Keywords: 6145 0 S 11100 0 E Deep-sea benthic biology Megafauna Hydrocarbon seep Chemosynthetic environment Remotely operated vehicle Seafloor geology Habitat heterogeneity a b s t r a c t Release of hydrocarbons from sediments is important in increasing habitat heterogeneity on deep ocean margins. Heterogeneity arises from variation in abiotic and biotic conditions, including changes in substratum, geochemistry, fluid flow, biological communities and ecological interactions. The seepage of heavy hydrocarbons to the seafloor is less well studied than most other cold seep systems and may lead to the formation of asphalt mounds. These have been described from several regions, particularly the Gulf of Mexico. Here, we describe the structure, potential formation and biology of a large asphalt mound province in Block 31SE Angola. A total of 2254 distinct mound features was identified by side-scan sonar, covering a total area of 3.7 km 2 of seafloor. The asphalt mounds took a number of forms from small (o0.5 m diameter; 13% observations) mounds to large extensive (o50 m diameter) structures. Some of the observed mounds were associated with authigenic carbonate and active seepage (living chemosynthetic fauna present in addition to the asphalt). The asphalt mounds are seabed accumulations of heavy hydrocarbons formed from subsurface migration and fractionation of reservoir hydrocarbons primarily through a network of faults. In Angola these processes are controlled by subsurface movement of salt structures. The asphalt mounds were typically densely covered with epifauna (74.5% of mounds imaged had visible epifauna) although individual mounds varied considerably in epifaunal coverage. Of the 49 non-chemosynthetic megafaunal taxa observed, 19 taxa were only found on hard substrata (including asphalt mounds), 2 fish species inhabited the asphalt mounds preferentially and 27 taxa were apparently normal soft-sediment fauna. Antipatharians (3.672.3% s.e.) and poriferans (2.671.9% s.e.) accounted for the highest mean percentage of the observed cover, with actinarians (0.970.4% s.e.) and alcyonaceans (0.470.2% s.e.) covering smaller proportions of the area. Asphalt mounds represent a common and important habitat on several margin systems globally and should be recognised in future environmental assessment and management of these areas.

As human activities continue to move further offshore (Bett 2001;Glover and Smith 2003), they come into contact with deep-sea environments and populations that are often not well understood. Deep-ocean basins cover more than 60% of the Earth's surface, yet much of the deep-sea remains unexplored. Recent efforts have been made to address the historical under-sampling of the deep sea by establishing long-term seafloor observatories, some autonomous and some connected to shore stations via electro-optical cables. Here we describe the first results from two long-term autonomous observatory platforms used to study deep-sea ecology in the vicinity of oil and gas industry activity in the Atlantic Ocean offshore of Angola. AbstractThe DELOS (Deep-ocean Environmental Long-term Observatory System) project is a long-term research program focused on understanding the impacts of oil and gas extraction on deep-sea ecosystems. We have installed two seafloor observation platforms, populated with ROV-serviced sensor modules, at 1400 m water depth in the Southeast Atlantic off the coast of Angola. The 'impact' Near-Field platform is located 50 m from subsea oil production facilities. The 'control' Far-Field platform is 16 km distant from any industry seafloor activity. Each platform includes oceanographic, acoustic, and camera sensor modules. The latter carries two still cameras providing close-up and wide-angle views of the seabed. The Far-Field platform is also equipped with a sediment trap that deploys to 100 m above the seafloor. The instrumented platforms were installed in Feb 2009, and the sensor modules subsequently serviced in Aug 2009, Feb 2010, and Aug 2010. Here, we report on our first experiences of operating the observatories and present some of the first data. The oceanographic data (temperature, salinity, oxygen concentration) and biological observations (demersal fish and benthic invertebrates) suggest that the two study sites have near identical environmental characteristics. We, therefore, believe that these sites are appropriate as control and impact locations for long-term monitoring of potential anthropogenic effects referenced to natural background environmental variation. We suggest that DELOS-type observatories, particularly operated as pairs (or in networks), are a highly effective means of appropriately monitoring deep-water resource exploitation-both hydrocarbon extraction and mineral mining.

