PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES.
Plastic pollution in oceans and rivers is of growing concern. Aquatic ecosystems play an important role in transport and storage of plastic waste from land-based storage to riverine and marine environments. This focus issue brings together new insights on the sources, transport dynamics, fate, and impact of plastic pollution through aquatic environments. The work collected in this focus issue shows that urban areas, transportation infrastructure, and wastewater treatment plants are consistently identified as sources for micro-, meso-, and macroplastics. Transport dynamics of plastics over land and through rivers were found to be driven by human factors, flood and storm events, and hydrodynamics, and combinations thereof. Most plastics were found not to make it to the open sea, but rather beach, float in coastal waters, or accumulate on land and within river systems. When exposed to the environment, both conventional and biodegradable plastics degrade into smaller pieces. Yet, the degradation and fragmentation of plastics in the environment remain unresolved. Future work should focus on transferability of new river and region specific insights, collection and exploration of large-scale and novel datasets, source and entry point identification, and understanding fundamental transport mechanisms. This focus issue provides new insights on sources, transport, fate, and impact of plastics, but also emphasizes that need for further work on plastics in aquatic ecosystems.
<p>The Black Sea region receives significant anthropogenic pollution inputs from rivers, coastal populations, and maritime activities. The use of a harmonized approach for monitoring floating marine litter in the Black Sea has revealed high densities of items in certain parts of the basin, including a predominance of plastic materials and a large number of plastic and polystyrene fragments. Although available data on marine litter are still rather limited in most compartments of the marine environment (beach litter, floating litter, and seabed litter), the European Commission has started to develop guidelines for the establishment of reference values and thresholds for beach litter following statistical approaches. In the case of floating litter, baselines and thresholds have not yet been established. In this study, we explore the statistical approach used by the European Commission to assess potential baselines and thresholds for floating marine litter in the Black Sea. Existing datasets were organized into groups according to distance from the coastline for comparison with basin-wide results. To explore potential baselines levels, the lower percentiles of the different datasets were calculated. For the proposal of potential thresholds, the selected percentiles were compared with different median confidence interval levels to calculate overlapping ranges. Depending on the distance from the coast,&#160;<span>the resulting</span><span>&#160;</span><span>the baselines and thresholds could fluctuate up to six times. These results could be proposed as interim reference levels for further marine litter assessments.</span></p>
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