Abstract
Aquaculture and marine renewable energy are two expanding sectors of the Blue Economy in Europe. Assessing the long-term environmental impacts in terms of eutrophication and noise is a priority for both the EU Water Framework Directive and the Marine Strategy Framework Directive, and cumulative impacts will be important for the Maritime Spatial Planning under the Integrated Maritime Policy. With the constant expansion of aquaculture production, it is expected that farms might be established further offshore in more remote areas, as high-energy conditions offer an opportunity to generate more power locally using Marine Renewable Energy (MRE) devices. A proposed solution is the co-location of MRE devices and aquaculture systems using Multi-Purpose Platforms (MPPs) comprising offshore wind turbines (OWTs) that will provide energy for farm operations as well as potentially shelter the farm. Disentangling the impacts, conflicts and synergies of MPP elements on the surrounding marine ecosystem is challenging. Here we created a high-resolution spatiotemporal Ecospace model of the West of Scotland, in order to assess impacts of a simple MPP configuration on the surrounding ecosystem and how these impacts can cascade through the food web. The model evaluated the following specific ecosystem responses: (i) top-down control pathways due to distribution changes among top-predators (harbor porpoise, gadoids and seabirds) driven by attraction to the farming sites and/or repulsion/killing due to OWT operations; (ii) bottom-up control pathways due to salmon farm activity providing increasing benthic enrichment predicated by a fish farm particle dispersal model, and sediment nutrient fluxes to the water column by early diagenesis of organic matter (recycled production). Weak responses of the food-web were found for top-down changes, whilst the results showed high sensitivity to increasing changes of bottom-up drivers that cascaded through the food-web from primary producers and detritus to pelagic and benthic consumers, respectively. We assessed the sensitivity of the model to each of these impacts and the cumulative effects on the ecosystem, discuss the capabilities and limitations of the Ecospace modeling approach as a potential tool for marine spatial planning and the impact that these results could have for the Blue Economy and the EU’s New Green Deal.
Highlights
The concepts of “Blue Growth” and “Blue Economy” refer to sustainable use of ocean resources enhancing economic growth within a system that preserves marine ecosystem health
Species biomasses were extracted within the region for each scenario and biomass changes for scenarios 2–6 were visualized by standardizing the species biomasses by the baseline in scenario 1 “no addition of the Multi-Purpose Platforms (MPPs)” (Table 3 and Figure 5)
The results showed between ± 5–25% relative changes for most of the functional groups due to the MPP pressures (Table 3 and Supplementary Figures 3, 4)
Summary
The concepts of “Blue Growth” and “Blue Economy” refer to sustainable use of ocean resources enhancing economic growth within a system that preserves marine ecosystem health. The energy trilemma on providing secure, sustainable, and affordable energy is a growing challenge, which drives expansion of renewable energy production from the marine environment (World Energy Council, 2019). The sustainable use of marine resources is facing the challenge of providing food and energy for an increasing global human population, which is expected to exceed 9 billion by the middle of the twenty-first century (United Nations, 2019). Many SDGs directly relate to fisheries and aquaculture, both of which are of critical importance in providing nutrition and employment to millions around the world (Food and Agriculture Organization [FAO], 2020). Aquaculture production has seen an annual global increase of ∼6% between 2001 and 2016 and in EU it is expected to increase to 30% by 2030 (Food and Agriculture Organization [FAO], 2020)
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