Spatiotemporal Variability of Benthic Communities on Weathervane Scallop Beds off Alaska

Abstract

Marine benthic communities are critical biotic components of habitat due to their roles in ecosystem function and health and as indicators of ecosystem change. Benthic communities are receiving increasing attention as institutions adopt ecosystem‐oriented research approaches. We conducted a multidecadal analysis of benthic communities in areas targeted by a commercial weathervane scallop Patinopecten caurinus fishery on the continental shelf off Alaska. Using bycatch data collected by onboard observers during 1996–2012, we analyzed spatiotemporal patterns in community composition on weathervane scallop beds. We also explored whether spatiotemporal differences were related to environmental (sediment and depth) and anthropogenic (dredging effort) variables. Statistically significant (P < 0.05) temporal changes in community composition occurred during 1996–2012, with a split between 1996 and 1999 and subsequent years. Taxa contributing to temporal changes were not consistent across fishery registration areas. Significant spatial differences in community structure were detected both at the scale of registration areas (200–2,000 km) and individual scallop beds (<50 km). We also found significant correlations between benthic species composition and environmental and anthropogenic variables over space and time. Although the relationships were generally weak, the ecological associations were consistent with expected depth and sediment relationships in this region. Our results are directly relevant to the habitat objective of the scallop fishery management plan, inform essential fish habitat designations for weathervane scallops and other commercially important species, and serve as a baseline against which to compare future changes associated with fishing and climate change. Ensuing research should include the collection of environmental data at the spatial scale of individual scallop beds as well as controlled experiments on the impacts of fishing on benthic communities and their recovery.