Planktonic larval duration and settlement marks on the otoliths of Mediterranean littoral fishes.

Abstract

The planktonic larval duration (PLD) was estimated for 42 species of littoral fishes from the northwestern Mediterranean Sea. Daily increments and settlement marks on the otoliths (sagittae or lapilli) of new settlers and post-settlers were used to determine the larval stage duration. We also used PLD in the new settlers of some species to confirm the accuracy of the settlement marks in post-settlers. The duration of the planktonic larval stage ranges from 9 days in Symphodus ocellatlls to 55 days in Xyrichtis Iloracu/a and 71 days in Lipophrys trig/oides. Species in the same family did not display any clear tendency toward having similar PLDs. On the other hand, larval duration tended to be similar within a genus, with the exception of Lipophrys. Among conspecifics, the time spent in the plankton usually varied only by 27 days, except in Aidablel111ius sphylJx, Lipophrys trig/aides, Coris julis and Thalassoma pavao No clear patterns were discernible in genera, with some species that settled in winter and other species that settled in summer, although we observed a certain tendency of individuals of closely related species (e.g. family Sparidae) to have a shorter larval duration in the warmer part of the year than in the colder part of the year. Settlement marks have been observed on the otoliths of all the species studied, and the PLDs in new settlers are an appropriate means of validating settlement marks. A rapid decrease in increment width over settlement (type la) is the most common type of mark (66.7% of the total species studied).