Review: the energetic value of zooplankton and nekton species of the Southern Ocean
Résumé
Understanding the energy flux through food webs is important for estimating the capacity of marine ecosystems to support
stocks of living resources. The energy density of species involved in trophic energy transfer has been measured in a large
number of small studies, scattered over a 40-year publication record. Here, we reviewed energy density records of Southern
Ocean zooplankton, nekton and several benthic taxa, including previously unpublished data. Comparing measured taxa,
energy densities were highest in myctophid fishes (ranging from 17.1 to 39.3 kJ g−1 DW), intermediate in crustaceans (7.1
to 25.3 kJ g−1 DW), squid (16.2 to 24.0 kJ g−1 DW) and other fish families (14.8 to 29.9 kJ g−1 DW), and lowest in jelly
fish (10.8 to 18.0 kJ g−1 DW), polychaetes (9.2 to 14.2 kJ g−1 DW) and chaetognaths (5.0–11.7 kJ g−1 DW). Data reveals
differences in energy density within and between species related to size, age and other life cycle parameters. Important taxa
in Antarctic food webs, such as copepods, squid and small euphausiids, remain under-sampled. The variability in energy
density of Electrona antarctica was likely regional rather than seasonal, although for many species with limited data it
remains difficult to disentangle regional and seasonal variability. Models are provided to estimate energy density more
quickly using a species’ physical parameters. It will become increasingly important to close knowledge gaps to improve the
ability of bioenergetic and food web models to predict changes in the capacity of Antarctic ecosystems to support marine life.