SCAR Biology Symposium 2017
The SCAR Biology Symposium 2017 took place in Leuven, Belgium. Researchers from every continent gathered to show and discuss their most recent findings and at the same time took the opportunity to meet friends from Antarctic expeditions and previous symposia. As usual, it was a fruitful and fun meeting, this time accompanied with the mild Belgian summer weather. Enrique Isla and collaborators presented two posters with results from the ECOWED and previous expeditions. In one of them, the results of organic carbon and biogenic silica content in the continental shelf on the eastern side of the Filchner Trough showed that the biogenic matter is more concentrated close to the ice shelf and at the continental shelf break; however, the reasons remain unknown. On the other hand, benthic macrofaunal abundances were better correlated to organic carbon contents than to biogenic silica.
The second poster showed results on the cytotoxical potential of sediment extracts from various regions along >4500 km of the continental shelf and glacial troughs of the Weddell Sea and the vicinity of the Antarctic Peninsula and the South Shetland Islands. The results showed that the sediment extracts from the Filchner Trough and the southeastern Weddell Sea had low cytotoxical values, whereas the sediment from the vicinity of the Antarctic Peninsula and the South Shetland Islands had similar cytotoxical potential to that found in Mediterranean ports. This pattern matched with that of ship traffic, which is higher in around the Antarctic Peninsula than in the southeastern Weddell Sea, where environmental conditions are harsher for it.
The abstracts of the presentations are here below:
Distribution of biogenic silica and organic carbon in sediment of the “Filchner- Rønne Outflow System” in the southern Weddell Sea.
Organic carbon (OC), biogenic silica (bSi) and grain size were measured in 16 sediment cores from the continental shelf and slope and the inner trough of the remote Filchner-Rønne Outflow System (FROS) to identify potential organic matter hotspots which may help analyzing the distribution of benthic communities in the area. Sediment sampling was carried out with a multicorer, which enables the collection of the sediment water inter-phase with rather small disturbance. The results present here correspond to the inventories of the upper 5 cm sediment column, the section that contains the most recently deposited material and also exposed to the most intense trophic activity of benthic organisms. The highest OC values were found in samples from the continental slope of the eastern flank of the Filchner Trough, whereas the highest bSi concentrations corresponded to samples from the continental shelf of the same flank. The lowest values for both parameters were associated to the continental shelf and slope of the western flank, whereas samples from the axis of the trough showed intermediate values despite their higher water depth. No significant relationship among biogenic variables and fine sediment (combined fraction of silt and clay) were found; however, samples with the coarser sediment coincided with the highest OC contents and contrastingly, the highest bSi and fine sediment contents were measured in the same samples. Preliminary results showed that the spatial distribution of macrobenthos abundances (ind m-2) match better with OC concentrations, particularly at the shelf break, than with bSi.
Poster Leuven 2017 OCbSiGS
Toxicity in sediments across the Antarctic continental shelf.
Sediments act as long term sink for hydrophobic pollutants and the assessment of their toxicological quality provides information on the environmental characteristics where they were generated at upper layers of the water column. The toxicity and presence of CYP1A inducers in Antarctic continental shelf sediments were investigated to estimate the potential anthropogenic impact in a remote, presumably pristine area of the world ocean. CYP1A inducers, e.g., polycyclic aromatic hydrocarbons, dioxins and dioxine-like compounds are related to anthropogenic activity. The fish hepatoma cell line PLHC-1 was exposed to organic extracts of 12 samples of the upper 5 mm of the sediment column from four zones to assess and compare among them the a-priori negligible impact of anthropogenic pollution. The regions under investigation were the Drake Passage off the South Shetland Islands and the Bransfield Strait (DP), the NW Weddell Sea (NW), the Filchner shelf at the southernmost Atlantic (SW) and the Austasen shelf at the easternmost Weddell Sea (EW). The regions DP and NW are currently exposed to comparatively higher ship transit, whereas EW and SW undergo less transit and harsh environmental conditions, which require ship ice-breaking capabilities. Preliminary results revealed striking values of sediment toxicity. On the one hand, the DP and NW sediment extracts showed cytotoxicity in PLHC-1 cells and significantly induced the activity 7-ethoxyresorufin O-deethylase (EROD) after 24 h exposure at concentrations comparable to those found in Mediterranean coastal areas, whereas on the other hand, no cytotoxicity and low or no presence of CYP1A inducers were detected in SW and EW samples. These findings strongly suggest that anthropogenic activities are clearly impacting the Antarctic continental shelf threatening the rich and diverse shelf benthic communities, formerly thought as relatively isolated from anthropogenic pollution. The investigation is still open to identify the potential sources of these pollutants and their historical records.
Poster Leuven 2017 Toxicity