In many nearshore waters around the world, seagrasses and mangroves (coastal saltwater forests) provide habitat and food for diverse organisms and valuable ecosystem services to people. Although human activities threaten these habitats, assessing their status and trends is made difficult by a lack of coordination, standardization, and integration between in situ and remotely sensed observations.
To advance coordinated international observations of these ecosystems, including observations of essential ocean variables (EOVs) and essential biodiversity variables (EBVs), multidisciplinary experts recently convened at a workshop jointly sponsored by the Global Ocean Observing System (GOOS) and the Marine Biodiversity Observation Network (MBON). Participants focused on current in situ and remote sensing observing capabilities, the technological innovations required to overcome the limitations of these two approaches, and how to promote data accessibility for use by a range of stakeholders.
Most seagrass monitoring is done in situ. Global monitoring networks (e.g., SeagrassNet, Seagrass-Watch) use similar low-cost protocols, such as visual surveys, offering promise for efforts to standardize best practices and interoperability. Remote sensing tools that generate high spatial resolution multispectral and hyperspectral images based on reflectance signatures provide data on seagrass spatial coverage at larger scales, but in situ verification is needed for species identification and plant health assessment.
The Global Mangrove Watch (GMW) has documented a nearly 6% decline in global mangrove extent since 1996 using satellite data and available in situ observations. In situ sampling efforts are essential for validating maps derived from such satellite data and for assessing species composition, but at present these efforts are very limited and are not coordinated with each other. Thus, extracting similar data fields from existing data sets is resource intensive.
Building a System of Global Observations
Workshop participants made recommendations for future seagrass observing, including integrating remote sensing and in situ data, linking existing in situ capacity across nations and networks, and leveraging these capabilities with promising technologies such as photo and video transects, including those produced using autonomous underwater vehicles. Participants agreed that advances in artificial intelligence applications for image processing will be needed to improve and speed up transformation of images into data products.
Participants also offered recommendations to improve mangrove observations, including linking in situ data (e.g., species composition surveys) to satellite data to validate maps and identifying existing in situ and drone sampling capacities and gaps.
For both seagrass and mangrove ecosystems, workshop participants agreed that coordinated observations will benefit from standardizing which plant parameters are measured as indicators of ecosystem health and condition; adopting data management practices based on findable, accessible, interoperable, and reusable (FAIR) principles; organizing disparate data; and linking data systems to the Ocean Biogeographic Information System and the World Conservation Monitoring Centre. Standard operating procedures for OceanBestPractices could be developed from the Blue Carbon Manual (mangroves) and the protocols of SeagrassNet and Seagrass-Watch. Training and capacity development will be critical to expanding global coverage and ensuring continuity of observations.
Strengthening a Support Network
Overall, workshop attendees concluded that the success of coordinated global seagrass and mangrove observations will require strengthening engagement between the field observation and remote sensing communities and nurturing partnerships, including those with developing countries. Coordination and governance can be facilitated by system-specific groups such as the International Seagrass Experts Network and GMW and by GOOS and the MBON, which are working to implement observations of essential ocean variables to strengthen global observing, conservation, and sustainable development.
The participant list and presentations are available at the workshop website. We acknowledge support from NASA, GOOS, and the Consortium for Ocean Leadership, and we thank the participants for their contributions.
Emmett Duffy, Tennenbaum Marine Observatories Network and Marine Global Earth Observatory, Smithsonian Institution, Edgewater, Md.; Lisa Maria Rebelo, International Water Management Institute, Vientiane, Laos; and Patricia Miloslavich ([email protected]), Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia; also at Oceans and Atmosphere, Commonwealth Scientific and Industrial Research Organisation, Hobart, Australia, and Universidad Simón Bolívar, Caracas, Venezuela