[Composition and structure of the macrofauna associated with beds of two bivalve species in Cubagua Island, Venezuela] (original) (raw)
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Composition and structure of the macrofauna associated with beds of two bivalve species in Cubagua Island, Venezuela. Bivalve aggregations constitute a microhabitat for a wide variety of organisms in intertidal, subtidal and deep-water marine benthic habitats. Increase in density of bivalve beds could offer more crevices and substratum for the associated fauna, affecting community composition. Beds of the Atlantic Pearl Oyster (Pinctada imbricata) and the Turkey Wing (Arca zebra) of contrasting population densities were evaluated to determine the composition and structure of the associated macrofauna of three taxa (Crustacea Decapoda, Mollusca and Echinodermata). We evaluated plots of three levels of bed density in both species, the associated fauna were identified and counted. Other species were collected by qualitative samples. Univariate and multivariate descriptors were tested comparing the associated fauna between the beds of two species at three levels of density. In these beds a total of 104 species belonging to 58 families were recorded. Mithraculus forceps (Majidae), Crucibulum auricula (Calyptraeidae) and Ophiotrix angulata (Ophiothrichidae) were the most common species found in these assemblages. The medium and high-density bivalve beds exhibited greater species number, abundance, Shannon diversity, evenness, taxonomic diversity, and taxonomic distinctness of associated fauna, than low-density bivalve beds. Moreover, multivariate analysis detected different assemblages of associated fauna between beds with different densities. Additionally, similarities were found in the communities of macrofauna in both beds of P. imbricata and Arca zebra. Our results suggest that bivalve aggregations at Cubagua Island provide additional habitat for macrofauna living in other shallow habitats such as Thalassia beds, corals and rocky environments. Bed density, associated with topographic complexity, represents an important factor for the composition and complexity of the associated fauna. Rev. Biol. Trop. 61 (2): 669-682. Epub 2013 June 01.
Oceanic islands have special ecosystem dynamics due to their isolation and weather conditions influenced by the sea. This is also the case for Malpelo Island, located at the Colombian Pacific, where previous studies showed an invertebrate composition strongly dominated by predatory species. With the aim of contributing to the knowledge of these organisms on the island, 22 sample plots were surveyed, covering three types of microhabitat, classified according to the type of soil, shadow, and vegetation. Sampling took place between May and June 2006, by direct catches. A total of 1294 specimens from seven classes and 25 orders were obtained. Diversity was determined by microhabitat structure complexity, being more diverse the one that presented the greatest degree of heterogeneity. The order Araneae presented the highest number of species, Coleoptera the highest abundance and Staphylinidae the highest relative abundance. Predators showed the highest richness (45.3 %) and abundance (40....
2011
Las islas oceánicas poseen ecosistemas con dinámicas especiales debido a su aislamiento y condiciones climáticas influenciadas por el mar. Es el caso de la isla Malpelo, localizada en el Pacífico colombiano, en donde estudios previos mostraron una composición de invertebrados fuertemente dominada por depredadores. Con el propósito de contribuir al conocimiento de estos organismos en la isla, se realizaron muestreos en 22 parcelas, abarcando tres tipos de microhábitat, clasificados de acuerdo al tipo de suelo, sombra y vegetación. Las colectas se realizaron entre mayo y junio de 2006, mediante captura directa. Se obtuvieron 1294 especímenes, pertenecientes a siete clases y 25 órdenes. La diversidad estuvo determinada por la complejidad en la estructura del microhábitat, siendo más diverso el que presentó un mayor grado de heterogeneidad. El orden Aranae presentó el mayor número de especies, Coleoptera la mayor abundancia y Staphylinidae la mayor abundancia relativa. Los depredadores presentaron la mayor riqueza (45.3 %) y abundancia (40.6 %) de todos los gremios tróficos. Estos resultados refuerzan la idea de que el sistema terrestre de Malpelo es dependiente del mar.
