LIPOFUSCIN (AGE PIGMENT) AS AN INDEX OF CRUSTACEAN AGE - CORRELATION WITH AGE, TEMPERATURE AND BODY-SIZE IN CULTURED JUVENILE HOMARUS-GAMMARUS L

Morphological lipofuscin was quantified in laboratory cultured Homarus gammarus to determine if the amount of pigment was correlated with ag e and culture temperature in this species. Two cohorts were monitored for 34 and 18 months, respectively. An age dependent accumulation of l ipofuscin concentration (expressed as % area fraction) occurred (Y = - 2.22 + 0.084X, R(2) = 46.8%, p less than or equal to 0.0001 and incorp orating carapace length as a covariate). Carapace length accounted for 3.3% of the variation in lipofuscin. The effect of temperature on lip ofuscin accumulation was assessed using three regimes: 8, 11 and 13.5 +/- 5 degrees C. Temperature had a significant effect on lipofuscin ac cumulation (F = 15.9, p less than or equal to 0.0009). Carapace length also responded significantly to temperature although the trend was no r linear (F = 68.1, p < 0.0001). There was no significant correlation between lipofuscin concentration and body size in lobsters of the same age (r = 0.067, -0.2, 0.154 and 0.5 for each of four groups). The age dependent increase in morphological lipofuscin and the lack of correl ation between body size and lipofuscin in cultured H. gammarus indicat es significant potential for this technique as a method of ageing lobs ters. As lipofuscin accumulation is a function of metabolic age, facto rs other than temperature, such as population density, which affects g rowth rate in the wild, could potentially affect metabolic rate and th erefore lipofuscin accumulation. However the independence between grow th and lipofuscin in laboratory animals indicates that this may not be a problem.