Molluscan communities of the rocky intertidal zone at two sites with different wave action on Isla La Roqueta, Acapulco, Guerrero, Mexico.
ABSTRACT Molluscan mol·lus·can also mol·lus·kan
Of or relating to the mollusks.
A mollusk. communities were studied on two shores, one exposed and the other sheltered from wave action by determining the diversity, richness, density, dominance, and similarity Similarity is some degree of symmetry in either analogy and resemblance between two or more concepts or objects. The notion of similarity rests either on exact or approximate repetitions of patterns in the compared items. of the groups of species found in the upper part of middle intertidal zone The intertidal zone, also known as the littoral zone, in marine aquatic environments is the area of the foreshore and seabed that is exposed to the air at low tide and submerged at high tide, i.e., the area between tide marks. . The sample area per location and date was 20 [m.sup.2]. The samples were taken quarterly during the year. Species richness This article or section is in need of attention from an expert on the subject.
Please help recruit one or [ improve this article] yourself. See the talk page for details. was found to he 44 species for both sites combined. The exposed site had a greater richness (41 species) and lower density (64.2 organisms/[m.sup.2]), whereas the sheltered site showed a higher density (88.08 organisms/[m.sup.2]) and smaller richness (33 species). Thirty species (68.8%) were determined to be common. The exposed shore had more confined con·fine
v. con·fined, con·fin·ing, con·fines
1. To keep within bounds; restrict: Please confine your remarks to the issues at hand. See Synonyms at limit. species. The Shannon-Wiener diversity index (H') was higher for the exposed site (3.165 bits/individual). A comparison of means by the Mann-Whitney tested indicated that the annual means of H' were equal between the two sites. Qualitative (Jaccard) and quantitative (Morisita-Horn) similarity scores In Sabermetrics and APBRmetrics, similarity scores are a method of comparing baseball and basketball players (usually in MLB or the NBA) to other players, with the intent of discovering who the single most similar historical player is to a certain player. were high at 0.682 and 0.622, respectively. The mean density of gastropods was the same at both locations, because bivalves showed significant differences with higher densities at the sheltered site. The malacologic community of the two sites was very similar. However, changes in richness and diversity over time were greater at the sheltered shore, while these changes were more gradual at the exposed shore, reflecting a greater stability of the malacologic community at the latter location.
KEY WORDS: molluscan communities, rocky intertidal in·ter·tid·al
Of or being the region between the high tide mark and the low tide mark.
in , wave action, Acapulco
The Pacific rocky coast has a very variable relief, which determines microenvironmental conditions at each location, which in turn control the distribution of species. Molluscs stand out because of their abundance Abundance
See also Fertility.
horn horn of Zeus’s nurse-goat which became a cornucopia. [Gk. Myth.: Walsh Classical, 19]
conical receptacle which symbolizes abundance. [Rom. Myth. and variety of forms, and have been connected with the development of many cultures.
It is important to measure some of the ecological ecological
emanating from or pertaining to ecology.
the state of balance in an ecosystem when its inhabitants have established their permanent relationships with each attributes of the communities, so that comparison can be made with species found at other locations. The information also has practical application for the purpose of management, appropriate use, conservation, and environmental monitoring. On the overall geographic scale, climate is the principal factor that determines the type of communities, whereas on a smaller scale it is more difficult to establish which factors govern the grouping of species. Various physical factors are known to intervene intervene v. to obtain the court's permission to enter into a lawsuit which has already started between other parties and to file a complaint stating the basis for a claim in the existing lawsuit. in the shaping of the structure of communities, one of them being exposure to waves. Studies of molluscan populations and communities along the Mexican Mexican
named after or originating in Mexico.
Mexican beaded lizard
(Heloderma horridum Pacific have historically focused on species of commercial interest (Baqueiro & Stuardo 1977, Baqueiro 1979, Rfos-Jara et al. 2001), and the majority of these have been conducted on the continental shelf (Reguero & Garcia-Cubas 1989, Landa-Jaime & Arciniega-Flores 1998). There have been few investigations in the particular case of rocky shores Rocky shore is an intertidal area on seacoasts where solid rock predominates. Rocky shores are biologically rich environments, and make the ideal natural laboratory for studying intertidal ecology and other biological processes. , where most of the authors have carried out taxonomic tax·o·nom·ic also tax·o·nom·i·cal
Of or relating to taxonomy: a taxonomic designation.
