Shaping the way forward through seagrass mapping
Seagrass from Milne Bay, Papua New Guinea Source: Dr Patrick Pikacha/Alluvium
28 February 2025 - Seagrass ecosystems are important in providing several ecosystem services. They provide habitats for marine species, including fish, reptiles, and invertebrates, contributing to wider, broader food webs. They also help to regulate water quality by filtering out pollutants and sediments. Additionally, they help to protect shorelines from erosion and are significant carbon sinks. Recent studies have reported that 16 seagrass species have been identified in the Pacific. Given this significance, the UN General Assembly has declared since 2022, March 1st as World Seagrass Day.
Unfortunately, seagrass ecosystems are under threat from numerous factors, including pollution, coastal development, extreme events and climate change. A study published in the Proceedings of the National Academy of Sciences in 2009 found that global seagrass meadows are declining at a rate of 7 per cent annually. As a result, it is important to monitor seagrass ecosystems to track changes in their health and extent. This information can be used to inform management decisions and support conservation efforts.
The Pacific Community (SPC), together with its partners, the Secretariat of the Pacific Regional Environment Programme (SPREP) and Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ Pacific), are currently involved in efforts to provide support across the Blue Pacific to foster seagrass conservation and management through the Management and Conservation of Blue Carbon Ecosystems (MACBLUE) project.
Importance of Seagrass Mapping
SPC’s Digital Earth Pacific programme, a free and open digital public infrastructure, is currently mapping the seagrass ecosystem to monitor seagrass status and extent. The maps will provide a baseline for assessing changes in seagrass cover over time, which can help identify declining or recovering areas.
This will help inform decisions about coastal development, fishing, and other activities that may impact seagrass ecosystems (e.g., marine habitats for fisheries), as well as identify areas of high seagrass biodiversity and prioritise them for conservation and intervention actions in environmentally degraded zones.
Generally, these maps, once finalised, can be used to raise awareness about the importance of seagrass ecosystems and the threats they face.
Usage of Maps
While seagrass mapping has been done on small scales in the past, this process will be unique in several ways. Firstly, it will use a combination of incorporated tidal dynamics to map seagrass, providing a more comprehensive picture of seagrass distribution. Secondly, it will use Sentinel-2 satellite imagery, which has a high spatial and temporal resolution, allowing for the detection of fine-scale changes in seagrass cover. For greater ownership, it will be carried out in partnership with countries in the region, which will help build capacity for seagrass monitoring and conservation.
The maps will be very useful in providing a more accurate and up-to-date picture of seagrass distribution than has been available in the past. These maps provide an unprecedented scale of analysis for MACBLUE countries where most seagrass mapping is done on a small scale.
They will be able to detect changes in seagrass cover over time, which can help identify declining or recovering areas. These will be instrumental in informing management decisions and supporting conservation efforts.
Building capacity for seagrass monitoring
SPC’s Digital Earth Pacific (DE Pacifc) programme has provided workshops and training for Pacific government officials, focusing on seagrass mapping tools and techniques. These workshops aim to enhance participants' knowledge of seagrass ecology and management and build a regional network of seagrass experts.
Last year, during the 2024 Pacific GIS and Remote Sensing User Conference, the MACBLUE project hosted a capacity-building workshop for conference attendees on cloud-native computing for supervised classification of coastal ecosystems. This is just one of the many capacity-building organised in upskilling and familiarising Pacific GIS officials with the use of the Digital Earth Pacific platform products such as ecosystems classifications including seagrass.
Currently, seagrass preliminary beta products are able to identify a number of preliminary changes in seagrass cover, including changes in seagrass extent. The maps may be able to detect areas where seagrass has been lost or gained.
The Way Forward
The seagrass mapping products are expected to be completed later this year with validations from partner countries. Once completed, they will be made available to the public and used to inform management decisions and possibly support conservation efforts . In the future, the project team hopes to continue monitoring seagrass ecosystems in the region and develop new tools and techniques for seagrass mapping and management.
Reposted from SPC website.