Integration of a miniaturized conductivity sensor into
an animal-borne instrument. Boehme L. , Lovell P. , Morris A. and Pascal R.
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1Scottish
Oceans Institute, University of St Andrews – lb284@st-andrews.ac.uk
Instrumentation Group, University of St Andrews
3National Oceanography Centre, Southampton
2SMRU
Relating marine mammal movements and behaviour to
fine-scale ocean structure requires oceanographic
information on similar spatial and temporal scales. The
appropriate environmental information is usually not
readily available especially in high latitude oceans. One
way to solve this mismatch is to deploy oceanographic
sensors on the animals themselves to obtain in-situ
information without any spatial or temporal lag.
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antenna
temperature probe
inductive cell
pressure sensor
battery
communications port
wet-dry sensor
Current CTD-Satellite Relay Data Logger (CTD-SRDL) with CTD head
(black) based on an inductive cell (2).
Bottom left picture shows a CTD-SRDL deployed on a Southern
elephant seal at the beginning of the deployment. Top right picture
shows an instrument on a Weddell seal after several months. The
antenna is kinked because of repeated bending when the seal is
moving through its breathing hole.
The aim of this project is to modify and improve an
existing miniature conductivity-temperature sensor and
incorporate it into the proven design of a Satellite Relay
Data Logger.
A reduction in the size of the oceanographic sensor would
enable us to add other sensors and use other telemetry
systems without increasing the package size.
The use of an electrode instead of a inductive cell will
reduce the effect of nearby objects on the conductivity
measurements (Boehme et al., 2009)
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Integration of a miniaturized conductivity sensor into an animal-borne instrument.
In this study, we modified an existing miniature
conductivity-temperature sensor of about 10x10mm
(Huang et al., 2011) nad designed a new control board to
deliver temperature and conductivity measurements via
an I2C interface.
Three miniature sensors (left) and one sensor with new
control board (right) ready to be interfaced with a SRDL.
Current animal-borne instruments using an inductive cell
to measure the salinity of the surrounding water need a
‘rigid’ attachment, which is normally only possible when
the animal can be restrained during the attachment
procedure limiting their use to seals and small cetaceans.
This new sensor is not influenced by the attachment
method and would therefore be able to provide accurate
measurements while rotating around a barb attachment
as is used to tag large cetaceans.
References
The sensor is currently undergoing lab and field tests to
determine the accuracy and effect of bio-fouling on the
sensor’s reliability.
Boehme, L., P. Lovell, M. Biuw, F. Roquet, J. Nicholson, S. E. Thorpe, M.
P. Meredith, and M. Fedak (2009), Technical Note: Animal-borne CTDSatellite Relay Data Loggers for real-time oceanographic data
collection, Ocean Science, 5(4), 685-695.
This methodology provides for ecosystem studies of a
range of marine animals (e.g. large cetaceans, fish, birds)
that are not currently feasible.
Huang, X., R. W. Pascal, K. Chamberlain, C. J. Banks, M. Mowlem, and
H. Morgan (2011), A Miniature, High Precision Conductivity and
Temperature Sensor System for Ocean Monitoring, Ieee Sens J, 11(12),
3246-3252.
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Design studies for new animal-borne instruments using the
miniature sensor. GPS/Iridium-CTD-SRDL (left) and cetacean SRDL
for barb attachment (left)