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By land or by stream? contribution of constrained dispersal by adult caddisflies to diversity loss from urban headwaters
Citation:
Smith, R. F., W. O. Lamp, AND E. PILGRIM. By land or by stream? contribution of constrained dispersal by adult caddisflies to diversity loss from urban headwaters. Presented at Society of Freshwater Science, Louisville, KY, May 20 - 24, 2012.
Impact/Purpose:
The objective of this task is to develop molecular indicators to evaluate the integrity and sustainability of aquatic fish, invertebrate, and plant communities.
Description:
The adult stage of streams insects is responsible for important life-cycle processes such as dispersal and reproduction, yet interactions of adult stream insects with terrestrial landscapes are rarely studied. This trend is especially problematic in urbanized landscapes where these processes may mitigate the impacts of poor habitat quality on larval stages in the stream. With the help of DNA barcoding for species identification, we surveyed the adult and larval caddisfly assemblages at urban and rural streams to 1) compare spatial and temporal patterns of adult activity between urban versus rural streams; 2) determine patterns of immigration to urban headwaters; and 3) determine if flight ability explains immigration patterns. Spatial and temporal patterns of abundance and richness differed between urban and rural headwaters. Many taxa were able to migrate to streams where their larvae were absent, and those taxa were generally better fliers than those who did immigrate. Patterns of land-use at the landscape scale explained patterns of immigration as well. These results suggest that species traits and landscape scale processes determine isolation of urban headwater streams.