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This paper gives an overview of the phytoplankton and zooplankton community composition in the North Sea and how this has fluctuated through the latter half of the 20th Century in response to environmental change. The study is based on a unique long-term dataset of plankton abundance in the North Atlantic and the North Sea acquired by the Continuous Plankton Recorder (CPR).

The dinoflagellate genus Ceratium dominates the phytoplankton community in the North Sea, but diatoms are also important, especially in the southern part. The normal annual blooms of plankton are discussed, as are harmful algal blooms (HABs), which appear to be on the increase, possibly due to a combination of climatic variability and eutrophication.

Among the zooplankton, copepods are particularly important and constitute a major food resource for many commercial fish species, such as cod and herring. Calanus is the dominant copepod genus in the North Atlantic.

Other important components of the plankton — meroplankton, picoplankton and megaplankton — are also reviewed. Very small picoplankton (~1 micron in diameter) and much larger gelatinous members of the megaplankton (e.g. jellyfish and ctenophores) are poorly sampled by the CPR. Although the picoplankton represents a sizeable fraction of total primary production, its role in the marine ecosystem is poorly understood.

The introduction of non-indigenous plankton in ship’s ballast water has been in progress for about a century. There is growing concern about the risk of alien species, and the importance of protecting native bio-diversity.

This report was prepared by scientists from the Sir Alister Hardy Foundation for Ocean Science (SAHFOS), which specialises in the study of plankton in the North Atlantic and the North Sea.

The SEA3 report has been written as an addendum to the more comprehensive SEA2 document. The two papers give an overview of the phytoplankton and zooplankton community composition in the North Sea and how this has fluctuated through the latter half of the 20th Century in response to environmental change. The study is based on a unique long-term dataset of plankton abundance in the North Atlantic and the North Sea acquired by the Continuous Plankton Recorder (CPR).

The dinoflagellate genus Ceratium dominates the phytoplankton community in the North Sea, but diatoms are also important, especially in the southern part. The normal annual blooms of plankton are discussed, as are harmful algal blooms (HABs), which appear to be on the increase, possibly due to a combination of climatic variability and eutrophication.

Among the zooplankton, copepods are particularly important and constitute a major food resource for many commercial fish species, such as cod and herring. Calanus is the dominant copepod genus in the North Atlantic.

Other important components of the plankton — meroplankton, picoplankton and megaplankton — are also reviewed. Very small picoplankton (~1 micron in diameter) and much larger gelatinous members of the megaplankton (e.g. jellyfish and ctenophores) are poorly sampled by the CPR. Although the picoplankton represents a sizeable fraction of total primary production, its role in the marine ecosystem is poorly understood.

The introduction of non-indigenous plankton in ship’s ballast water has been in progress for about a century. There is growing concern about the risk of alien species, and the importance of protecting native bio-diversity.

This report was prepared by scientists from the Sir Alister Hardy Foundation for Ocean Science (SAHFOS), which specialises in the study of plankton in the North Atlantic and the North Sea.

The plankton community in the SEA4 area is similar to that in the North Sea, with variations in the abundances of some individual species. Emphasis in this review is put on trends in the abundances of major phytoplankton and zooplankton taxa over the last 40 years. The study is based on a unique long-term dataset of plankton abundance in the North Atlantic and the North Sea acquired by the Continuous Plankton Recorder (CPR). 

In the phytoplankton community, conspicuous trends are the steady increase in Phytoplankton Colour (an indicator of phytoplankton biomass) since 1960 and the mid 1980s peak in Thalassiosira spp. abundance. Among the zooplankton the decline in the abundance of Calanus finmarchicus and the increase in that of Calanus helgolandicus since 1960 are probably related to increasing sea surface temperatures in the northeast Atlantic.

Phytoplankton blooms are discussed, from the normal annual blooms to harmful algal blooms (HABs). Because of the extensive fish farm industry in coastal regions of SEA4, there is considerable interest and ongoing research into HABs, but there is no clear evidence that they are increasing in frequency or intensity due to anthropogenic eutrophication.

Other important components of the plankton meroplankton, picoplankton and megaplankton are also reviewed. For a more detailed discussion of the various components of the plankton community, the reader should refer to the SEA2 report.

This report was prepared by scientists from the Sir Alister Hardy Foundation for Ocean Science (SAHFOS), which specialises in the study of plankton in the North Atlantic and the North Sea.

This report provides data on the plankton community in the SEA 5. Data for this report were provided by the Continuous Plankton Recorder Survey, as well as sourced from outside organisations.

The SEA 5 area is influenced by the Shelf Edge Current, which breaks off its main route in the form of the Fair Isle Current, the Dooley Current and the East Shetland Inflow. Oceanic water flows into the North Sea in this area, causing periodic incursions of associated planktonic organisms.

