MSM46: Forschungsfahrt MSM46
Cruise results and the post-cruise analyses of material collected during the cruise will permit to investigate a number of topics and to characterize the status of environmental conditions in eastern Canadian coastal waters. Four themes are retained:
1. Recent (micro)biological and biogeochemical processes in hypoxic areas and coastal ecosystems with pelagic salinity and oxygen gradients: i) microbiological investigations focus on the microbial adaptation (biodiversity and activity of size-fractioned microbial communities) along the horizontal salinity gradient from the Gulf of Stl. Lawrence (GSL) to the Lower St. Lawrence Estuary (LSLE); ii) benthological studies relate to the long term adaptation of benthic macrofauna to oxygen minimum conditions along dissolved oxygen gradients from GSL to LSLE. The results on distribution, composition and functional diversity will be compared to other hypoxia facing benthic ecosystems (e.g. Baltic Sea). Communities of hypoxic zones will be compared to adjacent oxic seabed ecosystems (e.g. Hudson Strait, Labrador Current areas). iii) biogeochemical studies (dissolved oxygen, alkalinity, nutrients) will a.o. identify the contribution of different water masses to the bottom waters of the LSLE. iv) studies on annual suspended matter fluxes (e.g. organic carbon) using sediment traps, iii) bio-optical measurements to improve the accuracy of remote sensing derived data (e.g. primary productivity)
2. Contaminant and pollution history in eastern Canadian coastal ecosystems. For the pollution history the full range of organic POPs (PCBs, DDTs, PAH, HCB, Chlorinated pesticides) and inorganic (Hg) hazardous substances will be measured in the sediments.
3. Sub-recent and past changes in hypoxia and ocean dynamics in the GSL and the LSLE to distinguish the effects of anthropogenic (eutrophication) from natural (large scale ocean circulation) pressures.
4. Natural drivers of ecosystem changes by reconstructing the mid to late Holocene climatic evolution and ocean circulation changes in the eastern Canadian coastal waters with particular emphasis on marginal basins and large fjord systems. Monitoring past changes in hydrographic and biogeochemical properties and comparing those with new results obtained for major surface water masses in the open Labrador Sea (MSM45) as well as with other climate data, will shed new light into mechanisms causing Holocene climate fluctuations in the North Atlantic region.
Complementary to the field experiments we will set up a three-dimensional ecosystem model for the Gulf of St. Lawrence region. The combined approach of proxy studies and numerical simulations will allow to extrapolate the rather point proxy investigations to the whole LSLE/GSL. Modell experiments will support field experiments and data for hypothesis testing and quantifying the impact of forcing parameters.