A/Prof Michael Ellwood
Australian National University
Research voyage to the southern extension of the East Australian Current (EAC) to study ocean iron inputs and cycling.
The EAC is the southward moving current along the eastern margin of Australia. At the EAC’s southern extent near Tasmania, the nutrient depleted but iron rich waters of the EAC mix with the cool, nutrient rich and iron depleted Southern Ocean water. Where these waters mix, large spring phytoplankton blooms tend to occur. This voyage aims to determine the sources and cycling of iron and associated trace elements during a spring-time phytoplankton bloom and contrast this to waters where the spring bloom is muted.
There is one supplementary project on this voyage:
- Spatial and temporal variability in the distribution and abundance of seabirds (Dr Eric Woehler, BirdLife Australia): Project to study the spatial and temporal distribution of seabirds and marine animals in the oceans around Australia (multi-year project).
As a result of this voyage, researchers found that the EAC is highly dynamic with significant north-south and east-west temperature, nutrient and chlorophyll gradients. A springtime bloom characterised in the southern extension of the EAC was identified to have significant spatial and temporal changes. In addition, new areas of seafloor were mapped, providing high resolution imagery of several seamounts.
Researchers investigating the EAC now have a clearer understanding of factors that drive primary production in the southern extension of the current. This includes a thorough biogeochemical analysis of the relevant water masses immediately prior to the beginning of the spring bloom.
A wide range of seabird observations were made during the voyage, with a total of 30 species and 8,000 individual birds observed. This data will contribute to the wider BirdLife Australia project dataset and provide important information about the spatial and temporal distributions of seabirds.
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