Variation in species diversity of deep-water megafauna assemblages in the Caribbean across depth and ecoregions.

Diversity patterns of the deep-sea megafauna in the Caribbean Basin and the Guiana ecoregion were analyzed in order to test the hypothesis of species richness variation as a function of depth and the hypothesis of non-differences between ecoregions by analyzing spatial patterns of five taxa and a merged assemblage. Collections of five taxa (corals, sea stars, sea urchins, sea lilies and gastropods) were obtained from seven oceanographic expeditions aboard the R/V Pillsbury at 310 stations between 60 and 7500 m depth. Data were sorted according to depth zones and ecoregions and were analyzed in order to estimate species richness, changes in species composition and distinction of ß-diversity by species turnover or by nestedness. The observed patterns of diversity were consistent between taxa and their assemblage: Species richness increased from the continental shelf (60-200 m deep) to the slope (200-2000 m deep), followed by a decrease at the continental rise-abyssal zone. We detected marked changes in species composition according to depth ranges. Changes in species composition in relation to ecoregions were also detected. In general, the Caribbean Basin lacks important physical barriers, causing high deep-sea ecosystem connectivity; however, variation in composition could be related to changes in environmental conditions associated with productivity and/or continental influences.

A single-use site selection technique, using GIS, for aquaculture planning: choosing locations for mangrove oyster raft culture in Margarita Island, Venezuela.

Oyster culture has a potential to generate income for coastal communities and to lessen pressure on natural overexploited populations. A project to transfer mangrove oyster Crassostrea rhizophorae raft culture technology to selected coastal communities in Margarita Island, Venezuela is being developed, and an optimum location selection technique was devised. To pick the variables or factors that determine site suitability, a bibliographic database was made, aspects of interest chosen, and the most comprehensive ones singled out, eliminating redundant ones. Twenty variables were grouped in criteria based on the way they influence the project. Variables were classified as intrinsic environmental, environmental extrinsic, logistic, and socioeconomic criteria. Thirty-five experts were asked to evaluate the factors and to score each according to their suitability weight. Logistic criterion received the highest values, followed by environmental extrinsic issues. A Geographic Information System using a base map compiled from 1:25,000 scale maps was developed. A thematic map for each factor was completed, dividing graphically the 3896-km2 study area into polygons of equal weight for each factor. The Multi-Criteria Evaluation (MCE) was used to combine the variables. Resultant vectors in thematic maps were added to obtain smaller polygons with the same value sum. Finally, MCE was used to generate a final output: the optimum sites for oyster aquaculture resulting from the added values of over 3000 polygons in the maps, for the 20 criteria. Higher scores were reached in 13 areas covering 4.1 km2, those places having the optimum conditions for oyster raft aquaculture in the region. Additional locations meeting 75% to 70% of the demanded criteria for a final suitable selection cover 137 sites encompassing 37.5 km2.

Programa caricomp: monitoreo a largo plazo de los ecosistemas marinos del Parque Nacional Morrocoy, Venezuela / Carimp program: long-term monitoring of marine ecosystems at Morrocoy National Park, Venezuela

Se reportan los resultados recabados durante la ejecución del programa CARICOMP (Caribbean Coastal Marine Productivity). Este programa tiene como objetivo principal estudiar la estructura y funcionamiento de los tres principales ecosistemas costeros del Caribe: bosques de manglares, praderas de fanerógamas marinas y arrecifes coralinos. En estos estudios participan actualmente más de 12 laboratorios de nueve países caribeños, formando una red de centros integrados. En Venezuela el programa está representado por la Fundación La Salle y por el INTECMAR (USB), instituto que ha monitoreado rutinariamente estos ambientes en el Parque Nacional Morrocoy durante casi una década, desde 1992 hasta el presente. Así, se han registrado variables fisicoquímicas y biológicas en varias localidades, determinándose la estructura, composición y productividad de estos sistemas marinos. Esta información permite establecer comparaciones con los datos obtenidos por los otros laboratorios, proporcionando una base de datos local y regional lo suficientemente robusta como para documentar (a largo plazo) respuestas de umbral de estos ecosistemas a los cambios globales, incluyendo impactos humanos y cambios climáticos