Plankton biodiversity in the Southern Ocean
NIWA is conducting a five–year study to map changes in the distribution of plankton species in surface waters between New Zealand and the Ross Sea. Officially known as Continuous Plankton Recorder Time Series, this study is part of a Ministry of Fisheries marine biodiversity programme.
Long-term monitoring of plankton is essential to understanding the impacts of climate change and ocean acidification on marine ecosystems. Plankton play a key role in marine ecosystems because they form the basis of marine food webs and are important in biogeochemical processes such as carbon cycling. Changes in plankton abundance, diversity, and distribution could have cascading effects through the ecosystem.
Antarctic plankton are expected to be particularly sensitive and vulnerable to climate change and increased CO2 through such things as changes in sea ice patterns and ocean currents, increased sea temperatures and UV levels, and ocean acidification.
At present, we lack information on plankton distribution in large parts of the Southern Ocean surrounding Antarctica. The Australian Antarctic Division has been coordinating a survey of plankton using Continuous Plankton Recorders (CPR) in Southern Ocean waters south of Australia since 1991. Their CPR data have already identified major changes in zooplankton composition in eastern Antarctic waters that could have a major impact on higher predators.
The area south of New Zealand, including the Ross Sea, has not been well sampled.
NIWA is conducting a 5–year study to map changes in the distribution of plankton in surface waters between New Zealand and the Ross Sea, Antarctica. Data will be collected with a Continuous Plankton Recorder (CPR) towed behind a commercial toothfish vessel as it transits to and from Antarctic toothfish fishing grounds in the Ross Sea. Data will be collected each summer over a five–year period (2008–13).
Phytoplankton, zooplankton and life stages of krill will be identified according to strict protocols and counts and biomass estimates made. These will be analysed — along with CPR data collected on RV Tangaroa’s 2006 and 2008 Ross Sea voyages — to determine trends in plankton distribution, diversity, and abundance. They will also be compared with data collected by the Australian Antarctic Division as part of the Southern Ocean CPR Survey.
NIWA technician Karen Robinson will be identifying the plankton from the surveys in collaboration with members of the Australian Antarctic Division.
The study is funded through the Ministry of Fisheries marine biodiversity programme.
The first year of sampling has been completed. The CPR was successfully deployed on Sanford Ltd fishing vessel San Aotea II in December 2008 and January/February 2009. Identification of the plankton collected is underway.
Final results of the study will be reported in June 2013.