Interaccion trofica entre dos estrellas de mar (Astropecten riensis y Tethyaster vestitus) en Golfo Triste, Venezuela

Distribution, population parameters, and diet of Astropecten marginatus (Asteroidea: Astropectinidae) in the Venezuelan Atlantic coast. Astropecten marginatus is a sea star widely distributed in Northern and Eastern South America, found on sandy and muddy bottoms, in shallow and deep waters. To describe some of its ecological characteristics, we calculated it spatial-temporal distribution, population parameters (based on size and weight) and diet in the Orinoco Delta ecoregion (Venezuela). The ecoregion was divided in three sections: Golfo de Paria, Boca de Serpiente and Plataforma Deltana. Samples for the rainy and dry seasons came from megabenthos surveys of the "Línea Base Ambiental Plataforma Deltana (LBAPD)" and "Corocoro Fase I (CFI)" projects. The collected sea stars were measured, weighted and dissected by the oral side to extract their stomach and identify the preys consumed. A total of 570 sea stars were collected in LBAPD project and 306 in CFI one. The highest densities were found during the dry season in almost all sections. In LBAPD project the highest density was in "Plataforma Deltana" section (0.007±0.022ind/m 2 in dry season and 0.014±0.06ind/m 2 in rainy season) and in the CFI project the densities in "Golfo de Paria" section were 0.705±0.829ind/m 2 in rainy season and 1.027±1.107ind/m 2 in dry season. The most frequent size range was 3.1-4.6cm. The highest biomass was found in "Golfo de Paria" section (7.581±0.018mg/m 2 in dry season and 0.005±6.542x10 -06 mg/m 2 in rainy season for 2004-2005 and 3.979±4.024mg/m 2 in dry season; and 3.117±3.137mg/m 2 in rainy season for 2006). A linear relationship was found between the sea star size and its weight but no relationship was observed between its size and the depth where it was collected. Mollusks are dominant in the sea star diet (47.4% in abundance). The diet in any of the sections, seasons or between projects or size class was heterogeneous, using multivariate ordinations (MDS) and SIMPER analysis and there was no difference in the prey number or food elements that a sea star can eat. Although A. marginatus has been described as a predator, in this study were also inferred scavenger and detritivorous habits.

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Biomagnification of mercury through the food web of the Santos continental shelf, subtropical Brazil

Muto¹,

Soares²,

Sarkis³

et al. 2014

Mar. Ecol. Prog. Ser.

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This study was conducted on the continental shelf surrounding a large metropolitan region on the coast of São Paulo State, Southeast Brazil. This region harbours a large industrial plant and the largest port in Latin America, both of which release pollutants into the Santos−São Vicente estuarine system. High levels of Hg have been reported in sediments and fish from the estuaries and Santos Bay; however, data for the biota in offshore waters are scarce, and the biomagnification of Hg across the food web here has never been assessed. In this study, the trophic structure of the Santos shelf was addressed through the carbon and nitrogen stable isotope compositions of different species across a trophic gradient. We determined the total Hg levels (THg, dry weight) of invertebrates and fish to estimate the rate of biomagnification of this metal in the benthic and pelagic food webs. The lowest mean THg levels were found in zooplankton (0.006 µg g ). Overall, the Hg concentration in fish was below the recommended limit for human consumption. The THg and δ 15 N were positively correlated in both food webs; however, the rate of biomagnification was higher and the basal Hg was lower in the pelagic food web. These differences may be related to the differing bioavailability of mercury in water and sediment, the higher diversity of prey and more complex feeding interactions in the benthic food web, and metabolic differences among different taxa.

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Interaccion trofica entre dos estrellas de mar (Astropecten riensis y Tethyaster vestitus) en Golfo Triste, Venezuela

Cited by 3 publications

References 1 publication

Echinoderms from Venezuela: Scientific Recount, Diversity and Distribution

Echinoderms from Venezuela: Scientific Recount, Diversity and Distribution

Distribución, parámetros poblacionales y dieta de Astropecten marginatus (Asteroidea: Astropectinidae) en el Atlántico venezolano

Biomagnification of mercury through the food web of the Santos continental shelf, subtropical Brazil

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