Download The Continuous Plankton Recorder Survey

DEPARTMENT for ENVIRONMENT, FOOD and RURAL AFFAIRS
Research and Development
CSG 15
Final Project Report
(Not to be used for LINK projects)
Two hard copies of this form should be returned to:
Research Policy and International Division, Final Reports Unit
DEFRA, Area 301
Cromwell House, Dean Stanley Street, London, SW1P 3JH.
An electronic version should be e-mailed to [email protected]
Project title
The Continuous Plankton Recorder Survey - Fisheries Investigations
DEFRA project code
MFO422
Contractor organisation
and location
SIR ALISTER HARDY FOUNDATION FOR OCEAN SCIENCE (SAHFOS)
THE LABORATORY
CITADELL HILL
PLYMOUTH
PL1 2PB
Total DEFRA project costs
Project start date
£ 494531
01/04/98
Project end date
31/03/02
Executive summary (maximum 2 sides A4)
The last year of the current contract supporting this unique long term Survey was most successful.
The Continuous Plankton Recorder's (CPR) 70th year was one of great achievement. The logged
mileage of the survey at 110,143 nautical miles (nm) increased to the highest level since 1977 and
this was the first year that100,000 nm were towed in the North Atlantic since 1973. More than 5,000
samples were analysed during the year. Since SAHFOS was formed in 1990, the number of miles
towed and samples analysed have increased steadily and the last time that more than 5000 samples
were analysed in a year was 1972. Our good publication record in high profile journals improved yet
again, with an increase in collaborative research covering a wide range of themes. All this reflects
the hard work of SAHFOS staff in all areas, plankton analysis, workshops and administration.
The Anniversary Symposium on the ‘Achievements of the Continuous Plankton Recorder survey and
a vision for its future’ was held on 7 August 2001 at the Royal College of Physicians in Edinburgh,
Scotland, back-to-back with a symposium of the International Council on the Exploration of the Sea
(ICES) on ‘Hydrobiological Variability in the ICES-Area, 1990-1999’. This provided an opportunity for
a week-long presentation, to a wide audience based on the CPR and our anniversary.
Since January 1946 a total of 214 ships have towed CPRs in the survey. The largest towing vessel
was the ARCO (Polar) Independence which towed on the AC route between Valdez, Alaska and
Long Beach, California in the North east Pacific from March to August 2000. She is a VLCC of
265,000 tons deadweight (cargo carrying capacity). In contrast, the smallest vessel would appear to
be the Côtes du Manche, a French Research vessel of 230 tonnes gross, which towed in the eastern
CSG 15 (Rev. 6/02)
1
Project
title
The Continuous Plankton Recorder Survey - Fisheries
Investigations
DEFRA
project code
MFO422
Channel in 1999. In October 2001 the brand new P&O Irish Sea ro-ro passenger ferry European
Ambassador towed a plankton recorder between Dublin and Liverpool at 25.6 knots. This is the
fastest speed at which a CPR has been successfully towed. The longest ever continuous CPR tow
of 3,508 nm was also completed in 2001. Seven filter cassettes were needed for this mammoth
exercise over ten days in June by the large ro-ro, Skaubryn of Seaboard Shipping.
The high productivity of our staff, as reflected in the publications list for 2001, has been maintained
with an increase to more than 40 refereed papers in press or published, and more than 50, if grey
literature is also included. What is particularly gratifying are the partnerships that have been
developed with scientists from other institutions in a wide range of disciplines. For example, CPR
data has been used to help interpret long-term changes in basking shark populations and in other
studies linked to hydrographic and remote sensing surveys. CPR data also contributed substantially
to the EU OMEX study at the Celtic Sea shelf break.
