Stygobiont Diversity in the San Marcos Artesian Well and Edwards Aquifer Groundwater Ecosystem, Texas, USA

The Edwards Aquifer and related Edwards-Trinity of Central Texas, USA, is a global hotspot stygobiont biodiversity. We summarize 125 years biological investigation at the San Marcos Artesian Well (SMAW), best studied most biodiverse groundwater site (55 taxa: 39 described 16 undescribed) within Groundwater Ecosystem. Cluster analysis redundancy (RDA) incorporating temporally derived, distance-based Moran’s Eigenvector Mapping (dbMem) illustrate temporal dynamics in community composition 85 high-frequency samples from SMAW. Although hydraulic variability to precipitation discharge partially explained changes SMAW, large amount autocorrelation between remains unexplained. potential mechanisms by which can affect structure deep, phreatic karst aquifers. also compile information on 12 other sites with 10 or more documented stygobionts used RDA assess relative influences distance type three measures β-diversity. Distance was important predictor total dissimilarity replacement, although important. Species richness difference not predicted either type.