Data

Your access to IMOS Animal Tagging data discovery and exploration is through the Australian Ocean Data Network (AODN) Portal.

SRDL CTD Tags

Instrumented seals are filling very important gaps in the Southern Ocean, a very data-poor region of the world oceans, and therefore are becoming increasingly utilised by oceanographers studying the role of the Southern Ocean and Antarctica in global climate. Seal-derived data are making a growing contribution to climatologies built upon existing oceanographic databases, such as the World Ocean Database (Roquet et al. 2014).

Seal-based hydrographic data can also be used to produce improved state estimates of the ocean circulation; evaluation and validation of sea ice production estimation, drift velocity and fast ice mapping by the satellite remote sensing community. With the addition of a fluorometer on CTD-SRDLs, this technology is quickly becoming a major source of information on the primary production in the iron-limited Southern Ocean. The seal dataset is also contributing to our understanding of the use of oceanographic features by foraging southern elephant seals in the Southern Ocean, and more particularly in the Kerguelen Plateau region, and is now successfully used to improve model-derived estimates of animal movements (Roquet et al. 2014).

The satellite tag data is relayed and locations computed using the global Argos satellite system. This system relays an unbiased sample of detailed individual dive records. Sensors include depth, temperature and salinity. The data provides oceanographic quality temperature & salinity profiles in near real-time. Different tags are used on different species collecting different range of data as follows:

Australian Fur Seal, Australian Sea Lion, New Zealand Fur Seal and Southern Elephant Seal - CTD Satellite Relay Data Loggers (SRDL) that collect conductivity, temperature and depth information.

On some Australian Sea Lions - CTD/Fluorometer Satellite Relay Data Loggers (SRDL) that collect conductivity, temperature, fluorescence profiles and depth information.

Weddell Seals - Satellite Relay Data Loggers (SRDL) that collect temperature and depth information.

Validation of seal-derived hydrographic data. Comparisons between DH500 values (Dynamic Height Anomaly at 20 dbar relative to 500 dbar), obtained from (a) raw seal data, (b) adjusted seal data, and (c) the World Ocean Database (WOD35). (d) Mean and standard deviation of the differences with WOD-based DH500 values binned using a 0.05 dyn m interval are presented for both adjusted (red boxes) and raw (blue) seal data. On each box, the central mark is the median, while the edges of the box and whiskers are respectively the 16th and 3rd percentiles. Adjustments on seal data improve significantly comparisons with WOD data (Roquet et al. 2014)

Near Real Time Data

Loggers developed at the University of St Andrews Sea Mammal Research Unit transmit data in near real-time via the Advanced Research and Global Observation Satellite (ARGOS) system. The Satellite Relay Data Loggers are deployed on marine mammals, with data being collected in the Southern Ocean, the Great Australian Bight, and off the South-East Coast of Australia. Data parameters measured by the instruments include time, conductivity (salinity), temperature, and depth.

The CTD-SRDLs record hydrographic profiles during the ascent of animals retaining only the deepest dive in each six-hour time interval, and transmitting profiles in a compressed form (between 10 and 25 data points per profile, depending on the tag program) through the ARGOS system.

The near real-time data are made freely available daily via the Global Telecommunication System (GTS) of the World Meteorological Organization (WMO, see www.wmo.int), for immediate use. 

Delayed Mode Data

Delayed mode data is all the data transmitted via satellite and processed by Sea Mammal Research Unit (SMRU).

CTD - parameters measured by the instruments include time, conductivity (salinity), temperature, fluorescence and depth.

Diving - parameters measured by the instruments include start and end time and interpolated longitude/latitude of each individual dive, post-dive surface duration, dive duration, maximum dive depth, intermediate dive depths and times.

Haulout - a haulout begins when the SRDL has been continuously dry for a specified length of time (usually 10 minutes). It ends when continuously wet for another interval (usually 40 seconds). Haulout data parameters measured by the instruments include haulout start and end dates and longitude/latitude, and haulout number.

Argos locations - location data parameters measured by the instruments include time, longitude, latitude, location quality, along with other diagnostic information provided by Argos (http://www.argos-system.org/).

Summary Statistics - as well as sending records of individual events such as dives and haulouts, the SRDL also calculates summary statistics of those events over a specified time period (usually 3, 4 or 6 hours). Summary statistics computed by the instruments include the proportion of time spent diving, at the surface and hauled-out, the number of dives, and the average, standard deviation and maximum dive duration and dive depth during each summary period. These statistics are based on all the data recorded by the SRDL and so are not prone to distortion by variations in the efficiency of transmission via Argos.

 

 

 

Movie showing SST from SRDL tagged animals

GLS Tags

Geolocation archival (GLS) tags are used in seabirds such as short-tailed shearwaters (Puffinus tenuirostris) and snow petrels (Pagodroma nivea) and can store data from up to four sensors (e.g. date, time, temperature, and light levels). Unlike GPS tags these tags must be retrieved from their data to be downloaded. The light levels are used to calculate the time of dawn and dusk, which can be used to estimate an approximate daily position of the animal.

Biotrack MK-19 GLS, MK3005 and MK14 tags sample light level every minute and record the maximum light measurement in every five minute period, which is the primary data for estimating initial location. They also sample the time when an activity (wet or dry) state change occurs, with water temperature recorded after twenty minutes in the wet phase, which acted as auxiliary environmental data for estimating initial location. Prior to deployment, GLS temperature sensors are calibrated, in a water bath at 2 °C increments between 0 °C to 24 °C and then at 28 °C, to cover the SST range of the expected foraging area.

The activity status of the tag can be used to infer foraging locations and behaviour. Shearwaters, for example, feed from the surface of the water mostly by surface plunging and pursuit diving, an activity that could be indicated by the tags when they sample the time when an activity (wet or dry) state change occurs.

 

 

Foraging trip (> 5 days, grey) summaries for 27 geolocation tag equipped Short-tailed shearwaters on Wedge Island, in 2010–2011 by breeding phase. Breeding outcomes for each tracked individual are indicated, including; non-breeding (green), failed egg (purple), failed chick (blue) and successful chick (pink). Pairs are displayed with bold text (Cleeland et al. 2014).

References

Fabien Roquet, Guy Williams, Mark A. Hindell, Rob Harcourt, Clive McMahon, Christophe Guinet, Jean-Benoit Charrassin, Gilles Reverdin, Lars Boehme, Phil Lovell and Mike Fedak. 2014. A Southern Indian Ocean database of hydrographic profiles obtained with instrumented elephant seals. Scientific Data. 1: 140028.

Cleeland, J.B., M.-A. Lea and M.A. Hindell. 2014. Use of the Southern Ocean by breeding Short-tailed shearwaters (Puffinus tenuirostris). Journal of Experimental Marine Biology and Ecology. 450: 109-117.