| Summary: | The ontogenetic development of the sagittal otoliths of Lypophris pholis during embryonic, larval, settlement and recruitment stages was examined from eggs, new settlers and recruits collected during low tides in several Portuguese rocky beaches. The eggs were reared under controlled-laboratory conditions until the larval stage. Viewed by scanning electron microscopy, sagittae recorded eight to ten micro-increments before hatching in late embryo phases. In larval otoliths a visible hatching check was observed and micro-increments were deposited on a daily basis. Early settlers presented in the otolith edge two types of settlement marks (Ia and Ib). Furthermore micro-increments in sagittae were also shown to be deposited daily in early juveniles using fluorescent dyes. Pelagic larval duration estimated from micro-increments counts until the settlement marks in recruits collected along the occidental Portuguese coasts ranged from 57 to 73 days. Moreover pelagic larval duration showed a latitudinal reduction trend from North to South probably related the regional seawater temperatures. Settlement sizes did not show however any regional differences suggesting to be a more conservative character within species. Age at coastal recruitment varied between 85 and 109 days, but northern individuals were recruit with an older age. Back calculated spawning, hatching and settlement dates appear to be unrelated to the lunar cycle for L. pholis.
|
|---|