Modeling Small Scale Impacts of Multi-Purpose Platforms: An Ecosystem Approach

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.

Quantifying habitat provisioning at macroalgal cultivation sites

“…Models can also be used to assess cumulative ecosystem impacts of IMTA systems or multipurpose platforms such as integrated aquaculture and marine renewable energy sites to inform marine spatial planning and policy related to EAA. 280…”

“…As ecosystems are complex, models can tend to oversimplify aquaculture–environmental relationships 71 ; however, as our understanding of these systems improves, the usefulness of habitat provisioning models will also increase. Models can also be used to assess cumulative ecosystem impacts of IMTA systems or multipurpose platforms such as integrated aquaculture and marine renewable energy sites to inform marine spatial planning and policy related to EAA 280 …”

Exploring multiple stressor effects with Ecopath, Ecosim, and Ecospace: Research designs, modeling techniques, and future directions

“…Izquierdo-Gomez et al (2016) similarly modeled effects of escaped farmed fish on local fisheries via forcing functions for escapees. Serpetti et al (2021) modeled the effects of a combined offshore energy -aquaculture site in Ecospace through four pathways: increased primary production, forcing detritus from the fish farm based on an external model, environmental response functions for marine mammals sensitive to noise (reduced consumption with smaller distance to the source), and an attracting effect on predators (by designating the fish farm as the most suitable habitat). Also Harvey (2018) modeled noise impacts on marine mammals in Ecospace as reduced habitat foraging capacity (see also Section 6.3.9).…”

“…Also Halouani et al (2020) explored the exclusion of fishing from wind farms in Ecospace. Second, Serpetti et al (2021) modeled potential impacts of a combined offshore wind -aquaculture installation (see also Section 6.3.6), including avoidance behavior as an environmental response function based on distance to the installation. Third, Raoux et al (2019Raoux et al ( , 2017 directly forced biomass increases of functional groups expected to benefit from the addition of hard substrate.…”

“…AquacultureFerriss et al, 2016;Forrestal et al, 2012;Han et al, 2018Han et al, , 2017Izquierdo-Gomez et al, 2016;Li et al, 2014;Lin et al, 2009;Livne et al, 2020;Manju Lekshmi et al, 2020;Serpetti et al, 2021;Wu et al, 2016 • andYou, 2021;McGill et al, 2017;Niiranen et al, 2008;Rohal et al, 2020;Sandberg et al, 2007;Suprenand et al, 2019;Tierney et …”