A successful proposal by SAHFOS to the Scientific Committee on Ocean Research (SCOR) for a
new Working Group (115) on ‘Standards for the Survey and Analysis of Plankton’ moved forward in
the year with the appointment of Dr Ivan Heaney, DANI, Northern Ireland as Chairman. The aim of
the Working Group is to develop standards for sampling, analysis and storage of data and samples
obtained by high speed and extensive sampling systems and to assess current and future
technological needs as a contribution to GOOS and GLOBEC. Part of the original aim of the
proposal was to help ensure that the different CPR surveys that exist or are in process of being
established should try and standardise approaches to enable easy intercomparison between their
results. Other plankton sampling systems, based on acoustics, video etc. are also included in the
study.
The number of data requests increased in 2001 by almost 50% on the previous year. A copy of the
complete database is now held at the British Oceanographic Data Centre and is updated annually.
Throughout the period of the contract the CPR Survey has made an increasing contribution to the
environmental sciences, and in particular to work on fisheries. The time-series is unique in its spatial
and temporal coverage of the European fisheries areas, and its full potential is still being explored.
CSG 15 (Rev. 6/02)
2
Project
title
The Continuous Plankton Recorder Survey - Fisheries
Investigations
DEFRA
project code
MFO422
Scientific report (maximum 20 sides A4)
Introduction (Objectives 1 & 6)
The Accumulation of data by the CPR Survey has demonstrated clear patterns in the distribution of plankton
on a broad geographical scale, relating to latitudinal gradients, the position of current systems and the
proximity of the shelf areas. A wealth of data continues to be acquired on diurnal, annual and long term
changes of the plankton community. An 'Atlas of Plankton for the North Atlantic' has been produced and
continues to be improved and added to. The following report summarises some of the more recent papers
produced by the Foundation's staff.
Ocean climate anomalies and the ecology of the North Sea (Objectives 2 & 3)
While atmospheric variability plays a key role in the overall long-term and regional patterns of phytoplankton,
oceanic influences on the North Sea ecosystem have been underestimated in the past (Edwards et al. 2001).
The anomalous phytoplankton colour values and large community shifts recorded by the CPR survey are
associated with anomalous oceanographic events seen during the late 1970s/early 1980s and the late
1980s/early 1990s. The period in the late 1970s/early 1980s was anomalous in the North Sea, characterised
by reduced salinities and temperatures caused primarily by the unusual hydro-climatic conditions and a
change in the overall North Atlantic Current dynamics. In the North Sea during the late 1970s, there was an
initial reduction in inflow of Atlantic water, followed by a salinity anomaly and changes to the circulation of the
North Sea. A reduction in the inflow of generally warmer North Atlantic current waters, and the arrival of the
Great Salinity Anomaly (GSA) in the North Sea, may have conspired together to produce a cold-boreal climate
within the North Sea (evident in the plankton community). This physical switch may have been initiated by a
decrease in the flow of the North Atlantic Current.
There is clear evidence that during this period the reason why there was a reduction in overall phytoplankton
biomass, and a dramatic shift in community and diversity, was due to a later spring bloom and a retarded
seasonal growth period. Many spring species failed to materialise during this period (causing an obvious
decline in the overall mean diversity and a large inter-annual shift in community) and many that did, appeared
much later in the season.
The second anomalous event occurred in the late 1980s/early 1990s and is opposite to the previous period,
with the North Sea inversely characterised by high salinities and temperatures. The biological response to the
late 1980s/early 1990s event was exceptional. Phytoplankton colour in 1989 was nearly three standard
deviations above the long-term mean (its highest ever value) in the North Sea. In 1989, the North Sea was
punctuated by a succession of exceptional phytoplankton blooms, with many species reaching their seasonal
peak one to two months earlier. These patterns are also reflected in many other biological time-series (e.g.
benthic biomass, fish) including zooplankton abundance recorded by the CPR survey. It is suggested that
these hydrographic events conspire to produce anomalous ocean climate conditions in the North Sea which
persist for a number of years and are significant enough to alter the overall ecology of the North Sea. (M.
Edwards: [email protected]).
