Using the Continuous Plankton Recorder to investigate the absence of North Atlantic right whales (Eubalaena glacialis) from the Roseway Basin foraging ground

North Atlantic right whales (Eubalaena glacialis) were absent from Roseway Basin, located off southeastern Nova Scotia, for a 7-year period (1993–1999). The objective of this study was to examine the availability of the right whale's main prey, Calanus finmarchicus, in Roseway Basin during those 7 years to determine if the whales’ absence was due to inadequate prey resources. Since we had no historical data on zooplankton abundances at depth on the Scotian Shelf, near-surface zooplankton abundance data from the Continuous Plankton Recorder were used to infer water-column abundances. In addition, environmental parameters that are often correlated with high zooplankton concentrations were examined. The hypotheses tested were that changes in these parameters would be detectable between three time periods: pre-1993, 1993–1999 and post-1999. Calanus finmarchicus abundance was found to be lowest during 1993–1999, suggesting that right whales were not foraging in Roseway Basin because of the near-absence of their main prey species. Decreased in situ salinity and density proved to be indicators of the changes in circulation in the 1990s that may have affected the advection of C. finmarchicus onto the Scotian Shelf.

Bottom-up effects of climate on fish populations: data from the Continuous Plankton Recorder

The Continuous Plankton Recorder (CPR) dataset on fish larvae has an extensive spatio-temporal coverage that allows the responses of fish populations to past changes in climate variability, including abrupt changes such as regime shifts, to be investigated. The newly available dataset offers a unique opportunity to investigate long-term changes over decadal scales in the abundance and distribution of fish larvae in relation to physical and biological factors. A principal component analysis (PCA) using 7 biotic and abiotic parameters is applied to investigate the impact of environmental changes in the North Sea on 5 selected taxa of fish larvae during the period 1960 to 2004. The analysis revealed 4 periods of time (1960–1976; 1977–1982; 1983–1996; 1997–2004) reflecting 3 different ecosystem states. The larvae of clupeids, sandeels, dab and gadoids seemed to be affected mainly by changes in the plankton ecosystem, while the larvae of migratory species such as Atlantic mackerel responded more to hydrographic changes. Climate variability seems more likely to influence fish populations through bottom-up control via a cascading effect from changes in the North Atlantic Oscillation (NAO) impacting on the hydro dynamic features of the North Sea, in turn impacting on the plankton available as prey for fish larvae. The responses and adaptability of fish larvae to changing environmental conditions, parti cularly to changes in prey availability, are complex and species-specific. This complexity is enhanced with fishing effects interacting with climate effects and this study supports furthering our under - standing of such interactions before attempting to predict how fish populations respond to climate variability

A 60-year ocean colour data set from the continuous plankton recorder

The phytoplankton colour index (PCI) of the Continuous Plankton Recorder (CPR) survey is an in situ measure of ocean colour, which is considered a proxy of the phytoplankton biomass. PCI has been extensively used to describe the major spatiotemporal patterns of phytoplankton in the North Atlantic Ocean and North Sea since 1931. Regardless of its wide application, the lack of an adequate evaluation to test the PCI's quantitative nature is an important limitation. To address this concern, a field trial over the main production season has been undertaken to assess the numerical values assigned by previous investigations for each category of the greenness of the PCI. CPRs were towed across the English Channel from Roscoff to Plymouth consecutively for each of 8 months producing 76 standard CPR samples, each representing 10 nautical miles of tow. The results of this experiment test and update the PCI methodology, and confirm the validity of this long-term in situ ocean colour data set. In addition, using a 60-year time series of the PCI of the western English Channel, a comparison is made between the previous and the current revised experimental calculations of PCI.

Macroscale factors affecting diatom abundance: a synergistic use of Continuous Plankton Recorder and satellite remote sensing data

Diatoms exist in almost every aquatic regime; they are responsible for 20% of global carbon fixation and 25% of global primary production, and are regarded as a key food for copepods, which are subsequently consumed by larger predators such as fish and marine mammals. A decreasing abundance and a vulnerability to climatic change in the North Atlantic Ocean have been reported in the literature. In the present work, a data matrix composed of concurrent satellite remote sensing and Continuous Plankton Recorder (CPR) in situ measurements was collated for the same spatial and temporal coverage in the Northeast Atlantic. Artificial neural networks (ANNs) were applied to recognize and learn the complex non-monotonic and non-linear relationships between diatom abundance and spatiotemporal environmental factors. Because of their ability to mimic non-linear systems, ANNs proved far more effective in modelling the diatom distribution in the marine ecosystem. The results of this study reveal that diatoms have a regular seasonal cycle, with their abundance most strongly influenced by sea surface temperature (SST) and light intensity. The models indicate that extreme positive SSTs decrease diatom abundances regardless of other climatic conditions. These results provide information on the ecology of diatoms that may advance our understanding of the potential response of diatoms to climatic change.

