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  • 1
    Publication Date: 2016-12-20
    Description: Trophic structure is among the most fundamental characteristics of an ecosystem since it is a useful way to determine the main energy flow at the ecosystem level. In the Magellan Strait, the local spatial heterogeneity at the shallow-waters ecosystems may have a great variety of potential food sources; however, knowledge about their biological communities and their structure is still unclear. We examined the trophic structure of shallow-water-mixed bottom communities at two sites in the sub-Antarctic Magellan Strait based on carbon (d13 C) and nitrogen (d15 N) stable isotope ratios. The benthic communities were composed of 46 species from 20 major taxa at Bahı´a Laredo (BL) and 55 species from 18 major taxa at Punta Santa Ana (PSA). Benthic macroalgae and organic matter associated with sediment are the major primary food sources at both sites. Although both sites are quite similar in their food sources and in their vertical trophic structure (C three trophic levels), the food web structure varied distinctly. Functionally, predators and grazers dominated both communities, but top predators were shorebirds, carnivore anemones and predatory nemerteans at BL, and sea stars, shorebirds, crabs and fishes at PSA. The distinct differences in the trophic structure at BL and PSA highlight the important variability of d15 N at the base of the benthic food web, the role of local environmental conditions and community dynamics in structuring shallow-water communities.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 2
    Publication Date: 2021-05-19
    Description: El gastrópodo carnívoro Trophon geversianus (Pallas, 1774) es una de las especies bentónicas explotadas comercialmente en la región de Magallanes, de la cual no existe información relacionada a su productividad biológica. En este trabajo, se estimó la producción secundaria y productividad de una población intermareal de T. geversianus a través del modelo de redes neurales. Los muestreos se realizaron estacionalmente en Bahía Laredo, estrecho de Magallanes entre los meses de agosto 2007 y abril 2008. La longitud de los ejemplares de T. geversianus fluctuó de 12,4 a 55,4 mm (28,4 ± 7,4). La población presentó una distribución unimodal. Las densidades medias estacionales oscilaron entre 0,23 ind m-2 y 0,97 ind m-2, mientras que la biomasa media varió entre 0,041 g PSLC m-2 y 0,194 g PSLC m-2. La producción secundaria anual promedio estimada para T. geversianus varío entre 0,03 y 0,16 g PSLC m-2 año-1 y la productividad estimada fue de 0,7 año-1. En la razón P/B se observó una correlación significativa con el peso corporal de T. geversianus. La productividad estimada para T. geversianus es consistente con los valores reportados en la literatura para otras especies de moluscos marinos de las áreas Antártica, Subantártica y Chilenas.
    Description: Although the carnivorous gastropod Trophon geversianus (Pallas, 1774) is one of the commercially harvested benthic species in the Magellan region, no information is available on its biological productivity. Secondary production and productivity (P/B ratio) from an intertidal population of T. geversianus was estimated using the neural networks model. Seasonal sampling was carried out in Bahía Laredo, Estrecho de Magallanes between August 2007 and April 2008. Individual lengths of T. geversianus ranged from 12.4 to 55.4 mm (28.4 ± 7.4). The population showed a unimodal size distribution. The seasonal average density ranged from 0.23 ind m-2 to 0.97 ind m-2, while average biomass varied between 0.041 g AFDW m-2 and 0.194 g AFDW m-2. Mean secondary production was estimated to range between 0.03 and 0.16 g AFDW m-2 yr-1 and estimated productivity was 0.7 year-1. The P/B ratio was significantly correlated with body size of T. geversianus. The estimated productivity values of T. geversianus are consistent with those reported in the literature for others molluscan species from Antarctic, Subantarctic and Chilean waters.
    Description: Published
    Description: Gastropoda, Razón P/B
    Keywords: Gasterosteidae ; Muricidae ; Marine molluscs ; Secondary production ; Biological production
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
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