Water Quality and Health of Coral Reefs

Abstract

This study estimates the impacts of degraded water quality parameters and a continued warmer climate on coral reef abundance in the Florida Keys National Marine Sanctuary (FKNMS). Degraded water quality effects can be directly observed in corals’ reduced recruitment, decreased calcification, shallower depth distribution limits, altered composition (more heteroptrophic fauna), and loss of biodiversity (ISRS, 2004). The following species Scleractinia, stony coral, and Octocorallia, soft coral, are the primary focus of this study. Understanding the effects of increased turbidity, nitrates, silicates, and temperature on coral cover is crucial given the important ecosystem and economic roles coral reefs play. Analysis of the 10-year data on coral coverage and nutrient concentration in the FKNMS indicates that enhanced levels of nitrite and nitrate combined significantly reduce total coral coverage in the Keys. Initially elevated levels of silicate enhance the abundance of corals, however, excessive levels result in significant decline in coral ecosystem. The regression results also show that the increased turbidity is associated with low coral coverage and warmer climate negatively impacts coral abundance. Analyzing by types of corals, stony corals exhibit more sensitivity to nutrient pollution and enhanced turbidity levels relative to octocorals. Both types of corals remain sensitive to warmer climate. The results of this research have significant policy implications. For policy making related to the Florida Keys Marine Sanctuary, this research suggests that management efforts geared towards efficient water pollution control can greatly enhance coral reef abundance in the Keys. Furthermore, coordinated efforts at local, regional, and national levels may deem vital for the achievement of these sustainability goals. General implication of the results are that corals remain highly sensitive to climatic and anthropogenic stressors even in marine sanctuaries, and these effects are likely severe and more alarming for reefs in unprotected areas.