L.sup.-1])                   300.0    299.8    236.5
N[O.sub.3.sup.-] ([micron]g [L.sup.-1])     120.0    119.0    114.4
N[H.sub.4.sup.+] ([micron]g [L.sup.-1])      66.0     29.2     35.8

Weeks                                               3rd week

Variable                                    12-06    12-09    12-12

Wind (m [s.sup.-1])                           3.0      6.7      2.3
Conductivity ([micron]S [cm.sup.-1])         40.5     42.6     46.2
Water temperature ([grados]C)                26.9     26.7     28.6
DO (mg [L.sup.-1])                            6.6      5.8      7.8
pH                                            6.6      6.0      6.2
Turbidity (NTU)                               4.1     27.0     18.7
PT ([micron]g [L.sup.-1])                    22.7     21.6     26.3
PDT ([micron]g [L.sup.-1])                    9.5      8.2     16.6
P[O.sub4.sup.-3] ([micron]g [L.sup.-1])       4.7      4.5      3.8
NT ([micron]g [L.sup.-1])                   310.0    300.6    339.5
N[O.sub.3.sup.-] ([micron]g [L.sup.-1])     136.0    134.0     97.6
N[H.sub.4.sup.+] ([micron]g [L.sup.-1])      75.0     73.9     44.0
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Author:Aparecida Felisberto, Sirlene; Rodrigues, Liliana
Publication:Acta Scientiarum Biological Sciences (UEM)
Date:Oct 1, 2010
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