Deepwater represents a significant proportion of future oil and gas exploration and production. Scientists have however stated that the deepwater environment is less well understood than the dark side of the moon. At the same time there is increasing pressure from NGOs to postpone deepwater exploration until more is known about potential impacts. In partnership with the marine science community, and via capacity building in Angola, BP has developed and installed the world's first Deepwater Environmental Long-term Observatory System (DELOS) off the coast of Angola. Two environmental monitoring stations were installed, one in the near field and one in the far field 16 kms distant from, and upstream of, any infrastructure. These subsea platforms will be in place for around 25 years and, for the first time ever, will provide scientifically defensible data to distinguish between anthropogenic and natural change in the deep sea. Without this understanding future changes in the deepwater environment could be incorrectly attributed to E&P operations.The data collected will be fundamental in helping Industry and the scientific community to build a long-term picture of deep-sea processes and ecology. In particular, it will enable us to:Measure and monitor deep-sea biological communities Monitor the pace of recovery from any unforeseen impacts Differentiate between natural & anthropogenic changes and provide a linkage between marine biodiversity & climate change The development of the system from concept through to fabrication, installation, and first data recovery is outlined including a first use of non-corrosive Glass Reinforced Plastic (GRP) as the primary structural element for a deepwater subsea facility. The selection of the various instrumentation modules and their application is discussed.

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Environmental Risk Assessment is a key element of a successful Environmental Management System. Hazards arise in all oil and gas exploration and production activities and risk management decisions should be based upon an understanding of these hazards, both in terms of environmental effects and the probability of occurrence. The purpose of the assessment process is to ensure that environmental risks are evaluated in a comprehensive and structured manner and that rational approaches are adopted to both the setting of acceptance criteria and the decision making and prioritising which forms an integral part of the risk management process. This paper outlines various complementary techniques which can be employed to assist the risk management process and discusses their potential application in the preparation of an Environmental Case. Introduction In order to manage environmental issues successfully, it is necessary to evaluate all possible environmental hazards which could arise from both routine operations and accidental events. Risk management decisions should be based upon an understanding of these hazards, in terms of both environmental consequences and probability of occurrence. While routine discharges are not strictly speaking a "risk" in that we know that they will occur on a regular or ongoing basis, the UKOOA Environmental Risk Assessment Workgroup decided to include routine events in the assessment process in order to develop a comprehensive methodology which can be used to aid decision making for all environmental aspects of the E&P lifecycle (exploration, appraisal, production, decommissioning). Environmental assessments typically examine only the effects on the environment from accidental and operational discharges (e.g. oil spills, air emissions, waste disposal, ground contamination). In practice, the risk to the organisation extends more widely than this; reflecting regulatory, political and market pressures which stem from public concern about the environment, and which have a direct bearing on the company's profitability. Analysis of risk needs to take account of this wider context, including the potential for consumer action such as boycotts of products and services. There is therefore a need to incorporate these external elements into environmental management decisions. Individual organisations must set their own criteria which will take into account their company policy, area of operation and reputational goals. This paper outlines a methodology to address these factors in the risk management process. The Environmental Risk Management Process The effectiveness of any environmental assessment and risk management process is dependent upon careful planning and execution of the various tasks within the timeframe of the overall activity. Hazard identification and therefore risk-based decision making is easier if it is undertaken proactively as an integral part of the activity in question, rather than as a critical review of decisions already undertaken. If risk management decisions are to be made in a timely and efficient manner it is important that the evaluation process is started as early as possible subject to the availability of the necessary information. When used this way, environmental management decisions will add value rather than being seen as a restrictive or negative constraint on progress, requiring rework and additional cost. For a new development project, the environmental risk management process involves a number of stages, beginning with the evaluation of the overall sensitivity of the area and then becoming more precise and focused as the necessary detail becomes available in the project development cycle. P. 159^