Fishery and physical modulation of ecosystem dynamics (Objective 5)
This work has developed with the incorporation of additional data and further statistical analysis. Application of
multiple regressions have improved understanding of the negative correlation between the cod recruitment
and young fish in the CPR survey in the North Sea (r = - 0.589). The output multiple regression relating cod
recruitment to a range of variables showed that the NAO in the previous year and CPR young fish gave a
correlation coefficient of 0.657. Including up to 5 variables only improved the correlation to 0.683. These
results suggest that the numbers of young fish spawned, or variations in the adult stocks of clupeids and
sandeels (the dominant taxa in the CPR young fish in the North Sea) in combination with the NAO have a
substantial influence on cod recruitment. In the case of CPR young fish, the best pair of variables for providing
the most highly correlated output was the abundance of spring phytoplankton in the previous year and the Gulf
CSG 15 (Rev. 6/02)
3
Project
title
The Continuous Plankton Recorder Survey - Fisheries
Investigations
DEFRA
project code
MFO422
Stream North Wall Index in the previous year (r = 0.744). There was only a small improvement by the addition
of further variables. This indicates that the environmental variation was dominant in controlling the abundance
of CPR young fish. These, and other results from the programme, indicate that the evidence for top-down
modulation of the planktonic ecosystem is not as strong as previously indicated from the results of correlations
between the fisheries data and the output of the CPR survey in the North Sea.
The divergence between the abundance of Centropages typicus in the North Sea in the early 1980s and the
levels expected from the highly significant correlation with temperature have been further analysed. The
phytoplankton colour index in winter was at its lowest levels during this period, and it appears that this was
related to climate, the numbers of days of cyclonic and northerly weather were high in this period, particularly
in spring (A. Lindley: [email protected]).
Recent prevalence of temperate Atlantic species in the North Sea (Objective 3)
The Temperate Atlantic index (copepod species associated with temperate conditions), mapped at five-yearly
intervals for the month of October (approximate annual peak of abundance), shows a general long-term
increase (1958-1998;). Between the late 1950s and mid 1970s, Temperate Atlantic species were confined to
relatively deep (>15-20m) water in the western, central and southern areas of the North Sea, reflecting the
inflow of Atlantic type water through the English Channel and Fair Isle Current. Temperate Atlantics were
particularly rare in the late 1960s in the far north-eastern North Sea, since when their spatial distribution has
exploded outward and northward. It is likely that during the late 1950s and 1960s winters were too cold for
Temperate Atlantic zooplankton to survive in the North Sea, which has been changed by the recent, relatively
clement, January and February sea temperatures. The recent prevalence of temperate Atlantic species in the
North Sea is thought to be reflecting the milder climatic conditions seen over the last decade in the North Sea,
as well as an increase in Atlantic inflow. (D. Beare: [email protected]).
Spatial variability of calanoid copepod diversity (Objective 2)
Ecosystems are fundamentally structured in space and time and the identification and the quantification of
scales of variability has occupied a central importance in ecology for a few decades (e.g. Levin 1992, Mann &
Lazier 1996). Haury et al. (1978), by the use of a three-dimensional time-space plot estimated the spatial and
temporal structure of zooplankton biomass variability. At all spatial scales, physical features often represented
important factors involved in the control of spatial and temporal patterns of biomass variability. Similar
conclusions have been subsequently found (e.g. Mann and Lazier 1996, Beaugrand et al. In press).
The Sen’s point cumulative semi-variogram has been applied to the CPR data to assess the spatial scales of
variability of the pelagic calanoid copepod diversity. Mapping of the regional dependence of the calanoid
diversity showed that diversity varies at a smaller spatial scale in neritic than in oceanic regions. European
shelf sea diversity changes during dark periods for distances ranging from 300 to 450 km. Canadian
continental shelf sea diversity varies at a greater scale, more than twice the rate in European seas. In oceanic
regions, diversity is spatially stable in the Atlantic Arctic province (Longhurst 1998, about 1000 km) and in the
northern boundary of the subtropical gyre (about 800 km on average). Lower-scale spatial patterns in calanoid
diversity are observed in the Gulf Stream extension (as defined by Beaugrand et al. 2001), in the path of the
North Atlantic Current west of the mid-Atlantic ridge and west of Europe.