tax works (Morris 1966, Keen 1971, Holguin-Quinones & Gonzalez-Pedraza 1989, 1994, Sevilla 1995, Reyes-Gomez & Salcedo-Vargas 2002), and others have been concerned with the zonation zo·na·tion
1. Arrangement or formation in zones; zonate structure.
2. Ecology The distribution of organisms in biogeographic zones. , richness and species diversity of molluscs (Villalpando-Canchola 1986, Salcedo-Martinez et al. 1988, Castillo-Rodriguez & Amezcua-Linares 1992, Romfin-Contreras et al. 1991, Esqueda et al. 2000, Villarroel et al. 2000) and the different regions exposed to waves (Garcia-Lopez 1994, Del Rio-Zaragoza & Villarroel-Melo 2001).
The main economic activity in the State of Guerrero is tourism and to a lesser degree fishing. However, there is little known about marine faunistic fau·nis·tic
Of or relating to the geographic distribution of animals.
fau·nisti·cal·ly adv. resources, despite that it involves an extensive coastline that encompasses three marine regions prioritized for the conservation of the coastal and ocean biodiversity biodiversity: see biological diversity.
Quantity of plant and animal species found in a given environment. Sometimes habitat diversity (the variety of places where organisms live) and genetic diversity (the variety of traits expressed of Mexico, and Mexico's National Commission on Biodiversity (CONABIO CONABIO Comisión Nacional Para El Conocimiento Y Uso de La Biodiversidad (Spanish: National Commission for the Knowledge and Use of Biodiversity, Mexico) ) has indicated that there is a lack of knowledge about this region (Arriaga et al. 1998). Isla La Roqueta is located within this zone.
The aim of this investigation is to determine the diversity, density, dominance, and similarity among the groups of mollusc mollusc
members of the phylum Mollusca, which comprises about 50,000 species. Includes snails, slugs and the aquatic molluscs—oysters, mussels, clams, cockles, arkshells, scallop, abalone, cuttlefish, squid. species in the high intertidal zone of a shore exposed to wave action and one not, under the supposition that locations that differ in exposure also differ in composition of the malacologic community.
Area of Study
Isla La Roqueta is located in Acapulco, Guerrero, and the sample sites were as follows: (a) Playa playa
or pan or flat or dry lake
Flat-bottomed depression that is periodically covered by water. Playas occur in interior desert basins and adjacent to coasts in arid and semiarid regions. Zoologico is situated 16[degrees]42'11.2"N and 99[degrees]54'8.8"W, and is a shore exposed to wave action. Its massif mas·sif
1. A large mountain mass or compact group of connected mountains forming an independent portion of a range.
2. is composed of intrusive in·tru·sive
1. Intruding or tending to intrude.
2. Geology Of or relating to igneous rock that is forced while molten into cracks or between other layers of rock.
3. Linguistics Epenthetic. igneous rocks igneous rock: see rock.
Any of various crystalline or glassy, noncrystalline rocks formed by the cooling and solidification of molten earth material (magma). , and has a firm substrate The base layer of a structure such as a chip, multichip module (MCM), printed circuit board or disk platter. Silicon is the most widely used substrate for chips. Fiberglass (FR4) is mostly used for printed circuit boards, and ceramic is used for MCMs. with a large amount of fissures, cracks, and cavities all over the area; (b) Playa Palmitas is situated 16[degrees]49'25.6"N and 99[degrees]54'41.2"W. It is a sheltered shore with a massif composed of intrusive igneous rocks. It has a firm substrate with a large amount of fissures, cracks, and cavities. The climate is hot and sub-humid, with rains in the summer and with 5% to 10% winter rain (Garcia 1981).
