Marine Mammals as Ocean Samplers
Seals are top predators that are sensitive to changes in climatic variation and the distribution and abundance of their prey. The responses of seals often manifest in changes in their foraging location, foraging success and reproductive output. Therefore, monitoring the distribution of these predators at sea, achieved via contemporary logger tags, can provide information on the spatial and temporal variability of their prey and their environment. As seals forage successfully, they increase their stores of blubber, become more positively buoyant and change how they sink or float in the water. Change in the daily rate at which they sink or float, known as drift rate, can then provide a measure of biological productivity. The power of such an approach is that combining at-sea movements of multiple individuals enables identification of important persistent and ephemeral biodiversity hotspots in the Southern Ocean. This program is also highly complementary with ongoing monitoring of lower trophic level abundance in the Southern Ocean.
The Satellite Relay Data Loggers are deployed on marine mammals, including Elephant Seals, Weddell Seals, Australian Fur Seals, Australian Sea Lions, New Zealand Fur Seals. Data is being collected in the Southern Ocean, the Great Australian Bight, and off the South-East Coast of Australia.
A total of 304 tags have been deployed since 2007 collecting 228,843 CTD profiles and 3,677,294 individual measurements.