Environmental significance of freshwater mollusks in the Southern Pampas, Argentina: to what detail can local environments be inferred from mollusk composition?

BERNAVA GUSTAVO VICENTE; TIETZE, ELEONOR; DE FRANCESCO, CLAUDIO G.

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2010

0018-8158

Abstract The aim of the present contribution is toassess whether the abundance of mollusk species in theSouthern Pampas (Argentina), an environmentallyhomogeneous region, reflect the local conditions ofwater bodies. In order to test this hypothesis, acomprehensive study was conducted in 30 sitesregularly distributed across the region. At each site,the abundance of mollusk species was determined, anda series of physico-chemical measurements taken.Principal Component Analysis (PCA) and ClusterAnalysis (CA) were used for the ordination of samplingsites based on the measured environmental variables.In addition, Canonical Correspondence Analysis(CCA) was conducted to explore the relationshipsbetween environmental variables and mollusk abundances.Mollusk species were represented by thegastropods Biomphalaria peregrina, Chilina parchappii,Heleobia parchappii, Physa acuta, Pomaceacanaliculata, Stenophysa marmorata, Uncancylusconcentricus and the bivalve Musculium argentinum.Although aquatic vegetation cover, conductivity, andsubstrate were among the main parameters influencingmollusk distribution, their effect was insufficient toexplain the spatial distribution pattern of the species ina regional scale. It is because the Southern Pampas is avery homogeneous area, and the ranges of theseenvironmental conditions are within the range ofecological tolerance of most of the species represented.Yet, some species resulted good indicators of environmentalconditions at local (microhabitat) scale, i.e.,particular microhabitats that occur in different waterbodies as well. In fact, even distributed in manydifferent water bodies along the Southern Pampas C.parchappii is always linked to lotic environments, andU. concentricus is exclusively restricted to hardsubstrata. On the other hand, H. parchappii is the onlyspecies represented in mesohaline waters and P. acutaappeared to be a good indicator of pollution in the area.EN ESTE ARTICULO SE ME AGRADECE LA COLABORACION