Abstract Summary
The Government of Mauritius is committed to ensuring responsible and sustainable development of the aquaculture industry in the island. Thirty-one sites have been allocated for marine-based aquaculture both lagoonal and offshore exploitation. One of the criticisms normally levied against floating cage aquaculture is the impact on the biodiversity in the surrounding waters. The objectives of this research were to assess in and around each potential and operational aquaculture site: (1) the water quality, as affected by seasonal variation, (2) the biodiversity, (3) the heavy metal in sediment, water and fish, (4) the distribution patterns, biomass estimates and diversity of planktons, and, (5) the survival and growth rates of cultured and natural reef-building corals. Methodologies included line transect intercept (LIT) for coral assessment, a variety of visual census techniques for biodiversity assessment including fish, plankton were sampled using a variety of plankton nets and analysed in laboratory-based microscopy techniques while coral growth were calculated using the scion-image software. Results showed the presence of various species of fishes and nudibranchs on the seabed just below the nets as well as on the ropes, cetaceans (e.g. Tursiops aduncus) and several green sea turtles (e.g. Chelonia mydas). Fluorescence sea light equipment showed the presence of coral recruits of 1-2 cm on the fixed floating buoys and ropes. Most of the parameters were within the acceptable range, except for total suspended solids, nitrates and phosphates which were slightly over the recommended values as per the Mauritius Coastal Water Quality Guidelines. Diatoms dominated the abundance with 33 genera followed by 11 genera of dinoflagellates and 3 genera of cyanobacteria. Coral cultured had a >80% survivorship and they were tested under two conditions with one cleaned for fouling organisms while the second aspect was to allow growth of cultured corals on their own. Result revealed a slight difference in growth performance between both conditions. These data revealed that the current fish farm studied is not causing damage to the surrounding marine environment.
