These Terms of Reference describe the purpose, role, composition, and working modalities of the COBSEA Working Group on Marine and Coastal Ecosystems. Purpose - 3. The COBSEA Working Group on Marine and Coastal Ecosystems is established to provide guidance and support on the implementation of COBSEA work on the marine and coastal ecosystems, therefore supporting the development and execution of COBSEA Strategic Directions 2023-27 and the Marine and Coastal Ecosystems