This report is a contribution to the Strategic Environmental Assessment (SEA4) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). This report summarises the geological history of the SEA4 area from Pre-Cambrian times to the present day, sets the framework in which oil and gas fields have been discovered to the west of Shetland, and discusses the seismicity of the area. A generalised geological map of the area is presented and three approximately NW-SE trending sections across the southern part of the SEA4 area are shown. The petroleum geology of the area is reviewed and the geological settings in which oil has been found at the Clair, Foinaven, Schiehallion and Loyal oilfields is described. Other hydrocarbon fields to the west of Shetland, for which there are no immediate development plans, are briefly touched on. The seismicity of the SEA4 area, which is very low, is discussed.

This report is a contribution to the Strategic Environmental Assessment (SEA5) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). Macrofuanal analysis was undertaken on 61 seabed samples from 13 locations to the southwest of Shetland that were contaminated by oil from the Braer tanker spill. The data report presents the resulting species list and abundance data, together with biomass data and the size measurements of selected taxa.

This report is a contribution to the Strategic Environmental Assessment (SEA5) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). This report provides data on the plankton community in the SEA 5 of the North Sea. 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: phytoplankton and zooplankton community composition; Phytoplankton blooms; Abundance of the copepod Calanus; Mero-, pico- and megaplankton; Phytodetritus and vertical fluxes.

This report is a contribution to the Strategic Environmental Assessment (SEA6) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). The study area dealt with in this report includes all of the Irish Sea that falls within Irish Jurisdiction. The report is intended to complement a similar study of UK waters in the Irish Sea undertaken as part of the UK Government's Strategic Environmental Assessment (SEA6). The aim of this report is to present an up-to-date overview of all relevant data concerning methane-derived authigenic carbonate and features associated with shallow gas and seabed fluid flow in the Irish sector of the western Irish Sea. It presents a detailed assessment of potential gas sources and migration pathways, shallow gas, gas-related seabed structures and evidence of present day gas seepage in the study area.

This report is a contribution to the Department of Trade and Industry's (now Department of Energy and Climate Change) Strategic Environment Assessment SEA2 for the North Sea. It draws on a wide range of data sources to provide an overview of the chemicals used in the offshore oil and gas industry, of the chemicals already in the environment and of those released into the environment from other sources. Considering the whole sea area, it should be noted that the water samples with the highest levels of chemical contamination are found at inshore estuary and coastal sites subject to high industrial usage. Approximately 2,000 chemical products are used by the offshore oil and gas industry. In 1999 some 180,000 tonnes of chemicals were discharged into the UK sector of the North Sea. Produced water is now the main source of contaminants, having overtaken drill cuttings since oil-based muds were replaced by less harmful alternatives. 24,286 tonnes of chemicals were reported as discharged to the UKCS in produced water in 1999. As oilfields mature, the amount of produced water increases. The range of chemicals used by the offshore oil and gas industry, the means of regulating them and of monitoring their use, are discussed. Evidence of biological effects caused by the release of contaminants into the sea is reviewed.

This report is a contribution to the Strategic Environmental Assessment (SEA2) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). SEA2 focuses on the mature areas of the North Sea UK continental shelf which is divided into 3 areas - Northern, Central and Southern North Sea. This paper provides an overview of cephalopods - squid, octopus, cuttlefish in the SEA2 area. Cephalopods are short-lived, carnivorous animals that have rapid growth rates and play an important part in oceanic and coastal food webs. They are preyed on by cetaceans, fish and seabirds, and are predators themselves, feeding on fish, crustaceans, molluscs and cephalopods. Knowledge of cephalopod distribution in Scottish waters is mainly based on information from commercial whitefish vessels that catch squid as a by-catch. The loliginid squid Loligo forbesi is the predominant species. English cephalopod landings are dominated by cuttlefish caught in the English Channel outside the area of interest. The benthic octopod Eledone cirrhosa, though a highly valued species in southern Europe, is usually discarded by fishermen in Scottish waters. Fishery management statistics indicate that the areas of highest abundance of Loligo forbesi and of Eledone cirrhosa lie outside the SEA2 area. Cephalopods naturally accumulate high levels of trace metals. The potential of drilling operations to introduce trace metals into the sea is discussed. It is concluded that the overall impact on cephalopods and cephalopod fisheries in the SEA2 area by further oilfield development would be slight.

This report is a contribution to the Strategic Environmental Assessment (SEA3) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change) and is an addendum to "SEA2 Technical report 009 - Cephalopods, covering overview of cephalopod population, ecology, fisheries, sensitivity" by same authors. This paper provides an overview of cephalopods - squid, octopus, cuttlefish - in the SEA2 and SEA3 areas of the North Sea. Cephalopods are short-lived, carnivorous animals that have rapid growth rates and play an important part in oceanic and coastal food webs. They are preyed on by cetaceans, fish and seabirds, and are predators themselves, feeding on fish, crustaceans, molluscs and cephalopods. Knowledge of cephalopod distribution in Scottish waters is mainly based on information from commercial whitefish vessels that catch squid as a by-catch. The loliginid squid Loligo forbesi is the predominant species. English cephalopod landings are dominated by cuttlefish caught in the English Channel outside the area of interest. The benthic octopod Eledone cirrhosa, though a highly valued species in southern Europe, is usually discarded by fishermen in the SEA2 and SEA3 areas. Fishery management statistics indicate that the areas of highest abundance of Loligo forbesi and of Eledone cirrhosa lie outside the SEA2 and SEA3 areas. Cephalopods naturally accumulate high levels of trace metals. The potential of drilling operations to introduce trace metals into the sea is discussed. It is concluded that the overall impact on cephalopods and cephalopod fisheries in the SEA2 and SEA3 areas by further oilfield development would be slight.

This report is a contribution to Strategic Environmental Assessment SEA2 conducted by the Department of Trade and Industry (now Department of Energy and Climate Change) and it reviews the distribution and character of pockmarks - shallow seabed depressions - which are common in the area of the North Sea to the north-east of Scotland known as the Fladen Ground. Pockmarks are believed to be produced by the escape of fluids (gas or water, but generally gas in the North Sea) from the seafloor and are found in areas where the seabed sediments are soft, silty clays. Processes of pockmark formation, their geometry, age and distribution, and the sources of gas in the underlying geological strata are discussed. While the great majority of pockmarks are inactive at the present time, a few are observed to be actively seeping gas. In order to provide a stronger basis upon which the significance of pockmarks within mature oil and gas provinces of the North Sea might be assessed, the Department of Trade and Industry commissioned the acquisition of new data directed towards increasing the scientific understanding of sandbanks and pockmarks as part of the SEA2 process. The survey vessel Kommandor Jack was chartered in April 2001 and, among other operations, conducted high-resolution geophysical surveys of pockmarks in the Fladen Ground. Preliminary results from that operation are included in this report.

This report is a contribution to the Strategic Environmental Assessment (SEA6) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). 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.

This report is a contribution to the Strategic Environmental Assessment (SEA7) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). The purpose of this report was to provide an assessment of the plankton ecology for SEA7. 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.