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

Abstract

SUMMARY: Ecological work carried out on the Antarctic and Magellan shelves since the first IBMANT conference held at the UMAG, Punta Arenas in 1997 is summarized to identify areas where progress has been made and others, where important gaps have remained in understanding past and present interaction between the Antarctic and the southern tip of South America. This information is complementary to a review on shallow-water work along the Scotia Arc (Barnes, 2005) and recent work done in the deep sea (Brandt and Hilbig, 2004). While principally referring to shipboard work in deeper water, above all during the recent international EASIZ and LAMPOS campaigns, relevant work from shore stations is also included. Six years after the first IBMANT symposium, significant progress has been made along the latitudinal gradient from the Magellan region to the high Antarctic in the fields of biodiversity, biogeography and community structure, life strategies and adaptations, the role of disturbance and its significance for biodiversity, and trophic coupling of the benthic realm with the water column and sea ice. A better understanding has developed of the role of evolutionary and ecological factors in shaping past and present-day environmental conditions, species composition and distribution, and ecosystem functioning. Furthermore, the science community engaged in unravelling Antarctic-Magellan interactions has advanced in methodological aspects such as new analytical approaches for comparing biodiversity derived from visual methods, growth and age determination, trophic modelling using stable isotope ratios, and molecular approaches for taxonomic and phylogenetic purposes. At the same time, much effort has been invested to complement the species inventory of the two adjacent regions. However, much work remains to be done to fill the numerous gaps. Some perspectives are outlined in this review, and suggestions are made where particular emphasis should be placed in future work, much of which will be developed in the frame of SCAR's EBA (Evolution and Biodiversity in the Antarctic) programme.Keywords: macrobenthos, Antarctic, Magellan region, biodiversity, biogeography, ecology, evolution, disturbance.RESUMEN: LA CONEXIÓN ANTÁRTICO-MAGALLÁNICA: ECOLOGÍA DEL MACROBENTOS EN LA PLATAFORMA Y TALUD SUPERIOR, UN INFORME SOBRE LA LABOR REALIZADA. -Las investigaciones ecológicas llevadas a cabo en la plataforma antártica y de Magallanes, desde la primera reunión del IBMANT en Punta Arenas en el año 1997, se resumen en este trabajo, con el fin de identificar las áreas en que se han realizado progresos considerables, así como aquellas en las que aún quedan muchos aspectos por cubrir para poder comprender tanto el pasado como el presente de las interacciones entre las áreas antárticas y el "Cono Sur" de Sudamérica. La información que aquí se ofrece complementa la revisión de los trabajos realizados en aguas someras a lo largo del Arco de Scotia (Barnes, 2005) así como los trabajos más recientes ejecutados en el mar profundo (Brandt and Hil...

The Macrobenthic Ecology of the Straits of Magellan and the Beagle Channel

“…Despite the low number of stations sampled for the overall area under investigation, clear patterns were established by the diversity analysis. Both the range of abundance and biomass and the means calculated for these parameters strongly resemble other values reported for the Straits of Magellan and the Beagle Channel, and for Antarctica (see Table 2 in Arntz et al 2005). This is consistent with observations on the absence of latitudinal trends in this region (Brey & Gerdes 1999, Gerdes & Montiel 1999, Piepenburg et al 2002.…”

“…Although glaciation in the biogeographic Magellan region (sensu Camus 2001) did not reach the extent experienced by Antarctica, an extensive ice cap from 35 to 55°S did exist during the Late Glacial Maximum (LGM), approximately 21 ky ago (Benn & Clapperton 2000). The processes of gradual warming following the LGM explain much of the modern biogeographic pattern in the Magellan region (Arntz et al 2005). During the glacial period sea level was between ca.…”

Composición y Estructura de la Comunidad Macrobentónica en el Sitema Interior de Canales y Fiordos del Extremo Austral de Chile

“…Este patrón también es común en las comunidades de áreas subantárticas, en donde las comunidades de aguas poco profundas son relativamente pobres debido a la influencia del hielo, con un aumento en la riqueza de especies hacia aguas más profundas, en donde el impacto de los disturbios generados por el hielo es menor (cf. Arntz et al 2005).…”

“…84.000 km de costa lineal (Mutschke, 2008) y su origen asociado a la historia glaciar pasada y su influencia actual en el cono sur de Sudamérica (Clapperton et al 1995;McCulloch et al 1997;Kilian et al 2007), generan una enorme variedad de hábitats específicos ecológicamente jóvenes (Camus, 2001) y de numerosos tipos de comunidades asociadas (cf. Arntz et al 2005). Consecuentemente, la diversidad se presenta con una amplia heterogeneidad de valores.…”

“…Esta situación contrasta negativamente con la importancia económica y ecológica que se le otorga al área marina austral. Por una lado, se la señala como sector relevante para contribuir a la explotación y el cultivo de recursos marinos y, por otro, se le considera clave para contribuir a explicar patrones ecológicos y biogeográficos a lo largo de la costa del Pacífico o gradientes de diversidad hacia o desde los ecosistemas marinos antárticos (Brattström & Johanssen, 1983;Lancellotti & Vásquez, 2000;Gray, 2001;Arntz & Ríos, 1999;Camus, 2001;Arntz et al 2005;Fernández et al 2000;Escribano et al 2003;Valdovinos et al 2003;Montiel et al 2005).…”