INDIVIDUAL VARIATION IN, AND THE EFFECT OF REARING TEMPERATURE AND BODY SIZE ON, THE CONCENTRATION OF FLUORESCENT MORPHOLOGICAL LIPOFUSCIN IN THE BRAINS OF FRESH-WATER CRAYFISH, CHERAX-CUSPIDATUS (CRUSTACEA, PARASTACIDAE)

1. 1. Fluorescent lipofuscin in histological sections from the olfactory lobes of 44 thirty-week-old Cherax cuspidatus, reared under a variety of environmental conditions, was quantified using epifluorescence microscopy and image analysis. 2. 2. Variation in body size and lipofuscin volume fraction was relatively large. 3. 3. Both ambient temperature and body size appeared to influence lipofuscin quantities significantly, confirming the underlying connection with metabolic rate. 4. 4. Effects from parentage, oxygenation, food type or sex were not detected. 5. 5. The variation observed in animals of the same age, reared under identical conditions, would seem to preclude the use of the pigment for very precise chronological age determination, particularly where animals are subject to variable environmental temperatures. However, this variation is yet to be placed in perspective against the maximum levels of lipofuscin achieved in old age in this species. © 1990.