Using systematic conservation planning to align priority areas for biodiversity and nature-based activities in marine spatial planning: A real-world application in contested marine space

To support sustainable growth of ocean-based economies, many countries are engaging in marine spatial planning (MSP) processes, which require robust decision-support tools. Systematic conservation planning (SCP) is commonly used in decision-making to guide spatially efficient protected area expansion. Here we contend that SCP can also be used to streamline MSP negotiations by developing a coherent, integrated portfolio of sites for multiple sectors that depend on biodiversity being maintained in a good state, as a counterpoint to spatial priorities for those commercial and industrial activities that have negative environmental impacts. We demonstrate this in Algoa Bay, South Africa, given the social-ecological complexity of the bay, and its central location in the first national MSP process. In anticipation of this national process, a civil-society-led Community of Practice was established with a core team to lead stakeholder engagement, data acquisition and management, and SCP analyses. More than 500 stakeholders participated in the project and many contributed spatial data or engaged in expert-based participatory mapping. Spatial products were supplemented with existing, published datasets. Altogether, conservation targets were set for 115 biodiversity features and 22 nature-based activities, with the cost layer built from data on 10 commercial and industrial activities, cumulative pressures (n = 31) on ecosystems, and planning-unit area. All targets were met in 15% of the study area, of which only a third (4%) was outside of marine protected areas, demonstrating that it is possible to align multi-sector priorities for intact biodiversity. This approach can be widely applied in MSP to support sustainable ocean economies.