The sample was taken from the upper part of middle intertidal zone of the two locations. The sampling dates were December of 2000 and March, June, September and December of 2001. The calculated area for the sample size was 20 [m.sup.2] for each station, determined by the method of species area (Brower et al. 1998). Collection was at 2 vertical levels of the upper part of the middle intertidal zone, called level I with its lower limit adjacent to the barnacle barnacle, common name of the sedentary crustacean animals constituting the subclass Cirripedia. Barnacles are exclusively marine and are quite unlike any other crustacean because of the permanently attached, or sessile, mode of existence for which they are highly zone, and level II with its upper limit next to the periwinkle periwinkle, in zoology
periwinkle, any of a group of marine gastropod mollusks having conical, spiral shells. Periwinkles feed on algae and seaweed. and limpet limpet, marine gastropod mollusk with a simple, flattened, conical shell, found in cooler waters of the Atlantic and the Pacific oceans. Certain species creep over rocks, feeding on algae during high tides, but when the tide recedes they return instinctively to the zone. A strip 30 m long and 2 m wide was used, which was parallel to the coastline, and the sampling unit was a quadrant quadrant, in analytic geometry
1 In analytic geometry, one of the four regions of the plane determined by two lines, the x-axis and the y-axis. 1 m squared. Sampling was systematic (Scheaffer et al. 1987), randomly selecting the starting point Noun 1. starting point - earliest limiting point
terminus a quo
commencement, get-go, offset, outset, showtime, starting time, beginning, start, kickoff, first - the time at which something is supposed to begin; "they got an early start"; "she knew from the and placing the quadrant in level I. After finishing the first sampling unit, the quadrant was placed in level II, directly above level I. All the molluscs that were found in the quadrant were identified and counted. After completing both levels, a space of 2 m was left before establishing new quadrants until completing 20 [m.sup.2].
Taxonomic identification of the molluscs was according to according to
1. As stated or indicated by; on the authority of: according to historians.
2. In keeping with: according to instructions.
3. Morris (1966), Keen (1971), Skoglund (1991, 1992), Reyes-Gomez and Salcedo-Vargas (2002).
Analysis of Data
The density of the molluscs was determined as number of organisms/[m.sup.2]. Species richness constituted the number of species present per site. A species was considered dominant if it showed a density equal to or greater than 1 organism/[m.sup.2] in at least one of the samplings. Cumulative dominance was defined as the sum of individual dominances. The frequency of appearance was determined as the total number of samples in which each species was recorded and expressed as a percentage. A confined species was defined as the only species present in one of the sites. The difference between means of species richness was evaluated with the Mann-Whitney test (Daniel 2002). Similarity between the sites was measured by using the qualitative presence/absence index of Jaccard and the quantitative Morisita-Horn index based on abundance (Magurran 1989). Species diversity was determined with the Shannon-Wiener index II' (Margalef 1974), and the Mann-Whitney test was used to compare the mean values of diversity H' (Daniel, 2002).
A total of 41 species were found (Table 1) corresponding to 31 genera genera, in taxonomy: see classification. and 19 families, of which 75.6% belonged to the class Gastropoda, 17.1% to the class Bivalvia, and 7.3% to the class Polyplacophora Noun 1. class Polyplacophora - small class of marine mollusks comprising the chitons; sometimes considered an order of the subclass Amphineura
Mollusca, phylum Mollusca - gastropods; bivalves; cephalopods; chitons . The lowest richness was found in the samplings of March and June with 21 species and the greatest in December of 2001 with 26 species (Fig. 1).
[FIGURE 1 OMITTED]
The mean density during the annual cycle was 64.2 organisms/ [m.sup.2], which fluctuated among the different sampling times from 29.9 to 87.3 organisms/[m.sup.2].
Sixteen dominant species were recorded and in the annual cycle these species accumulated ac·cu·mu·late
v. ac·cu·mu·lat·ed, ac·cu·mu·lat·ing, ac·cu·mu·lates
To gather or pile up; amass. See Synonyms at gather.
To mount up; increase. to 98.02% dominance. The quantity of dominant species fluctuated per date from 5 in December of 2000 to 10 in December of 2001 (Table 2). The frequency of appearance of the dominant species was distributed in the following manner: nine had 100%, three 80%, three 60% and one 40%.
Of the 9 species that showed 100% frequency of appearance, the gastropod gastropod, member of the class Gastropoda, the largest and most successful class of mollusks (phylum Mollusca), containing over 35,000 living species and 15,000 fossil forms. Plicopurpura patula pansa (Gould 1853) and the bivalve bivalve, aquatic mollusk of the class Pelecypoda ("hatchet-foot") or Bivalvia, with a laterally compressed body and a shell consisting of two valves, or movable pieces, hinged by an elastic ligament. Chama echinata (Broderip 1835) had densities equal to or greater than 1 for all the sampling dates.
