Instrumentation
Instrumentation of Continuous Plankton Recorders
Overview of instruments used and data
collected
The CPR is an ideal platform for sampling oceanographic parameters
and the CPR survey routes provide extensive spatial coverage in the
marine environment. The combination of these two factors enables
SAHFOS to instrument the CPRs and provide additional valuable
datasets at relatively little extra cost.
Since 1994, CPRs on certain routes have been instrumented to
measure sea surface temperature, salinity, CPR sampling depth and
phytoplankton chlorophyll fluorescence. The datasets are collected
to complement the CPR plankton data and to ground-truth data
collected by other sensors used in the same regions. In addition
the instrument data can frequently be used to validate the launch
and recovery information returned by the towing vessel on the CPR
log sheet.
Temperature Data
Vemco Minilog temperature sensors
| There are several Vemco minilog
temperature sensors in operation on CPRs. The temperature ranges of
the minilogs used by SAHFOS are -4°C to +20°C and -5°C
to +35°C. A minilog can take up to 8000 measurements with a
sampling interval of between 1 second and 6 hours. |
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Link to
SAHFOS temperature dataset
Aquapack - from Chelsea Technologies Group.
This instrument has been used previously to log conductivity, temperature, depth and fluorescence data on several CPR routes but has now been replaced by the Minipack (see below).
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Minipack - from Chelsea Technologies Group This compact high-specification instrument consists of a chlorophyll fluorometer, conductivity, temperature and depth sensor coupled with a data logger. The SAHFOS Minipack has recently been used on the CPR towed northwards from the Iberian Peninsula across the Bay of Biscay, traversing the Celtic Sea and into the Irish Sea. |
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Richard Brancker Research (RBR) TR1050P temperature sensor and XR620 CTD The TR1050 high-specification temperature sensor, purchased by the Meteorological Office, has been used on the CPR towed from Bilbao to Portsmouth by the Pride of Bilbao ferry. More recently the instrument has been replaced by RBR XR420 and 620 CTD instruments. SAHFOS has an additional RBR XR620 CTD with the addition of the Turner Cyclops chlorophyll fluorometer which is used on the trans-Pacific CPR tow from Canada to Japan. |
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Star-Oddi Data Storage Tag for conductivity, temperature and depth
SAHFOS has recently purchased 4 Star-Oddi miniature DST-CTD (Data Storage Tag for conductivity, temperature and depth). These instruments, originally designed as fish tags, will be used on the new CPR routes in the Norwegian Sea.
Calibration of Instruments
The minilogs, Aquapacks and minipacks are calibrated three times a year against independent readings from a mercury in glass thermometer. Temperature measurements are considered to be accurate to +/- 0.1°C.
Future instrumentation changes
It is envisaged that the XR420 CTD and F sensor will be a replacement instrument for the aquapacks and minipacks in the future. Currently one of these sensors is deployed on a CPR on the M route.
The performance of these in-situ sampling instruments is currently monitored in-house yearly or half-yearly. Temperature measurements are considered to be accurate to +/- 0.1°C and salinity to 0.2 psu.
| SAHFOS is currently developing a water sampler in collaboration with CEFAS and funding from DEFRA for use on CPRs. The intention is that this instrument will collect and store 10 samples of 125ml of seawater with preservative if required. The samples will be taken at timed intervals along a CPR route. It is hoped that this instrument will reveal information on Harmful Algal Bloom species and other delicate phytoplankton taxa that may be under-estimated by CPRs |  |
Previous Instruments developed with SAHFOS
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The U-Tow The U-Tow design was originally commissioned by SAHFOS in the mid 1990's as an enhancement to the fixed depth Continuous Plankton Recorder (CPR). U-Tow is a high capability, undulating Towed-Vehicle with the ability to have a large onboard payload for oceanographic sensors, analyzers and samplers. The system was tested over a number of years, and although it could be tailored to suit a particular monitoring application, it was not found not to be a suitable towed vehicle to replace the CPR. Further information about the U-Tow can be provided by Tony Walne (anwa@sahfos.ac.uk) |
U-Tow (courtesy of WS Envirotech). |
Automated Phytoplankton Analysis and Plankton Image Library
During the period when the U-Tow was under development and testing, Karl Embleton used the U-Tow as a platform for phytoplankton collection and developed an automated phytoplankton analysis system and plankton image library. The phytoplankton pattern recognition system was trained on 76 different classifications of microplankton. Images of each classification were stored onto disk to act as templates for the pattern recognition process. Comprehensive tests of the system were performed on six phytoplankton samples from Liverpool Bay and from station L4 in the English Channel. All the samples were analysed using both the automated system and manually. The variation between manual and automated estimates of cell numbers was found to be no greater than that between the different manual analyses, i.e. the automated system is at least as good as a human analyst. A particular advantage of the system is that it is easily expandable with images of new species. A CD-ROM was produced which contains all the software for the complete phytoplankton automated analysis system. Considerable progress has been made in the field of automated counting and recognition of phytoplankton within the two Defra U-Tow contracts. Karl Embleton has now moved to Manchester University to continue work with pattern recognition systems in the field of medical science.
