Correlation between coral lesions and skin hyperpigmentation in reef fish of the Southwest coast of Grenada

Abstract

Marine ecosystems rely on hard corals. Since 2014, a rapidly spreading disease causing stony coral tissue loss disease (SCTLD) has devastated coral reefs in the Caribbean. In 2019, corals exhibiting necrotic lesions compatible with SCTLD were documented on the coast of Grenada in the West Indies. These lesions, hereafter called Stony Coral Necrotic Lesions (SCNL), are associated with coral death. Concomitantly on the same reefs, signs of skin hyperpigmentation were detected in French grunt (Haemulon flavolineatum) and ocean surgeonfish (Acanthurus bahianus). This field study investigated potential correlations between SCNL abundance in representative transects and fish hyperpigmentation across 12 dive sites on Grenada's Southwest coast. The percentage of corals displaying SCNL was 45% of hard coral colonies. The study found a significant correlation (P = 0.004) between the percentage of fish affected by hyperpigmentation in a given reef and the abundance of SCNL in corals of the same dive site on evaluated transects. Sites located in St-Georges Bay also tended to have a higher proportion of diseased corals, but no significant difference was noted between study regions. This preliminary study provides insights into SCNL in Grenada and establishes a foundation for future longitudinal investigations including further evaluation of human-induced stressors that may threaten coral and fish health and make them more susceptible to diseases.