The densities of the class Gastropoda for all the dates were higher than those of the classes Bivalvia and Polyplacophora. The highest density of the class Gastropoda was seen in September of 2001, whereas the lowest was recorded in December of 2000. The class Bivalvia showed the highest density in June and the lowest in September (Table 2).
The Shannon-Wiener index for the annual cycle was 3.165 bits/individual, oscillating os·cil·late
intr.v. os·cil·lat·ed, os·cil·lat·ing, os·cil·lates
1. To swing back and forth with a steady, uninterrupted rhythm.
2. among the different samples from 2.432 to 3.250 bits/individual (Fig. 2).
[FIGURE 2 OMITTED]
A total of 33 species (Table 1) were found corresponding to 28 genera and 20 families, of which 78.8% belonged to the class Gastropoda, 18.2% to the class Bivalvia and 3.0% to the class Polyplacophora. The least richness was found in the samples of September with 16 species and greatest in December of 2000 and March and June of 2001 with 22 species (Fig. 1).
The mean density during the annual cycle was 88.08 organisms/[m.sup.2], which varied among the different sampling dates from 62.85 to 123.85 organisms/[m.sup.2].
Eleven dominant species were recorded and these species accumulated over the annual cycle to 98.26% dominance. The quantity of dominant species fluctuated per date from seven in December of 2001 to nine in June and September (Table 3). The frequency of appearance of the dominant species was distributed in the following manner: eight had 100%, two 80% and one 40% frequency. Of the 8 that showed 100% frequency of appearance, the gastropods P. Patula pansa, Mancinella triangularis triangularis /tri·an·gu·la·ris/ (-ang?gu-lar´is) [L.] triangular.
[L.] triangular. (Bleainville 1832) and Petaloconchus complicatus Dall, 1908 as well as the bivalves Chama echinata, Brachidontes semilaevis (Menke 1849) and Isognomom janus (Carpenter 1857) had densities equal to or greater than 1 at all the sampling dates.
The densities of the class Gastropoda were higher than those of the classes Bivalvia and Polyplacophora in the samples from June and September, whereas the class Bivalvia showed higher densities than those of the classes Gastropoda and Polyplacophora in samples from December of 2000 and March and December of 2001. The highest density for the class Gastropoda was seen in September of 2001, whereas the lowest was recorded in December of 2000. The class Bivalvia showed a higher density in December of 2001 and the lowest in September of the same year (Table 3).
The Shannon-Wiener index for the annual cycle was 2.863 bits/individual, oscillating among the different samples from 1.972 to 2.911 bits/individual (Fig. 2).
Thirty species (68.8%) were common to both sites. Eleven confined species were found at the exposed location, whereas there were only 3 at the sheltered site (Table 1). In the annual cycle, the Jaccard similarity index was 0.682 and the Morisita-Horn quantitative index was 0.622.
The mean number of species found per date was 23 species (SD = 2.12) for the exposed shore and 19.8 species (SD = 3.03) for the sheltered one. The difference between these mean values for the two sites was not statistically significant (Mann-Whitney = 6.0, P = 0.222).
At the exposed site, the mean total density of dominant molluscs of the class Gastropoda for all the samples was 52.43 organisms/[m.sup.2] (SD = 21.24), whereas at the sheltered site it was 44.05 organisms/[m.sup.2] (SD = 33.03). A comparison of the two mean values showed no statistical difference (Mann-Whitney = 9.0, P = 0.465). For the class Bivalvia, there were 9.48 organisms/m2 (SD = 7.13) at the exposed site and 42.5 organisms/[m.sup.2] (SD = 16.23) on the sheltered shore.
The two locations showed high diversity values, and in comparing the mean Shannon-Wiener indices for the five collections, there were no statistically significant differences (Mann-Whitney = 8.0, P = 0.421) (Fig. 2).
This study found a greater number species than that reported to date for the upper part of middle intertidal zone of the study area. Villalpando-Canchola (1986) collected 34 species at Isla la Roqueta, in an area referred to as level I, which included the upper part of middle intertidal zone, whereas Garcia-Lopez (1994) found 36 species in the same zone.
The exposed site showed a greater richness, more confined species, a higher number of dominant species, but a lower density. In all the samples, the class Gastropoda showed the greatest density. This site exhibited greater variation with respect to the number of dominant species among the sampling dates, and only two of these species had the characteristic of persisting per·sist
intr.v. per·sist·ed, per·sist·ing, per·sists
1. To be obstinately repetitious, insistent, or tenacious.
2. during the entire cycle as dominant species. These findings indicate that the dominant community showed more mobility among its species.
