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L'Antàrtida, molt més que gel J.M. Gili, A. Palanques, C. Orejas, E. Isla, N. Texidó, S. Rossi i P. López-González. Les comunitats bentòniques antàrtiques: el resultat d’una llarga història. The high Antarctic benthos is unusual in a number of ways, notably in the depth of the shelf, the dominance of suspension feeders and the development of complex three-dimensional biogenic structures on soft bottoms. Although the Antarctic shelf fauna contains a recent component, which probably arrived along shallow water routes, it is dominated by endemic taxa whose evolutionary history can be traced back at least to the Cretaceous. Here we argue that the composition of these modern communities is the result of a low-sedimentation environment, which was characteristic of Cretaceous epicontinental seas and is matched in the modern high Antarctic marine environment due to the lack of riverine continental runoff. Other characteristics such as the absence of big predators, a high diversity pool despite slow reproduction processes and trophic adaptations to feed on the small plankton fraction (as occurred in the palaeooceans) are also discussed. Based on these arguments, we propose that existing benthic communities in the high Antarctic have evolved since the middle of the Eocene, when the ice sheets formed, from a pool of relict species of the Cretaceous. |
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