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). Cephalopods are short-lived molluscs, characterised by rapid growth rates, and are important predators and prey in oceanic and neritic environments. They are active predators at all stages of their life-cycle and generally regarded as opportunistic, taking a wide variety of prey. Cannibalism has been frequently recorded in cephalopod species. Cephalopods also sustain a number of marine top predators such as fish, birds and marine mammals, especially whales. Many species are powerful swimmers and carry out vast feeding and spawning migrations, thus influencing prey and predator communities strongly on a seasonal and regional basis. As cephalopods are important elements in food webs they interact with commercial fisheries of finfish. Evidence exists that fishing pressure has changed ecological conditions and shifts in community structures have occurred with cephalopod stocks slowly replacing predatory fish stocks. Their commercial significance to world fisheries is of relatively recent, but growing, importance. From a commercial point of view, the most important cephalopod species in the SEA6 area is Loligo forbesi, which is landed as a by-catch of the demersal trawl fishery (82 tonnes in 2002). But the species Alloteuthis subulata, although of no commercial value, has an important ecological role in the coastal food webs, since it is the most commonly recorded cephalopod species in the stomach contents of demersal fish in UK waters.

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). Seven marine mammal species are known to occur regularly in the SEA6 area. A relatively small but fairly discrete population of grey seals utilises all but the northwest Irish Sea. Harbour seals are found primarily in the far north of the area. Harbour porpoises are seen year round throughout the area and bottlenose dolphins are present year round off Wales. Minke whales, Risso's dolphins and short-beaked common dolphins are regularly seen in summer mainly in the far south. The report discusses the distribution and abundance of these mammals and their ecological importance. Marine mammals make use of sound for a variety of purposes: finding prey, detecting predators, communication and probably navigation. The offshore oil and gas industry generates underwater noise at every stage of the process: during exploration seismic surveys, drilling, production and decommissioning. The effects of these different sources of underwater noise on marine mammals are discussed. The use of explosives for underwater cutting and demolition during the decommissioning of platforms and installations may pose a serious threat to some marine mammals. The effects of pollution on seals and cetaceans are discussed, including the effects of oil spills. The prevalence of disease among the marine mammal populations is reviewed.

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). Twenty-one cetacean species have been recorded in the SEA7 region. Of these, ten species are known to occur regularly: harbour porpoise, bottlenose dolphin, short-beaked common dolphin, Risso's dolphin, white-beaked dolphin, Atlantic white-sided dolphin, long-finned pilot whale, killer whale, sperm whale and minke whale. Five further species, though not very often recorded, and primarily associated with deep water, probably also occur regularly: striped dolphins, fin whales, northern bottlenose whales, Cuvier's beaked whale and Sowerby's beaked whale. There are occasional at-sea records of a further 6 species: Sei whale, humpback whale, blue whale, northern right whale and false killer whale. Pygmy sperm whales and at least three further species of beaked whale might also be expected in the general area on occasion. In this report, each of the more abundant species is briefly described with particular reference to its distribution and abundance in the SEA-7 area.

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) and discusses the potential for prehistoric archaeological remains to exist on the continental shelf part of the SEA4 area. The combination of post-glacial sea level rise and the subsidence of the shelf to the north of the Scottish mainland indicates that a large area of the present shelf, out to a water depth of about 150m on either side of the Orkney-Shetland Ridge, may have been dry land over 5000 years ago. Submarine archaeological studies in the Danish archipelago have established that coastal sites were an optimal place for prehistoric occupation. There is a great density of prehistoric sites in the Orkney and Shetland archipelagos, dating back to as early as 6000 years BP. Submerged sites could date back to about 9000 years BP. While shelf sites exposed to strong currents and Atlantic storm conditions are unlikely to have survived, the survival of more protected sites is quite likely. Locations where prehistoric remains might occur and have a high chance of survival are discussed. The potential impact of oil and gas operations on submarine archaeological remains is discussed. Pipe entrenching is the most likely process to uncover prehistoric archaeological deposits.

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) . The development of the deep-water oil industry to the west of Shetland led to extensive regional surveys of the seafloor environment, so that the deep-water benthos of the SEA4 area are now at least as well known as in any other deep-water area worldwide. Extensive surveys of the Faeroe-Shetland Channel, funded by the Atlantic Frontier Environmental Network and by the Department of Trade and Industry, took place between 1996 and 2002. This report provides an overview of these surveys. The ecology of the benthos in the SEA4 area is strongly influenced by the hydrography of the region, in particular the complex temperature regime, and by the nature of the seabed sediments. Additional files (xls, doc, cdr) are also available.

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). The report identifies coastal and near-shore conservation sites within the SEA4 area which are protected by international, national and local conservation designations as well as describing the sites and reasons for their protected status. At the northern extremity of Britain, the SEA4 area combines very productive waters with spectacular and distinctive coastal scenery. The combination of rich food sources and relative lack of disturbance make it host to abundant bird populations, including rare species not found elsewhere in the United Kingdom. Among the conservation sites are sea inlets, mud and sand flats, lagoons, salt marshes, sand dunes, shingle, sea cliffs, fresh water bogs and marshes, heath, scrub and grassland.

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). The report describes the field of mud diapirs in the northern part of the SEA4 area, known as the Pilot Whale Diapirs, which were mapped during a multibeam survey carried out in 2002. A diapir is a fold or dome caused by more plastic rocks at depth, such as salt or mud, intruding overlying denser rocks, generally driven by their own buoyancy. Sometimes a diapir breaks through to the seafloor. The diapir field extends over an area some 60 km across, creating a very variable seabed terrain. The largest diapirs have produced elevations at the seafloor of more than 120m. The largest diapirs in the group are thought to have intruded to the seafloor from 500m or more beneath it. The evidence suggests that the diapirism was initiated between 5 and 1 million years ago, but it does not appear to be continuing at the present time.

This report is a contribution to the Strategic Environmental Assessment (SEA4) conducted by the Department of Trade and Industry. 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.

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 (SEA4) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). This report is a synthesis of information on human activities which might have an impact on, or themselves be affected by, further oil and gas developments in the SEA4 area. The activities include fishing, mariculture, shipping, energy (both existing oil and gas developments and renewable energy), telecommunications, military activities, waste disposal, dredging and aggregate extraction, tourism, coastal and marine archaeological sites. The SEA4 area hosts a wide variety of different users. Some have been there for centuries, others are more recent arrivals. Among the older industries and activities are fisheries, ports and shipping and military activities; the oil and gas industry and mariculture are newer arrivals. Orkney and Shetland have provided major infrastructure for the North Sea oil and gas industry since the 1970s, and there have been producing oil fields to the west of Shetland since 1997. Finfish and shellfish farming are important industries in the coastal regions of the SEA4 area.