Los arrecifes coralinos de Golfo Dulce, Costa Rica: aspectos geológicos

Abstract

Abslrad: The coral reefs and coral cornmunities in Golfo Dulce, soulhem Pacific Coast of Costa Rica, are described. The Inner Gulf reefs are characterized by a high topographic relief, low coral diversily and live coral covegage, and high dead coral coverage. The reefs can be zoned into: l. A reef-flat zone, where dead Pocíllopora and Psammocora are predorninant, togetber witb live and dead rnicroatolls of Porí/es loba/a. 2. A reef-edge zone, where tbere is a mar­ ked change in physiognorny, from a relatively horizontal reef-flat to an a1rnost vertical reef-fronL Tbis is tbe zone witb highest live coral coverage and is for tbe most part Porí/es loba/a. 3. A reef-front, extending frorn 2 to 10 m deptb, made up mainly of dead Porí/es lobala. The Outer GuIf reeís are characterized by a low topograpbic relief, high live coral coverage and diversity, and low dead coral coverage. A total of nine sc1eractinian species were found in Golfo Dulce. Most abundant are PorÍJes lobala, Psammocora stella/a and Pocillo poro damicornis, which have also becn present tbere tbroughout tbe Holocene. Twenty four fish species were observed in two reefs. Most of them are impor­ tant for tbe artesanal fisheries of Golfo Dulce. Otber species are important recf herbivores or coralli vores. Intemal ro-ral bioerosion (chief1y boring bivalves: Lithophaga) is more important tban extemal bioerosion.. Enviromnental conditions at Golfo Dulce were conducive to reef growth in tbe recent past but are now deteriorating as a result of Íhcreased sediment loads. Deforestation, pemicioÍls agricultural practices and miniog in tbe Golfo Dulce watershed must be brought under control and erosion reduced. H tbese were possible a program of reef rehabilitation by transplanti ng corals could be started to recover sorne oí tbe reefs.