Sascha K. Hooker and Ian L. Boyd. 2003.
Deep-Sea Research I 50: 927-939.
Diving marine predators have been used to collect data on ocean temperature, but salinity measurements have not previously been incorporated into predator-borne data loggers. Here we present data on initial calibration and field trials of a new conductivity, temperature and depth (CTD) data logger used alongside a satellite-positioning transmitter to provide three-dimensional oceanographic information. This provides CTD data analogous to that collected by a ship-deployed undulating oceanographic recorder. Calibration tests of these units showed a near-field effect caused by the proximity of material to the tag, but demonstrate that the resulting data offset can be removed by post-hoc calibration. Field tests of the system were conducted on sixteen female Antarctic fur seals (Arctocephalus gazella) at Bird Island, South Georgia. These results matched those found by standard ship-based survey techniques, but suggest temporal variability in the structure and location of the two water masses found to the north of South Georgia. Overall, this initial proof-of-concept work is encouraging; future refinement of this technique is likely to provide an additional data source for both oceanographers and biologists.
Keywords: salinity; CTD; marine predators; oceanography