Beschreibung: Environmental factors can affect the rate of ageing and shape the lifespan in marine ectotherms. The mechanisms and the degree of - environmental influence on aging can best be studied in species with wide ranging biogeographic distribution. One of the biomarkers of physiological ageing is the fluorescent age pigment lipofuscin, which accumulates over lifetime in tissues of bivalves. We compared lipofuscin accumulation rate in muscles and respiratory tissues of the extremely long lived bivalve Arctica islandica from five geographically distinct populations (Northern Norway, White Sea, Kiel Bay, German Bight and Iceland). Maximum investigated chronological age across different populations in the present study differed from 40 years in Kiel Bay to 192 years at Iceland. An inverse association between lipofuscin deposition rate and recorded maximum age was observed through inter-population comparisons. In most cases lipofuscin accumulated exponentially over age in a tissue specific manner. The age specific lipofuscin content was significantly higher in respiratory than muscles tissues in all populations. Cellular lipofuscin granule area can be used as indicator of aging across A. islandica populations with the variance in granule accumulation depending on the annual variations of salinity in different marine regions, but not on the habitat specific thermal envelope.

Beschreibung: Increasing temperatures and glacier-melting at the Western Antarctic Peninsula (WAP) are causing rapid changes in shallow coastal and shelf systems. Climate change related rising water temperatures, enhanced ice scouring as well as coastal sediment run-off in combination with changing feeding conditions and microbial community composition will affect all elements of the nearshore benthic ecosystem, a major component of which is the Antarctic soft shell clam Laternula elliptica. 454 RNA sequencing was carried out on tissues and hemocytes of L. elliptica, resulting in 42.525 contigs of which 48% were assigned putative functions. Changes in the expression of putative stress response genes were then investigated in hemocytes and siphon tissue of young and old animals subjected to starvation- and injury-experiments in order to investigate their response to sedimentation (food dilution, starvation) and iceberg scouring (injury). Analysis of antioxidant defense (Le-SOD, Le-catalase), wound repair (Le-TIMP, Le-chitinase), stress and immune response genes (Le-HSP70, Le-actin, Le-theromacin) revealed that most transcript were more clearly affected by injury rather than starvation. The up-regulation of these genes was particularly high in the hemocytes of young, fed individuals after acute injury. Only minor changes in expression were detected in young starved and old animals. The stress response of L. elliptica thus depends on the nature of the environmental cue and on age. This has consequences for future population predictions as the environmental changes at the WAP will differentially impact L. elliptica age classes and is bound to alter population structure.