Biology subjects

Schiebelhut, L. M.

Publications and source records attributed to Schiebelhut, L. M..

3 recordsLinked to original sources

bioRxiv2026

Molecular Star Gazing: Development and Validation of an Environmental DNA Assay for the Imperiled Sunflower Sea Star (Pycnopodia helianthoides)

The sunflower sea star (Pycnopodia helianthoides) suffered a catastrophic population decline across its range from 2013 to 2017 due to the devastating Vibrio pectenicida FHCF-3 driven sea star wasting disease (SSWD) pandemic with minimal signs of population recovery. The functional extinction of this apex predator across substantial parts of its range has created a need to identify and track the remaining intact populations. Environmental DNA (eDNA) approaches provide a simple, cost-effective, and non-destructive method for monitoring occurrences, and in some cases abundances, of marine species, consistently outperforming visual occurrence monitoring efforts in sensitivity, speed, and cost. Here, we designed, developed, and validated a P. helianthoides-specific eDNA assay to identify refugia, using both quantitative and digital droplet PCR approaches. We first generated the most comprehensive sea star mitochondrial genome reference database to date (n=93 taxa, n= 15 novel). We then used unikseq and Geneious bioinformatics software to identify the unique nad5 gene region and design a highly specific hydrolysis probe-based PCR assay. We validated the performance of this assay through laboratory, mesocosm, and field testing, demonstrating a highly specific and sensitive assay. In a field application of the new assay across regions in British Columbia, Canada, we found a positive correlation between P. helianthoides eDNA concentrations and biomass density, especially when appropriately accounting for spatiotemporal integration scales (R2=0.67). The eDNA assay provides a rapid and scalable tool for monitoring the sunflower sea star which has been proposed for listing as threatened under the U.S. Endangered Species Act of 1973. Molecular tools like the one presented here enhance management and recovery efforts not only by identification and monitoring of remnant wild populations, but also by helping to assess population level response and recovery following reintroduction efforts.

molecular biology↗

bioRxiv2025

Genomic separation of Salish Sea and Pacific outer coast populations of the keystone sea star Pisaster ochraceus

Understanding dispersal and population structure in marine species is critical to forecasting ecological responses to climate change. The ochre sea star (Pisaster ochraceus), an intertidal keystone predator along the North American Pacific coast, has long been considered to have little spatial genetic structure due to its extended larval dispersal period and thus high potential for gene flow. Here we characterize the spatial genomic architecture of P. ochraceus using whole-genome sequencing (WGS) data from individuals spanning over 3,000km of coastline from Alaska to southern California. Our analyses of putatively neutral SNPs evince considerable mixing throughout the latitudinal range yet reveal substantial population structure between outer Pacific coast populations and those residing within the semi-enclosed estuary of the Salish Sea, suggesting restricted gene flow and demographic divergence between these regions. Genomic divergence is further supported by evidence of selection, with outlier loci highlighting extended regions of low diversity in the Salish Sea, consistent with recent selective sweeps and potential local adaptation to the distinct estuarine conditions. These findings are consistent with the role of oceanographic barriers or environmental heterogeneity in shaping population structure in P. ochraceus, challenging an earlier notion of range-wide homogeneity. By exploring neutral and adaptive genetic diversity in this keystone marine species, we provide valuable insights for its capacity to persist in a rapidly changing world.

evolutionary biology↗

bioRxiv2020

Evidence for boundary layer oxygen diffusion limitation as a key driver of asteroid wasting

Sea star wasting disease describes a condition affecting asteroids that resulted in significant Northeastern Pacific population decline following a mass mortality event in 2013. The etiology of sea star wasting is unresolved. We hypothesized that asteroid wasting is a sequela of microbial organic matter remineralization near respiratory surfaces which leads to boundary layer oxygen diffusion limitation (BLODL). Wasting lesions were induced in Pisaster ochraceus by enrichment with a variety of organic matter (OM) sources and by experimentally reduced oxygen conditions. Microbial assemblages inhabiting tissues and at the asteroid-water interface bore signatures of copiotroph proliferation before wasting onset, followed by the proliferation of putatively facultative and strictly anaerobic taxa. These results together illustrate that suboxic conditions at the animal-water interface may be established by heterotrophic bacterial activity in response to organic matter loading. Wasting susceptibility was significantly and positively correlated with rugosity, a key determinant of boundary layer thickness. At a semi-continuously monitored field site (Langley Harbor), wasting predictably occurred at annual peak or decline in phytoplankton biomass over 5 years, suggesting that primary production-derived OM may contribute to BLODL. Finally, wasting individuals from 2013 - 2014 bore stable isotopic signatures reflecting anaerobic processes which suggests that this phenomenon may have affected asteroids during mass mortality. The impacts of BLODL may be more pronounced under higher temperatures due to lower O2 solubility, in more rugose asteroid species due to restricted hydrodynamic flow, and in larger specimens due to their lower surface area to volume ratios which affects diffusive respiratory potential. Moreover, our results demonstrate that marine invertebrate disease may result from heterotrophic microbial activity that occurs adjacent to respiratory tissues, which raises important questions about the etiology of marine diseases in other benthic taxa.

ecology↗