The sheltered site showed less richness, fewer confined species, a lower number of dominant species, but a higher density. Among the samples, the highest densities per date alternated between the classes Gastropoda and Bivalvia. This location exhibited less variation with respect to number of dominant species among the sampling dates, and six of these species showed the characteristic of remaining the dominant species throughout the entire cycle. These findings indicate that the dominant community had less mobility among its species.
Lewis (1964) found a greater richness and more confined species in an exposed site, and Del Rio-Zaragoza and Villarroel-Melo (2001) also determined a greater number of species in an exposed site, whereas Spight (1978) reported a greater abundance in a sheltered site. However, Garcia-Lopez (1994) reported a greater number of species at Isla la Roqueta for the sheltered sites studied.
The density of molluscs for the combined dominant species that belonged to the class Gastropoda did not differ between the two locations studied, and gastropods showed the highest abundance of species at both locations. Holguin-Quinones and Gonzalez-Pedraza (1989), Castillo-Rodr/guez and Amezcua-Linares (1992), Garcia-Lopez (1994), and Villarroel et al. (2000) also reported that gastropods displayed the greatest species richness among the classes of molluscs.
On the other hand, the density of molluscs for the combined dominant species belonging to the class Bivalvia did show differences between the two sites, such that the sheltered shore showed a greater number of bivalves.
The molluscs of the class Polyplacophora was recorded as dominant species only at the exposed location.
The percentage of cumulative dominance of the species that had densities equal to or greater than 1 organism/[m.sup.2] was similar for the two sites and was over 98% of the whole malacologic community.
A comparison of the mean values for species richness for all the sampling dates did not show significant differences, indicating that the two locations are similar with regard to richness. This same situation was seen when comparing the mean values for the diversity index H', which indicates that the sites studied over the annual cycle can be considered equally diverse. However, the values recorded for both richness and the H' index of the sheltered site for each of the samples, demonstrated greater changes in the malacologic community, whereas in the exposed site these values showed more gradual changes.
In this study, the value for the Shannon-Wiener diversity measure for the exposed site was greater when considering the annual cycle. In a study of the same locations where the present work was conducted, Garcia-Lopez (1994) recorded a lower H' index value at the exposed site (1.606 bits/individual), and higher value for the sheltered site (3.817 bits/individual).
The number of common species between the two locations was very high, which was reflected in the value for the Jaccard index The Jaccard index, also known as the Jaccard similarity coefficient, is a statistic used for comparing the similarity and diversity of sample sets.
The Jaccard coefficient is defined as the size of the intersection divided by the size of the union of the sample . However, Garcia-Lopez (1994) reported a lower index (0.375) for these same locations. According to the Morisita-Horn index, the two sites were quantitatively very similar.
The malacologic community of the upper part of middle intertidal zone of two locations with different exposure to waves was found to be very similar, contrary to the proposed hypothesis of this investigation. However, there are some differences that are important to point out. At the sheltered shore, seasonal changes in richness and diversity were greater despite the lesser variation in its dominant community. At the exposed shore, these changes were more gradual over time despite a greater variation in the dominant community, reflecting a greater stability of the malacologic community at this site.
