DEVELOPMENT OF A NOVEL INVERTEBRATE INDEXING TOOL FOR THE DETERMINATION OF SALINITY IN AQUATIC INLAND DRAINAGE CHANNELS Alexander G. G. Pickwell A thesis submitted in partial fulfilment of the requirements of the University of Lincoln for the degree of Master of Philosophy in Biology This research programme was carried out in collaboration with the Environment Agency August 2012 Page i Certificate of Originality This is to certify that I am responsible for the work submitted in this thesis, that the original work is my own, except as specified in the acknowledgements and in references, and that neither the thesis nor the original work contained therein has been previously submitted to any institution for the award of a degree. Signature: Name: Alexander G. G. Pickwell Date: 31st August 2012 Page i Abstract Salinisation of freshwater habitats is an issue with global implications that can have serious detrimental effects on the environment resulting in an overall loss in biodiversity. Whilst increases in salinity can occur naturally, such anthropogenic actions as the disposal of industrial and urban effluents and the disturbance of natural hydrological cycles can also result in the salinisation of freshwater habitats. The Water Framework Directive (WFD) requires Member States to restore all freshwater habitats to “good ecological status” and to prevent any further deterioration. Macro-invertebrates are widely used as indicators of river condition for a wide range of reasons and have been designated a key biological element in the assessment of aquatic habitats by the WFD. A review of the available literature, however, found no macro- invertebrate-based biotic indices have been developed for the detection and determination of salinity increases in freshwater habitats that are suitable for application in the United Kingdom for the purposes of the WFD. To this end, a biotic index based on the aquatic macro-invertebrate community response to changes in salinity, termed the Salinity Association Group (SAG) index, was developed. The potential of the SAG index for assessing water quality in terms of salinity in freshwater systems was investigated using data collected from survey sites in Lincolnshire and Norfolk, England, and the results compared to several published salinity indices. Whilst the SAG index was found to show both geographic and seasonal dependence, as is common among many biotic indices, the proposed metric exhibited a stronger relationship to salinity than macro-invertebrate indices employed in Europe for the purposes of the WFD show to their specific pressure. Furthermore, the SAG index was found to be highly selective to only salinity concentration, was significantly related to salinity when used with less detailed information and significantly discriminated between the salinity classes defined by the WFD. It is also highlighted that application of the SAG index with such predictive models as the River InVertebrate Prediction And Classification System (RIVPACS) can resolve the exhibited geographical and seasonal dependence. Page ii In a comparison of the SAG index with the published indices, it was found that the SAG index was the superior metric in terms of recognising abundance as required by the WFD, reliably indicating changes in salinity, compatibility with sampling protocols employed by England’s regulatory authority and producing a linear output. Consequently, it was concluded that the SAG index surpasses other published metrics for the detection and determination of salinity increases in freshwater habitats and is a viable biomonitoring tool suitable for use in England for informing aquatic habitat management decisions, research application and the purposes of the WFD. It is proposed, however, that more rigorous sampling protocols for both macro-invertebrate and environmental data may result in more accurate metric scores and reveal further issues or benefits associated with the SAG index and could also be used to further refine the metric. It is also suggested that adaptation and examination of the SAG index at a larger geographical scale would further demonstrate the validity of the proposed metric and illustrate the potential of the SAG index for worldwide application. Furthermore, intercalibration of the SAG index to harmonise WFD reference conditions and class boundaries across Europe would allow the application of the SAG index throughout Europe for the purpose of the WFD. Page iii Acknowledgements The author wishes to acknowledge: The project work, for which this thesis is a culmination, was part-funded by the Broads Authority, a grant from the Alice McCosh Trust and a grant from the Environment Agency, without which this project would not have proceeded. The author is immensely grateful to all three parties. The author would also like to acknowledge the following for advice, information or materials given: The staff at the Spalding office of the Environment Agency, Dorothy Gennard and Ron Dixon (University of Lincoln), Pam Taylor (British Dragonfly Society), Helen Booth and Jeremy Halls (Halcrow Ltd), Mike Elliott (Institute of Estuarine & Coastal Studies), Clive Doarks and Rick Southwood (Natural England), Roy Baker (Norfolk and Norwich Naturalists' Society), Nigel Dunthorne (Rockland Wildfowlers Association), Tim Strudwick and Matt Wilkinson (Strumpshaw Fen Nature Reserve), Charles Deeming, Paul Eady, Jamie Legge, Amanda Mylett and Tom Pike (University of Lincoln), Joe Cullum, Derek Howlett and Chris Mutten. The author wishes to thank: Richard Chadd, Chris Extence and Helgi Gudmundsson (Environment Agency) for the advice, support and assistance provided during the course of this work, Mike Dunbar (Environment Agency) and Paul Corcoran (National Suicide Research Foundation) for statistical advice, and the numerous members of staff at the University of Lincoln who offered their assistance and encouragement. The author wishes to thank friends and family members for their unrelenting support in all of my endeavours. Special mention must also be made for James Coulter, Louise Hopkins and Rachel Farrow for their support and assistance, which were always given without question. The views expressed in this body of work are those of the author, and not necessarily those of the Environment Agency. Page iv Table of Contents List of Figures ........................................................................................................................ ix List of Tables ........................................................................................................................ xii List of Plates ........................................................................................................................ xvi List of Abbreviations and Symbols ..................................................................................... xvii 1 INTRODUCTION................................................................................................................ 1 1.1 Aims and Objectives ................................................................................................... 3 2 LITERATURE REVIEW ........................................................................................................ 4 2.1 Salinisation ................................................................................................................. 4 2.2 Measurement of Salinity ............................................................................................ 7 2.3 Classification of Surface Waters Based on Salinity ...................................................... 8 2.4 The Scale of Salinisation in Freshwater Habitats ....................................................... 10 2.5 The Impact of Salinisation on Freshwater Habitats ................................................... 11 2.6 Legislation and Water Quality .................................................................................. 13 2.6.1 The Water Framework Directive ......................................................................... 14 2.7 The Assessment of Water Quality............................................................................. 16 2.7.1 Biological Organisms Used for the Assessment of Water Quality ........................ 19 2.7.1.1 Fish ............................................................................................................... 20 2.7.1.2 Macrophytes ................................................................................................ 23 2.7.1.3 Phytoplankton and periphyton ..................................................................... 25 2.7.1.4 Macro-invertebrates ..................................................................................... 28 2.8 Approaches to Biological Monitoring........................................................................ 32 2.8.1 Functional Approach .......................................................................................... 32 2.8.2 Biotic Indices ...................................................................................................... 34 2.8.3 Multimetric Indices ............................................................................................ 36 2.8.4 Multivariate Approaches .................................................................................... 37 2.9 Salinity Indices ......................................................................................................... 38 2.9.1 Comparison of Salinity Indices ...........................................................................