C.W. Clark, Cornell University, M.L. Tasker, Joint Nature Conservation Committee, M. Ferguson, Amerada Hess Limited, J.P. Hartley, Amoco (UK) Exploration Company, I. Fletcher, Arco British Ltd., A. Whitehead, BP Exploration Operating Company, A.A. Duff, Chevron UK Ltd., J.F. Appelbee, Conoco (U.K.) Ltd., C. Pickton, Deminex UK Oil and Gas Limited, J. Spink, Elf Enterprise Caledonia Limited, C. MacDuff-Duncan, Esso Exploration and Production UK Ltd., S.J. Knight, Kerr-McGee Oil (UK) PLC, A.H. Walls, Mobil North Sea Ltd., A. Onder, Shell UK Exploration and Production, J. Urbanus, Texaco North Sea UK Company, and I. Buchanan, Total Oil Marine PLC. Abstract It is well known that baleen whales produce a variety of low-frequency sounds. The song of the humpback whale, Megaptera novaeangliae, is the most popular example, while the sounds of other species such as blue Balaenoptera musculus, fin Balaenoptera physalus, and minke Balaenoptera acutorosfrata whales remain less familiar. Assessment of the seasonal occurrence and the relative numbers of whales in an area has relied almost exclusively on visual survey methods. Such methods depend entirely on whales surfacing to breath and cannot be used at night or when visibility conditions are poor, and are only good for distances within a few miles of the sighting platform. Because of the limitations inherent in any visual survey method, broad-based, ocean-area surveys are relatively expensive and cannot adequately sample the habitats frequented by whales. Recent access to fixed arrays of bottom-mounted hydrophones has provided a novel mechanism for simultaneously documenting the presence of whales throughout large areas of the Atlantic Ocean. Such coverage would be impossible using traditional visual methods. A recently initiated project is now underway to systematically describe the seasonal occurrences, distributions, and relative numbers of blue, fin, humpback and minke whales in the UK region using passive acoustic techniques. Data from this study are intended to provide information to both document the presence of and reduce the potential impact of oil and gas development and operation activities on whales. This paper presents some existing results from the western North Atlantic and very briefly describes preliminary results from the UK region. Introduction In 1971 Payne and Webb first postulated that several species of large baleen whales, the blue and fin whales, might acoustically communicate over great distances. Their evidence in support of this hypothesis was based on the fact that the sounds from these animals are infrasonic (ca. 20 Hz), loud (ca. 188 dB re 1 Pa at 1m), and highly patterned. Using the narrowband sonar equation and a simple spherical-cylindrical transmission loss model, they estimated that in the ocean prior to the advent of modern engine-driven ships, whales could hear each other across thousands of miles of ocean. In the age of modern shipping came a resultant increase in ambient noise in the frequency band below 100Hz due primarily to propeller cavitation noise. As a result of this increase in ambient noise levels, Payne and Webb estimated that the range of communication for whales was reduced to several hundreds of miles. This long-range communication hypothesis has never been tested due to the difficulties of demonstrating communication for whales swimming in the open ocean. However, there is every reason to support the conclusion that whales rely heavily upon sound production and perception for survival. Their inner ears are remarkably well adapted for detecting and encoding low frequency sounds. They are acoustically prolific throughout the oceans during all months of the year. P. 23^

As exploration and production move into ever deeper waters, the tools and techniques for assessing the environmental impacts of deepwater projects are being developed. This paper outlines the various complimentary techniques that BP Angola is using to describe biodiversity and to monitor the environment in water depths ranging from 1200m to over 2000m.These include:wide ranging, snap-shot in time benthic surveys, which are targeted based on the geophysical information we have in the area mainly looking at seabed microfauna, using a variety of physical and photographic sampling techniques, including the deployment of BP Angola's deepwater short term environmental platform.Short range, extended timescale monitoring with Remotely Operated Vehicles of opportunity mainly photographic looking at larger animals, with trials of traps to gather microfauna. The ROV also photographs animals within the water column as it travels between the rig and the well.Observations of marine mammals, turtles, birds and surface visible fish from seismic and survey vessels.Long term (25 years) monitoring of deep ocean environmental processes with the deployment of deep sea environmental platforms; a cooperative project involving Scripps Institution of