Mussels as mangrove facilitators for coastal defense (MUMACO)

Mangrove forests provide many ecosystem services such as food, timber and coastal protection. Despite these vital functions, global mangrove forest cover is declining mainly due to unsustainable aquaculture. The coastal mangrove ecosystem of the Demak region in Java, Indonesia is no exception. Here, shrimp cultivation in ponds or so-called tambaks is the main driver of mangrove deforestation. Local communities depend on shrimp cultivation but also suffer from the consequences of mangrove loss: regular floods seriously threaten the coastal villages. Thus, there is a need for a restoration program that enables natural mangrove recruitment, coastal protection and simultaneously provides the communities with an alternative livelihood, without which unsustainable practices of mangrove deforestation and pond excavation will continue. In the MUMACO project (Mussels as mangrove facilitators for coastal defence), bamboo poles serve as coastal protection and open the opportunity to cultivate the native green mussel Perna viridis. At the same time, the mussel-covered poles provide artificial substrate to an otherwise empty seafloor, creating habitat for many other species. The aim of this PhD thesis is to assess the effects that mussel-covered poles have on the local ecosystem. Pelagic, benthic and epifaunal communities will be monitored throughout the duration of the project. Morphological identification of collected specimens will be supplemented with genomics-based identification of bulk samples and environmental DNA to provide a thorough overview of the expected biodiversity changes. Stable isotope and stomach content analyses will provide insights in possible food web changes. In combination with size-frequency distributions and monitoring primary production, this will reveal whether or not the ecological carrying capacity of the ecosystem is enhanced. This will all help understand the extent to which changes in biodiversity can be explained by attraction or production and can help to prevent overfishing of additionally enabled fisheries.