Spatial and temporal patterns of settlement among sparid fishes of the genus Diplodus in the northwestern Mediterranean

Juvenile settlement of 3 sparid fish species, Diplodus puntazzo, Diplodus sargus and Diplodus vulgaris, was studied over 3 yr at 20 stations located at 5 sites in the NW Mediterranean Sea: 1 site in Spain (Girona), 2 in France (Banyuls and Marseille) and 2 in Italy (Portofino and Elba). When all sites and years were combined, 71% of the settlers recorded belonged to D. vulgaris, 25 % to D. sargus and 4% to D. puntazzo. Settlement was seasonal, with D. sargus settling in May-June, D. puntazzo in October-November, and D, vulgaris in 2 pulses, the first in November-December and the second in January-February. Settlement intensity varied spatially, temporally, and among species. At a small spatial scale (within site), settlement intensity varied between stations and particularly between years. At a large spatial scale (among sites), settlement intensity varied among sites, with Marseille and Girona generally experiencing higher settlement than other sites. No difference in settlement intensity was observed between protected and unprotected areas. The settlement of D. sargus was higher in 1994 than in 1993 and 1995 at all sites, suggesting the influence of meso-scale hydroclimatic conditions on the settlement success of this species. The settlement of D. vulgaris was higher in 1993 in the western part of the NW Mediterranean, and in 1994 in the eastern part. No consistent spatial trend over time was seen for D, puntazzo. Thus, settlement intensity of Diplodus species to nearshore habitats in the NW Mediterranean exhibited high year-to-year variations at both local and regional scales.