Abstract
Reefs formed by scleractinian cold-water corals represent unique biodiversity hot spots in the deep sea, preferring aphotic water depths of 200–1000 m. The distribution of the most prominent reef-building species Lophelia pertusa is controlled by various environmental factors including dissolved oxygen concentrations and temperature. Consequently, the expected ocean deoxygenation and warming triggered by human-induced global change are considered as a serious threat to cold-water coral reefs. Here, we present results on recently discovered reefs in the SE Atlantic, where L. pertusa thrives in hypoxic and rather warm waters. This sheds new light on its capability to adapt to extreme conditions, which is facilitated by high surface ocean productivity, resulting in extensive food supply. Putting our data in an Atlantic-wide perspective clearly demonstrates L. pertusa’s ability to develop population-specific adaptations, which are up to now hardly considered in assessing its present and future distributions.
Highlights
Being ecosystem engineers, framework-forming scleractinian cold-water corals (CWCs) provide habitat for thousands of deep-sea species, revealing remarkable levels of biodiversity as found in tropical coral reefs (Henry and Roberts 2017)
The distribution of the most prominent reef-building species Lophelia pertusa is controlled by various environmental factors including dissolved oxygen concentrations and temperature
Lophelia pertusa is the dominant reef-forming CWC in the Atlantic, and based on its distribution correlated with ocean conditions, upper and lower tolerable limits for basic oceanographic parameters were proposed for this species (e.g., Davies and Guinotte 2011)
Summary
Framework-forming scleractinian cold-water corals (CWCs) provide habitat for thousands of deep-sea species, revealing remarkable levels of biodiversity as found in tropical coral reefs (Henry and Roberts 2017). Lowest DOconc inhabited by this species apparently differs between NE Atlantic (* 3.7 mL L-1; Dullo et al 2008) and NW Atlantic (* 2 mL L-1; e.g., Brooke and Ross 2014) reef sites. These observations are corroborated by laboratory experiments, revealing that L. pertusa individuals collected from DOconc of 6 mL L-1 at the Scottish margin, NE Atlantic, were unable to maintain normal aerobic functions at DOconc \ 3.2 mL L-1 (Dodds et al 2007). The regional adaptation of the Angolan CWC to such extreme conditions sheds new light on their potential capability to cope with expected future environmental changes in the ocean
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