Integrated planning for land–sea ecosystem connectivity to protect coral reefs

Coral reefs are threatened by human activities both on the land and in the sea. However, standard approaches for prioritizing locations for marine and terrestrial reserves neglect to consider connections between ecosystems. We demonstrate an integrated approach for coral reef conservation with the objective of prioritizing marine reserves close to catchments with high forest cover in order to facilitate ecological processes that rely upon intact land–sea protected area connections and minimize negative impact of land-based runoff on coral reefs. Our aims are to (1) develop and apply simple models of connections between ecosystems that require little data and (2) incorporate different types of connectivity models into spatial conservation prioritization. We compared how, if at all, the locations and attributes (e.g., costs) of priorities differ from an approach that ignores connections. We analyzed spatial prioritization plans that allow for no connectivity, adjacent connectivity in the sea, symmetric and asymmetric land–sea connectivity, and the combination of adjacent connectivity in the sea and asymmetric land–sea connectivity. The overall reserve system costs were similar for all scenarios. We discovered that integrated planning delivered substantially different spatial priorities compared to the approach that ignored connections. Only 11–40% of sites that were high priority for conservation were similar between scenarios with and without connectivity. Many coral reefs that were a high priority when we considered adjacent connectivity in the sea and ignored land–sea connectivity were assigned to low priorities when symmetric land–sea connectivity was included, and vice versa. Our approach can be applied to incorporate connections between ecosystems.