ABSTRACT
Resumen Introducción: La Reserva Marina El Pelado es una importante área protegida de la costa ecuatoriana debido a la conectividad que tiene con otras áreas marinas protegidas. Objetivo: Identificar patrones de variación espacial en la estructura comunitaria del macrobentos de fondos someros. Materiales y Métodos: Se muestrearon diez sitios en la zona cercana a la costa y al Islote El Pelado. La abundancia de macroinvertebrados y organismos sésiles se estimó visualmente mediante buceo a lo largo de dos transectos en banda paralelos a la costa. Cada transecto fue de 50 m de longitud y 5 m de ancho, con una superficie total de 500 m2 por localidad. Se registró salinidad, pH, cloro residual, oxígeno, material flotante, coliformes fecales, mercurio, aceites y grasas en la superficie del mar. Resultados: Se identificaron 92 especies (86 especies de invertebrados y 6 especies de macroalgas); el grupo mejor representado fue el de los cnidarios con 31 especies de 13 familias, seguido de los moluscos con 15 especies de 11 familias. Las especies con mayores abundancias media fueron de macroinvertebrados Echinometra vanbrunti (21.54%), de organismos sésiles Bugula californica (34.2%). Conclusiones: No se encontraron diferencias significativas en la diversidad, riqueza y equidad de especies del macrobentos entre las zonas de estudio.
Abstract Introduction: The El Pelado Marine Reserve is an important protected area of the Ecuadorian coast due to the connectivity it has with other marine protected areas. Objective: Identify patterns of spatial variation in the community structure of shallow fund macrobenthos. Materials and Methods: Ten sites were sampled in the area near the coast and the El Pelado Islet. The abundance of macroinvertebrates and sessile organisms was estimated visually by diving along two parallel transects parallel to the coast. Each transect was 50 m long and 5 m wide, with a total area of 500 m2 per location. Salinity, pH, residual chlorine, oxygen, floating material, fecal coliforms, mercury, oils and fats were recorded on the sea surface. Results: 92 species were identified (86 species of invertebrates and 6 species of macroalgae); the best represented group was the cnidarians with 31 species from 13 families, followed by the molluscs with 15 species from 11 families. The species with higher average abundances were of macroinvertebrates Echinometra vanbrunti (21.54%), sessile organisms Bugula californica (34.2%). Conclusions: No significant differences were found in the diversity, richness and equity of macrobenthic species between study areas.
Resumo Introdução: A Reserva Marinha El Pelado é uma importante área protegida da costa equatoriana, devido à conectividade que tem com outras áreas marinhas protegidas. Objetivo: Identificar padrões de variação espacial na estrutura da comunidade de macrobentos fundos rasos. Materiais e Métodos: Dez locais foram amostrados na área próxima à costa e na Ilhota de El Pelado. A abundância de macroinvertebrados e organismos sésseis foi estimada visualmente mergulhando-se ao longo de dois transectos paralelos paralelos à costa. Cada transecto tinha 50 m de comprimento e 5 m de largura, com uma área total de 500 m2 por localização. Salinidade, pH, cloro residual, oxigênio, material flutuante, coliformes fecais, mercúrio, óleos e gorduras foram registrados na superfície do mar. Resultados: foram identificadas 92 espécies (86 espécies de invertebrados e 6 espécies de macroalgas); O grupo mais bem representado foi o de cnidários com 31 espécies de 13 famílias, seguido dos moluscos com 15 espécies de 11 famílias. As espécies com maior abundância média foram de macroinvertebrados Echinometra vanbrunti (21,54%), organismos sésseis Bugula californica (34,2%). Conclusões: Não foram encontradas diferenças significativas na diversidade, riqueza e equidade das espécies macrobênticas entre as áreas de estudo.
