Although ascidians form a conspicuous part of sessile assemblages in the Caribbean, no specialized inventories have been developed in Venezuela, except for a list of 15 species reported from Margarita Island (1984). Here we present the results of a taxonomic workshop held in the Universidad de Oriente, Boca del Rio, Margarita Island during April 20-25 of 2009, sponsored by the NaGISA-Caribbean Sea program. La Restinga National park was surveyed and we found 29 species belonging to 19 genera and 10 families. The most abundant colonial species were Clavelina oblonga, Aplidium accarense, Polyclinum constellatum, Distaplia bermudensis, Symplegma rubra, S. brakenhielmi, Botrylloides nigrum and Ecteinascidia turbinata. Among the solitary ascidians Phallusia nigra, Ascidia curvata, Microcosmus exasperatus, Styela canopus, Styela sp.1 and Styela sp. 2 were the most abundant. The ascidian diversity in this lagoon is one of the highest for similar habitats in the Caribbean and seven species are new registers for Venezuela (Ascidia curvata, Ecteinascidia styeloides, Aplidium accarense, Distaplia stylifera, Trididemnum orbiculatum, Symplegma rubra, and S. brakenhielmi). One point of concern for the conservation of la Restinga National Park is the presence of possible introduced species, and some management procedures are suggested.

Abundance of Diadema antillarum (Echinodermata: Echinoidea) in the coasts of Venezuela. Diadema antillarum is a shallow-water sea-urchin from the tropical Atlantic whose populations almost disappeared in 1983-84 because of widespread mortalities which reached 87-100 %. In Venezuela, urchin population densities before the mortality event were comparable to those of other Caribbean regions; however, later abundancies remain unknown. The objectives of this study were to evaluate the recent densities of certain D. antillarum populations along the Venezuelan coasts and compare the densities at the Parque Nacional Mochima before and after the mortality. At each location urchin densities were determined by means of transects using 1m 2quadrats as sampling units. The highest mean densities were observed at the sites on the central coast: Ensenada de Oricao, 0.28 ind/m 2 (2002) and 1.05 ind/m 2 (2003), and Chichiriviche de la Costa, 0.84 ind/m 2 (2002) and 0.74 ind/m 2 (2003). In Mochima, the mean density before the mortality for D. antillarum oscillated between 0.28 and 4 ind/m 2 , after the mortality event the mean density varied between 0.15 ind/m 2 (2000) and 0.47 ind/m 2 (2000). The populations of D. antillarum studied at Parque Nacional Morrocoy and Refugio de Fauna Silvestre Cuare showed highest densities at Playuela (0.43 ind/m 2) and Cayo Sur (0.95 ind/m 2) respectively, whereas other sites showed densities below 0.1 ind/m 2. The density registered at Playuela in 2003 is lower than that reported before the mortality event (0.58-3.64 ind/m 2). The density for Parque Nacional Archipiélago de Los Roques, specifically for the Arrecife de Herradura remained constant between 2002 and 2003 with values between 0.22-0.23 ind/m 2 respectively. To conclude, the sea urchin abundancies observed at most of the Venezuelan coastal sites that we studied were higher than those reported for other areas of the northern Caribbean, even though the values have not yet returned to those preceding the 1984 mass-mortality event, due to the slow recovery of the populations.

Background: This study compiles the diversity of sea anemones in different shallow habitats (i.e. rocky shores, coral reefs, mangroves and sandy bottoms) in several locations of Venezuela, including the most important marine reserves of Venezuela:

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