Biodiversity as a dynamic variable in the Gulf of Maine continuous plankton recorder transect

Studies relating biodiversity to ecosystem processes typically do not take into account changes in biodiversity through time. Marine systems are highly dynamic, with biodiversity changing at diel, seasonal and inter-decadal timescales. We examined the dynamics of biodiversity in the Gulf of Maine pelagic zooplankton community. Taxonomic data came from the Gulf of Maine continuous plankton recorder (CPR) transect, spanning the years 1961–2006. The CPR transect also contains coincident information on temperature and phytoplankton biomass (measured by the phytoplankton color index). Taxonomic richness varied at all timescales considered. The relationships between temperature and richness, and between phytoplankton and richness, also depended on temporal scale. The temperature–richness relationship was monotonic at the multi-decadal scale, and tended to be hump-shaped at finer scales; the productivity–richness relationship was hump-shaped at the multi-decadal scale, and tended to be monotonic at finer scales. Seasonal biodiversity dynamics were linked to temperature; inter-decadal biodiversity dynamics were linked to phytoplankton.

Going Global: planning the next 80 years of the Continuous Plankton Recorder Survey

Going Global: planning the next 80 years of the Continuous Plankton Recorder Survey. Operated by the Sir Alister Hardy Foundation for Ocean Science (SAHFOS), the Continuous Plankton Recorder (CPR) survey is the world’s largest, sampling 4 ocean basins, and longest running (since 1931) plankton biodiversity monitoring programme. Having sampled enough miles to circumnavigate the globe over 200 times, the CPR database houses over 2.5 million entries, describing the distribution of 500 phytoplankton and zooplankton taxa. Routinely sampling in the Arctic, Atlantic, Pacific and Southern Oceans, the survey analyses 4000 samples yearly. Data collected from these samples are made freely available for bona fide scientific purposes. The CPR survey data is used to generate a better understanding of changes in the plankton and to date some 1000 papers have been published on plankton biodiversity. This year sees the 80th anniversary of the CPR survey and to celebrate and build upon this unique monitoring programme, SAHFOS intends to further develop its global plankton perspective. Work will be extended into the South Atlantic and Indian Ocean and an international partnership with complementary surveys in Australia, Canada, America, Japan and South Africa will be implemented. The Digital Object will describe the CPR survey using compilations made by Plymouth Art College and BBC film footage.

Ecological Investigations with the Continuous Plankton Recorder: The Phytoplankton in the Southern North Sea. 1932-37.

1. The changes in the composition and distribution of the plankton of the southern North Sea have been investigated month by month, from June 1932 to December 1937; the present report deals with the phytoplankton. The survey was carried out by the Continuous Plankton Recorder, towed at a standard depth of 10 metres, by ships on regular steamship lines across the North Sea from Hull towards the Skagerrak, to Bremen and to Rotterdam, and later between London and Esbjerg. 2. The material and methods are described, together with a discussion on the validity of this type of survey and some comparison of its results with those obtained by other methods (pp. 76-86). 3. Particular attention has been paid to Rhizosolenia styliformis (pp. 92- 107), Biddulphia sinensis (pp. 108-115), Phaeocystis (pp. 149-153), and the Dinoflagellates (pp. 134-149); of these the first three are known to be of particular importance in relation to the herring fisheries. More generalised data are available for the principal diatoms other than R. styliformis and B. sinensis (pp. 116-134). 4. The main part of the work is an ecological study of the phytoplankton changes in time and space over the 5½ years. Each year is marked by some distinct variations in the abundance and the times of increase, maximum numbers and decline as recorded in the different forms. These variations in the annual cycles are compared on the different lines by a series of graphs arranged against a time scale of months, a set for each year being placed side by side (Plates I-XXI). More detailed studies by more frequent records were made in the autumns of 1934, 1935, 1936 and 1937 (cf. Figs. 3 and 4). The changes in spatial distribution are shown by a series of monthly maps arranged in a similar manner for each year (Plates XXII-LXIV). These intensive studies of the changes in time and space are also intended to form the basis for correlations with other features in the general ecology of the area (e. g. the zooplankton, hydrology, meteorology and fisheries) to be made in later publications. 5. Whilst each form has shown its own peculiar features, a trend towards a general increase in the phytoplankton as a whole has been observed during the period, although the years 1934 and 1936 have in some respects shown deviations and regressive features, and not all organisms have revealed the same trend. The possible relation of this gradual trend to other events observed in recent years in these and neighbouring waters is discussed (pp. 162-167). 6. The application of these results to the study of patchiness (pp. 154-158), inter-relationships in the plankton (pp. 159-160) and to water movements (pp. 160-162) is briefly discussed.

