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Presents an abstract of the article "Measurements of Erodibility and Settling Velocity of Intertidal and Subtidal Cohesive Sediments in a Coastal Lagoon, the Danish Wadden Sea," by T. J. Anderson, K. T. Jensen, L. Lund-Hansen, K. N. Mouritsen, and M. Pejrup.

"Effects of resuspension on the release of dissolved, redox sensitive elements (Fe, Mn) was studied in cylindrical microcosms. Effects from changing water stirring velocity in sediment pools were evaluated through measurements of pore water profiles of dissolved Mn, Fe and redox potential. Mn was a good natural marker to follow such effects. At current velocities below the threshold velocity for resuspension (37 cm s-1), Mn release rates to overlying water were 100 times higher compared to steady-state values. Pulse increases in Mn concentration were the result of convective currents inside flow chambers. These results were strongly supported by measurements of Eh profiles in the sediment pore water. Furthermore, impacts from increasing stirring velocity were found down to 1.9 cm depth below the resuspended layer of sediment. [ABSTRACT FROM AUTHOR]

The yearly nutrient supply from land and atmosphere to the study area in SW Kattegat is 10 900 tons of N and 365 tons of P. This is only few percent of the supply from adjacent marine areas, as the yearly transport through the study area is 218000 tons of N and 18250 tons ofP. Yearly nent of the year) resuspension. Resuspension frequency in deep water is less than 1 percent of the year. Resuspension rates, as averages for the study area, are 10-17 times higher than net deposition rates. Because of resuspension, shallow-water sediments are coarse lag deposits with small amounts of organic matter (1.1 percent) and nutrients (0.04 percent N and 0.02 percent P). Deepwater sediments, in contrast, are fine grained with high levels of organic matter (11.7 percent) and nutrients (0.43 percent N and 0.15 percent P). Laboratory studies showed that resuspension changes the diffusive sedimentwater fluxes of nutrients, oxygen consumption, and penetration into the sediment. Fluxes of dissolved reactive phosphate from sediment towater after resuspension were negative in organic-rich sediments (13.2 percent organic matter) with low porosity (56) and close to zero in coarse sediments with a low organic matter content (2.3 percent) and high porosity (73). Fluxes of inorganic N after resuspension were reduced to 70 percent and 0--20 percent in relation to the rates before resuspension, respectively. [ABSTRACT FROM AUTHOR]

Our ability to assess biodiversity at relevant spatial and temporal scales for informing management is of increasing importance given this is foundational to identify and mitigate the impacts of global change. Collecting baseline information and tracking ecological changes are particularly important for areas experiencing rapid changes and representing data gaps such as Arctic marine ecosystems. Environmental DNA has the potential to provide such data. We extracted environmental DNA from 90 surface sediment samples to assess eukaryote diversity around Greenland and Svalbard using two separate primer pairs amplifying different sections of the 18S rRNA gene. We detected 27 different phyla and 99 different orders and found that temperature and the change in temperature explained the most variation in the community in a single linear model, while latitude, sea ice cover and change in temperature explained the most variation in the community when assessed by individual non-linear models. We identified potential indicator taxa for Arctic climate change, including a terebellid annelid worm. In conclusion, our study demonstrates that environmental DNA offers a feasible method to assess biodiversity and identifies warming as a key driver of differences in biodiversity across these remote ecosystems.