Pelagic-benthic coupling in the Antarctic climate modulator: ecological reactions to climate change in the Weddell Sea, Antarctica (ECOWED).
Name: ANT-XXXI/2 (PS96) – ECOWED III
Ship: Research Vessel Polarstern.
Distance: 8551 nautical miles.
Started: December 6, 2015. Finished: February 14, 2016.
Departure port: Cape Town, South Africa
Arrival port: Punta Arenas, Chile
The broad continental shelf at the southern Weddell Sea is incised by the Filchner Trough (FT), which gives place to the water circulation system known as the Filchner Ronne outflow system. Earlier studies on the Filchner Ronne outflow system (ANT-XXIX/9 – ECOWED II) showed that the FT area and its vicinity present contrasting characteristics. On the eastern side of the FT, macrobenthic communities were more abundant than those thriving on the axis and the western side, whereas organic carbon concentration in the surface sediment (upper 5 cm) presented similar distributions. At the sea surface, sea ice coverage seems to be more persistent on the western side, suggesting that sea ice limits benthic growth. However, samples from the western side of the FT are still scarce limiting the developing of solid conclusions. The expedition ANT-XXXI/2 (PS96) – ECOWED III aimed to break through the sea ice on the western side of the FT and enlarge the sample collection of the area to improve our understanding on the pelagic-benthic coupling in that area.
Investigate the benthic community and sediment characteristics and their relationships to the environmental conditions at the sea surface in the Filchner Ronne Outflow system and its vicinity.
To get benthic animal samples we use Agassiz trawl, which provide semi-qualitative information on the benthic community. We also use a submarine high-resolution camera mounted on an OFOS (Ocean Floor Observation System) to observe the seabed and its larger inhabitants (visible for the human eye). Sediment samples are recovered with a multicorer, which enables getting the water-sediment interface almost undisturbed. This is very important to analyze the most recently deposited material onto the seabed.
Meteorological conditions in the Antarctic can turn adverse because of the combination of wind and sea ice, which sometimes is dense and impedes the access to target places. During the expedition to the western flank of the Filchner Trough we could not reach as much stations as we would like. However, we visited 8 stations with the multicorer, all of them on western flank FT. In total we generated more than 200 sediment samples, which are yet to be fully analyzed. In addition, 16 benthic community stations were performed with the OFOS and the multibox corer that will provide hundreds of samples from different communities and taxonomic groups. At the moment they are also in the analytical process. On board image analyses enabled the observation of benthic communities, which appeared comparatively poorer than those commonly found at the eastern side of the FT.
It is still early to draw conclusions because most of the samples are still under analyses; however, they soon will be available in this web page!
PhD in Natural Sciences
PhD Marine Science
Silvia De Diago