Coral calcification responses to the North Atlantic Oscillation and coral bleaching in Bermuda

Abstract

The North Atlantic Oscillation (NAO) has been hypothesized to drive interannual variability in Bermudan coral extension rates and reef-scale calcification through the provisioning of nutritional pulses associated with negative NAO winters. However, the direct influence of the NAO on Bermudan coral calcification rates remains to be determined and may vary between species and reef sites owing to implicit differences in coral life history strategies and environmental gradients across the Bermuda reef platform. In this study, we investigated the connection between negative NAO winters and Bermudan Diploria labyrinthiformis, Pseudodiploria strigosa, and Orbicella franksi coral calcification rates across rim reef, lagoon, and nearshore reef sites. Linear mixed effects modeling detected an inverse correlation between D. labyrinthiformis calcification rates and the winter NAO index, with higher rates associated with increasingly negative NAO winters. Conversely, there were no detectable correlations between P. strigosa or O. franksi calcification rates and the winter NAO index suggesting that coral calcification responses associated with negative NAO winters could be species-specific. The correlation between coral calcification rates and winter NAO index was significantly more negative at the outer rim of the reef (Hog Reef) compared to a nearshore reef site (Whalebone Bay), possibly indicating differential influence of the NAO as a function of the distance from the reef edge. Furthermore, a negative calcification anomaly was observed in 100% of D. labyrinthiformis cores in association with the 1988 coral bleaching event with a subsequent positive calcification anomaly in 1989 indicating a post-bleaching recovery in calcification rates. These results highlight the importance of assessing variable interannual coral calcification responses between species and across inshore-offshore gradients to interannual atmospheric modes such as the NAO, thermal stress events, and potential interactions between ocean warming and availability of coral nutrition to improve projections for future coral calcification rates under climate change.

Coral and Seawater Metagenomes Reveal Key Microbial Functions to Coral Health and Ecosystem Functioning Shaped at Reef Scale

“…The reef system in Bermuda is the most northern in the Atlantic and experiences large seasonal variations in environmental conditions [48]. In addition, fine-scale variations in temperature, light, and seawater chemistry occur between the outer rim reefs at the edge of the platform and inner lagoon patch reefs [49] with the inner patch reefs historically being warmer and more thermally variable [48,[50][51][52][53]. We showed in Lima et al [54] that the coral SML microbiome from the inner patch reefs and the outer rim reefs in Bermuda can be modeled according to the local annual thermal profile.…”

Brooded coral offspring physiology depends on the combined effects of parental press and pulse thermal history

“…Reef site characteristics are known to shape adult coral physiology (Castillo & Helmuth, 2005;Kenkel et al, 2013;Wall et al, 2018), as environmental signals influence organismal homeostasis (Sokolova et al, 2012) and drive performance through acclimation (Somero, 2010) and adaptation (Barshis et al, 2018). In Bermuda, the Patch and Rim reef sites differ in temperature, with Patch reefs historically being warmer and more thermally variable than Rim reefs (Figure 1; Courtney et al, 2017Courtney et al, , 2020de Putron et al, 2017;de Putron & Smith, 2011;Goodbody-Gringley et al, 2018). The dynamic nature of coral-algal symbiosis facilitates the ability for corals to inhabit a wide range of environmental conditions, with plasticity in endosymbiont densities and photosynthetic pigments driven by light conditions to minimize photo-oxidative damage and maximize photosynthetic potential (Mccloskey & Muscatine, 1984).…”

Increasing coral calcification in Orbicella faveolata and Pseudodiploria strigosa at Flower Garden Banks, Gulf of Mexico

“…Future work is required to better understand if there are additional mechanisms behind the correlation between density and minimum SST that we observed. The interaction between upwelling and thermal stress on coral calcification can be complex and species-specific, requiring future study (e.g., Courtney et al 2020).…”