MERCES webinar on Building a Business Case for Marine Ecosystem Restoration -18 November 2019

MERCES webinar on "Building a Business Case for Marine Ecosystem Restoration" - 18 November 2019


The fourth MERCES webinar focused on issues relating to the valuation of three major ecosystem services relating to seagrass meadows, but which were also relevant to mangrove forests and salt marshes.  

Prior to the webinar a large number of different organisations were contacted to publicise the two talks and to provide them with details of other MERCES project outputs.  The webinar was introduced by DSES highlighting 1) the work of MERCES project and 2) the many MERCES deliverables on marine ecosystem restoration would become available in the coming months.

The webinar included two talks: 

1) Dr. Per-Olav Moksnes, Department of Marine Sciences, University of Gothenburg, Sweden on ‘Seagrass loss and restoration - implications for the value of carbon and nitrogen stocks’ 

2) Dr. Richard Unsworth, Seagrass Ecosystems Research Group, University of Swansea, Wales, on ‘The importance of restoring seagrass meadows for global fisheries production’


Dr Moksnes described how over 60% of the eelgrass along the Swedish NW coast has vanished since the 1980s. The main cause has been the over-supply of nutrients from land causing eutrophication. Fast-growing algae have smothered the eelgrass. Management actions to reduce eutrophication and to improve water quality, however, have not led to the natural recovery of seagrass.  The loss of the eelgrass has led to the loss of the stabilising effect of the eelgrass on the sediment. The increase in wind-driven resuspension of the sediment has made the water turbid and the eelgrass has been unable to regrow. This has resulted in the loss of important ecosystem services, including the long-term storage of carbon and nutrients in the sediment. 

Little is known about how the extensive losses have affected the carbon stocks, and if eelgrass restoration can be used to facilitate recovery of meadows and their ecosystem services. New studies show that eelgrass losses in this system result in extensive release of both carbon and nitrogen with a high cost to society (estimated to 100,000 Euro per hectare of eelgrass). Methods for eelgrass restoration in Swedish waters have recently been developed, but large scale recovery is challenged by local regime shifts resulting from the loss of eelgrass. On the Swedish coast the best method for restoration in areas where eelgrass can return is by planting the eelgrass shoot by shoot by divers.  Areas re-sown at a density of 16 shoots m-2in June 2015 increased to 95 shoots m-2by September 2015 and in the following year had increased to 270 shoots m-2, approaching the densities found in natural eelgrass habitats. However, the method is labour intensive and slow, and costs about 170,000 Euros per hectare. New methods in sand capping sediments to reduce resuspension are being tested.

Dr Unsworth described the significant role seagrass meadows play in supporting fisheries productivity and food security across the globe, and how the management of seagrass habitats is not adequately reflected in the decisions made by authorities with statutory responsibility for their management and for fisheries. This leads to planning decisions that ultimately result in widespread seagrass loss. 

Seagrass is an important habitat for fish by providing a complex 3D, highly productive and well-oxygenated environment.  Seagrasses stimulate abundant food resources and provide shelter from predators for juvenile fish. The increase in survival rate and saving of energy produces healthier young fish. Seagrasses also provide a trophic subsidy to surrounding habitats through export of some of their carbon, even to the deep sea in some areas.

Seagrasses support 20% of the world’s biggest fisheries, such as Alaskan pollock, Atlantic cod and Pacific herring. In the Mediterranean Sea seagrass-associated fish species contribute 30 to 40% of the value of commercial fisheries and about 29% to recreational fisheries expenditure, making a direct annual contribution to commercial fisheries of 58-91 M Euros and 112 M Euros to recreational fisheries, and hence to local communities. In Indonesia 60% of the most-favoured fish to eat use the seagrass habitat and two-thirds of the fishing effort occurs within seagrass areas. Many fisheries are unregulated, unmanaged and unsustainable. In Indonesia 26% of the fish caught are under the size of maturation. The use of mosquito nets in East Africa and semi-permanent fish fence structures are leading to significant reductions in fish and increases in by-catch. 

Models of fisheries seldom include the loss of habitat as an important factor in their analyses. Failure to include reductions in spawning habitat, refuge degradation and increases in anoxia can lead to poor management decisions. There are only a few studies showing fisheries enhancement through marine ecosystem restoration and more studies are required to demonstrate the link. There needs to be better integration of fisheries, biodiversity and environmental management.  Seagrass restoration = fisheries recovery.

The webinar was attended by 88 participants, including the two speakers and four MERCES/GRID hosts. Several registrants came from the same organisation and so it is likely the number of attendees was close to 100. The attendance was greater than that reported for the first three MERCES webinars.  A total of 147 people registered for the webinar.  All registrants have been contacted to inform them of where they can access the archived webinar.

European registrants for the webinar came from Austria, Belgium, Bulgaria, Croatia, Denmark, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and UK.  Additional registrants came from Bermuda, Brazil, Canada, Colombia, Indonesia, Jamaica, Kenya, Libya, Mexico, Mozambique, Russia, South Africa, Thailand, Tunisia and the USA. 

A good discussion was developed using the questions posed by the attendees.  The webinar registrants were sent web links to the archived webinar and the report on the webinar.

The webinar was attended by 26 companies, including environmental SME consultancies, coastal engineering and financial interests. A large number (31) came from Government Departments and organisations advising government policy. Four members of the European Commission registered.  Twenty four registrants came from NGOs and 57 from research institutions. Five registrants came from organisations involved in international development. 


The webinar was archived and can be found at: 

YouTube ( and on