Abstract
Patterns of aquatic invertebrate diversity in vernal pools may be driven by physical and chemical factors in conjunction with dispersal capabilities. By comparing this system to metacommunities, the local and between community factors may predict why species assemble or co-occur within a given space. Because the study of metacommunities involves both the interactions within individual communities and the dispersal patterns between communities, it allows ecologists to better understand the relative roles of local- and regional-scale processes on diversity. This study examined in situ relative effects of various physical and chemical factors on aquatic invertebrate communities within vernal pools in eastern Sacramento County with particular attention on the effect of hydrologic connectivity via overland surface flow on diversity. Light Detection and Ranging (LIDAR) data was used in conjunction with the ArcHydro model to determine water flow and hydrologic connectivity between pools at the study sites. The vernal pool aquatic communities are verifiably linked within the landscape. Even though surface water connectivity was not significantly related to diversity over the four sample periods, the pools are linked by the unique abilities of these species to disperse in this temporary aquatic environment. Connectivity was significant (among many other physicochemical factors) for richness of flatworms and snails (opportunistic species) and density of crustaceans. So although it does play a small role in driving where species co-occur, future designs of vernal pool restoration and creation efforts do not need to evaluate the connectivity patterns in vernal pools to maximize taxa diversity. Other physicochemical factors that shaped diversity include dissolved oxygen and water quality. Dissolved oxygen was positively related to overall taxa richness, as many species in vernal pools are gill-breathers. Overall taxa diversity of the pools measured by the Shannon diversity index was negatively related to total dissolved solids, a measure of water quality. For this reason, maintaining the health of these ecosystems by avoiding water quality impacts associated with development and stormwater runoff is imperative to maintain the diversity and stability of these sensitive habitats.