The Caribbean waters of Venezuela are composed by a large variety of habitats, with over 2800 km of coastline, islands, and islets. This area is a transitional zone between two main biogeographic provinces, the Caribbean and the Brazilian, separated by the fresh water outflows of the Orinoco and Amazon rivers, and is therefore expected to be an area of high species diversity. However, concerning the study of molluscs, Venezuela is probably the poorest known region in the Caribbean. The best compilation of opisthobranch species known in Venezuela was produced almost a decade ago, mentioning the occurrence of 57 species, plus seven determined only to genus level. In this work, 134 species are reported for Venezuela (71 are illustrated), representing about 40 % of the entire diversity of opisthobranchs known in the Caribbean. Among the species occurring in Venezuela, 49 have here the southern limit of their distribution range and only one the northern limit. Forty-six species are recorded for the first time to the country and one is a new record for the Caribbean Sea, namely Placida cremoniana. In addition, the distribution and ecology of the species are given based in literature and new data.

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El Niño Southern Oscillation (ENSO) has generated global coral massive bleaching. The aim of this work was to evaluate the massive bleaching of coral reefs in Puerto Cabello, Venezuela derived from ENSO 2010. We evaluated the bleaching of reefs at five localities both at three and five meter depth. The coral cover and densities of colonies were estimated. We recorded living coral cover, number and diameter of bleached and nonbleached colonies of each coral species. The colonies were classified according to the proportion of bleached area. Satellite images (Modis Scar) were analyzed for chlorophyll-a concentration and temperature in August, September, October and November from 2008-2010. Precipitation, wind speed and air temperature information was evaluated in meteorological data for 2009 and 2010. A total of 58.3% of colonies, belonging to 11 hexacoral species, were affected and the greatest responses were observed in Colpophyllia natans, Montastraea annularis and Montastraea faveolata. The most affected localities were closer to the mainland and had a bleached proportion up to 62.73±36.55%, with the highest proportion of affected colonies, whereas the farthest locality showed 20.25±14.00% bleached and the smallest proportion. The salinity in situ varied between 30 and 33ppm and high levels of turbidity were observed. According to the satellite images, in 2010 the surface water temperature reached 31ºC in August, September and October, and resulted higher than those registered in 2008 and 2009. Regionally, chlorophyll values were higher in 2010 than in 2008 and 2009. The meteorological data indicated that precipitation in November 2010 was three times higher than in November 2009. Massive coral bleaching occurred due to a three month period of high temperatures followed by one month of intense ENSO-associated precipitation. However, this latter factor was likely the trigger because of the bleaching gradient observed. Rev. Biol. Trop. 60 (2): 527-538. Epub 2012 June 01.

Predation rate of Coralliophila abbreviata (Neogastropoda: Coralliophilidae) on some coral species at Parque Nacional Morrocoy, Venezuela. Coralliophila abbreviata is a tropical gastropod of the Caribbean Sea. This gastropod is an important corallivore. The objective of this work was to estimate the predation rate of C. abbreviata on some coral species in the coral reefs of Morrocoy National Park, Venezuela. The localities were Cayo Sombrero and Cayo Peraza. We evaluated the rate on five coral species: Montastraea annularis, Colpophyllia natans, Diploria strigosa, Diploria labyrinthiformis and Agaricia agaricites. We used three experimentals treatments. in treatment 1 we marked colonies with buoys that had been predated by C. abbreviata. in treatments ii and iii we used exclusion cages. Treatment ii included the colony with its predators and treatment iii was the control (only the colony). The injuries of the colonies were measured every 4 days for at least a month. The predation rate in treatment i varied depending on the coral species. The highest rate was on C. natans Un factor importante que puede definir la estructura de las comunidades coralinas son los organismos depredadores (coralív-oros), los cuales pueden representar una amenaza potencial para estos sistemas; (Moran 1986; Birkeland y Lucas 1990, Turner 1994, Knowlton 2001) debido a que pueden generar efectos negativos en la diversidad (Baums et al. 2003).Coralliophila abbreviata (Lamarck, 1816) es un molusco depredador de corales, común en las aguas tropicales del Atlántico Occidental; posee una distribución que abarca desde Bermudas hasta Venezuela. Se encuentra en aguas someras y habitualmente permanece en agregaciones mayores a veinte individuos sobre las colonias coralinas (Ward 1965), específicamente en la frontera entre el tejido vivo y el tejido muerto (Lewis 1960). Se ha estimado que C. abbreviata puede consumir 9 cm 2 /día de tejido coralino vivo (Ott y Lewis 1972).Estos moluscos se alimentan de tejido coralino mediante una probóscide que insertan sobre la cavidad celentérica del coral que, a través de una acción enzimática, provoca la fragmentación del epitelio. No posee rádula y el tejido que succiona pasa directamente al esófago mediante una bomba bucal que conduce el alimento hacia su intestino (Soong & Chen 1991). Miller (1981 reporta que C. abbreviata depreda por lo menos 14 especies de corales escleractínidos en el Caribe.En enero de 1996 el Parque Nacional Morrocoy (PNM) sufrió una mortalidad masiva en el sistema arrecifal, Laboy-Nieves et al. (2001) reportaron la muerte del 90% de la cobertura coralina, por lo que la depredación por C. abbreviata podría afectar la recuperación de los arrecifes coralinos en la zona de estudio. Si esta aseveración es correcta, se esperaría encontrar que C. abbreviata presente una tasa de depredación superior o igual, a la estimada por otros investigadores en los arrecifes del Caribe sobre especies coralinas presentes en el área de estudio.En tal sentido, se pretende estimar la tasa de depreda...

Two new species of the genus Rissoella Gray, 1847 are described from Venezuela, one from the National Park Morrocoy, Rissoella morrocoyensis sp. n. and the other from the Wildlife Refuge Isla de Aves, Rissoella venezolanicola sp. n. Rissoella morrocoyensis sp. n. has a deep umbilicus (partly closed), preumbilical cord, black head, hypobranchial gland marked by a pale yellow boomerang-shaped ribbon and it lives on the leaves of the seagrass Thalassia testudinum Banks & König, 1805. Rissoella venezolanicola sp. n. has an angled preumbilical cord which extends to the columella delimiting a trapezoid, a hypobranchial gland marked by a yellow quaver-shaped ribbon and protoconch with fuchsia highlights. It lives on the brown alga Dictyota spp. The records of Rissoella in the Caribbean are revised and illustrations, a comparative table and a key to the Caribbean species known for the genus are provided.