Ecological niche and species distribution modelling of sea stars along the Pacific Northwest continental shelf

Abstract

AbstractAimPopulations of several sea star species were devastated by a disease in 2013–2014 from Alaska to Baja California. However, their exact distributions and ecological requirements are unknown and better knowledge could help identify populations that are at risk. This study aimed to assess patterns of distribution and determine ecological requirements of several sea star species affected by the disease.LocationContinental shelf from southern Washington State to northern California, USA.MethodsA large occurrence dataset (5385 data points) of 11 taxa was gathered from bottom trawl surveys and underwater video footage, along with data for 13 oceanographic and seafloor environmental parameters. Species distribution modelling (Maxent) and ecological niche (outlying mean index) analyses were applied to these biotic and abiotic datasets.ResultsEach species showed contrasting ecological niches and modelled distributions, the main explanatory factors being depth, temperature, salinity, sediment mean grain size and the presence of rocky outcrops. Despite these species being recorded from Alaska to California, some sea stars showed very narrow distributions, whereas other taxa were widely distributed in the whole area.Main conclusionsThe modelled ecological niches and distributions of these 11 sea star taxa showed a high degree of differentiation. Because intertidal and shallow subtidal populations were drastically affected by the 2013–2014 disease, recovery will depend on health of subtidal populations and the ability of the species to disperse and recolonize shallower areas. Our study will serve as a useful reference of the species distributions before the disease started. This distributional data and assessment of influential environmental factors will be valuable for future predictions or studies of the effects of bottom‐contact ocean‐use activities on sea star species as well as the effects of climate change. Understanding habitat conditions favourable for these species may be helpful in managing population recovery following disease outbreaks or other catastrophic events.