Copper effects on biomarkers associated with photosynthesis, oxidative status and calcification in the Brazilian coral Mussismilia harttii (Scleractinia, Mussidae).

Seawater contamination with metals, such as copper (Cu), is a notable local impact threatening coral reefs. Cu effects on biomarkers associated with photosynthesis, oxidative status and calcification were evaluated in the Brazilian coral Mussismilia harttii using a marine mesocosm facility. Polyps were kept under control conditions (1.9 µg L-1 Cu) or exposed to dissolved Cu (3.0, 4.8, and 6.7 µg L-1) for 12 days. Photochemical efficiency of the photosystem II of symbiotic algae (zooxanthellae) was measured and polyps were analyzed for antioxidant capacity, lipid peroxidation, DNA damage, and carbonic anhydrase Ca-ATPase, Mg-ATPase and (Ca,Mg)-ATPase activities after 12 days. Results highlighted the effects of Cu exposure, leading corals to an oxidative stress condition [increased total antioxidant capacity (TAC) and DNA damage] and a possible reduced calcification ability [decreased (Ca,Mg)-ATPase activity]. Therefore, biomarkers associated with oxidative status (TAC and DNA damage) and calcification [(Ca, Mg)-ATPase] are indicated as good predictors of corals health.

Impact of oil spills on coral reefs can be reduced by bioremediation using probiotic microbiota.

Several anthropogenic factors, including contamination by oil spills, constitute a threat to coral reef health. Current methodologies to remediate polluted marine environments are based on the use of chemical dispersants; however, these can be toxic to the coral holobiont. In this study, a probiotic bacterial consortium was produced from the coral Mussismilia harttii and was trained to degrade water-soluble oil fractions (WSFs). Additionally, we assessed the effect of WSFs on the health of M. harttii in tanks and evaluated the bacterial consortium as a bioremediation agent. The consortium was responsible for the highly efficient degradation of petroleum hydrocarbons, and it minimised the effects of WSFs on coral health, as indicated by raised photosynthetic efficiencies. Moreover, the impact of WSFs on the coral microbiome was diminished by the introduced bacterial consortium. Following introduction, the bacterial consortium thus had a dual function, i.e promoting oil WSF degradation and improving coral health with its probiotic features.