The Plymouth Quest research vessel taking samples for the Western Channel Observatory
ADVANCING OCEAN MONITORING
THROUGH TECHNOLOGY
BY KIRA COLEY, PLANET OCEAN LTD
Covering more than 70 percent of the surface, the ocean is a key driving force for regulating
climate and supporting life on Earth. While there has always been a degree of natural variability in our seas, the increase of industrial activity in “the blue frontier” has tipped the natural
balance of this complex system. For decades, ocean observatories have been monitoring
changes to ocean dynamics, shaping climate policy, conservation and coastal management
practises. Given its importance, researchers must overcome challenges for long-term monitoring in often hostile and complex marine environments. The last decade has seen advancements in robust remote sensing technology, making previously difficult locations accessible to
scientific investigation and providing unprecedented insights into one of the busiest shipping
lanes on the planet, the English Channel.
Scientists have been sampling the coastal waters of the English Channel for more than a century. The western channel, off
Plymouth, is the point where coastal and oceanic waters meet,
making it an interesting, but difficult location for researchers
to monitor biological and chemical changes over long time
scales. With over 500 ships per day, the Channel has traffic on
both the UK-Europe and North Sea-Atlantic routes, and is the
world's busiest seaway.
Optical Oceanographer and WCO Technical Manager at the
Plymouth Marine Laboratory.
TECHNOLOGY IN OCEAN MONITORING
Until relatively recently, regular vessel sampling was the main
form of data collection, encompassing over 50 measurements
made by PML scientists covering physics, chemistry and biology. Biological and chemical measurements such as phytoplankton pigment concentrations and nutrients are analysed back at
the laboratory using water samples taken from multiple
depths at the station. The long-term data collected from research vessels is used to establish a baseline for studying how
humans are affecting the oceans through climate change. Unfortunately this method of sampling is highly weatherdependent and usually only achievable on a weekly basis, creating large temporal gaps in the data.
Over the last few decades, intensification of measurements in
this challenging location has led to the formation of the Western Channel Observatory (WCO), hosted at the UK’s Plymouth
Marine Laboratory (PML). The WCO uses a range of advanced
technology and monitoring platforms to overcome the high
level of vessel activity in often hostile conditions, providing
high quality, long term oceanographic datasets as well as be- To fill these gaps, the WCO are using an advanced suite of reing an internationally important biodiversity reference site.
mote sensors and monitoring platforms, providing unarguably
high quality data at new levels of temporal resolution. One of
Funded largely through the NERC National Capability pro- the major developments of the WCO was the deployment of
gramme, the WCO is part of the UK Integrated Marine Ob- two large scientific data buoys which combined routine in-situ
servatories Network (IMON) and forms part of major science sampling with modelling and remote sensing. The variety of
programmes such as the NERC Shelf Seas Biogeochemistry instrumentation and ruggedness of design was essential to
(SSB). Internationally, the WCO is involved in cross channel monitoring the hostile conditions of the Channel - with waves
programmes such as INTERREG, MARINEXUS, RECIF, VALMER up to 6m, strong winds and the high volume of boat traffic.
and CHARM.
Powered by a combination of solar and wind energy, the
“The WCO produces considerable scientific outputs, on aver- buoys carry an impressive array of equipment covering a range
age over 20 high quality refereed scientific papers and several of conditions; L4, a coastal station some 6 nautical miles south
PhD successes per year. There have been several ICES reports of Plymouth, captures information about inputs from the local
on ocean climate and marine biology, which include data and estuaries and E1, an open shelf environment located approxiauthors involved in WCO. The world leading ecosystem mod- mately 20 nautical miles south of Plymouth. Capable of providelling group based at PML also utilise the data for model de- ing a continuous or hourly stream of data, these fixed
velopment and validation.” Explains Dr James Fishwick, Bio- platforms are an integral part of understanding the dynamics
of each site. The high-frequency, small-scale data, allows researchers to look at short-term changes and see how they
affect longer-term trends.
The range of oceanographic instruments on the buoys include
the Wet Labs Water Quality Monitor, measuring temperature,
salinity, dissolved oxygen, turbidity and chlorophyll fluorescence; a WET Labs Environmental Characterisation Optics series coloured dissolved organic matter flourometer; Satlantic
ISUS in-situ ultraviolet spectrophotometer nitrate sensor; and
Satlantic SeaFET pH sensor.
