Natural variability in seawater temperature compromises the metabolic performance of a reef-forming cold-water coral with implications for vulnerability to ongoing global change

• Published in: Coral reefs Vol. 41; no. 4; pp. 1225 - 1237
• Main Authors: Gómez, Carlos E., Gori, Andrea, Weinnig, Alexis M., Hallaj, Adam, Chung, Hee Jin, Cordes, Erik E.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-08-2022; Springer Nature B.V
• Subjects: Ambient temperature; Ammonia; Aquatic crustaceans; Artemia; Associated species; Biomedical and Life Sciences; Calcium; Calcium carbonate; Calcium carbonates; Canyons; Carbonates; Catabolism; Climate change; Cold; Continental margins; Coral reefs; Corals; Deep sea; Deep sea environments; Deep water; Deep water habitats; Ecological effects; Environmental conditions; Excretion; Expeditions; Freshwater & Marine Ecology; Gulf Stream; Heat treatment; Heat waves; Life Sciences; Lipid metabolism; Lipids; Lophelia pertusa; Metabolic response; Metabolism; Multiship expeditions; Oceanography; Probability theory; Proteins; Seawater; Seepages; Surface water; Survival; Temperature effects; Temperature tolerance; Thermal stress; Underwater exploration; Vulnerability; Water temperature; Deep ocean; Ecophysiology; Gulf Stream; Temperature increase
• ISSN: 0722-4028; 1432-0975
• DOI: 10.1007/s00338-022-02267-2

Seawater temperature is one of the main variables that determines cold-water coral distribution worldwide. As part of an initiative to explore new areas of deep-sea habitats along the Southeast United States (SEUS) continental margin, a series of expeditions were carried out as part of the Deep-Sea Exploration to Advance Research on Corals/Canyons/Cold seeps (DEEP SEARCH) project. During these explorations, a cold-water coral reef complex composed mainly of
Lophelia pertusa
was located off the coast of South Carolina at 650–850 m depth. In this geographic area the species normally has a thermal tolerance between 6 and 12 °C with the capacity to form extensive calcium carbonate structures, thus creating complex habitat for a variety of associated species. Owing to the paucity of these structures and the unusual environmental conditions of this geographic area, with regular arrival of warm surface waters from the Gulf Stream, the main aim of this study was to understand the physiological response of
L. pertusa
to the variation in extreme temperature events in this region. Short-term experiments simulated the rate of temperature increase from the ambient temperature (8 °C) to the environmental maximum (14 °C) (heat-wave treatment). We found that temperature had a significant effect on the metabolic functions through an increase in respiration (0.108 to 0.247 µmol O
2
g
−1
DW h
−1
) and excretion rates (0.002 to 0.011 µmol NH
3
g
−1
DW h
−1
) at 14 °C. Oxygen to Nitrogen ratios (O:N) also showed an effect of temperature where corals switched from lipid-dominated toward a mix of lipid-protein and protein-dominated catabolism. To further characterize the metabolic response, feeding assays (capture rate of
Artemia
) were performed at the same temperature range with an overall three-fold decrease in capture rates under 14 °C compared to ambient temperature, thus increasing the probability of temperature-induced metabolic stress. Our results suggest that temperature variations affect the metabolic response of cold-water corals, particularly along the SEUS continental margin. Since the incursion of warm surface water to deeper zones is predicted to increase in frequency and duration due to climate change,
L. pertusa
may be implicated negatively, followed by ecological consequences for the survival and functionality for the ecosystem it supports.