Continental Shelf Processes
The Kangaroo Island-Eyre Peninsula region hosts one of Australia’s distinct marine upwelling systems. Both historical and SA-IMOS Node data indicate that upwelling originates to the south and south-east of Kangaroo Island, is largely sub-surface and is directed to the north and north-west. An additional feature of the upwelling events is currents are generally too weak and/or infrequent to transport upwelled water from the shelf slope off Kangaroo Island to the surface off the Eyre Peninsula, where primary productivity would likely take place. Consequently, the nutrient rich upwelled water appears to reside in a sub-surface “Kangaroo Island cold pool” (McClatchie et al 2006), however high rates of productivity have been found in upwelled water below the surface mixed layer (van Ruth, 2009). The Bonney and Otway coasts are also regions of intense upwelling during summer. In conjunction with the west-ward Flinders Current, submarine canyons may also be important to upwelling in the region.
The southward facing shelves of the region are also exposed to internal waves and tides (Coastal Trapped Waves) that may be important to slope boundary layer mixing and possibly important to the global heat balance. Such internal waves and associated mixing have been found elsewhere (eg., the North West Shelf, Hawaii) although we know nothing about their importance for Australia’s southern shelves.
Key Science Questions
Upwelling and downwelling
- What is the temporal and spatial variability and nature of cross-shelf exchange (upwelling and downwelling) including carbon, for the Kangaroo Island – Eyre Peninsula region and what role do canyons, the gulfs and coastal trapped waves play?
- What is the temporal and spatial variability and nature of cross-shelf exchange (upwelling and downwelling) for the Bonney and Otway Coastal regions?