Thoughts on controls on evolution and dispersal of benthos in the Magellan-Scotia Sea region: a workshop proposal

Abstract

SUMMARY:The Scotia Arc and the Scotia Sea comprise a geologically young feature of the Earth's surface that evolved over the last 40 million years (Ma) or so, between the southern tip of South America and the northern tip of the Antarctic Peninsula. With the notable exception of the much younger South Sandwich Islands, the islands, banks and seamounts of the arc represent dispersed fragments of a previous continental link between southern South America (Magellan region) and the Antarctic Peninsula. The benthic marine shelf faunas of the region are the focus of the IBMANT (Investigación Bioló-logica Marina en Magallanes relacionada con la Antártida) programme, and those of the surrounding oceanic deeps are the focus of ANDEEP (Antarctic Benthic Deep-Sea Biodiversity). Elucidating the potential relationships between the faunas of the region and the profound geographical, oceanographic and climatic changes undergone by the region in later Cenozoic time is hampered by significant unknowns in the geological history, the expense of further geoscientific exploration to fill these, and a general lack of communication between the biological and geological science communities. It is suggested that the time is opportune for a truly multidisciplinary workshop at which all the involved science communities have much to gain from the others.Keywords: Antarctic, evolution, invertebrates, faunistic exchange, interdisciplinary perspectives. RESUMEN: REFLEXIONES SOBRE LOS CONTROLES DE LA EVOLUCIÓN Y DISPERSIÓN DE ORGANISMOS BENTÓNICOS EN LA REGIÓNMAGALLÁNICA Y DE SCOTIA: UNA PROPUESTA DE TRABAJO. -El Arco de Scotia y el Mar de Scotia tienen características geológicas jóvenes, que evolucionaron en los últimos 40 millones de años (Ma), a partir de los actuales Cono Sur de América del Sur y extremo septentrional de la Península Antártica. Con la notable excepción de las mucho más jóvenes Islas Sánd-wich del Sur, las islas, bancos y montes sumergidos del arco representan fragmentos dispersos de una conexión continental previa entre la parte austral de Sudamérica (región magallánica) y la Península Antártica. La fauna marina bentónica de plataforma de la región ha sido el objetivo del programa IBMANT (Investigación Biológica Marina en la Región Magalláni-ca relacionada con la Antártida) y la concerniente con las profundidades oceánicas circundantes son el eje de estudio del ANDEEP (Antarctic Benthic Deep-Sea Biodiversity). La dilucidación de las relaciones potenciales entre las faunas de la región y los profundos cambios geográficos, oceanográficos y climáticos que sucedieron durante el Cenozoico tardío está dificultada por significativos desconocimientos en la historia geológica, los costos de exploraciones científicas adicionales para resolverlos, y una falta general de comunicación entre las comunidades científicas biológicas y geológicas. Se sugiere que es tiempo oportuno para un verdadero trabajo multidisciplinario en el cual las comunidades científicas involucradas tienen mucho por ganar unas de otras.

The biodiversity of the deep Southern Ocean benthos

“…Owing to its importance to the understanding of the origin of the Antarctic Circumpolar Current (ACC), there have been numerous studies of the tectonic evolution of Drake Passage and the Scotia Sea. Ideas on the time of opening of Drake Passage and the Scotia Sea and their possible effects on the marine biota were reviewed by Thomson (2004Thomson ( , 2005, and the resultant oceanographic changes by Mackensen (2004). There is general agreement that the old continental link between South America and the Antarctic Peninsula began to disintegrate ca 40 Myr ago (Lawver & Gahagan 2003) or even 50 Myr ago (Livermore et al 2005), but the detailed history is far from resolved (cf.…”

The Antarctic-Magellan connection: macrobenthos ecology on the shelf and upper slope, a progress report

“…in the sea with specific tectonic, climatic, glaciological or oceanographic events. Hopefully, however, we may be able-in close cooperation with other disciplines-to identify some major events when several important groups were affected at the same time (see Thomson, 2005).…”

“…Photos AWI; W. Arntz. common heritage of those parts of the great south continent, which drifted apart while major ocean gateways opened around Antarctica, giving rise to a vigorous circumpolar current system and the Antarctic Convergence (Polar Front). Unfortunately, the exact temporal sequence of those large-scale events in the past, particularly where the Drake Passage is concerned, is not yet as clearly understood as would be desirable for the purpose of linking environmental and evolutionary processes (see Thomson, 2005). It is very likely that major events, rather than gradual cooling over large periods, had marked effects, but we are still unable to establish a close connection between past physical events and biological processes.…”

The Magellan-Antarctic Connection: links and frontiers at southern high latitudes. Summary review

“…Among these are issues to be solved by geologists, palaeontologists and oceanographers, such as the exact timing of the final ocean gateway opening and the onset of a vigorous circum-Antarctic current system (Barker and Burrell, 1977;Barker and Thomas, 2004;Mackensen, 2004;Thomson*). Furthermore, the use of molecular approaches for the timing of biogeographic, radiation and extinction events has by no means been further advanced: depending on the method applied the results may differ by several million years (Hillis et al, 1996).…”