The report addresses the following issues:

• Phytoplankton and zooplankton community composition
• Phytoplankton blooms
• Abundance of the copepod Calanus
• Mero-, pico- and megaplankton
• Phytodetritus and vertical fluxes

Report prepared by the Sir Alister Hardy Foundation for Ocean Science.

In advance of SEAs for areas 6, 7 & 8, a series of data assessment projects were instigated. The purpose of these projects was to assess the extent, quality and accessibility of data relating to specific environmental factors. In some cases, the project leaders produced brief explanatory notes describing the environmental factor being considered, in other cases the project was limited to a data search alone.

The contractors were asked, where possible, to enter the data onto an "End-Note®" database file in order that bibliographic searches may be made.

Please note that the boundary between SEAs 6 and 7 changed during the time these reports were produced, so may appear in a different position in some reports.

This report summarises information on the ecology of planktonic species found in the SEA6 area. The Irish Sea is very diverse not only in the physical-chemical regimes operating upon it, but in the ecology of planktonic organisms found there.

Data on the nutrient chemistry of the Irish Sea shows that the eastern Irish Sea is more heavily impacted by nutrients owing to freshwater run-off from land, which is far greater than in the western Irish Sea. Nutrients increased from the 1950’s to the 1980’s after which time the concentrations have levelled off and in some case declined. The phytoplankton biomass appears to have mirrored the influence of the nutrients both in time and space. Highest biomass (inferred from chlorophyll analysis) is generally found in regions of low salinity and tends to be greatest in the eastern Irish Sea. The phytoplankton community has also been shown to vary throughout the seasons and also within different regions or ‘ecohydrodynamic’ domains of the Irish Sea.

The zooplankton community of the Irish Sea has also undergone significant change over the last thirty or so years. The most noticeable of these changes being a significant decrease in abundance of most of the species recorded. Some species distributions and abundances have been shown to be influenced by climate and it is highly likely that other species of plankton in the Irish Sea are also affected in this way. Climate, or more specifically the North Atlantic Oscillation (NAO), certainly has a major impact upon the physical-chemical environment of the region and this has a direct influence upon the ecology of planktonic organisms found in the Irish Sea.

The report was prepared by K. Kennington and W Ll. Rowlands of the Port Erin Marine Laboratory, University of Liverpool.

SEA7 Technical Report - Plankton

The purpose of this report is to provide the DTI with an assessment of the plankton ecology for the Strategic Environment Assessment (SEA) of area 7.

Owing to the size of the area being assessed this report divides the region into two sections. The basis of this division follows the 200m depth contour generally accepted as being the boundary between the shelf edge and oceanic realms. The first section being waters found on the continental shelf and are therefore more prone to freshwater runoff from land and anthropogenic inputs. The second section represents waters off the shelf edge, these waters are of a more oceanic origin and are less impacted by inputs from land-based sources.

Information on the nutrient biogeochemistry (nitrate, phosphate and silicate) are presented for three geographical provinces, the oceanic and shelf edge realms outlined above and also for the Clyde Sea area this being a region noted as having elevated nutrient loadings from anthropogenic sources.

The major sources of information on the nutrients of the SEA7 region come from the ICES and BODC data sets as well as from data presented in the scientific literature.

Information on the phytoplankton (the plant members of the plankton) comes from several sources including ICES, SAMS and the NIO at Southampton. This data is augmented by specific case-studies of the SEA7 region taken from the scientific press. Zooplankton (the animal component of the plankton) data is also presented as geographic plots from the Continuous Plankton Recorder (SAHFOS) data-set held by the Sir Alistair Hardy Foundation for Ocean Sciences.

This report was prepared by K Kennington of Port Erin, Isle of Man and D Johns of SAHFOS.

In advance of SEAs for areas 6, 7 & 8, a series of data assessment projects were instigated. The purpose of these projects was to assess the extent, quality and accessibility of data relating to specific environmental factors. In some cases, the project leaders produced brief explanatory notes describing the environmental factor being considered, in other cases the project was limited to a data search alone.

The contractors were asked, where possible, to enter the data onto an "End-Note®" database file in order that bibliographic searches may be made.

Please note that the boundary between SEAs 6 and 7 changed during the time these reports were produced, so may appear in a different position in some reports.

In advance of SEAs for areas 6, 7 & 8, a series of data assessment projects were instigated. The purpose of these projects was to assess the extent, quality and accessibility of data relating to specific environmental factors. In some cases, the project leaders produced brief explanatory notes describing the environmental factor being considered, in other cases the project was limited to a data search alone.

The contractors were asked, where possible, to enter the data onto an "End-Note®" database file in order that bibliographic searches may be made.

Please note that the boundary between SEAs 6 and 7 changed during the time these reports were produced, so may appear in a different position in some reports.