Microhabitat requirements for settlement of juvenile sparid fishes on Mediterranean rocky shores

Abstract

Microhabitat attributes were characterized for recently settled juvenile fishes in six species of Sparidae (Diplodus annularis, D. puntazzo, D. sargus, D. vulgaris, Oblada melanura, and Sarpa salpa) on the rocky shore near Marseille, French Mediterranean coast. Depth, slope, type of substratum, biotic cover and hydrodynamic conditions were recorded wherever sparid recruits occurred. Juvenile Diplodus annularis settled in Posidonia oceanica seagrass beds at 5–8 m deep. The five other sparid species recruited in very shallow water (<2 m). D. puntazzo, D. sargus and D. vulgaris were observed in sites presenting a gentle slope with coarse sand, gravel, pebbles or boulders. Sarpa salpa was less dependent on slope for recruitment, but was always associated with macroalgae. Oblada melanura settlement occurred on rocky areas with various slopes, and was favoured by the presence of overhangs. When growing, juvenile sparids extended their home range vertically into deeper zones, and laterally in more exposed areas. Time partitioning in the use of suitable microhabitats for recruitment was observed for some species. Juveniles of Diplodus puntazzo and D. vulgaris shared the same sites from March to May, both exhibiting relatively low abundances. D. sargus recruited in far higher abundance in the same sites from May to September. Specific improvements in coastal man-made structures (harbours, artificial beaches) are suggested in order to increase the recruitment of some littoral fish species.