Occurrence of the autofluorescent pigment, lipofuscin, in polar crustaceans and its potential as an age marker

Abstract.

In crustaceans, the lack of reliable methods often prevents the determination of individual age. The quantification of the autofluorescent age pigment, lipofuscin, has revealed promising results in boreal and tropical species. We studied the presence of morphological lipofuscin and its possible application as an age marker in five Arctic and five Antarctic species, comprising decapods, amphipods and a euphausiid. Lipofuscin granules were located in the brain, using confocal fluorescence microscopy, and quantified from digital images. The pigment was found in 94 of 100 individuals and in all 10 species, and granules occurred in easily detectable amounts in 5 species. Two scavenging amphipod species, the Antarctic Waldeckia obesa and the Arctic Eurythenes gryllus, revealed the most conspicuous and numerous granules. There was a broad, though weak, correlation of lipofuscin concentration with individual body size within a species, but not with absolute body size of one species compared to another. In larvae of the decapod Chorismus antarcticus, lipofuscin accumulation was quantified over the 1st 4 months after larval release. Morphological lipofuscin is a potential index of age in those investigated species with a sufficient accumulation rate of the pigment.