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Seagrass Restoration: A story of succes or not?

Cado van der Lelij, J.A. (2010) Seagrass Restoration: A story of succes or not? Bachelor's Thesis, Biology.

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Throughout the world, ecosystems provide countless of services for humanity. Seagrass ecosystems are one of such systems. They are one of the most productive and valuable primary producers in the world, as they are of great importance for marine biodiversity, ecological and economical reasons (Burke et al., 2001; Costanza et al., 1997; Duarte and Chiscano, 1999). Seagrass meadows, varying from small patches to vast fields, inhabit shallow estuarine environments of all the world’s continents except Antarctica (Green and Short, 2003; van der Heide et al., 2009). Seagrasses have come to dominate many marine coastal ecosystems and have proven to be a robust species, but during the last decades, over 90000 ha of seagrass loss has been documented worldwide (Short and Wyllie-Echeverria, 1996; Burke et al., 2001). Multiple stressors, such as eutrophication, disease, sedimentation and toxicity events (van der Heide et al., 2009) can act simultaneously at different temporal and spatial scales, resulting in large scale seagrass-loss (Orth et al., 2006). Currently there are approximately 19 monitoring programs that involve 30 seagrass species in 44 countries (Orth et al., 2009). Regardless of all our efforts, restoration and transplantation projects have a low success rate; only 30% of conservation projects are successful (Fonseca et al., 1998). In this thesis, I wish to examine various case studies to gain insight into which abiotic and biotic factors influence the outcome of a conservation project. In this thesis, four different case studies have been discussed; Orbetello lagoon, Tampa Bay, Chesapeake Bay and the Wadden Sea (Lenzi et al., 2003, Greening et al., 2006, Orth et al., 2009 and van Katwijk et al., 2009, respectively). During the thesis a distinction is made between two different means of conservation projects; 1) Habitat restoration, where abiotic an factors of a system are brought back into favorable conditions, either directly or indirectly, for seagrasses to thrive in and 2) Seagrass transplantation, where seagrasses shoots are transplanted through various techniques, hereby (re)introducing seagrass in the hope that it can populate the area. Habitat restoration, in the case of Orbetello lagoon, showed 50 times more seagrass recovered in ha, and in Tampa Bay, seagrass recovered was at most 10 times more, when compared to the transplantation efforts in the Chesapeake Bay and the Wadden Sea are It can be concluded that the main factor influencing the success of restoration projects is to what extend a seagrass meadow is exposed to currents and wave action. Even if moderate levels of eutrophication persist, restoration can still be a success. When comparing the nutrients concentration between the Orbetello lagoon and the Wadden Sea, it is shown that in the Orbetello lagoon restoration was a success, whereas in the Wadden Sea it was not. This confirms the conclusion stated above. The two different means of restoring seagrass habitats do not exclude one another.

Item Type: Thesis (Bachelor's Thesis)
Degree programme: Biology
Thesis type: Bachelor's Thesis
Language: English
Date Deposited: 15 Feb 2018 07:44
Last Modified: 15 Feb 2018 07:44

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