Effects of environmental characteristics on the fish assemblages of high latitude kelp forests in South-central Alaska

Abstract

Alaskan kelp forests are patchy habitats, varying greatly in size, physical complexity, and biotic and abiotic characteristics, and are important to fish communities. Patchy habitats often support different communities on patch edges versus interiors, while patch size and physical complexity are typically correlated to the resident community structure. This study quantified the biological and physical heterogeneity within different sized kelp forests and identified which factors are important in structuring the associated fish communities. Fish and habitat surveys were conducted at ten kelp forests of varying sizes. Significantly different fish communities were found at edge compared to interior locations. The relative abundance of seven species explained 91.4% of the variability in the fish community. Fish community structure was not correlated with kelp forest size or the species composition of canopy forming kelps. Instead, it related to the abundances of two understory kelps, bottom rugosity, and water depth. Together these benthic attributes correlated with 53.6% of the fish community variability. These findings suggest that within patchy systems that are spatially and structurally non-uniform, associated fish species composition and abundance may be more directly linked to location within the patch and year-round habitat complexity rather than habitat patch size or foundational species composition.