Oceanography, Aberdeen University, Texas A&M University at Galveston and Southampton Oceanographic Centre. These platforms should help us understand the linkages between deepwater biodiversity and climate change. The data gathered is used in managing the environmental impacts from our operations and also in our Environmental Impact Assessments.In addition, the data is shared with the wider scientific community and used in local capacity building to ensure added value. The described techniques represent a major step forward in the characterisation of deepwater environments and are applicable in other deepwater areas. Introduction Deepwater is becoming an increasingly important oil province.In 2003, 65% of exploration finds were in water depths greater than 1,000m.At BP, we estimate that over half of the field development projects underway in 2012 will be in water depths of over 1000m and up to 2500m or even deeper. Very few of the many ecosystems found at depths below 200m have been studied.However, research over the past decade has revealed remarkably high levels of biodiversity associated with many deep-sea ecosystems. The oil industry is faced with the challenges of:Understanding the deepwater environment sufficiently well to plan and deliver appropriate management measures to reduce the impact of our operations to an agreed acceptable standard.Developing "public trust" in our deep water operations.Balancing the economic and political drivers for "pace" with the need for knowledge of the deep water environments in which we plan to operate. In common with almost all deep water provinces, there is very little known about the deepwater environments offshore Angola.BP Angola has therefore developed a programme of studies, in collaboration with Angolan and international scientists, to provide information for environmental impact assessments and management, and to enhance the wider knowledge base of deep sea biodiversity. The Angolan Deepwater Environment Over 70% of the Earth's surface is ocean.The sea contains most of the higher order biological diversity on Earth, with many millions of species in the seafloor sediments and associated with cold seeps, deep water corals and other features, most of them not yet discovered. BP's operations in Angola are in Blocks 18 and 31 in water depths of 1,000m to in excess of 2,000m (figure 1).The marine environment is heavily influenced by the Congo River and a number of regional currents. The Congo River Offshore Plume: The Congo River has the second highest river discharge in the world. The river has an average discharge of 41 000 m[3]/s of water and 41 million metric tonnes per year of suspended sediment.This sediment is carried west north-west in the nearshore waters and south-southwest in the offshore waters.

Understanding the utilisation of seafloor heterogeneity by different fish species is an essential prerequisite for the implementation of effective spatial management of marine ecosystems. The North Sea has long been a vital ground for the exploitation of natural resources, supporting one of the world's most active fisheries as well as oil and gas exploration which has resulted in the construction of over 500 offshore platforms across the region. These facilities represent the major manmade structures installed on the seabed, adding substantial components of seafloor heterogeneity to the normally flat, featureless or soft sedimentary surroundings.While there is a growing body of evidence demonstrating that a variety of fishes aggregate around these subsea features, it still remains unclear whether the fish individuals merely concentrate around the structures from surrounding areas or whether such effects can have beneficial effects for fisheries by facilitating net increase in fish stock sizes. The research presented here investigates the relationship between fish and the physical presence of artificial structures in order to elucidate the potential role of offshore oil and gas platforms in the ecology of fish populations in the North Sea.To capture representative fish specimens closely associated with offshore platforms, seasonal fish sampling has been carried out since September 2010 at the BP Miller platform, a large steel jacketed facility in the Central North Sea. Although fishing from an operational platform is normally banned in the North Sea due to safety concerns, the Miller platform provides a unique opportunity for researcher to examine the possible effects of obsolete platforms on fish populations because it ceased production in 2007 and has since been used as a search and rescue helicopter base with minimum manning.Results show that commercially important fish such as cod (Gadus morhua), haddock (Melanogrammus aeglefinus) and saithe (Pollachius virens) were the most characteristic species observed around Miller platform. However, there were marked changes in species composition and their relative abundances between seasons as well as years, suggesting highly dynamic nature of interactions between fish movements and the physical presence of the platform. Based on these results together with a range of studies from the relevant literature, implications for the ecological impacts of decommissioning on North Sea fish populations will be discussed.