A negative relationship has been found between the diversity value and its regional dependence in almost all
areas. This indicates that the more local the spatial changes in diversity are, the higher the diversity is.
However, this result should not be inferred for the whole ocean or not be considered as a primary factor that
explains regional difference in diversity. Examination of a global scale map of planktonic foraminiferan diversity
and maps of eddy energy does not visually show a strong link in subtropical and equatorial areas. The central
gyre of the North Pacific, which is characterised by a high diversity, has a low average eddy kinetic energy.
Thus, the negative link between diversity and regional dependence is not likely to be true at a global scale, but
may be a characteristic of pelagic ecosystems in the northern North Atlantic Ocean. Furthermore, the
relationship seems to become positive at the northern boundary of the subtropical gyre . A large area in the
CSG 15 (1/00)
4
Project
title
The Continuous Plankton Recorder Survey - Fisheries
Investigations
DEFRA
project code
MFO422
North Sea also exhibits a positive link between diversity and its regional dependence. (G. Beaugrand:
[email protected]).
Plankton changes in the Northwest Atlantic
Continued research into the Northwest Atlantic has highlighted further plankton responses to hydro-climatic
events. The observed response of Calanus hyperboreus to the production of Labrador Sea Water (Johns et al.
2001) has led to a closer examination of the plankton community of the area, notably of the arctic – boreal
dinoflagellate Ceratium arcticum. This species, which occurs on over 40% of CPR samples from the Grand
Banks area, has increased in abundance significantly during the past 40 years. In addition to this increase, the
seasonal dynamics have altered, with C.arcticum now more abundant throughout the winter – spring period,
with a drop in the population during the autumn months. This atypical seasonal cycle could suggest a shifting
and lengthening of the growing period for the species. Phytoplankton colour values have also increased
dramatically in the Grand Banks area, although C.arcticum appears to be the only phytoplankton species that
has altered in abundance and seasonality.
The exact mechanisms behind the observed phenomena are unknown, but likely to be an interaction between
various hydro-climatic processes (e.g. the state of the NAO, Labrador Sea deepwater production, and the
thermohaline circulation, etc.). The well – documented ground fish collapse on the Banks, along with the
increase in capelin and decline in Calanus finmarchicus, could suggest an anthropogenically - induced trophic
cascade, brought about by commercial over-fishing. It is likely that in reality, the Banks represent a highly
complex ecosystem, being forced both environmentally and anthropogenically through fishing. (D. Johns:
[email protected]).
Genetic analysis of CPR material
Genetic DNA data can help interpret greatly the geographic distribution, relationships and the temporal
changes of populations of animals and plants (population ecology). Because of its temporal perspective,
archival material, as a source of genetic data, is potentially invaluable in population ecology. Traditionally, like
the CPR archive, most archive material is stored in formalin and genetic analysis has been difficult. Recently,
methods have been developed to obtain DNA from formalin-fixed material of suitable quality to allow molecular
genetic analyses. In the CPR survey these molecular methods have been developed (Kirby & Reid, 2001) to
enable the genetic analysis of the samples held in the CPR archive on both temporal and geographic scales.
Our ability to obtain DNA sequence from CPR survey material represents an important breakthrough and
creates new opportunities to exploit the extensive CPR archive to investigate change in marine plankton
communities. Potential applications are to use the CPR archive to obtain data on geographical variability and
long-term changes in the ecology and population dynamics of key planktonic and pelagic species. Pertinent
issues that can be addressed include recent changes in fisheries and their planktonic food sources, fish larval
recruitment, and patterns of stock recovery following over-fishing.
In addition to the examination of fisheries, other opportunities for this new work include the identification of
invertebrate planktonic larvae and their developmental stages through the differences in their DNA. Although
an identifiable larva was used in our preliminary studies, the new ability to use DNA to classify ‘unidentifiable’
larvae represents an important advance in marine biology. (R. Kirby: [email protected]).
