Accrescimento e composizione delle larve di acciuga (Engraulis encrasicolus) in zone a diverse condizioni idrologiche del canale di Sicilia

The present job has taken in examination Engraulis encrasicolus larvae caught in the Sicily Channel. The larval age has been estimated through a methodology that utilizes the daily otolith (sagittae) micro-increments reading; such assessment have been correlated with the oceanographic parameters data of the Sicily Channel. The Gompertz equation has showed the growth of this species in the sampled lengths range. For year 2004, a growth rate of 0.77 mm/day has been esteemed and for 2007 a growth rate of 0.65 mm/day. The relationship between the otolith diameter and the larval length has been fitted with a potential equation, and in particular two different curves have been determined for the two years. The Mann-Whitney U Test has underlined that the differences among the observed values (Temperature, Salinity, O2 and Fluorescence) result to be significant (p <<0.05). Another investigation has concerned the comparative analysis, through spectrophotometry, of the larval biochemical components (lipids, proteins and carbohydrates) of E. encrasicolus caught in the Sicily Channel and in the continental shelf of Libya during the Oceanographic Cruise named MedSusMed 2006. The differences of protein content and proteins and lipids accumulation rates for the larvae length result to be significantly different for the two investigated zones, and this has been justified by the different oceanographic conditions present in the two sampling areas.