Quantification of the age-pigment lipofuscin in brains of known-age, pond-reared prawns Penaeus japonicus (Crustacea, Decapoda)

A quantitative study of the lipofuscin content was carried out by image ana lysis in brains of known-age, pond-reared Penaeus japonicus (Crustacea, Dec apoda) with the aim of assessing the applicability of the lipofuscin techni que as an estimator of the physiological age in penaeids. With this purpose , three distinct measurements of lipofuscin levels (% area fraction, granul e density and mean granule size) were recorded in ten sections of the olfac tory lobe cell mass (OLCM) per animal. The image analysis was based on the autofluorescence Emitted by the pigment, which accentuates the contrast bet ween the lipofuscin granules and the background tissue. The concentration o f lipofuscin increased significantly with age and was independent of sex. T he relationship between age and lipofuscin concentration (area fraction and granule density) was best described by a seasonalized von Bertalanffy func tion, since the accumulation rate of the pigment dramatically slowed down i n fall-winter, probably as a result of reduced seasonal metabolism. The pre sent results confirm the potential of the lipofuscin method in the estimati on of physiological age in penaeids and suggest that the application of thi s methodology can be useful in studies of age structure in wild populations and in the assessment of natural resources. (C) 2000 Wiley-Liss, Inc.