Multi-stressor impacts of ocean warming and acidification on the regeneration andbiomineralisation of Psammechinus miliaris

Resumo

Ocean warming and acidification are significant consequences of climate change
that pose a major threat to marine ecosystems. These stressors can disrupt key
biological processes in marine invertebrates, such as regeneration and calcification, which are vital for survival, mobility, and defence. Sea urchins, as ecologically important benthic grazers, rely on the ability to regenerate tube feet and calcify spines to maintain function in dynamic coastal habitats. This thesis investigates the response of the coastal sea urchin Psammechinus miliaris to simulated future ocean conditions, focusing on the mechanisms underpinning tube foot regeneration and spine calcification. Through histological analysis, thermal performance range characterisation, and combined multi-stressor exposure to elevated temperature and pCO2 conditions, the research establishes that temperature is a key factor driving regeneration and calcification. Epimorphosis was the primary regenerative pathway in tube feet, following the stages of wound-healing, blastema formation, differentiation and innervation, and growth. Elevated temperatures significantly increased regeneration and calcification rates, surpassing the species’ thermal niche, while low temperatures hindered regeneration. Acidification alone had little effect on early regenerative stages but negatively interacted with warming to influence calcification in spines, which became structurally compromised under high pCO2. Mortality increased when exposed to multiple stressor conditions, particularly during seasonal transitions, highlighting reduced thermal tolerance under acidified
conditions. The thesis reveals tissue-specific sensitivities that may detrimentally
impact the resilience of P. miliaris to future ocean conditions, with implications for their ecological role and population stability.

Data do prémio	4 dez. 2025
Idioma original	English
Instituição de premiação	University of the Highlands and Islands
Promotores	Super DTP
Supervisor	Michael Burrows (Supervisor) & Helena Reinardy (Supervisor)