Ecological Investigations with the Continuous Plankton Recorder: The Copepoda of the Southern North Sea. 1932-37.

I. The monthly changes in the distribution and abundance of the Copepoda in the southern North Sea have been investigated from June 1932 to December 1937 by using the Continuous Plankton Recorder. This was towed at a standard depth of 10 metres by ships sailing on regular lines from Hull to Rotterdam, to Bremen and towards the Skagerrak, and later from London to Esbjerg. 2. The methods are described and those limitations which apply more particularly to the Copepoda are discussed (pp. 175 to 186 and 198 to 203). 3. The first part of the report deals with the Copepoda as a whole, i.e. the total population. The difference between the summer and winter distributions is stressed. The variations in numbers from year to year are found to be considerable and it is suggested that they are sufficiently large to be reflected in the success or failure of the broods of those fish which are at some period of their development dependent upon the Copepoda for food. 4. The second part deals with the data concerning the constituent species or groups of allied species ; a list of these is given on p. 197. 5. The group Paracalanus + Pseudocalanus was by far the most abundant and together with the genera Temora and Acartia was found to be responsible for most of the fluctuations in the population (pp. 205 to 208). 6. The distributions, seasonal and spatial, of the other common forms are described, with the exception of that of Oalantts finmarchicus which is to be the subject of a later report. 7. The recorder results are compared with the findings of the International Council survey from 1902 to 1908; some marked disagreements are discussed (pp. 227 to 232). 8. The appearance of the northern forms Oandacia armata and Metridia lucens during the winters of 1932-33, 1933-34 and 1937 are recorded (pp. 222 to 223) 9. A summarised account of the main seasonal changes in the area is given (pp. 232 to 234) and followed by a brief comparison of the 5½ years investigated.

Ecological Investigations with the Continuous Plankton Recorder: The Zooplankton (other than Copepoda and Young Fish) in the Southern North Sea, 1932-37.

I. The report describes the main monthly changes in the distribution and abundance of the zooplankton, other than Copepoda and young fish (dealt with in separate reports), over the southern part of the North Sea from 1932 to 1937. The work is part of the survey carried out by Continuous Plankton Recorders towed at a depth of 10 metres on regular steamship lines between England and the Continent. 2. The limitations to the sampling method are discussed, and it is shown to be unsuitable for recording Mysidacea and Euphausiacea on account of their marked diurnal variation due presumably to vertical migration; they are omitted from the report. 3. The changing distribution of Sagitta, Limacina, Clione, Lamellibranch larvae, Cladocera, Caprellid Amphipoda, Decapod larvae, Echinoderm larvae and Oikopleura are shown in a series of monthly charts while their seasonal fluctuations are compared in time-chart histograms. 4. The Alima larvae of Squilla are recorded on a few occasions in the regions where the Channel opens into the North Sea. 5. The distributional characteristics of the different forms, i.e. their tendencies to even or " patchy " production, are compared.

Continuous Plankton Records: General Introduction to the 1938-39 Survey

The Bulletins in this volume, except the last, deal entirely with the results of this expanded survey of 1938 and 1939. They show for the first time, month by month, the main changes in the plankton over practically the whole of the North Sea for a year and eight months. They form an important basis for comparison with the results of the post-war survey, revived on an even more extensive scale and to be described in later volumes.