Fishes are but one element of a complex ecosystem. The invertebrate component of a community may interact with fish species in several ways, from creating habitats to acting as a food source. Large invertebrates (such as corals and sponges) create structure that fishes may use as shelter, camouflage, or as a place to lay eggs. Alternatively, some predators such as octopus may find concealment among these same invertebrates and negatively impact fish populations. Other invertebrates are a direct food source for many fish species. To facilitate a more complete understanding of how notothenoid fish interact with the rest of the ecosystem, my graduate student Andrew Thurber and I are incorporating a benthic invertebrate aspect into the ICEFISH research.
The invertebrate community is of intrinsic interest as well, from biodiversity and ecological processes perspectives. Biodiversity in nearby Antarctic waters is high, though certain major groups of invertebrates are conspicuously absent. The planned cruise track includes sites above and below the Antarctic Convergence, a strong oceanographic separation between water masses. Comparisons of species on either side of the Convergence will let us test whether this is a barrier to invertebrate species. The young stages, or larvae, of marine invertebrates are usually microscopic and generally moved about by currents, so we predict that there will be similar species at islands on the same side of the Convergence, but a different group of species on the other side.
Invertebrates that are abundant in the Antarctic generally exhibit very slow growth, due to adaptations to low temperatures, seasonal changes in daylight, and annual pulses of food availability. Thus, community recovery from disturbances is likely to be slow. As these remote places become more accessible and susceptible to anthropogenic (human) pressures like fishing and pollution, a solid baseline of data and information on the sensitivity of the ecosystem will help establish reasonable protective measures.