Pacific coral reefs of panamá: Structure, distribution and predators

Structural coral reefs of Recent age are undergoing vigorous growth on the eastern Pacific continental shores of Panamá. Coelenterate hermatypes include 20 species; 3 are hydrocorals in the genus Millepora, a notable new record for the eastern Pacific region; the abundant scleractinians are Pocillopora (4 spp.), Pavona (6 spp.) and Porites (5 spp.).Pocillopora is the chief constructor of mound and fringing reefs with massive Pavona and Porites sometimes important at the reef base. Uninterrupted Pocillopora growth characterizes some fringing reefs, forming a vertical framework with observed maximum thickness of 6 m. Binding of coral by encrusting coralline algae imparts a more rigid and coherent structure to the reef crest and peripheral faces. Intra-reef and flanking sediments contain over 90% calcareous matter; the predominant grain constituents are Pocillopora, cirriped and mollusk fragments. Reefs attain their greatest development in the Gulf of Chiriquí; the reason for this is sought in the high and stable thermal conditions of this area. Radiometric dating indicates that net vertical reef growth may approach 1 m/250 years or 4000 B.

Important coral predators include fishes, a gastropod, paguran decapods andAcanthaster (in certain areas). Quantitative measurements of the feeding rates and population densities of corallivores indicate that predators may destroy approximately one-third of the annual growth of aPocillopora coral community.