Sea star abundance from surveys along the Oregon and Northern California rocky intertidal coastline from 2000 to 2024

This dataset includes sea star abundance data collected as part of the study described below. See the "Related Datasets" section for size structure data.

Mass mortality from disease epidemics can challenge the resistance and resilience of populations and communities. Assessing the impacts of such events and their consequences is crucially dependent on long-term datasets In 2013-16, sea star wasting disease (SSWD) caused population-wide crashes of the archetypal keystone species, the sea star Pisaster ochraceus, along the North American west coast. We used two long-term datasets to assess the resilience of Pisaster populations to this perturbation in Oregon: a 16-year time series (2007-2023) of annual predation rate at 7 sites, and a 23-year time series (2001-2024) of density and size of Pisaster at 8 sites. In spring 2015, a novel and massive Pisaster recruitment event occurred at all sites, averaging 3.00 ± 0.57 recruits m-2 (± SE), an 8,100% increase compared to pre-SSWD. Elevated but spatiotemporally variable recruitment has persisted over the subsequent decade. Before SSWD, population size structure was relatively stable, consisting mostly of large adults with virtually no recruitment. After the outbreak, density, average size, and biomass density declined at nearly all sites, while SSWD persisted at low levels, averaging ~4% symptomatic per year. As of the current period (2021-2024), density and biomass density had recovered at all sites and often overshot prior levels, but average body size recovered at only 3 of 7 sites. However, the 2014 crash and the post-2014 recruitment events apparently destabilized the populations; density remains more variable among years at all but two sites.