TABLE 1. Molluscan species observed at both locations of collecting sites in the upper part of middle intertidal zone on Isla la Roqueta, Acapulco, Guerrero, Mexico; Dec. 2000-Dec. 2001. Gastropoda 1. Cantharus sanguinolentus (Duclos. 1833) (C) 2. Columbella fuscata Sowerby, 1832 (C) 3. Conus nux Broderip, 1833 (S) 4. Crucibulum scutellatum (Wood, 1928) (C) 5. Crepidula excabata (Broderip, 1834) (E) 6. Diodora inaequalis (Sowerby, 1835) (E) 7. Fissurella asperella Sowerby, 1835 (E) 8. Fissurella gemmata Menke, 1847 (C) 9. Fissurella nigrocincta Carptenter, 1856 (C) 10. Fissurella obscura Sowerby, 1835 (E) 11. Hoffmannola hansi Marcus & Marcus, 1967 (C) 12. Leucozonia cerata (Wood, 1828) (C) 13. Lottia acutapex (Berry, 1960) (E) 14. Lottia mitella (Menke, 1847) (E) 15. Lottia pediculus (Philippi, 1846) (E) 16. Mancinella speciosa (Valenciennes, 1832) (C) 17. Mancinella triangularis (Blainville, 1832) (C) 18. Mitra tristis Broderip, 1836 (C) 19. Mitrella ocellata (Gmelin, 1791) (C) 20. Nerita scabricosta Lamarck, 1822 (C) 21. Nodilittorina aspera, (Philippi 1846) (C) 22. Nodilittorina modesta (Philippi, 1846) (C) 23. Opeatostoma pseudodon (Burrow, 1815) (C) 24. Petaloconchus complicates Dall, 1908. (C) 25. Petaloconchus macrophragma Carpenter, 1857 (C) 26. Planaxis obsoletus Menke, 1851 (S) 27. Plicopurpura columellaris (Lamarck, 1822) (C) 28. Plicopurpura patulo pansa (Gould, 1853) (C) 29. Siphonaria gigas Sowerby, 1825 (E) 30. Siphonaria palmata Carpenter, 1857 (C) 31. Stramonita haemastoma (Linnaeus, 1758) (C) 32. Tectura fascicularis (Menke, 1851) (C) 33. Thais kioskiformis (Duclos, 1832) (C) 34. Trimusculus stellatus (Sowerby, 1835) (S) Bivalvia 35. Arca mutabilis (Sowerby, 1833) (E) 36. Brachidontes semilaevis (Menke, 1849) (C) 37. Chama equinata Broderip, 1835 (C) 38. Choromitylus palliopunctatus (Carpenter, 1857) (C) 39. Isognomom janus Carpenter, 1857 (C) 40. Striostrea prismatica (Gray, 1825) (C) 41. Saccostrea palmula (Carpenter, 1857) (C) Polyplacophora 42. Chiton albolineatus Broderip y Sowerby, 1829 (E) 43. Chiton articulatus, Sowerby, 1832 (C) 44. Tonicia forbessi Carpenter 1857 (E) (C) Common species in both sites. (E) Confined species in exposed site. (S) Confined species in sheltered site. TABLE 2. Densities (organisms/[m.sup.2]) of the dominant species for sampling dates in the exposed site to wave action on Isla La Roqueta, Acapulco, Guerrero Mexico. Classes/Species Dec-00 Mar-01 Jun-01 Sep-01 Dec-01 Gastropoda Columbella fuscata 0.0 0.0 0.0 1.25 2.45 Crucibulum escutellatum 0.45 0.35 0.2 0.15 2.4 Fissurella gemmata 1.15 0.20 0.05 0.3 3.25 Fissurella nigrocincta 0.05 0.0 0.05 2.1 2.1 Hoffmannola hansi 0.35 0.7 1.4 0.0 0.0 Nodilittorina aspera 0.0 10.95 10.25 30.8 7.0 Nodilittorina modesta 0.10 1.95 0.0 0.0 0.1 Nerita scabricosta 0.0 0.0 0.1 1.55 0.35 Petaloconchus complicatus 0.50 24.6 34.15 16.1 20.3 Petaloconchus macrophracma 0.10 1.2 6.1 0.25 0.25 Plicopurpura panda pansa 10.10 9.3 10.05 12.85 9.8 Mancinella triangularis 5.7 0.3 2.7 9.0 6.7 Total 18.5 49.55 65.05 74.35 54.7 Bivalvia Chama equinata 9.2 3.2 1.75 2.6 8.4 Brachidontes semilaevis 0.0 0.05 17.75 0.65 0.45 Isognomom janus 0.15 0.65 1.7 0.35 0.5 Total 9.35 3.9 21.2 3.6 9.35 Polyplacophora Chiton articulatus 1.3 0.95 0.55 0.5 1.85 TABLE 3. Densities (organisms/[m.sup.2]) of the dominant species for sampling dates in the sheltered site to wave action on Isla La Roqueta, Acapulco, Guerrero Mexico. Classes/Species Dec-00 Mar-01 Jun-01 Sep-01 Dec-01 Gastropoda 1.3 0.0 0.05 0.0 0.0 Columbella fuscata 0.0 0.55 22.0 79.45 2.35 Nodilittorina aspera 1.0 2.05 7.05 3.35 0.95 Nodilittorina modesta 0.0 0.15 1.4 5.05 0.35 Nerita scabricosta 5.05 7.15 1.15 2.8 6.8 Petaloconchus complicatus 0.75 6.9 0.95 0.45 0.4 Petaloconchus macrophracma 9.0 6.6 7.4 6.7 9.55 