Metal accumulation induces oxidative stress and alters carbonic anhydrase activity in corals and symbionts from the largest reef complex in the South Atlantic ocean.

We evaluated the influence of metal accumulation on the oxidative status [lipid peroxidation (LPO) and total antioxidant capacity (TAC)] and carbonic anhydrase (CA) activity in host and symbionts of the coral Mussismilia harttii and the hydrocoral Millepora alcicornis collected in Abrolhos Reef Banks (Northeast Brazil), potentially impacted by a major mine dam rupture. Considering metal levels measured in reefs worldwide, Abrolhos corals had higher Fe and Mn levels than expected for preserved offshore reefs. Increasing concentrations of arsenic (As), chromium (Cr) and manganese (Mn) drove inhibition of CA and increased oxidative damage in the hydrocoral M. alcicornis. The impairment of enzymatic activity in the symbiotic algae of M. alcicornis may be related to the oxidative stress condition. The hydrocoral M. alcicornis was more affected by metals than the coral M. harttii, which did not show the expected CA inhibition after metal exposure. Our results suggest that CA activity can be applied as a complementary biomarker to evaluate the physiological impacts of environmental metal contamination in reefs. Also, the metal levels and biochemical biomarkers reported in the present study may provide reference data to monitor the health of reefs impacted by a relevant dam rupture.