Jan Holstein

Distribution and trajectories of floating and benthic marine macrolitter in the south-eastern North Sea

In coastal waters the identification of sources, trajectories and deposition sites of marine litter is often hampered by the complex oceanography of shallow shelf seas. We conducted a multi-annual survey on litter at the sea surface and on the seafloor in the south-eastern North Sea. Bottom trawling was identified as a major source of marine litter. Oceanographic modelling revealed that the distribution of floating litter in the North Sea is largely determined by the site of origin of floating objects whereas the trajectories are strongly influenced by wind drag. Methods adopted from species distribution modelling indicated that resuspension of benthic litter and near-bottom transport processes strongly influence the distribution of litter on the seafloor. Major sink regions for floating marine litter were identified at the west coast of Denmark and in the Skagerrak. Our results may support the development of strategies to reduce the pollution of the North Sea.

Arctic benthic diversity research with PANABIO: scale, sharing, and modelling

Arctic marine biota are affected profoundly and at large scales by accelerating environmental change, such as, e.g., ocean warming and sea-ice decline. Moreover, increasing human activities add further cumulative pressures. Substantial shifts in ecosystem functions and services, including biodiversity, are expected. To understand, predict, and mitigate the profound ecological consequences of such shifts, it is critical to identify and analyze the relationships between environmental drivers and ecosystem functions at a range of scales (local, regional, and pan-Arctic). We are addressing this challenge by means of a pan-Arctic knowledge system on benthic biota (PANABIO). Underpinned by international efforts to combine data and expertise, PANABIO integrates quality-controlled and geo-referenced data on benthic communities in a public data-warehouse. The system will serve as a versatile means for (a) providing ecological baseline-data to gauge ecosystem changes, (b) analysing coupling mechanisms between environmental drivers and ecosystem functions/services on regional and pan-Arctic scales, (c) developing future ecosystem scenarios in response to external forcing, and (d) creating online stakeholder-oriented visualization and analysis tools. The talk will introduce into PANABIO’s rationale, demonstrate the huge up-scaling of benthic data, report on our achievements to support data-sharing, as well as explain the approach how to use community-level distribution models to discern benthic communities in relation to multiple-factor environmental forcing, including sea-ice dynamics.