Plicopurpura patula pansa 6.1 2.6 5.15 3.15 4.55 Mancinella triangularis 23.2 26.0 45.15 100.95 24.95 Total Bivalvia 11.4 4.45 15.0 6.05 23.25 Brachidontes semilaevis 24.5 42.05 20.8 14.25 39.55 Chama equinata 1.25 1.65 2.75 2.0 3.55 Isognomom janus 37.15 48.15 38.55 22.3 66.35 Total Figure 1. Species richness observed by sampling dates for the exposed and sheltered sites on Isla La Roqueta. December to December 2001. Number of species Sampling dates Exposed Sheltered December-00 23 22 March-01 21 22 June-01 21 22 September-01 24 16 December-01 26 17 Note: Table made from bar graph. Figure 2. Shannon-Wiener diversity index values, observed for the Exposed and sheltered sites on Isla La Roqueta, December 2000 to December 2001. Shannon-Wiener index H' values Sampling dates Exposed Sheltered December-00 2.476 2.71 March-01 2.432 2.336 June-01 2.611 2.911 September-01 2.706 1.972 December-01 3.25 2.377 Note: Table made from line graph.
The authors thank CONACyT for the support offered for the development of this research and Dr. Gorgonio Ruiz Campos Campos (käm`ps), city (1996 pop. 391,299), Rio de Janeiro state, SE Brazil, on the Paraíba River near its mouth. for his review of the manuscript manuscript, a handwritten work as distinguished from printing. The oldest manuscripts, those found in Egyptian tombs, were written on papyrus; the earliest dates from c.3500 B.C. and valuable comments. Dr. Enrique Villalpando Canchola, provided invaluable help throughout the study. We appreciate the comments and suggestions from Dr. Emilio Michel Michel
named after Gaston Michel, a French surgeon (1875-1937).
metal skin sutures in various sizes from 8 to 16 mm long. Each clip is a 2 mm wide band of metal with a downturned sharp prong at each end. Morfin and Dr. Victor Landa Jaime. We also thank Dr. Albert Leyva for his help in the preparation of the manuscript.
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. Adam and Eve met here after 200 years. [Muslim Legend: Berra, 44]
flower symbolizing a rejoining. [Flower Symbolism: Jobes, 322]
Esau and Jacob
after many years, they are reconciled. [O.T. Nacional de Malacologia y Conquiliologia Ciudad Victoria Ciudad Victoria (sythäth` vēktō`ryä), city (1990 pop. , Tamps. Mexico. Resumenes. pp. 26-28.
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All the species of animals found in a particular region, period, or special environment. Five faunal realms, based on terrestrial animal species, are generally recognized: Holarctic, including Nearactic (North America) and Paleartic (Eurasia and northern Africa); malacologica de acompanamiento del caracol Purpura purpura
Presence of hemorrhages in the skin, often associated with bleeding from natural cavities and in tissues. Major causes include damage to small artery walls (as in vitamin deficiency or allergic reaction) and platelet deficiency (in association with such disorders as pansa (Gould 1853) en la zona mesolitoral de la Isla Roqueta, Acapulco, Gro., Mexico. Tesis profesional inedita. Escuela Superior de Ecologia Marina Marina
“a piece of virtue.” [Br. Lit.: Pericles]
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A small guitarlike instrument of Latin America, usually having four or five pairs of strings.
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A larval stage of a mollusk characterized by the presence of a velum.
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ARCADIO VALDES-GONZALEZ, (1),* PEDRO FLORES-RODRIGUEZ, (1,2) RAFAEL FLORES-GARZA (1,2) AND SERGIO GARCIA-IBANEZ (1)
* E-mail: firstname.lastname@example.org
(1) Doctorado en Ciencias Biologicas, Especialidad en Ecologia, Facultad de Ciencias Biologicas, Universidad Autonoma de Nuevo Leon, San Nicolas San Nicolas or San Nicolás ("Saint Nicholas") may refer to: