Abstract

Suspended sediments and eutrophication are considered main factors responsible for the high turbidities observed in Caribbean coastal waters. Turbidity is likely to be an important physical factor determining the health and structure of coral reef communities. Water turbidity can disrupt basic physiological functions leading to stress and reef degradation. The most evident effect is the reduction of light availability, which limits the photosynthetic capacity of the reef. Signs of organism stress include increased respiration rate, reduced growth and feeding rates, suffocation and in severe cases, death. Impacts of turbidity on fishes also include changes in social behavior and vision limitations that affect foraging success, predator avoidance, and ultimately fish production. Remote sensing has the potential to assess the spatial extent and level of water turbidity in terms of light attenuation coefficient (Kd PAR). In particular, the synoptic scale remote sensing offer for evaluating and monitoring coral reef ecosystems is useful for coastal marine resource management and conservation. However, interactions of physical and biological factors affecting the structure of reef communities must be assessed and calibrated to allow remote sensing to reach its full potential. This research investigates the relationship between water optical properties (Kd PAR) and coral and fish communities of reefs of fixed depth but exposed to different turbidity levels. We surveyed 35 reef sites in southwest Puerto Rico, where bio-optical (Kd PAR) measurements were taken, and fish and coral communities were characterized. A strong negative correlation was found between water turbidity and percent live coral cover. Structure of reef fish communities also varied significantly over the Kd range. However, reef rugosity and live coral cover were also important factors shaping the reef fish community

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