Tanzania & South Africa

Project duration:
2022 to 2025

project summary

The goal of the project “Nature based Solutions for Mitigation of Watershed Pollution: Cross-habitat facilitation by coastal seagrass meadows” (SOMWAT) is to assess the role of seagrass meadows for reducing watershed pollution in Tanzania and South Africa, thereby improving livelihoods of local communities.

Coastal habitats like mangroves, corals or seagrasses provide numerous livelihood benefits for local populations. Despite their importance, threats like climate change and pollution have led to degradation at an ever-increasing rate. Conservation and restoration efforts frequently show low long-term success rates.

SOMWAT especially looks at the role of seagrasses in this context. Seagrasses are well known for their ability to decrease anthropogenic pollution, thereby indirectly facilitating resilience in connected coastal habitats such as sponge gardens or coral and bivalve reefs. Understanding the potential of seagrasses to counteract these impacts will have great benefits for the management of adjacent reef areas. This in turn will also benefit local populations that rely on these habitats for their ecosystem goods and services.

Both field surveys and experiments will help to unravel underlying mechanisms through which seagrasses can enhance water quality and thereby benefit local communities that rely on healthy ecosystems for food production and tourism. The surveys and experiments will be conducted in collaboration with stakeholders, NGOs and local authorities in order to address the needs of local populations.


To assess the effects of seagrass meadows in improving water quality in adjacent reef areas and small aquaculture farms to improve and implement sustainable use of marine resources.

To assess the role of seagrass meadows in reducing watershed pollution through nutrient, pollutant and pathogen removal.

To identify pollutant sources, develop mitigation measures and water quality guidelines.

To assess the potential of local seagrass species to be used as indicators and monitoring tools to forecast detrimental effects of watershed pollution, and to take preventive management actions.

To enhance coral aquaculture via sexual reproduction and increasing coral resilience to anthropogenic disturbances such as elevated sea surface temperature by selectively culturing coral colonies that have survived recent bleaching events.

areas of work

  • Field studies in temperate estuaries (ZA) and tropical coral reefs (TZA) will identify how seagrass meadows take up and remove nutrients, pollutants, and pathogens from coastal waters.
  • Experiments will identify detrimental nutrient, pollutant and pathogen concentrations which need to be avoided to ensure sustainable coastal productivity and ecological functioning.
  • Surveys will measure nutrients, pollutants and microorganisms along estuary-to-coast gradients, i.e., in coastal waters, seagrass meadows and their adjacent bare sediments, and reef habitats.
  • Results and underlying data will be prepared for publication and will also be deposited in the PANGAEA database, including species list and distribution from the monitoring studies.
  • Stakeholder engagement will take place through established networks like the Western Indian Ocean Marine Sciences Organization (WIOMSA) in TZA and the South African Network for Coastal and Oceanographic Research (SANCOR).


Nelson Mandela University

The Institute of Marine Science (IMS)
University of Dar es Salaam

Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg