Depth distribution data were compared for 172 European and 157 Antarctic benthic invertebrate species occurring in the respective shelf areas. Antarctic species showed significantly wider depth ranges in selected families of the groups Bivalvia, Gastropoda, Amphipoda and Decapoda. No differences were found in Polychaeta, Asteroidea and Ophiuroidea, where European species also showed comparatively wide bathymetric ranges. These extended levels of eurybathy in the Antarctic benthos may be interpreted either as an evolutionary adaptation or pre-adaptation to the oscillation of shelf ice extension during the Antarctic glacial-interglacial cycle.

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Growth in ophiuroids is highly variable, and with increasing size and age of an ophiuroid specimen more and more of the innermost growth rings on the vertebral ossicles become overgrown and hence invisible. Two approaches to estimate individual age of slow growing brittle stars using the high Antarctic species Ophionotus victoriae are compared. One method interprets natural growth ring readings as size-increment data, whereas the second method compensates for growth ring overgrowth by means of an iterative corrective approach. Preconditions as well as advantages and disadvantages of both methods are discussed.

SUMMARY: This study aims on a first comparison of the shallow water (<550 m) ophiuroid fauna of the Magellan region and the high-Antarctic Weddell Sea. Five species are common to both the Magellan region (22 species) and the Weddell Sea (42 species). The most abundant Magellan species is Ophiuroglypha lymani, contributing 33% to total ophiuroid abundance and 44% to total ophiuroid biomass. The diets of O. lymani and of three closely related (same sub-family Ophiurinae) also dominant, Antarctic species are similar, indicate however slightly different feeding strategies. The Magellan species tends more towards microphageous grazing, whereas the Weddell Sea species act more like scavengers. Within the sub-family Ophiurinae growth performance of O. lymani is higher than in Antarctic species and in the range of boreal species. -El objetivo del presente estudio es realizar una primera comparación entre la fauna de ofiuroideos de aguas someras (<550 m) de la región de Magallanes y del Mar de Weddell (alta Antártida). Cinco de las especies estudiadas estan presentes tanto en la región de Magallanes (22 especies), como en el Mar de Weddell (42 especies). La especie magallánica más abundante es Ophiuroglypha lymani, contribuyendo en un 33-100% a la abundancia numérica total de ofiuroideos y en un 44-100% a la biomasa total de los mismos. La dieta de O. lymani y de tres especies taxonómicamente próximas (pertenecientes a la misma subfamilia: Ophiurinae), también dominantes, en la Antártida son similares, aunque presentan algunas diferencias en sus estrategias de alimentación. La especie magallánica tiende más hacia estrategias de tipo ramoneador micrófago, mientras que las especies del Mar de Weddell actúan más como carroñeros. Dentro de la subfamilia Ophiurinae, el crecimiento de O. lymani es mayor en comparación con el de las especies antárticas y está dentro del rango de las especies boreales.