It serves as an ideal field site for gathering baseline genetic data on these trematodes. The data from CSMR will be compared to trematode genetic data obtained from other C. californica populations and other Cerithidea species. UCSB Populations of organisms often exhibit surprisingly heterogeneous spatial distributions. Spatial heterogeneity may result from recruitment variation, habitat variability, or post-recruitment processess such as competition, predation, or disease. Furthermore, the parasites must recruit from one host to another to complete their life cycles, which may intensify or diminish spatial variability.
Digenetic trematodes have complex life cycles, which require at least two hosts.
In this study, the first intermediate host is the snail, Cerithidea californica . Second intermediate hosts include the crab, Hemigrapsus oregonensis, two fishes, Gillichthys mirabilis and Fundulus parvipinnus , and the clam, Tagelus californianus. The snail population at Carpinteria Salt Marsh harbors 13 different trematode species. Of these 13 species, two parasitize the crab, two parasitize the fishes, and one parasitizes the clam. These studies confirmed that there was significant spatial heterogeneity of trematode infections in the snail, crab, and clam populations, but not in the fishes.