Pathologies and mortality rates caused by organic carbon and nutrient stressors in three Caribbean coral species

Anthropogenic inputs, including organic carbon and nutrient loading, are increasingly changing the water quality on coral reefs. Herein we show that treatingMontastraea annularis, Agaricia tenuifoliaandPorites furcatawith various organic carbon sources (starch, lactose, arabinose and mannose) results in different species-specific and carbon-specific pathologies and rates of mortality. The variation in the pathological characteristics caused by stressors showed that visual cues for determining coral health and disease may be misleading. The probability of mortality increased significantly over time with continual exposure to several of the stressors, suggesting that chronic stressors may be more harmful than acute stressors. In contrast to the organic carbon sources, high concentrations of nutrients (phosphate, ammonium and nitrate) did not directly kill corals. The variation in coral responses to anthropogenic stressors means that changes on disturbed coral reefs will depend on the type of and duration of exposure to the stressor, as well as on the species of coral.