Understanding human-induced trophic cascades in coastal ecosystems

The main goal of ‘CASCADES’ is to increase our basic understanding of marine-terrestrial ecosystem connections in coastal Norway, and to discover how human activities influence these links. CASCADES will specifically focus on how human activities such as the capture of wrasses for use in salmon aquaculture, and the spreading of invasive species such as American mink, influences natural processes like the natural reestablishment of coastal predators such as the the European otter and how these effects cross ecotones and filter down the food web. The species groups involved in this study are of high cultural, ecological and economic value, including several species of wrasses, blue mussels, predatory fish, seabirds and semi aquatic mammals. The results of the study will give us detailed information on human influences on coastal ecosystems at several levels – from individual species to entire food webs. The project is a collaboration between the Norwegian Institute for Nature Research (NINA), the Institute for Marine Research (IMR), the University of Bergen (UiB), and the University of Highlands and Islands (Scotland). The project also involves a large reference group, including the Directorate of Fisheries, the Norwegian Environmental Agency, relevant County Governors, and County Municipalities and Naturvernforbundet Rogaland.

CASCADES is an international collaboration between coastal ecologists and geneticists. The project will also include a stakeholder group of national and regional environmental management authorities, and NGOs. CASCADES seeks to further our understanding of how current fisheries for cleaner-fish, which are essential for de-lousing farmed salmon in the Norwegian aquaculture industry, impacts the stability and long-term health of our coastal marine food webs in western Norway. Specifically, we aim to determine what cascading effects the cleaner-fish fishery has on other important marine species groups like shellfish and gadoids, as well as the wrasse species themselves. The project aims to discover what the cascading impacts of this fishery are on a more holistic perspective by studying diet composition of semi-aquatic predators between areas of intense fishing activity and marine protected areas. This will allow us to gauge how entire food webs are impacted by fishing activities related to aquaculture, and even gather information on cascading effects outside of the marine environment. CASCADES will also define to what extent past industries – specifically mink (Neovison vison) farming continues to impact coastal ecosystems throughout Norway and Europe. The project will focus specifically on the invasive mink’s relationship with vulnerable seabirds and its main native competitor, the Eurasian otter (Lutra lutra). Lastly, CASCADES will actively collaborate with government authorities for environmental management to increase public outreach and discuss future management of coastal Norwegian ecosystems in light of emerging research and pressing conservation needs.