Gap identification in coastal eutrophication research - Scoping review for the Baltic system case

Coastal eutrophication is a major issue worldwide, also affecting the Baltic Sea and its coastal waters. Effective man-agement responses to coastal eutrophication require good understanding of the interacting coastal pressures from land, the open sea, and the atmosphere, and associated coastal ecosystem impacts. In this study, we investigate how research on Baltic coastal eutrophication has handled these interactions so far and what key research gaps still remain. We do this through a scoping review, identifying 832 scientific papers with a focus on Baltic coastal eutrophication. These are categorized in terms of study focus, methods, and consideration of coastal system components and land -coast-sea interactions. The coastal component categories include coastal functions (including also socio-economic driver aspects), pressures that are natural (or mediated by a natural process or system) or directly anthropogenic, and management responses.The classification results show that considerably more studies focus on coastal eutrophication pressures (52%) or im-pacts (39%) than on characterizing the coastal eutrophication itself (20%). Moreover, few studies investigate pressures and impacts together, indicating that feedbacks are understudied. Regarding methods, more studies focus on data col-lection (62%) than on linking and synthetic methods (44%; e.g., modelling), and very few studies use remote sensing (6%) or participatory (3%) methods. Coastal links with land and open sea are mentioned but much less investigated. Among the coastal functions, studies considering ecological aspects are dominant, but much fewer studies investigate human aspects and the coastal filter function. Among the coastal pressures, studies considering nutrient loads are dom-inant, but much fewer studies investigate the sources of these loads, especially long-lived legacy sources and possible solutions for their mitigation. Overall, few studies investigate synergies, trade-offs and incentives for various solutions to address cross-scale multi-solution management.

Automated summary

Coastal eutrophication is a significant global issue, including in the Baltic Sea, and effective management responses require a good understanding of the various interacting pressures and impacts. This study reviewed the existing research on Baltic coastal eutrophication and found that there is a focus on pressures and impacts, but less on characterizing the eutrophication itself. Furthermore, research on the interactions between land, coast, and sea is limited.