First modelling approaches have revealed benthic crustaceans to be among the most important taxa regarding biodiversity and carbon-flow within the Weddell Sea benthos. Hardly any data on their age structure, growth patterns and productivity are, however, available which is partly due to the lack of appropriate methods for age determination in long-lived Crustacea. This study investigates the occurrence of the autofluorescent pigment lipofuscin, which universally accumulates progressively with time in post-mitotic tissue, and its potential as an age marker in selected polar Crustacea. Lipofuscin granules were located and identified in resin brain sections of 5 Antarctic and 5 Arctic species by means of confocal laser scanning and transmission electron microscopy. Lipofuscin quantification was performed by image analysis in which the pigment granules in selected brain areas were discriminated using greyscale thresholding and quantified as area fraction related to the surrounding tissue. Based on the lipofuscin concentration frequency distribution (LCFD) of a representative sample of the respective population, max. age and age distribution were computed for the decapod Notocrangon antarcticus and the amphipod Waldeckia obesa. From those data further population parameters were inferred.

The pigment was found in 375 of 401 analysed individuals and in all 10 species, but granules occurred in easily detectable amounts in only 5 species. The analysed pigment properties widely coincided with those published in literature, except for the location of high density areas in amphipods. A modal progression analysis of the LCFD of N. antarcticus (n=189) and W. obesa (n=159) showed 8 and 5 regularly-spaced modes, respectively, presumed to reflect consecutive annual age classes. Max. longevity was estimated as *10 and 6yrs in female and male N. antarcticus, respectively, and 8 and 5yrs in female and male W. obesa, respectively. No regular modes were obvious in the length-frequency distributions (LFD, n=951 and 386). Pigment accumulation was linear and accumulation rate did not differ between sexes. Annual accumulation rate in N. antarctius was considerably lower than rates published for lower latitudes decapods. Growth rates, annual productivity and mortality rates are also comparatively low in N. antarcticus and W. obesa (all values <1 a^-1). Values for the growth performance parameters psi and phi were, however, in the same range as those for lower latitude decapods and amphipods.

The results indicate that morphological lipofuscin regularly occurs in polar crustaceans. Low concentrations are apparently largely explained by the impact of temperature. Successful separation of age groups from LCFD demonstrates the advantage of lipofuscin-based over LFD-based age determination in long-lived Crustacea. The unresolvable pile-ups in the LFD of N. antarcticus and W. obesa proved to be multi-age-composed as known from other species. The estimates of population parameters are in accordance with findings in other polar marine invertebrates. The results are encouraging for future use of this method, e.g. in commercially exploited species, and possibly in non-crustacean taxa. Improvement of the technical procedure is, however, suggested for reasons of timesaving and signal intensity.