2010
RESUMEN Para estudiar la ictiofauna y herpetofauna de la península de Araya en el estado Sucre, se seleccionaron las albuferas de Bocaripo y Chacopata en la costa norte y las lagunas de Campoma y Buena Vista, al sur. Adicionalmente, se realizaron colectas en los ríos tributarios de las lagunas Casanay, Cariaco, Grande y El Cordón. Los peces se colectaron mediante diferentes técnicas y su identificación taxonómica se realizó mediante claves especializadas. Para los muestreos de anfibios y reptiles se efectuaron caminatas diurnas y muestreos nocturnos en las adyacencias de la laguna de Bocaripo. La identificación taxonómica se realizó por avistamiento directo o canto en anfibios. Se recopiló información bibliográfica sobre anfibios y reptiles del estado Sucre. Se determinó el porcentaje de especies presentes por localidad, así como el Índice de Similaridad de Jaccard. La ictiofauna mostró baja diversidad: seis especies en cuatro órdenes y cinco familias. Las localidades más afines fue...
Caldasia, 2012
From April 2009 to January 2010, the composition and structure of macroinvertebrates assemblages associated with floating vegetation and sediments from the wetland Jaboque (Bogotá, Colombia) were characterized. Physical and chemical water variables were also measured. Macroinvertebrates in the aquatic vegetation comprised 36 genera, (27 confirmed and nine unconfirmed), 27 families, ten orders and five classes. The most abundant families in the macrophytes were Glossiphoniidae, Hyallelidae, and Asellidae. The average abundance was 908 ind/m 2. The highest density was observed in January 2010 (1099 ind/m 2) and the lowest in October 2009 (805 ind/m 2). The lowest richness and abundance values were recorded during higher rainfalls seasons. Benthic macroinvertebrates included six genera and five families; Tubificidae, Physidae and Glossiphoniidae were the most abundant; average abundance was 21.5 ind/m 2 .Variables such as ammonia, dissolved oxygen, BOD 5 and temperature showed significant differences between climatic periods. According to the principal component analysis (PCA), the suspended solids explain most of the variation in the data (80.1%), followed by dissolved oxygen (65%). Along with ammonium (68.9%), these variables showed a greater influence on the diversity of aquatic macroinvertebrates. The canonical correlation analysis revealed that the abundance of family Glossiphoniidae was positively related to nitrate concentration and conductivity, while the family Tipulidae it was with dissolved oxygen, thus evidencing that eutrophic and saprobic conditions influence the abundance of these families, probably due to their adaptation to these characteristics. In general, the results are related with the high concentration of organic matter and high levels of eutrophication of this wetland.
Se evaluó la diversidad de la macrofauna en fondos blandos de la plataforma marina cubana norte y suroccidental. Se utilizaron índices de variación taxonómica que aportan una nueva dimensión en la interpretación de la diversidad de las comunidades, que son independientes del tipo de hábitat y del esfuerzo de muestreo, y tienen respuesta monotónica ante las perturbaciones del ambiente. La heterogeneidad de taxones fue significativamente mayor en los biotopos areno-fangoso con vegetación, arenoso con vegetación y arenoso con vegetación sobre fondo duro. La diversidad por biotopos reflejó un gradiente de menor a mayor tamaño de partícula y de ausencia a presencia de vegetación. La distinción taxonómica promedio (Δ+) esperada en estas zonas de la plataforma cubana es de 92,5, con límites de confianza de 95% entre 76,7 y 100. Las estaciones con distinción taxonómica promedio <92,5 y fuera del límite de confianza inferior, se pueden considerar con condiciones ambientales de deterioro o que favorecen la diversidad de algún grupo en particular. Los grupos dominantes en esta fracción del bentos son crustáceos y poliquetos, como ocurre en otras regiones tropicales y templadas. Estos resultados sirven de base para la evaluación y monitoreo ambiental del macrozoobentos como componente clave del funcionamiento de ecosistemas marinos en fondos blandos de Cuba.