Update on Ross Sea biodiversity
Science Centres: Aquatic Biodiversity and Biosecurity
Analysis of the huge volume of data and samples collected on last year’s New Zealand International Polar Year Census of Antarctic Marine Life (NZ IPY–CAML) voyage to the Ross Sea continues apace. Some early results are already being put to good use.
Scientists returned from the Ross Sea last year with a large volume of environmental data, more than 40,000 specimens and 55 hours of seafloor video footage (see earlier stories in ABBU26 and ABBU27). Taxonomists have so far identified at least five ‘new’ fish species (that is, species new to science), and many new records for the Ross Sea region. Excluding octopus and squid, about half of the 4592 invertebrate samples have so far been identified to family level, a third to genus level, and 20% to species level — a significant achievement. To date, 21 new invertebrate species have been identified, including two possibly new genera and species of black coral.
As well as providing a stocktake of biodiversity in the area, scientists are trying to understand the role different organisms play in the Ross Sea ecosystem. They are using various techniques — including analyses of gut contents, stable isotope signatures — to better understand who eats who. Genetic analyses are also being used to determine the level of interconnectedness between organisms in the Ross Sea and other parts of the Southern Ocean. These have already led to some surprising results, with some evidence for ‘cryptic species’ (separate species that look very similar) within the Ross Sea region.
Research that helps to advance our understanding of the marine environment will ultimately enhance our ability to manage human activities in the Ross Sea region. Here are some examples of how early results are being applied.
Identifying ‘bioregions’
Scientists have begun identifying and mapping ‘bioregions’ of the Ross Sea by combining data on the ocean’s physical and chemical properties with data on the distribution and abundance of fish, krill, and benthic invertebrates collected during the survey. These bioregions essentially define natural boundaries between habitats and assemblages of marine biota and can be used to identify areas that may require certain management measures or protection. The first Ross Sea Region Bioregionalisation and Spatial Ecosystem Processes Workshop took place in Wellington in June 2009.
Identifying Vulnerable Marine Ecosystems
Data from seafloor sampling and video analysis are being used to identify Vulnerable Marine Ecosystems (VME) in the Ross Sea region. Protection of VMEs (which include seamounts and hydrothermal vents) have been identified by the United Nations as areas vulnerable to damage by bottom fishing activities. The analyses were reported to a meeting of CCAMLR (Commission for the Conservation of Antarctic Marine Living Resources) in San Diego in early August 2009.
Silverfish biomass estimates used in ecosystem model
The voyage provided the first ever acoustic estimates of the biomass of the Antarctic silverfish — the most important prey species on the Ross Sea shelf eaten by whales, penguins, seals and fish. It also provided the first biomass estimates of demersal fish (bottom-dwelling fish, including rattails and ice cod) in the region based on the trawl survey. These estimates have recently been used to update a model of the Ross Sea ecosystem, presented by NIWA scientists to a meeting of CCAMLR in Norway in July 2009.
Setting toothfish bycatch limits
CCAMLR used abundance estimates of Whitson’s grenadier Macrourus whitsoni — important toothfish prey — from the voyage to set bycatch limits in the toothfish fishery in October 2008.
NZ IPY–CAML is a multi-agency project funded by the New Zealand Government.
Contact: Dr Don Robertson, NIWA Wellington or Dr Mary Livingston, Ministry of Fisheries.
