IDEA   23902
INSTITUTO DE DIVERSIDAD Y ECOLOGIA ANIMAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Glacier retreat and its consequences to coastal benthic ecosystems.
Autor/es:
SAHADE, RICARDO; MOMO, FERNANDO; SERVETTO, NATALIA; LAGGER, CRISTIAN; PATRICK MONIEN; TATIÁN, MARCOS; TORRE, LUCIANA; SCHLOSS, IRENE; ABELE, DORIS
Reunión:
Conferencia; SCAR 2016 Conference; 2016
Resumen:
The Antarctic Peninsula (PA) has lost almost 24 000 km2 of sea bed ice coverage in the last decades due to its rapid warming. This process can produce two-fold effects, on one side driving hydrological modifications on coastal regimes that could affect established communities and on the other hand opening new areas available for primary production and benthic colonization. These in turn can produce positive and negative feed-backs on climatic change by enhancing or reducing the change rate. Coastal benthic ecosystems along the PA are characterized by high diversities, abundances and biomasses, which can therefore play an important role in Carbon sequestration. Thus, when benthic assemblages are affected positive feedback could be expected and when favored increased Carbon sink could drive to negative feedback. Potter Cove (PC), South Shetland Islands, offered an excellent opportunity to asses both effects due to the retreat of the glacier that surrounds the cove and a long term monitoring program that allowed the establishment of baselines against which to compare changes. We recently reported a sudden shift in benthic communities structure related to increased sedimentation rates driven by the glacier retreat. This highlighted the potential role of sedimentation in driving major changes in coastal communities, especially in fjords systems, and also suggested the possibility of thresholds in environmental factors. This could be important in communities dynamics since gradual changes in environmental variables could not drive responses until the threshold is surpassed and trigger major shifts that could also be difficult to reverse. In this case sedimentation can affect benthic functioning and biomass reducing the potential Carbon sequestration of the system. On the other hand the glacier retirement also opened newly ice-free areas, including a new island. We could sample benthic communities after around six years of being free of ice and found a surprising assemblage characterized by high diversity, species richness, abundances, biomasses and a complex three dimensional structure. Ash-free dry mass was almost 850 g m2 more than an order of magnitude of the estimated mean in Antarctic shelves and even more than that expected in early successional stages. The finding of such developed assemblage in a new island, challenge the current prevailing image of slow colonization of Antarctic benthos and also opens the question of whether these assemblages could develop under glaciers in ice refuges. But also suggest that the negative feedback to climatic change in newly ice free areas could be more important than previously thought. These processes, i.e. environmental shifts that threaten coastal ecosystems and the opening of new areas available for colonization that could take place at previously unthought velocity could be especially intense in fjords along the AP. Since almost 90 % of the glaciers in the AP are in retreat these results acquire a high relevance.