Meeting Abstract

P2.12  Thursday, Jan. 5  Determinants of rotifer species diversity in aridland aquatic habitats WALLACE, R.L.*; SCHROEDER, T.; RIOS ARANA, J.V.; WALSH, E.J.; Ripon College, Ripon; University of Texas at El Paso, El Paso; Universidad Autonoma de Ciudad Juarez; University of Texas at El Paso, El Paso wallacer@ripon.edu

Compared to tropical and temperate environments, life for zooplankton in aridlands is precarious: vast tracts of dry land separate habitats and risk of drought is continual. However, many aquatic habitats in the Chihuahuan Desert (CD) harbor high levels of species diversity and endemism. Here we investigate the role of habitat permanence and physiochemical environment in determining rotifer community composition in CD waters. We sampled 163 habitats (76 permanent natural, 20 permanent artificial, 14 temporary, and 53 ephemeral) over a 6-yr period recording a suite of environmental parameters, as well as species composition. We identified over 250 rotifer species (ca. 12% of all monogononts); these belong to 51 and 77% of known genera and families, respectively. An RDA analysis of the entire data set shows that ca. 8% of species diversity is attributable to habitat characteristics. However, an analysis of taxonomic distinctness shows that the most diverse arrays of species are found in permanent habitats and nestedness analyses shows significant spatial structuring of communities: permanent to ephemeral (p=0.001; 4 null models). Species composition varied dramatically among the 4 habitat categories: Range, Mean (SD) – permanent natural 1-48, 10.1 (10.0); permanent artificial 1-33, 15.1 (12.1); temporary 1-33, 12.8 (8.6); ephemeral 1-14, 4.4 (2.9). To further investigate these patterns, we compared their species composition using several metrics of similarity that confirmed the high variability in community structure.