Date of Award

5-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Biology

Thesis Sponsor/Dissertation Chair/Project Chair

Colette Feehan

Committee Member

Paul A. X. Bologna

Committee Member

Matthew Schuler

Committee Member

William C. Sharp

Abstract

Ocean warming can have profound impacts on benthic marine invertebrates through direct physiological effects. Yet, the impacts of ocean warming on the long-spined sea urchin (Diadema antillarum), a keystone grazer on western Atlantic and Caribbean coral reefs, has received little attention. In the summer of 2023, the Caribbean basin experienced a strong marine heatwave event with sea temperatures ~1–3°C above average and the warmest on record in southern Florida. An ongoing field settlement sampling program for D. antillarum in the Florida Keys provided an opportunity to examine the correlative relationship between thermal exposure and larval settlement. Thermal exposure was quantified as the degree days (°D, thermal integral) above various putative thermal stress thresholds for the species inferred from the literature (30.1°C–31.6°C). Using local sea temperature data and D. antillarum settlement on standardized settlement plates in the warmest months of the year across six years (June–October of 2017–2023), the relationship between thermal exposure and settlement was assessed. Generalized linear models (Poisson, link = log) indicated weak to moderate evidence for a negative relationship between thermal exposure and total monthly D. antillarum settlement at a thermal stress threshold of 31.1°C–31.6°C. With the increasing threat of marine heatwaves under climate change, management of D. antillarum populations may need to take into consideration the impact of climate change on this species.

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