Other Regional Seas (Objective 11)
General
In the development of plans for monitoring Large Marine Ecosystems and extensive oceanic areas in GOOS,
the CPR approach is recognised as a practical and cost effective way to obtain synoptic plankton data. Sister
surveys already exist on the eastern seaboard of the USA at the Northeast Fisheries Science Center
(NEFSC), Narragansett, at the Australian Antarctic Division, Tasmania in partnership with the Japanese
National Institute of Polar Research (NIPR), Tokyo, and in the Baltic based at the Finnish Institute of Marine
Research (FIMR). Reports on progress during the year by these surveys are given in the next section. Draft
CSG 15 (1/00)
5
Project
title
The Continuous Plankton Recorder Survey - Fisheries
Investigations
DEFRA
project code
MFO422
memoranda of understanding were drawn up during the year to help strengthen collaboration between two of
the surveys; hopefully the MOUs can be agreed and signed in 2002.
The Pacific CPR Project
The second year of sampling in the Pacific was successfully completed in September 2001, with a further 5
tows from Valdez, Alaska to California and another June tow from Vancouver, Canada to Japan. Funding from
Japan allowed us to extend the tow all the way across the Pacific, making this the longest ever continuous
CPR tow.
SAHFOS also carried out a pilot tow from Valdez to California in the summer of 1997. There is a growing
consensus that the El Niño of 1998 marked the transition to a new ‘regime’ in the North Pacific. The pilot tow in
summer 1997 was carried out just at the start of the El Niño, whereas the tows in the survey proper of 2000
and 2001 were all carried out within the cooler period following the event. Eventually, summer comparisons for
all 3 years can be made, but with the currently available data we compared summer 1997 with summer 2000
(contrasting ‘regimes’) and late spring/early summer 2000 with late spring/early summer 2001 (similar
‘regimes’). Figure 9 shows the ratio of mean abundance of mesozooplankton individuals per sample (averaged
for 1° bands of latitude) for these two comparisons on the north-south transect.
As one might have predicted, the 1997 and 2000 comparison provides the greatest overall contrast. For most
of the open ocean region 1997 abundances were 5-10 times higher than in 2000 (mean ratio between 43° and
56°N is 6.2). The Alaskan shelf region, by contrast, was much lower, with abundances about one-third in 1997
of their 2000 values. The Oregon/Californian coastal region was also higher in 1997, though not so
dramatically – the mean ratio being just under 3 times higher in 1997. Taking the transect as a whole, we find
that the abundance of mesozooplankton in the summer of 1997 was twice as high as in 2000, although some
regions were lower, and some much higher.
The 2000 and 2001 comparison is also interesting. Again taking the transect as a whole, we find no difference
in the numbers of animals sampled. However, there is a clear switch between about 44° and 48°N between
higher abundances in the north in 2000 than in 2001 and higher abundances in the south in 2001 than in 2000.
So, although the overall biomass in the North Pacific was the same, its centre had shifted.
Marine Pollution Monitoring Management Group (Objective 4)
In May SAHFOS was pleased to act as host to the 47th meeting of the UK Marine Pollution Monitoring
Management Group (MPMMG), a group that is made up of representatives from all Government organisations
with monitoring obligations for statutory marine environmental protection. The aim of the group is to ensure
that monitoring of the marine environment is conducted in a co-ordinated and cost-effective way and meets
national and international requirements. One of their main responsibilities is the operation of the National
Marine Monitoring Programme (NMMP). The Director attends meetings of MPMMG as the CPR survey has
been incorporated as a component of the NMMP. Plans to revise the NMMP to provide a Comprehensive and
Coherent Monitoring network in the UK are well in hand. The development of indicators of the state of the
marine environment is an important part of these developments and SAHFOS is well placed to contribute in
this area because of the extensive time series that will enable robust estimates of variability to be guaged. A
revision of monitoring is needed at this time to cover new requirements of the OSPAR Convention (OSPAR),
THE North Sea Ministerial Conferences and European Directives on Urban Waste Water Treatment, Water
Framework, Habitats, Bathing Waters and Shellfish Waters. The new plans will also contribute to a Marine
Stewardship Report that is in preparation by Government. This wide ranging report will cover the ‘seven
threats to the seven seas’ (fishing, shipping, coastal development, dumping, offshore minerals, land-based
pollution and climate change).
