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oai:figshare.com:article/32641197 2026-10-01T16:25:13Z portal_1172 item_type_8 month_year_10_2026

Insights into the ecology of sea stars Samuel D.G. Smith (24169854) PUREID: 640456925 Sea Stars Benthic Ecology Trait-mediated Interactions Sea Star Wasting Disease Trophic ecology Marine biology Marine ecology Marine Disease Sea stars play a vital role in marine ecosystems, influencing prey distribution and abundance. While direct predation profoundly impacts community structure, trait-mediated interactions (TMIs) which may alter prey behaviour and morphology, are gaining recognition as equally critical. However, the importance of such non-consumptive effects within marine systems remains poorly understood. This thesis examines TMIs in a marine tri-trophic system: Crossaster papposus (top predator), Asterias rubens (mesopredator), and the ecosystem engineer Mytilus edulis (basal prey). With biogenic reef habitats threatened globally, discerning the precise mechanisms driving top-down control is crucial for conservation and management. Our laboratory experiments revealed no evidence of a cascading TMI in this system. C. papposus cues did not deter A. rubens from seeking mussel cues, nor did either predator's presence alter mussel behaviour. This outcome suggests that consumptive effects of predation may be the primary drivers of trophic interactions, with direct consumption rates regulating mussel populations. Beyond predator-prey dynamics, this thesis provides insights into an emerging disease present in Asteroidea. Signs consistent with sea star wasting disease (SSWD) were reported in both C. papposus and A. rubens. Observations of SSWD in C. papposus were presented, thus providing the first reports of its kind in Europe. Furthermore, a laboratory experiment was conducted to investigate the role of elevated temperature on SSWD in A. rubens. It was found that elevated temperature increased disease sign progression and severity, supporting SSWD as a temperature-sensitive condition. This work contributes to our understanding of sea star ecology and can inform future benthic habitat management. It suggests that the role of TMIs in trophic organisation may be context-dependent. The observed thermal sensitivity of SSWD is particularly concerning given projected climate warming. This adds further complexity when predicting implications for ecosystem function, and underscores the need for a holistic approach to management and conservation. 2026-10-01T16:25:13Z Text Thesis 10.17034/32641197.v1 https://figshare.com/articles/thesis/Insights_into_the_ecology_of_sea_stars/32641197 All Rights Reserved