A decrease in pH, increase in temperature, and pollution exposure elicit distinct stress responses in a scleractinian coral (Desmophyllum pertusum)

Abstract

Scleractinian corals create habitat that persists on geological timescales and supports some of the most diverse ecosystems on Earth. Throughout their depth range, these ecosystems are threatened by anthropogenic disturbances, including global ocean change and hydrocarbon extraction. While numerous studies have focused on how shallow-water corals respond to stressors, there is a paucity of research on deep-sea corals. Here, we analyze the gene expression patterns from a reef-forming deep-sea coral, Desmophyllum pertusum (previously Lophelia pertusa), exposed to oil and dispersant mixtures under current and projected future temperature and pH conditions. The overall gene expression patterns varied among coral colonies (genets), but dispersant exposure induced the strongest response. A Weighted-Gene Correlation Network Analysis (WGCNA) identified networks of co-expressed genes in response to different stressors. Gene ontology (GO) enrichment analysis revealed that D. pertusum exhibited the coral cellular stress response (CSR) during exposure to oil, dispersant, and a decrease in pH. Dispersant exposure elicited a response that included up-regulation of apoptosis, immune system, wound healing, and stress-related pathways. Coral nubbins exposed to oil exhibited signs of resource reallocation and a reduction in growth to maintain cellular homeostasis. The decrease in seawater pH resulted in a less severe stress response than dispersant exposure. These results support the idea that there is an underlying environmental stress response (ESR) shared by scleractinians, but that this response varies depending on the type and intensity of the stress with which they are challenged.