An Integrated Assessment of anthropogenic and climatic interactions with seagrass habitats in the Seychelles.
One of the inner granitic islands of the Seychelles archipelago, Mahé (152 km2) is the largest island and has 93% of the total population. The Seychelles are economically dependent largely on their marine resources primarily through tourism. However, land reclaimation, dredging, untreated sewerage outlets resulting from urban expansion, and soil run-off due to deforestation, are threatening many of the shallow coastal environments.
Although recent projects under the ‘Shoals of Capricorn’ programme have focused on mangrove and coral communities, relatively little work has been conducted on seagrass habitats in this region. Several studies have mapped and desicribed the extent of seagrass meadows around Mahe, little work has focused on the dynamics operating within these ecosystems or the biodiversity of the infauna with in the seagrass meadows of the innner islands. As these coastal marine ecosystems span the interface between land and sea they are easily accessible and thus vulnerable to disturbance. If chronic, these impacts may have long term effects on ecosystem stability.
This project involved an expedition to the Seychelles to:
- Determine the extent of seagrass habitats encompassed within two marine park boundaries in comparison to those of Mahé Island;
- Measure above- and below-ground biomass, leaf area and physical variables (temperature, salinity, depth, turbidity and water quality) of selected sites;
- Undertake a species diversity assessment of the benthic macroinvertebrates in seagrass ecosystems at selected sites and identify factors responsible for any differences in community structure observed;
- Evaluate the impact of terrestrial pollutants on seagrass composition, stand density and leaf area at one site;
- Qualitatively assesse the level of protection afforded to seagrass habitats by MPA status;
- Provide a baseline level of information regarding the seagrass beds around Mahé, against which future changes can be monitored.