Abstract: These guidelines for the conduct of benthic surveys at commercial aggregate extraction sites have been produced in response to the rapid increase in survey work for Environmental Statements to accompany dredging applications, and to impending legislation which will bring extraction activity under statutory control (see Introduction). The guidelines are designed to promote a comprehensive and consistent approach to the assessment of the seabed environment (i.e. sediments and the associated benthic fauna) as part of the planning process and, on granting of a permission to dredge, in response to any monitoring requirements. They have been written by scientists at the Centre for Environment, Fisheries and Aquaculture Science (CEFAS) on behalf of the UK Department for Transport, Local Government and the Regions, who will shortly assume the role of the regulator. Since the inception of the requirement for such benthic surveys, CEFAS, as an Executive Agency of the Department for Environment, Food and Rural Affairs (DEFRA), has led on the provision of scientific advice regarding their conduct, as well as carrying out related R&D programmes of a strategic nature in UK waters. The production of these guidelines was overseen by a Steering Group, membership of which is given at Annex I.
The increased demand for evaluations of environmental status at and around aggregate extraction sites, whether for Environmental Statements prepared by the industry or in connection with R&D and monitoring programmes, spans a period of less than ten years. Historically, the scientific study of coarser substrata has presented a significant challenge, largely on account of the difficulties in obtaining reliable quantitative samples. As a consequence, information on the nature and distribution of benthic assemblages, and on their wider role in the marine ecosystem, is considerably more limited than in areas of soft sediments.
Developments in sampling practices, such as the use of acoustic techniques for accurate discrimination of substratum type, thereby allowing inferences to be made concerning biological status, are proceeding rapidly. At the same time, there is increasing emphasis in national and international fora on the development of more holistic (ecosystem-level) approaches to marine environmental management, including evaluations of the scope for ‘cumulative’ or ‘in-combination’ effects. Given this, a question may reasonably be asked as to the correct timing for the production of study guidelines. In terms of the operational need for greater consistency in sampling and analytical approaches the answer is, unquestionably, now. However, a document of this nature cannot anticipate with certainty the consequences of all ongoing R&D effort, or of future developments in environmental policy, in specifying present requirements for the conduct of routine benthic surveys. The account therefore serves a dual purpose, namely the provision of guidance on established approaches accompanied, where appropriate, by evaluations of the .state of the art. Of parallel developments in UK methodologies which may influence the direction of future studies. It is recommended that the guidance is updated at appropriate intervals toincorporate significant improvements to current practices arising from such developments. Finally, this document is targeted at experienced marine scientists (especially benthic ecologists, sedimentologists and geophysicists) working on behalf of the industry or the regulator in the conduct of R&D or, more usually, on the implementation of environmental assessment and monitoring programmes. However, it is not intended as a substitute for appropriate consultation at critical stages in the environmental assessment process.
This is especially true at the initial design stage, when the guidelines contained herein are adapted to meet the circumstances prevailing at individual sites.