IDEA   23902
INSTITUTO DE DIVERSIDAD Y ECOLOGIA ANIMAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Benthic ecosystem responses to glacier retreatment process: a15 years case study at Potter Cove.
Autor/es:
SAHADE, RICARDO; ABELE, DORIS; FUENTES, VERÓNICA; LAGGER, CRISTIAN; TATIÁN, MARCOS; TORRE, LUCIANA
Lugar:
Barcelona
Reunión:
Simposio; SCAR XI Bilogy Symposium; 2013
Institución organizadora:
Scientific Committee on Antarctic Research
Resumen:
Glacier retreatment registered consistently along the Antarctic Peninsula, caused by its rapid warming, can impact coastal ecosystems in two folds. On one hand by affecting established communities by increased ice calving, sedimentation rates and fresh water input. On the other hand, this process is also opening new ice free areas available for colonization and establishment of benthic organisms. In Potter Cove both effects, marked shifts in established benthic communities structure and newly ice free areas densely colonized, have been observed. In the first case the most affected group were ascidians whose populations dropped down from a maximum of 26.8 ind.?m-2 to 8.16 ind.?m-2. Whereas the sea pen Malacobelemnon daytoni showed important population increments going from 27.06 ind.?m-2 and reaching up to 314.3 ind.?m-2. This species not only increased its population but also extended its distribution range, it was confined to shallow waters below 15 m depth and later effectively colonized bottoms up to 30 m depth. These shifts took place in a time span of almost 15 years but they were not gradual, the most marked changes occurred in the first 4 years, suggesting that both extremes could be two alternative states of equilibrium in this system. On the other hand, in a new island just uncovered by glacier retreatment and after 4 to 6 years of being ice free a dense community dominated by ascidians was registered. Densities measured are the highest ever reported, at least to our knowledge, reaching 419.16 ind.?m-2. These findings together are not only surprising but also challenge some established ideas of Antarctic ecosystem dynamics, i.e. the stability of Antarctic benthic communities, the velocity of colonization processes and growth rates of some Antarctic organisms or the suitability of under ice habitats for the development of benthic assemblages; depending whether the observed communities in newly ice free areas are the result of a rapid colonization process or if they were already established in ice refugia under the glacier. Then potential forcing factors driving the observed shifts in benthic assemblages are discussed on the basis of environmental data and available knowledge of the natural history of more affected species.