Influence of Sex Distorters on the Amphipod Corophium volutator (Pallas): a Key Species in the Intertidal Bay of Fundy Ecosystem

Recently, world leaders in conservation research have suggested that in order to effectively protect ecosystems and the services they provide, researchers should focus their studies on key and keystone species. The amphipod, Corophium volutator (mudshrimp), is a key species known to maintain sediment stability in the Bay of Fundy intertidal ecosytem. It is also prey for numerous fish and bird species. For example, over 80% of the world`s population of semi-palmated sandpipers (Calidris pusilla) rely almost exclusively on mudshrimp to provide fat reserves for their migration from hemispheric shorebird reserves in the Bay of Fundy to Central and South America, each year. Mudshrimp can experience high rates of local depletion from shorebirds and intertidal fish, from outbreaks of disease caused by macroparasites, and from stochastic environmental factors. Despite these influences, mudshrimp populations in the Bay of Fundy appear stable, perhaps due to their female-biased sex ratios. In spite of numerous efforts to identify reasons for this sex ratio bias, none have so far been identified. The aim of this study is to determine whether sex ratio distortion is caused by microparasites. In other amphipods, microsporidian parasites are able to distort the sex ratio of their hosts by converting genotypic males into phenotypic females. Recent evidence shows microsporidians are present in mudshrimp, but whether they are sex distorters remains to be seen. This research will test several predictions of hypotheses concerning sex ratio distortion by microsporidians using a variety of tested microscopy techniques, as well as PCR based genetic techniques. Identification of any such parasites will help us understand the factors promoting population stability, which is a crucial first step in the conservation of this unique ecosystem.