Ecological coherence of Marine Protected Areas: New tools applied to the Baltic Sea network

Abstract

1. Spatial connectivity is an essential process to consider in the design and assessment of Marine Protected Areas (MPAs). To help maintain and restore marine populations and communities MPAs should form ecologically coherent networks.How to estimate and implement connectivity in MPA design remains a challenge.2. Here a new theoretical framework is presented based on biophysical modelling of organism dispersal, combined with a suite of tools to assess different aspects of connectivity that can be integrated in MPA design. As a demonstration, these tools are applied to an MPA network in the Baltic Sea (HELCOM MPA).3. The tools are based on the connectivity matrix, which summarizes dispersal probabilities, averaged over many years, between all considered areas in the geographic target area. The biophysical model used to estimate connectivity included important biological traits that affect dispersal patterns where different trait combinations and habitat preferences will produce specific connectivity matrices representing different species. 4. Modelled connectivity matrices were used to assess local retention within individual MPAs, which offers indications about the adequacy of size when MPAs are considered in isolation. The connectivity matrix also provides information about source areas to individual MPAs, e.g. sources of larvae or pressures such as contaminants. How well several MPAs act as a network was assessed within a framework of eigenvalue perturbation theory (EPT). With EPT, the optimal MPA network with respect to connectivity can be identified. In addition, EPT can suggest optimal extensions of existing MPA networks to enhance connectivity. Finally, dispersal barriers can be identified based on the connectivity matrix, which may suggest boundaries for management units.5. The assessment of connectivity for the HELCOM MPA are discussed in terms of possible improvements, but the tools presented here could be applied to any region.

Combining seascape connectivity with cumulative impact assessment in support of ecosystem‐based marine spatial planning

“…Failing to include seascape connectivity in CIA will underestimate the full impact in apparently undisturbed areas caused by distant pressures (Manel et al., 2019). Where connectivity impacts reach far, management plans need to extend outside of the boundaries of MPAs (Jonsson, Moksnes et al., 2020). For the same reason, connectivity is important in MSP.…”

“…Metadata and assumptions for calculating cumulative impact and incorporating MSP scenarios are provided elsewhere (Hammar et al., 2020). The Symphony CIA tool is static and does not consider the spatial‐temporal relationships exerted by marine connectivity, despite the pronounced water exchange in the region and the vital role played by dispersed biological propagules (Jonsson, Moksnes et al., 2020). Symphony and CIA methodology in general produce relative estimates of environmental impact which are difficult to validate by quantitative measures.…”

Mapping and Evaluating Marine Protected Areas and Ecosystem Services: A Transdisciplinary Delphi Forecasting Process Framework

“…On the other side, we would need high resolution and (transdisciplinary) data to support the assessment of linkages between ES and socio-economic aspects, to bring accuracy and realism into the analysis to contrast the dimensions needed to take into account many other disciplines into the MPAs to ES connection (Cavaletti et al, 2020). Improving our understanding of connections between MPAs and ES also requires further understanding and consideration of the linkages between species traits, population, and ecosystem dynamics, and of spatial connectivity to assess MPAs networks (Jonsson et al, 2019). This may also further connect to models at the regional and global scale that encompass the social and economic relevance of biodiversity (such as the Ocean Health Index; Halpern et al, 2012Halpern et al, , 2014Blenckner et al, 2021), of place-based and practice-oriented methods [such as the Open Standards for the Practice of conservation approach used in quite a few coastal MPA processes across Sweden; Morf et al, forthcoming and e.g., Gee, 2019), and of the UN SDGs (Claudet et al, 2020).…”

Marine Protected Areas: At the Crossroads of Nature Conservation and Fisheries Management

“…The Baltic Sea, bordered by nine different countries (all but one forming part of the European Union), is one of the most managed seas in the world (Paasche et al, 2015;Reusch et al, 2018). The establishment of MPAs is one of the primary management tools employed to promote healthy Baltic Sea environments (Jonsson et al, 2020) and de facto MPAs have been established in this sea basin as early as 1932 (i.e., neartotal trawl ban in the Öresund; Anonymous, 1932). Even earlier than that, spatial protection measures for Baltic Sea fish spawning grounds (e.g., Strelasund) date back to the nineteenth century (World Wide Fund for Nature [WWF], 2017) and area closures as fisheries management tools are employed until this day (e.g., "Odra Bank closure" at the German-Polish border to protect juvenile flatfish, established in 2005).…”