Los moluscos marinos litorales del norte de la península de Macanao, Isla de Margarita, Venezuela

Abstract

En este estudio se analiza la composición y distribución de los moluscos marinos litorales del norte de la península de Macanao, Isla de Margarita, recolectados entre febrero y mayo de 2007 en trece localidades. Las colectas se hicieron manualmente y con equipo ligero de submarinismo. Se estudiaron 2270 ejemplares, distribuidos en 68 familias, 106 géneros y 152 especies, representantes de las clases Bivalvia Linnaeus, 1758, Gastropoda Cuvier, 1797 y Polyplacophora Gray, 1821. Los gasterópodos fueron la clase dominante con 89 especies, siendo las especies con mayor distribución Lottia antillarum (Sowerby, 1831) y Purpura patula (Linnaeus, 1758) con 84,6%. En bivalvos (55) las especies con mayor distribución fueron Isognomom bicolor (C.B. Adams, 1845) con una presencia de 76,9% y Arca zebra (Swainson, 1833) con 69,2%; y en los polyplacophoros Chiton marmoratus Gmelin, 1791 y Chiton tuberculatus Linné, 1758 con 69,2% y Acanthopleura granulata (Gmelin, 1791) con 53,8%. Los valores más altos de diversidad, equidad y riqueza se obtuvieron en la localidad VII de El Faro de Punta Tigre II con un H´ de 3,8 bits/ind, J´ 0,80 y una riqueza específica de 83; y los más bajos en la localidad VIII de La Auyama con un H´ de 2,17 bits/ind J` 0,95 y 10 especies. De los gasterópodos, 40,4% fueron carnívoros y el resto 59,6% herbívoros. En la clase Bivalvia, 49 especies (89,7%) fueron filtradores suspensívoros y solo 6 (11,3%) colectores de materia orgánica depositada. En general esta elevada riqueza es producto de la heterogeneidad de ambientes y sustratos, la elevada productividad de sus aguas y el bajo grado de intervención antrópica en la mayoría de sus localidades.

The composition and distribution of littoral marine molluscs from northern Macanao Peninsula, Margarita’s Island are studied. The samples were collected in thirteen sites between February and May 2007. The captures were performed manually and with the aid of snorkeling. Overall, 2270 individuals were studied. They were distributed among 68 families, 106 genera and 152 species, belonging to Bivalvia Linnaeus, 1758, Gastropoda Cuvier, 1797 and Polyplacophora Gray, 1821 classes. The Gastropods were the dominant class with 89 species, being Lottia antillarum (Sowerby,1931) and Purpura patula (Linnaeus,1758 ) the two species with greater distribution, present in 84.6% of the samples. Among the 55 bivalve species identified the ones with higher distribution were Isognomom bicolor (C.B. Adams, 1845) present in 76.9% and Arca zebra in 69.2% of the samples. For the Polyplacophora, Chiton marmoratus Gmelin, 1791 and C. Tuberculatus Linne, 1758 were present in 69.2% of the samples and Acanthopleura granulata (Gmelin, 1791) in 53.8%. The highest value in diversity, evenness and richness were obtained at the locality VII of El Faro de Punta Tigre II with (H`) 3.80 bits/ind, (J`) 0.80 and specific richness of 83. The lowest values were found at the locality VIII of La Auyama with (H`) 2.2 bits/ind (J`) 0, 95 and 10 species. Among the gastropods, 40.4% were carnivores and the rest (59.6%) were herbivores. In the class Bivalvia, 49 species (89.7%) were suspension feeders and only 6 (11.3%) were surface deposit feeders. All the species of Polyplacophora were herbivores. In general, this high specific richness is the result of the heterogeneity of environments and substrates, the richness of macroalgae, the high productivity of the waters and the low degree of anthropic intervention in most of the sites.