Cumulative impact assessments can show the benefits of integrating land-based management with marine spatial planning

Charles Loiseau (1, 2) , Lauric Thiault (1, 2) , Rodolphe Devillers (3) , Joachim Claudet (1, 2)

1 CRIOBE - Centre de recherches insulaires et observatoire de l'environnement
2 LabEX CORAIL - Laboratoire d'Excellence CORAIL
3 UMR 228 Espace-Dev, Espace pour le développement

Cumulative impact assessments can inform ecosystem-based management by mapping human pressures and assessing their intensity on ecosystem components. However, its use to inform local management is scarce, largely due to the need for fine-grained spatial data representing ecosystem threats that can assess impacts at a local scale. Here, we applied the cumulative impact assessment framework to Moorea's coral reef, French Polynesia to inform the ongoing revision of the island-wide marine spatial management plan. We combined high spatial resolution data on 11 local anthropogenic pressures and four ecological components with expert vulnerability assessments. Results revealed that the entire reef is impacted by at least four pressures: coral reef fisheries, agriculture, land use change and urbanization. These activities together contribute to 87% of the overall cumulative impact. Most importantly, landbased activities contribute to more than half (52%) of the overall impact. Other high-impact activities, such as reef-based tourism, remain very localized and contribute little to the overall human impact. These findings show that by focusing solely on reef-based activities, the current management plan misses critical sources of impact. Not considering land-based activities in the management may lead to decisions that could fail to significantly lower cumulative human impact on the reef. This study demonstrates how operationalizing the cumulative human impact framework at a local scale can help managers identify key leverage points likely to yield improved ecological outcomes.

Mots clés: Cumulative effect assessment; Threat maps; Human impacts; Land-based pressures; Coral reefs; French Polynesia

Domaines: Sciences de l'environnement

Charles Loiseau, Lauric Thiault, Rodolphe Devillers, Joachim Claudet. Cumulative impact assessments can show the benefits of integrating land-based management with marine spatial planning. Science of the Total Environment, 2021, 787, pp.147339. ⟨10.1016/j.scitotenv.2021.147339⟩. ⟨hal-03228740⟩