Efficient small-scale marine reserve design requires high-resolution biodiversity and stakeholder data

Establishing marine reserves is particularly challenging in highly populated coastal areas where stakeholders compete for resources and space, such as the Mediterranean Sea. While large-scale conservation planning is useful, there is a need for finer-grained assessments at local and regional scales. Yet fine scale environmental and socioeconomic data are not always available. Here, we evaluate the influence of the spatial resolution of biodiversity and socioeconomic data on the selection of priority areas for conservation in Montgri, the Illes Medes and the Baix Ter Natural Park, Spain. We used varying levels of habitat data, from fine-scale maps created using detailed bathymetry and underwater surveys to less detailed ones using existing data or broader classifications. We also used different estimates of the cost of protection, from a combined recreational and artisanal fishing cost obtained through local consultation and in situ mapping to simple indirect measures such as distance to port. Our results reveal that conservation planning scenarios that do not use fine-scale bathymetry are ineffective at protecting biodiversity and only represent 40% or less of the habitats. Scenarios that only include recreational fishing, which is limited to certain planning units in the park, perform very poorly at minimizing cost, highlighting the need to use cost estimates that include all planning units. We conclude that local-scale data will often be needed to support and guide local-scale efforts to expand or establish new marine reserves.

Automated summary

Establishing marine reserves in highly populated coastal areas requires fine-scale assessments and local-scale data to effectively protect biodiversity.