UC Marine Council

There is currently a dire need to assess the ecological function of our state's few remaining wetlands. The parasitic communities of larval trematodes that live within the abundant horn snail (Cerithidea californica) have shown great promise in serving as robust indicators of the community diversity and trophic functioning of wetlands. The snails and their parasites are easily sampled and this tool may prove to be a better alternative or complement to the extremely burdensome standard wetland assessment techniques. The ultimate goal is to be able to look at the details of snail parasite community structure at a site and strongly infer the status of the rest of the wetland community. We see great variation in snail parasite community structure between sites within wetlands. Much of this variation is assumed to be due to variation in bird and mammal site use. This is because various species of birds and mammals serve as final hosts for these complex lifecycle parasites and the snails are parasitized by the infectious stages that pass from the birds and mammals. To truly use these snail parasite communities as a meaningful assessment tool, we must determine the functional relationships between the birds and mammals that use a site and the community structure of parasites in snails. Unfortunately, typical visual bird surveys have proven to be too insensitive to pick up meaningful differences in final host site use. This is complicated by the fact that some potentially important final hosts are nocturnal (e.g. night herons and raccoons) and have not been surveyed. I propose to use video techniques, continuously sampling day and night, that will be sensitive enough to pick up any differences in final host bird and mammal site use. My observational and experimental work will refine the resolution of the snail parasite assessment tool.