Carbon-13 and carbon-14 abundances in alaskan aquatic organisms: delayed production from peat in arctic food webs.

Inputs of terrestrial peat carbon to the nearshore Alaskan Beaufort Sea from erosion and fluvial transport are of the same magnitude as in situ primary production within 10 kilometers of shore. Nevertheless, carbon-13/carbon-12 ratios and carbon-14 abundances in marine organisms show that only small amounts of the terrestrial carbon are transferred beyond the microbial level. Freshwater organisms, however, are heavily dependent on peat, as shown by pronounced seasonal radiocarbon depressions in resident fish and ducks. Tundra ponds and lakes are areas where accumulated terrestrial peat carbon is apparently transferred to aquatic insect larvae and passed on to higher organisms. The lack of functionally analogous abundant marine prey organisms may explain why peat carbon is not efficiently transferred to apical food web species in the marine environment.