Science

Introduction

The deep-sea environments, into which oil and gas operations have extended, are generally poorly understood. Surveys regularly discover new habitats and communities of animals previously unknown to science. Inevitably, there is a lack of historical data which can be used for baseline knowledge and prediction of potential impacts. It is, however, apparent that all deep-sea environments support a wide range of animals that contribute significantly to global biodiversity.

Background

By establishing long-term monitoring of the deep sea physical environment, and biological activity in that environment, it should be possible to compensate to a large degree for previous lack of knowledge. Very few deep-sea sites in the world’s oceans have been the subject of long-term
studies exceeding 5 years. The two best known examples are Stations M in the NE Pacific Ocean (SCRIPPS Institute of Oceanography, USA) at 4100 m depth, studied since 1989; and the Porcupine Abyssal Plain Sustained Observatory at 4850 m in the NE Atlantic Ocean (UK National Oceanography centre). At both stations, important annual cycles have been observed with considerable variability from year-to-year as well as changes in dominant fauna over decadal time scales. In an oil production area such natural changes need to be distinguished from any anthropogenic (man-made) influences imposed on the deep-sea environment.

Recognising this issue, a series of scientific meetings (BP Exploration, BP Angola, University of Aberdeen, MBARI, UK National Oceanography Centre, Angolan National Institute of Fisheries, Texas A&M University, Glasgow University, Scripps Institution of Oceanography) were set up to discuss the feasibility of establishing a long-term monitoring station within BP operating areas. The first meeting (September 2004) concluded the establishment of a long-term monitoring station in the Atlantic Ocean would, after a minimum 3 - 4 year time span, begin to allow discrimination of patterns of local change that could be compared with global changes. An objective should be the achievement of a 25 year time span of operation to allow monitoring for the lifetime of oil production in the area. This would provide long-term environmental assurance but also make a major contribution to science.

At the conclusion of the first meeting, Oceanlab (University of Aberdeen) were tasked with developing a number of design options to satisfy the compromise between scientific requirements and the practicalities of deploying a platform in the vicinity of BP offshore operations. A further meeting of the Steering committee in April 2005 discussed and enhanced both the scientific objectives and the specification for the Oceanlab designs. The DELOS platforms were deployed in February 2009.

Objectives

The DELOS system was designed around the concept of having two permanent monitoring platforms on the seafloor, a near-field platform located close to the subsea production infrastructure and a far-field platform located sufficiently distant from any industrial activity to be outside any zone of influence, and thus act as a ‘control’ site. This would allow both short-term (intra-annual and annual) and long-term (interannual and decadal) changes to be observed, and to enable any anthropogenic influences to be distinguished (by comparing the near- and far-field data). The specific objectives of the DELOS project are to:

  • Measure and monitor deep-sea biological communities.
  • Understand the pace of recovery from any unforeseen impacts.
  • Increase understanding of mechanisms linking climate change to deep-water ecology.
  • Determine long term natural environmental conditions at a deep water site in Block 18 (Angola Oil & Gas field) and compare with any changes observed at the near field monitoring sites.
  • Differentiate between natural and man-made changes, providing a linkage between marine biodiversity and climate change.
  • Determine the long term effects of the monitoring platform itself on natural processes.
  • Develop an understanding on the “reef effect” of large fixed structures in the deep-water environment.
  • Contribute to understanding of the potential effects of sub-sea equipment in general.
  • Contribute to individual & institutional capacity development in Angola.

The Site

DELOS is situted between the deep-sea sediment fans of two major rivers, the Congo and the Kwanza, off Angola in the SE Atlantic Ocean. The area is highly productive, with seasonal and annual variability influenced by the interactions of the Angola and Benguela current systems.