Abstract |
The effects of aquaculture on nematode communities were studied in two different areas (MD1 and MD3) of the Eastern Mediterranean in order to assess the temporal and spatial variation in the abundance of nematodes, the structure of the community and structure of feeding types, and the response of existing species to organic enrichment. For this, three seasonal samplings were performed in July 2001, October 2002 and March 2002. Samples were collected along transects towards the direction of the main current at a distance of 0 m (below cages) 5, 25 and 50 m from the edge of the cage. Samples were also collected from a control station, which was located in an area with similar depth and sediment type. The abundance of nematodes in area MD1 showed seasonality at stations located near the cages, a pattern that did not occur in area MD3. At MD1, different seasonal patterns in the community structure of nematodes were observed. Dominant species in the region for all three sampling periods and at all stations located near the cages was Daptonema sp.1. In contrast, no seasonal changes were observed at MD3 for any of the abundant species. The dominant species of all three sampling periods of this area were Microlaimus sp.1, Desmodora sp.1, Prochromadorella sp.1. In both areas the most abundant feeding group was that of epistrate feeders. The diversity in both regions increased with increasing distance from the cages. In both areas the control station had a larger number of species. This study indicates that nematodes can be a useful tool for assessing the environmental impact of aquaculture, however further research and use of mathematical techniques are needed because different species seem to respond differently to the observed environmental changes.
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