Soft corals are significant DMSP producers in tropical and temperate reefs

Abstract

Corals synthesise large quantities of the sulphur metabolite dimethylsulphoniopropionate (DMSP), which contributes to key roles in coral reef ecology including the capacity of corals to withstand various stressors. While closely related to scleractinian corals and often occupying similar ecological niche space, it is currently poorly defined to what extent soft corals produce DMSP. We, therefore, examined DMSP content within four key species of soft coral in February and July–August of 2017, including two temperate species from Sydney Harbour (Erythropodium hicksoni, Capnella gaboensis) and two tropical species from the Great Barrier Reef (Sinularia sp., Sarcophyton sp.). We compared DMSP content of these soft coral species to that of commonly occurring temperate (Plesiastrea versipora) and tropical (Acropora aspera) scleractinian coral species. DMSP content was normalised to coral protein content, with soft coral DMSP content highly variable across species and locations [56–539 nmol (mg protein)−1], and lower than for the tropical [1242–4710 nmol (mg protein)−1], but not temperate [465–1984 nmol (mg protein)−1] scleractinian species. Further comparison with previously published values demonstrated that soft coral DMSP content falls within the “low–mid range” of scleractinian corals. Notably, DMSP content was also higher in summer samples than winter samples for the scleractinian corals, but did not differ between seasons for soft corals. Such contrasting dynamics of DMSP production by soft corals compared to scleractinian corals indicates that the regulation of DMSP content differs between these two important benthic cnidarian groups, potentially as a consequence of dissimilar ecophysiological roles for this compound.