The WCO started collecting temperature and salinity timeseries in 1903 and is one of the longest in the world. Physical
parameters such as temperature and salinity play an important role in ocean biogeochemistry. While most changes in
physical conditions can be small, they can have profound
effects on the spatial and temporal distribution of nutrients
and biological communities.
Dr Fishwick explains, “The WCO has temperature and salinity
measurements dating back over one hundred years, but the
high quality, depth profiled Seabird CTD measurements only
started in 2002. With the addition of this CTD and the wealth
of data measured over such long timescales, we can start to
pull out trends in the data we couldn’t previously, investigating the possible long term heating of the water column and
the variability in the dataset.”
The principal stations of the Western Channel Observatory. The Observatory
"nodes" are marked with red circles. The black circles are historic stations.
The white circles mark the locations of the benthic survey.
Throughout the year, the WCO measures phytoplankton succession and the particular environmental conditions in which various species dominate. Since the development of the buoys, the
WCO has found that the weekly vessel sampling has been missing many short bloom events and the changes in the environmental conditions which triggered them. The buoys and its sensors have also allowed scientists to measure parameters through
periods of bad weather and provide high frequency data through
tidal cycles.
By measuring pigment assemblages and changes in primary production, researchers can begin to identify adaptations of these
species for the particular environmental niches they occupy. The
WCO has some of the longest time-series in the world for both
zooplankton and phytoplankton, creating an important biodiversity reference tool for species composition.
Nutrient concentration data are intrinsically linked to primary
productivity and the distribution of biological communities. Nitrate, nitrite, phosphate, silicate and ammonium nutrient data
have been collected since 2000 at station L4 using laboratory
based techniques. While the WCO routinely measures nutrient
levels, the addition of the remote sensors on the buoys has
meant that these parameters are measured on an hourly basis.
“It is not the ability to measure the nitrate, for example, which is
significant, but the ability to perform the measurements remotely at high frequency and with reliability that provides great insights, making these sensors invaluable. With the various parameters being regularly measured by PML using calibrated lab
based analysis, we can perform weekly calibrations to our remote sensors, providing an unarguably high quality dataset. PML
has operated the Satlantic ISUS and SUNA sensors for over five
years.” Dr Fishwick.
plankton of freshwater surges resulting from flood conditions in
the River Tamar. PML scientists found that 'freshening' events
brought extra nitrates into the sea from river run-off, and resulted in blooms at a time when conditions were otherwise unsuitable for accelerated plankton growth. While this has been suspected for many years, until now researchers had not been able
to recover any evidence.
Changes in marine physical processes can also affect weather
patterns and climatic variability. A TRIAXYS sensor at station E1
provides real-time data to the UK’s Met Office on spectral wave
characteristics capturing the swell height hitting the UK coastline.
The data feeds into forecasting models run by the Met Office for
both weather and sea state and has also proven useful to scientists investigating air-sea interactions. The near real-time data is
sent to the WCO website which is used by various local marine
users, including the shipping and fishing industries.
OVERCOMING CHALLENGES
While capturing so many parameters is necessary to fully understand the dynamics of each location, the WCO must operate a
substantial array of sensors on several platforms, causing logistical difficulties and large maintenance requirements. This is managed effectively through the introduction of procedures and
practices for maintenance and calibration, which have been supported through a number of collaborations - the WCO has benefitted from the recent high profile collaboration between PML
and the Met Office.
“The WCO has the rare ability to provide frequent high quality
vicarious calibrations to all the remote sensors, providing a high
quality assured data set. With so many sensors being deployed
on a continuous basis, the cost of factory calibrations will always
be high and this needs to be incorporated in the budgeting of the
Given its coastal location, the L4 buoy and its suite of advanced WCO. Collaborations are a great way to maximise on the deliversensors has provided information on the influence on phyto-
ables that can be achieved within various budgetary con- ing and weekly in-situ observations that gives researchers
straints.” Dr Fishwick.
unique insights into what is happening in the English Channel.
