Spatio‐temporal variability in abundance of the parrotfish, Sparisoma cretense, in SE Apulia (SE Italy, Mediterranean Sea)

Abstract

Spatio‐temporal variability in the abundance of the parrotfish, Sparisoma cretense, was investigated along the SE Apulian rocky coast (SE Italy, Mediterranean Sea). Underwater visual census surveys were carried out in three different times (August 2000, March 2001 and May‐June 2001) at four locations between Otranto (Lower Adriatic) and S.M. di Leuca (Ionian Sea), at three sites at each location, and at four depth levels from the surface down to about 30 m. The species was never observed near the surface nor in the deepest zones, while it was more abundant at 12–15 m (mean ± SE: 0.69 ± 0.05 individuals 100 m‐2) than at 5–7 m depth (0.27 ± 0.04 ind. 100 m‐2). This general pattern was observed during all three sampling times and at each location surveyed. Significant differences in the abundance of S. cretense were detected among depths, locations and, to a lesser extent, among times, while no differences were observed among sites within locations. This study provides evidence that, besides a given variability over a spatial scale of kilometres (i.e., among locations), this fish lives exclusively between about 5 and 15 m depth, suggesting that it could have specific habitat requirements in terms of physical conditions (e.g., water temperature, wave action) and substrate features (e.g., benthic cover). In addition; taking into account that juvenile parrotfishes appeared for the first time in August 2000 along the coast of SE Apulia, where neither adults nor juveniles had been previously recorded, these data could support the hypothesis that S. cretense is establishing a true population in this region. The results presented here, in fact show that the low winter water temperature did not affect survivorship of this ther‐mophilous fish.

Key words:

• Sparisoma cretense
• Visual census
• Spatio‐temporal variability
• Rocky substrates
• Climatic changes
• Mediterranean Sea