Simbionts of intertidal and subtidal mussels in the White Sea

Differences in intensity, abundance, prevalence and probability of infection with different symbionts between subtidal and intertidal Mytilus edulis were studied at 3 partly subtidal partly intertidal mussel beds in the White sea. Three zones were compared: intertidal (lower intertidal), zero-depth and subtidal (3m depth). 60 mussels from 3 1x1m quadrates (20 mussels per quadrate) were examined at each zone at each of the three sites. Three species of symbiotic protists and six metazoa symbionts species were discovered in the mussels. Also different free-living organisms were found in mussel's mantle cavities. Complex differences in infection probability, intensity and prevalence between subtidal and intertidal mussels were shown using permutational MANOVAs (p<0.05). These differences were visualized with nMDSs (stress<0.01), showing that mussels (or quadrates) from the lower and upper zones group at different sides of the nMDS diagram and mussels (or quadrates) from the middle zone are dispersed between them. Using GLMMs we showed that zone influences probability and abundance of mussel infection with commensal turbellaria Urastoma cyprinae and meatacercariae of three digenean species (Renicola roscovita, Himasthla sp. and unidentified meatcercariae) (p