Seascape complexity and habitat heterogeneity influence Alaskan eelgrass fish assemblages Marine Ecology Progress Series

Nearshore marine ecosystems along heterogeneous coasts are composed of dynamic and complex habitats that provide important services, including shelter and prey for juvenile, migratory, and residential species. Habitats often intermix, although we regularly study them in isolation without considering surrounding influences. In this study, we examined how fish assemblages differ in Southeast Alaska eelgrass meadows when the surrounding seascape includes or does not include adjacent kelp habitat, to test the role of the composition of nearshore coastlines on associated fish assemblages. We characterized habitats using aerial imagery and in situ sampling while quantifying eelgrass fish assemblages using beach seines. We found increased fish species richness and diversity in eelgrass when kelps are adjacent. The fish assemblage included greater prevalence of lingcod Ophiodon elongatus, whitespotted greenling Hexagrammosstelleri, sculpins (Cottoidea), Pacific sand lance Ammodytes personatus, and pink salmon Oncorhynchus gorbuscha. Some fish species, however, were more abundant within eelgrass habitat without adjacent habitats, including Pacific staghorn sculpin Leptocottus armatus, shiner perch Cymatogaster aggregata, and threespine stickleback Gasterosteus aculeatus. While both threespine stickleback and shiner perch were caught in both types of eelgrass habitats, juveniles of these species were more abundant in eelgrass without other adjacent habitat, indicating the role of eelgrass as potential nursery habitat. Seascape complexity, in which nearshore habitats are contextualized, is important for evaluating the role of these habitats for nearshore habitat conservation and fisheries management.