Dynamics of benthic ecosystem functioning in response to the disintegration of the ice shelves in the western Weddell Sea
Zusammenfassung der Projektergebnisse
Life at the Southern Ocean seafloor is increasingly exposed to climate-induced changes such as sea-ice decline. At the same time its role in recycling of organic matter exported from the surface waters to the seafloor, a crucial part of benthic ecosystem functioning, is not understood. The aim of this project was to give a first quantification of oxygen and nutrient fluxes at the seabed of the North-Western Weddell Sea, as well as to identify the driving factors from the fauna and environment for those fluxes. Given that the originally targeted Larsen Ice Shelf area - with its unique state as a recently shelf-ice free area - could not be reached due to heavy sea-ice conditions, the project investigated three areas around the tip of the Antarctic Peninsula. At an overall of 13 stations in the Drake Passage, Bransfield Strait and North-Western Weddell Sea, oxygen and nutrient fluxes and the present macrofauna could be determined for the first time from seafloor samples. For example, oxygen fluxes ranged from -3.9 to -6.4, -1.8 to -4.1 and -1.4 to -6.9 mmol m^-2 d^-1 in the Drake Passage, Bransfield Strait and Weddell Sea, respectively (with negative values indicating sediment oxygen demand, i.e., fluxes into the sediment). Fluxes of silicic acid ranged from 3.1 to 11, 0.6 to 3.8 and -3.9 to 4.6 mmol m^-2 d^-1 in the respective areas. The comparison with benthic flux data from other polar regions generally support the accuracy of this first quantification from the Weddell Sea region. At the same time, it underpins the heterogeneity of regional biogeochemical flux patterns, which cannot be simply explained by sea-ice cover alone. A multivariate distance-based Linear Model showed that bottom water temperature and abundance of echinoderms explained the pattern of oxygen and nutrient fluxes best, while proxies of organic matter did not play a role. The importance of echinoderm abundance (compared to groups like polychaetes) for the flux pattern is surprising and needs further investigation to corroborate these findings. Publications originating from this project are in progress, while key findings have already been presented to the international scientific community at major conferences. Work in this project has further contributed to the publications by Segelken-Voigt et al. (2016) and Degen et al. (2018), integrating benthic ecological analyses and functional trait theory in the Southern Ocean. Regular participation in SPP 1158 workshops guarantees the contribution of findings about benthic ecosystem functioning to the programs' interdisciplinary research focus of "Response to Environmental Change". Thus, this project has been the first to investigate the influence of environmental conditions and macrofauna on fluxes at the Southern Ocean seafloor, and has moreover advanced research in this field by the follow-up research, including meio- and macrofauna simultaneously for explaining patterns in sediment fluxes of the Southern Ocean.
Projektbezogene Publikationen (Auswahl)
- (2015) Comparative studies on benthic functions in the Arctic and Southern Ocean. Gordon Research Conference and Seminar 'Polar Marine Sciences', Ciocco, Italy, 14 - 20/03/2015
Link, H., Archambault, P., Piepenburg, D.
- (2016) Spatial distribution patterns of ascidians (Ascidiacea: Tunicata) on the continental shelves off the northern Antarctic Peninsula. Polar Biology 39(5), 863-879
Segelken-Voigt, A., Bracher, A., Dorschel, B., Gutt, J., Huneke, W., Link, H., & Piepenburg, D.
(Siehe online unter https://doi.org/10.1007/s00300-016-1909-y) - (2017) Leben am Meeresboden. In: Faszination Meeresforschung : ein ökologisches Lesebuch. , ed. by Hempel, G., Bischof, K. & Hagen, W. Springer, Heidelberg, Germany, pp. 179-210
Piepenburg, D., Brandt, A., Juterzenka, K. v., Link, H., Arbizu, P. M., Schmid, M., Thomsen, L. & Veit-Köhler, G.
(Siehe online unter https://doi.org/10.1007/978-3-662-49714-2_19) - (2018) Trait-based approaches in rapidly changing ecosystems: A roadmap to the future polar oceans. Ecological Indicators 91: 722-736
Degen, R., Aune, M., Bluhm, B. A., Cassidy, C., Kędra, M., Kraan, C., Vandepitte, L., Włodarska-Kowalczuk, M., Zhulay, I., Albano, P. G., Bremner, J., Grebmeier, J. M., Link, H., Morata, N., Nordström, M. C., Shojaei, M. G., Sutton, L., Zuschin, M.
(Siehe online unter https://doi.org/10.1016/j.ecolind.2018.04.050)
