Metacommunity dynamics of the built environment

Background/Question/Methods

The relative importance of the factors (i.e. local vs. regional, biotic vs. abiotic, stochastic vs. deterministic, etc.) thought to drive patterns of community is still not well understood for most systems. Furthermore, human development of the once natural landscape is occurring at unprecedented rates, representing a massive and unplanned ecological experiment affecting a variety of ecological interactions. The fragmenting and creation of new habitat types in the built landscape gives us a unique opportunity to apply metacommunity theory to simultaneously test how and to what extent each of these factors drive patterns of community assembly. We couple multi-year field surveys of built ponds and roadside drainage ditches, with laboratory and field experiments to examine how aquatic-pond metacommunities assemble over both time and space in a metropolitan area of east-central Illinois. Using GIS mapping of flood-zones, we categorized these aquatic habitats as either ponds or drainage ditches, being either connected to other aquatic habitats or isolated in space. We also used a field mesocosm experiment to determine if local species diversity influenced patterns of mosquito oviposition.

 Specifically we ask:

(1) How does regional connectivity influence community structure?

(2) How does the presence and abundance of zooplankton influence patterns of mosquito oviposition.

Results/Conclusions

To date, we have found 26 taxa occurring in our metacommunity. Community structure of aquatic invertebrates varied significantly based on their connectivity to other aquatic habitats (ANOSIM, p<0.05), which is largely driven by isolated drainage ditches being very different from all others. The number of egg rafts laid was quite variable and ranged from 0 rafts to 94 egg rafts over a period of seven days (both in replicates where zooplankton were present). Given this variability, preliminary research suggests that presence of zooplankton do not influence number of mosquito egg rafts (ANOVA, F_1,36=0.30, p>0.05).

Our study demonstrates that aquatic habitats in the built environment are, to some extent, structured by their degree of regional connectivity with other aquatic habitats. We expected that high community diversity of a resident species (in our system zooplankton) in a habitat would influence oviposition patterns of mosquitos, but preliminary evidence suggests that this is not the case. However, further study of a) the abiotic and water chemistry of these aquatic habitats and b) species-specific oviposition patterns based on zooplankton abundance and distribution will further elucidate the relative influence of these important ecological factors in determining patterns of community assembly and structuring through time.