ABSTRACT
Rhodoliths are the free-living forms of a number of nongeniculate coralline algae. Rhodolith beds are a common feature of subtidal environments and have been recognized as important carbonate producers and paleoenvironmental indicators, as well as recognized as habitat-forming species. The rhodolith structure provides a hard three-dimensional substrate serving as microhabitat for a wide range of biodiversity, including commercially importance species. The largest known latitudinal occurrence range of rhodolith beds ais on the Brazilian coastal shelf from 2°N to 25°S. Despite their importance for the Brazilian benthic communities, only in the last decade sampling efforts allowed a more comprehensive understanding of the beds' distribution, their structure and associated communities, as well as data concerning the influence of environmental factors on rhodolith bed structure and dynamics. In this work, we review the available information on the biodiversity associated with the recently described Brazilian rhodolith beds of the continental shelf and oceanic islands, focusing on the associated organisms with potential for bioprospection research.
ABSTRACT
Environmental response in the Pacific to aseismic Cocos Ridge subduction (Panama and Costa Rica). The evolution of the marine communities along the Pacific coast of Central America, may have changed in response to the formation of the Isthmus of Panama. To evaluate the effect of the Aseismic Cocos Ridge (DAC) subduction on the marine benthic communities, we reconstructed benthic assemblages from Neogene fossiliferous formations in Burica and Nicoya peninsulas of Panama and Costa Rica. Paleoecological and paleoenvironmental conditions were reconstructed by comparing community structure from bulk fossil samples with dredge collections from modern Tropical American seas, using principal component analysis. Our results indicate that during the early Pliocene, before the closing of the Isthmus, some oceanic islands existed with moderate upwelling in the Burica region. After the closure, during the late Pliocene and early Pleistocene the collision of the DAC caused an uplift of the seafloor, where water depth of 2 300m became shallow waters of less than 40m depth. Meanwhile, upwelling intensified in the open ocean the uplift that had formed small islands in coastal areas of Burica, creating protected areas and limiting the upwelling effect that was given in open ocean. The subduction of the DAC continued until the islands were joined to the mainland and gradually disappeared, allowing the return of the upwelling. During the middle Pleistocene a second process of accelerated uplift ith speeds of 8m/1 000 years provoked again the elevation of the seafloor and later the elevation of the Talamanca Range. The new range formed a barrier that blocked the passage of the Trade winds, created new ecological conditions and optimized and allowed the growth of the best coral reefs in the coasts of the tropical Eastern Pacific (POT) between Panama and Costa Rica. Rev. Biol. Trop. 60 (2): 893-908. Epub 2012 June 01.
Con el fin de evaluar el efecto de la Subducción de la Dorsal Asísmica de Cocos (DAC) durante las etapas finales de la formación del Istmo. Realizamos muestreos con bultos en afloramientos fosilíferos en las penínsulas de Burica y Nicoya. Las condiciones paleoecológicas y paleoambientales fueron reconstruidas a partir de la comparación entre la estructura de las comunidades fósiles, con las comunidades modernas dragadas de los mares de Panamá, usando análisis de componentes principales. Los resultados indican que antes del cierre del Istmo, existieron islas oceánicas y un afloramiento moderado en Burica. Posterior al cierre, el choque de la DAC provocó la elevación del fondo marino y las aguas que se encontraban a 2 300m pasaron a 40m. El afloramiento se intensificaba en mar abierto pero la dorsal había formado islas en Burica que limitaban el efecto del afloramiento en la costa. La subducción de la DAC continuó y las islas se unieron gradualmente a tierra firme y desaparecieron, permitiendo el afloramiento. Durante el Pleistoceno medio un segundo proceso de levantamiento acelerado continuó elevando el fondo marino y formó la Cordillera de Talamanca. La cordillera creó una barrera que bloqueó el paso de los vientos Alisios y originó condiciones ecológicas y optimas que permiten el crecimiento de los mejores arrecifes de coral costeros del Pacífico oriental tropical (POT) entre Panamá y Costa Rica.