Understanding the impact of farming on aquatic ecosystems
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| Defra Project WQ0112
UNDERSTANDING THE IMPACT OF FARMING ON AQUATIC ECOSYSTEMS Final Report 31 January 2008 Andrew Davey1 Mike Gardner1 Ian Johnson1 Stephen Nixon1 Michael Payne2 Holly Smith1 1 WRc plc, Frankland Road, Blagrove, Swindon, SN5 8YF 2 Michael Payne Environmental Consultants, Field Barn Farm, Boughton, Kings Lynn, PE33 9AH Table of contents 1 Introduction 1 1.1 Rationale 1 1.2 Aims and objectives 1 1.3 Scope of review 1 1.4 Approach 2 1.5 Trends in agricultural production and potential impacts on aquatic ecosystems 2 2 Impact of pollutants on aquatic ecosystems 4 2.1 Nitrate/nitrogen 4 2.2 Phosphorus 6 2.3 Ammonia 8 2.4 Soil sediment 10 2.5 Pesticides 12 2.6 Veterinary medicines 15 2.7 Faecal pathogens 16 2.8 Organic material 16 2.9 Endocrine disrupting chemicals 17 2.10 Other pollutants 19 2.11 Combined effects of different pressures 19 3 Indicators of pollution 20 3.1 Background 20 3.2 Species/biological quality elements indicative of the effects/impacts of farming 20 3.3 Monitoring under the Water Framework Directive 21 3.4 Use of biomarkers as early warning systems for farming-related activities 23 3.5 Summary 24 4 Understanding the impact of farming on aquatic ecosystems 25 4.1 Introduction 25 4.2 Knowledge of activities, pathways, processes, source apportionment and impacts 28 4.3 Quantification of scale and importance of impact 30 4.4 Improvement, development and implementation of cost-effective mitigation measures 31 5 Knowledge transfer plan 35 6 References 36 IntroductionRationaleThe Water Framework Directive (WFD), which came into force on 22 December 2000, is a wide ranging piece of European environmental legislation that sets objectives for protecting and enhancing water quality and the status of aquatic ecosystems. Specifically, it aims to achieve “good chemical and ecological status” in surface waters (rivers, lakes, transitional (estuarine) and coastal waters) by 2015, where "good" represents a slight deviation from minimally impacted reference conditions. To achieve this, the WFD makes provision for the establishment of River Basin Districts (RBDs) within which river basin management plans will be implemented to target both point and diffuse sources of water pollution. Farming activities are major sources of pressures on the water environment. The development and delivery of cost-effective measures to meet the objectives set out by the WFD requires an assessment of the contribution that agricultural land management practices makes to pollutant losses to water. In addition, the impact of those pollutants on the ecology of the receiving waters must be understood and quantified. In 2002, Defra conducted a Strategic Review of diffuse water pollution from agriculture in England, which assessed the environmental pressures and impacts exerted on water by agricultural practices and critically appraised the success of existing policy instruments to control such pollution1. While some of the impacts of pollution are well documented (e.g. eutrophication), there is now a need to pull together information on the effect of a wider range of pollutants across all types of aquatic ecosystem. This report summarises the main findings and conclusions from the study. It is accompanied by two Annexes with more detailed background information on some of the key aspects: sources and pathways of pollutants, and strategies to tackle agricultural water pollution are covered in Annex A, and indicators of pollution are covered in Annex B. Aims and objectivesThe aim of this report is to explore and benchmark current knowledge and understanding of the effects of farming on aquatic ecosystems in England and Wales and to identify future research needs. To achieve that aim the Defra Tender document indicated that the desk study should address the following points: The study should identify what data/information already exists, where it resides and how readily available it is. It should focus on the impact of pollutants/contaminants, including sediments, at the aquatic ecosystem level and on individual species, including vertebrates, invertebrates and algae etc. Existing knowledge on suitable indicator species for the effects of pollution/contamination, including those that could act as early warning markers, should be collated and discussed. Knowledge on the sources and exposure pathways of potential pollutants, and the relative contribution and effects of different farming management practices, should be discussed to provide context and background for the study. Recommendations for future R&D on the effects of farming on aquatic ecosystems should be proposed, and should focus in particular on research which could be used to identify cost-effective mitigation approaches. A knowledge transfer plan should be included. It is important to identify clearly the outputs and pathways to delivery from the proposed project. Scope of reviewFarming is defined as all agricultural and horticultural activities. Agriculture uses over 76% of the land area of England and Wales and horticulture is undertaken on around 1% of the total agricultural land in the UK.2 The main categories of pollutant arising from agricultural activities are: nitrate; ammonia; phosphorus; soil sediment; pesticides; veterinary medicines; faecal pathogens; organic material; endocrine disrupting chemicals; other hazardous substances such as heavy metals and hydrocarbons; and hydromorphological pressures such as land drainage, flood defence and water abstraction. Hydromorphological pressures that directly impact ecosystems and indirectly affect water quality are not discussed in detail in this review. This report reviews the impact of agricultural pollution on all surface waters (rivers, lakes, transitional and coastal waters). Groundwater provides base flow to many rivers and lakes and is an important transport pathway for pollutants such as nitrates. The importance of groundwater in the achievement of Good Ecological Status (GES) in dependent surface water bodies is recognised by the inclusion of ‘connection to groundwater’ as a quality element for the classification of the status of river and lake water bodies. The role of groundwater in modifying water quality and ecology is therefore integrated across all surface water body categories rather than considered separately. Further details of the scope of the review are provided in Annex A. Download 432.61 Kb. Share with your friends:
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