RAPID: Recolonization dynamics following mass mortality in the ecologically important sunflower star (Pycnopodia helianthoides)

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Many marine species are known for their large population sizes and high dispersal potential due to the time their larval offspring spend in the open ocean before settling into the adult habitat. Despite these characteristics, that often buffer against decimation, the sunflower sea star (Pycnopodia helianthoides) suffered major declines between 2013 and 2020 due to a disease outbreak and warming events, which led to listing by the IUCN as Critically Endangered. The sunflower star helps maintain ecological balance in kelp forest ecosystems; its absence across large swaths of its range has led to concerns for the future of the ecosystem. This loss has highlighted the need to better understand dispersal and recovery dynamics in this ecologically important species in a time when global change stressors are intensifying. The widespread loss of Pycnopodia — combined with recent sightings of new juveniles in the range where it’s been lost — created an opportunity to answer questions about the genetic relatedness among new colonists, source populations of colonists, patterns of gene expression, and associations with environmental factors, and their implications for the future of the species. The investigators are collaborating with a diverse team of partners already surveying the coast, to collect genetic information from new colonists. The research proposed here has direct and consequential impacts on conservation actions for Pycnopodia through ongoing collaborations with the Nature Conservancy and fills an important gap for future conservation decisions aimed at restoring this important member of the kelp forest ecosystem to its historical range. As more species come under threat from rapidly intensifying global change, understanding recovery dynamics is an important and necessary step in instigating conservation actions. The investigator is developing a teaching lesson for a nearby community college and an undergraduate student will be trained.Massive demographic declines associated with anthropogenically-induced stressors have increased in recent years, raising questions about species’ ability to recover. The ecologically important sunflower sea star (Pycnopodia helianthoides) has suffered a precipitous (88–100%) decline since 2013 due to sea star wasting (SSW) disease and warming. The widespread loss of Pycnopodia provides a backdrop against which recent sightings of new juveniles in the extirpated range offer an opportunity to examine the contributions of four processes — (1) sweepstakes reproductive success, (2) cohesive dispersal, (3) larval cloning, and (4) allele surfing — to the evolutionary trajectory of populations following mass mortality. Additionally, identifying propagules’ source populations, evaluating gene expression profiles, and analyzing genotype–environment associations of colonists can help elucidate potential colonization pathways that favor recovery or signal ongoing threats. The investigators are soliciting new opportunistic collections of Pycnopodia from many partners and are responding to any observation in California and Oregon to acquire the samples and generate the whole genome resequencing data needed to test hypotheses segregating the aforementioned processes. As more species come under threat from rapidly intensifying global change, understanding recovery dynamics is critical to understanding population dynamics in the marine benthic environment.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.