LONGITUDINAL VARIATION IN ZOOPLANKTON DELTA-C-13 THROUGH THE NORTHWEST PASSAGE - INFERENCE FOR INCORPORATION OF SEA-ICE POM INTO PELAGIC FOODWEBS

Previous research has demonstrated a west-to-east decrease in zooplank ton delta(13)C along the Alaskan coast. We extended the transect into the Canadian Arctic archipelago through the Northwest Passage in order to investigate whether this longitudinal gradient persists eastward. Contrary to the previous observations, zooplankton delta(13)C was foun d to be essentially invariate, despite a sampling survey length double that of the earlier studies. This resulted from zooplankton at the co ldest and ice-bound stations being found to be enriched in C-13 relati ve to what would be expected from the ambient water temperatures and c alculated [CO(2)aq] We suggest that this was due to the assimilation o f ice POM which, as has been demonstrated for other forms of benthic a lgae, is enriched in C-13 due to restraints on boundary layer diffusio n. The present results therefore support other traditional, non-isotop e research in suggesting that ice-bound polar foodwebs may be examples of aquatic systems where there is a functional energy connectivity be tween the attached and openwater environments.