The U-Tow (ex CPER) (Objective 10)
The U-Tow was towed at speeds up to 16 knots behind the ASC (Air Support Craft) Spitfire in January and the
RFA Grey Rover in March with the cable load monitored through a strain gauge. Loads of up to 1.6 tonnes
were observed. On both these trials the elevators proved to have insufficient torque to enable the U-Tow to
undulate satisfactorily at the higher speeds. In May W.S.Oceans Ltd. recommended a major upgrade of the
entire system following their success and experience in selling the U-Tow as a research vessel tool. With
CSG 15 (1/00)
6
Project
title
The Continuous Plankton Recorder Survey - Fisheries
Investigations
DEFRA
project code
MFO422
several delays these modifications were completed by October, but poor weather delayed a satisfactory trial of
the system until January 2002.
An experiment was carried out to compare the U-Tow and CPR zooplankton catching characteristics in
collaboration with Juha Flinkman (FIMR). A CPR and a U-Tow were towed simultaneously overnight at the
same depth on three occasions in the Gulf of Finland behind the R/V Aranda. The CPR filtering mesh was cut
to provide samples corresponding to the U-Tow samples. The CPR samples were analysed at SAHFOS with
the U-Tow samples being analysed at FIMR. Initial results suggest that for large organisms (greater than 2mm)
estimates of abundance are equivalent between the two instruments but that for smaller organisms the
difference in filtering mesh (CPR: silk, 280m, U-Tow: monofilament nylon, 200m) results in large differences
(T. Walne & J. Sidey: [email protected]).
Instrumentation (Objective 8)
CPRs are routinely instrumented on certain routes with logging instrumentation that records information on the
marine environment to supplement the plankton data. Vemco temperature sensors were deployed on
numerous CPRs in 2001, measuring the surface temperature distribution between Newfoundland and Iceland
along the ZC, ZB and Z routes in 2001. The surface temperature between about 53W and 50W shows a
wide variation reflecting movement of the Labrador current. In both 2000 and 2001 the colonial ciliate
Zoothamnium was found in autumn CPR samples between 53W and 43W. It had not been seen in this area
previously, but there was not a clear temperature signal when compared with earlier years when Z. pelagicum
was not found.
The CPRs towed on the Pacific route between Alaska and California were also fitted with temperature
sensors. Initial observations suggest that, compared with the previous year, the surface water temperature in
some areas was up to 3 C warmer in 2001. In December we made quasi-synoptic temperature
measurements on 5 CPR routes in the North Sea between 5th and 20th December. Of the 39 separate
deployments of these instruments on numerous CPRs, they returned a 100% success rate on the following
routes: A, AC, C, HE, LG, LR, V, Z/ZB/ZC. New software was purchased to replace the now defunct Windows
3.1 version along with a new reader, compatible with Windows 95/NT. Comparisons were made with the
temperature recorder from the Aquapack on six of the seven minilogs for calibration purposes. All six recorded
identical readings with the Aquapack.
SAHFOS now operates only two Aquapacks. One instrument flooded in February 2001 and was too expensive
to repair and Chelsea Instruments Ltd. requested the return of an instrument loaned to SAHFOS, to
supplement their hire pool. One instrument was committed to the R route from Felixstowe to Scheveningen in
collaboration with a CEFAS Smart mooring programme in the North Sea. The remaining instrument being
used where possible on the EB and EA route. However, with a turn round of at least 2 months, only 3
successful tows were achieved on this route in 2001.The Minipack is still in development as a potential
replacement to the Aquapack. An instrument was delivered to SAHFOS and tested in June and July 2001. It
was used on a CPR in the Gulf of Finland in August to monitor the CPR depth in relation to the length of cable
deployed behind the Finnish vessel Aranda. It performed well during an initial 3 hour tow, but failed to return
data in subsequent tows.
CSG 15 (1/00)
7