The combined influence of habitat connectivity and land use on zooplankton community structure

Background/Question/Methods

A growing body of evidence suggests that a combination of local and regional environmental factors can shape metacommunities. Theory and experimental work with model systems suggest that ignoring spatial dynamics of interacting communities could result in missing important drivers of local community structure, ecological dynamics and evolutionary processes. I conducted a survey of 51 permanent ponds across the state of Connecticut, evaluating the hypothesis that the combined impacts of surrounding human development (agricultural and urban/suburban) and habitat isolation are important factors contributing to the structure of zooplankton communities. A suite of local chemical, physical and biological properties and broader land use and connectivity traits were examined to explore corresponding patterns of crustacean zooplankton community structure.   

Results/Conclusions

Ponds in agricultural and urban contexts tended to be eutrophic to hypereutrophic with a higher pH and much higher conductivity than ponds in undeveloped landscapes. Ponds did not differ in depth, size, macrophyte cover or fish presence according to land use. Preliminary results suggest that zooplankton communities differ considerably in species richness, evenness and composition depending on land use type, measured chemical properties and isolation. Richness is highest in undeveloped sites and lowest in urban sites. Isolated habitats tend to have higher degrees of evenness compared with well connected habitats. Isolated communities are well represented by species with superior spatial dispersal and less reliance on temporal dispersal through resting eggs with long term diapause. 

One potential factor driving land use related community trends is the presence or absence of certain toxins in the environment. Next steps for analysis of this survey data will be to investigate to what extent zooplankton communities associated with urban or agricultural land use tend to be relatively resistant to toxins that are often used in these settings. A wealth of toxicity assay data available through US EPA’s ECOTOX database will allow investigation of this relationship.