Feeding preference between two species of marine isopods (Pentidotea) on healthy and wasting eelgrass (Zostera marina)

Abstract

Eelgrass meadows are critical habitat for biodiverse marine communities. San Juan Island eelgrass Zostera marina meadows are losing surface area. Eelgrass wasting disease is locally prevalent and correlated with the decline. Herbivores, including Pentidotea isopods, eat Z. marina and spread wasting disease. Recent studies on isopod feeding preference have found different preferences for wasting and healthy eelgrass between species. This study addresses a data gap by testing surface area consumed by Pentidotea wosnesenskii and Pentidotea montereyensis isopods when offered both healthy and wasting Z. marina. Both species of isopod consumed a larger surface area of healthy eelgrass. The difference between species was not statistically significant. Feeding on healthy eelgrass may exacerbate eelgrass wasting disease. Another local species, Pentidotea resecata, prefers consuming wasting tissue. These differences have implications for herbivore-eelgrass-pathogen interactions and the different dietary needs of Pentidotea isopods.