January 2004
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575 Reads
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9 Citations
Distribution patterns of two labrid fish, namely Coris julis and Thalassoma pavo, were assessed by visual census in autumn 2000 at four locations (with three sites per location), and at different depth levels (from 0 to about 30 m depth) in SE Apulia (SE Italy). Total abundance and juvenile density of T. pavo tended to be greater in shallow waters to about 10 m depth, in spite of some differences occur-red at the scale of sites. Conversely, C. julis showed low densities in waters shal-lower than 5 m, and higher values from 5 down to about 30 m depth. In the case of C. julis, differences in the pattern related to depth occurred at both the spatial sca-les examined (among locations and among sites within location). The patterns observed for the two species concerned both adult and juvenile fishes, which sug-gests the absence of evident ontogenetic shifts in habitat use during their life history. The results presented here suggest that the two species could segregate according to depth. T. pavo, due to its well known thermophily, could thus over-compete C. julis at very shallow depths where seawaters are warmer because of the seasonal thermocline (at least during the period of the year when sampling was performed). The patterns observed in this study may also provide useful informa-tion about the scenario that could take shape in areas of the NW Mediterranean, such as the Ligurian Sea, where T. pavo started increasing in abundance in the recent years.