However, the deeper water column still eludes the satellites
PML is also in the process of replacing the L4 buoy with a new
and the data buoys' instruments, therefore weekly samples
state of the art platform. The new buoy will have an integrated
collected from research vessels remain an important part of
autonomous water profiling system and the latest anti-fouling
technology to better support its suite of remote monitoring the WCO research. By filling temporal gaps and improving the
resolution and quality of the data, these datasets will support
sensors.
future climate models, ocean policy and coastal management
Multi-parameter instruments also benefit the WCO by reduc- practises.
ing the associated costs of purchasing several singleparameter systems, as well as streamlining control and data “The WCO continues to be involved in national and international science programmes and seeks to build on its scientific
integration. Limitations such as the number of communication
collaborations. To maximise the use of the extensive expertise
ports available, power capability or weight restrictions can
influence the size and number of sensors supported by the and platform availability within the WCO, PML applications are
striving to further develop our work within system developbuoy systems.
ment and testing. With the continuous development of tech“Sensors such as the WetLabs WQM have been invaluable in nology and autonomous robotic systems, the WCO is well
the data buoy programme. As all the control and data integra- placed as a testing and development site and we hope to furtion are performed on the sensor, this makes it much simpler ther build on the work already undertaken within this area.
to cable and integrate into our systems. Small things like the Technological advances in recent years have given us an unnumber of parameters measured using only one communica- precedented understanding of the marine environment. As
tion port on the buoy, logging and control system are signifi- new technologies continue to come online our ability to quancant, as they free up additional ports for other sensors,” said tify complex interactions through high frequency, autonomous
Dr Fishwick, “The major success of the WQM is the anti-fouling and mobile sensor platforms will be further enhanced. These
features it provides and as the sensors are integrated together new systems will enable us to measure through adverse
in one package they all benefit from this technology.”
weather conditions and collect a wealth of data in a much
The WCO strives to position itself at the forefront of scientific more cost effective manner ” Dr Fishwick.
research, continuing to produce high level scientific outputs
across a diverse scientific field. Ongoing developments in remote sensing technologies are equally essential to meeting
environmental monitoring needs. It is the combination of small
-scale data together with ecosystem modelling, remote sens-
PLATFORM
L4 BUOY
E1 BUOY
PLYMOUTH QUEST
ROSETTE
PLYMOUTH QUEST
UNDERWAY SENSOR
SUITE
PLYMOUTH QUEST
OPTICS RIG
SENSOR
Water Quality Monitor (WQM)
ECO CDOM Fluorimeter
ISUS Nitrate sensor
SeaFET pH Sensor
Hyperspectral Irradiance (Air)
StorX
Weather Station PB200WX
MANUFACTURER
WET Labs
Water Quality Monitor (WQM)
ECO CDOM Fluorimeter
SUNA Nitrate Sensor
PAR Sensor (Air)
2 x Watchmen Loggers
TRIAXYS (MET Office)
SBE 32 Carousel with 12 x 10L bottles and up the wire
comms
SBE19+ CTD (x3)
SBE 43 Dissolved Oxygen (x2)
C-Star, 25cm path length red
WET Labs
PAR Sensor (Air)
Satlantic
SBE 45 Thermosalinograph
SBE 38 Thermistor
PAR Sensor (Air)
HyperSAS (Occasionally)
C-Star, 25cm path length (Red)
ECO Triplet (Chl, Turbidity and CDOM)
Weather Station PB200WX
Sea-Bird Scientific
ACS
DH4
BBRTD
LISST-Holo (Plymouth University)
PLANET OCEAN SUPPORTING UK OCEAN MONITORING
Each platform at the Western Channel Observatory is equipped
with the latest in sensor and long term monitoring technology. The
majority of these systems have been provided by Planet Ocean and
partners.
Planet Ocean is proud to represent some of the world’s leading
scientific instrument manufacturers and bring you the very best
from each of their specialist areas of expertise.
For more information on these and any other products, visit the
website www.planet-ocean.co.uk or contact [email protected].
ACKNOWLEDGEMENTS
Dr James Fishwick, Bio-Optical Oceanographer and WCO Technical
Manager, at the Plymouth Marine Laboratory.
Satlantic
Airmar
Satlantic
AXYS
Sea-Bird Scientific
WET Labs
Satlantic
WET Labs
AIRMAR
WET Labs
Sequoia Scientific