Introduction

Abstract

The relationship between food web structure and function across two ocean biomes was investigated using an inverse method to recover solutions of food web carbon flows. We estimated the carbon exchanges between major assemblages within plankton food webs in the North Atlantic, using the JGOFS NABE data set (1989) and near the Western Antarctic Peninsula (WAP), using the Palmer Station LTER data set, two areas exhibiting strong seasonal phytoplankton blooms. The recovery of all the potential flows of carbon allowed a system-level analysis, providing insight to processes that are seldom measured in the field and a means of comparing food webs from different regions. In the NABE food web, the dominant carbon flows involved the microorganisms including bacterial carbon demand and grazing by microzooplankton and protozoans. In the WAP food web, krill had the most significant carbon flows including grazing of large phytoplankton and respiration.A comparison between the NABE and the WAP carbon-based food webs showed key differences. Recycling and the activity of the microbial food web were much greater in the NABE food web than in the WAP. However in the WAP inverse solution, the microbial food web was just as important as the classical food web (diatoms to krill to penguins) that is traditionally believed to dominate carbon flows. Carbon flows through the NABE and WAP regions were more highly dependent on recycling than would be anticipated from the size structure of the primary producers, when analyzed using a classification scheme of Legendre, L., Rassoulzadegan, F [1996. Food-web mediated export of biogenic carbon in oceans: hydrodynamic control. Marine Ecology Progress Series 145, 179–193].