"Trematodes require all of the pieces of the puzzle to complete their lifecycle," Lafferty said. "When we see a lot of parasites in an estuary, we know it is in good shape. For example, an estuary with high infection rates tells you that it is visited by many birds, and many types of birds."
The goal of the Sea Grant project is to establish a baseline snail-trematode count in marshes, particularly those slated for restoration. By comparing worm statistics before and after a restoration project, which could include activities such as digging channels or removing non-native plants, the biologists believe that wetlands managers will have a tool for gauging restoration success and its gaps.
If, for example, a certain trematode species is missing, it could indicate that its hosts are lacking appropriate habitats. "The trematode information provides a novel way to see what we need to alter to improve habitats," Kuris said.
The feasibility of the snail-as-data-logger idea was established at a case-study site at the Carpinteria salt marsh in Santa Barbara. There, the biologists showed the trematode community did indeed become measurably more vibrant after restoration, due to an increase in the number of birds foraging on infected fish and benthic invertebrates.
To further validate the method, UCSB graduate student Ryan Hechinger conducted four month-long bird surveys at the study site, using video cameras to capture images of as many birds as possible. The results proved encouraging as the video-based estimates of the bird community were in close agreement with those from the snail-trematode analysis. "The more birds there were at a site, the more parasites," Hechinger said. "The more kinds of birds, the more kinds of trematodes, just as we predicted."
Hechinger hopes to produce a manual for resources managers that will explain how to collect snails, identify the trematodes inside them, and then translate this i
Source:Society for Academic Emergency Medicine