The Wetland Potential of Sussex 2012 1 Authors Principal Author : Fran Southgate Sussex Wetland Landscapes Officer Sussex Wildlife Trust Contributing Authors : A Lawson, S McIntyre, M Allen, P Green, F Abraham, J Thompson, M Tink, R Baker, K Ryland, Dr C Joyce, Dr M.I. Hill, L Jackson, B Wadge, S Waite, N Flint, Dr N Burnside, Dr D Scott, P King, N Holmes, A Cundy, M Russell, H Brocklebank, E Pettifer, J Gould, P Roper, H Matcham. With thanks to :- East & West Sussex County Council Archives for Tithe maps Environment Agency and Natural England Sussex Biodiversity Record Centre Disclaimer: The information in this report was researched according to the available information on wetlands at the date of publication. Accurate data on the status of wetlands in the UK and Sussex is still limited. Where possible, factual evidence has been quoted although occasionally a subjective judgement has been made by the author, based on 15 years of local conservation experience. This report is by no means comprehensive and there are large omissions in representations of certain species and habitat groups. The reader is therefore asked to consider this report as an initial guide of the state and potential of Sussex wetlands. The Sussex Wetlands Project welcomes any approaches regarding how to lessen some of the data gaps in this report. For more detailed reviews of species groups please see http://sxbrc.org.uk/biodiversity/publications/#adastra 2012. 2 TABLE OF CONTENTS Summary ........................................................................................................................................................................... 2 Introduction ....................................................................................................................................................................... 4 PART 1 – Wetlands and Water ......................................................................................................................................... 5 1.1 What is a Wetland? ................................................................................................................................................. 5 1.2 What do wetlands do for us? ................................................................................................................................... 5 1.2.1 Treatment of run off and polluted water ...................................................................................................... 6 1.2.2 Saltmarsh - natures flood defence ............................................................................................................... 6 1.2.3 Attenuation of flooding.................................................................................................................................. 7 1.3.1 Domestic Supply................................................................................................................................................... 9 1.3.2 Agriculture and Business ...................................................................................................................................... 9 1.4 New ways of thinking about water and wetlands .................................................................................................. 10 1.5 Challenges to our wetlands ................................................................................................................................... 11 1.5.1 Invasive species ........................................................................................................................................... 11 1.5.2 Climate change ............................................................................................................................................. 12 PART 2 Wetland status .................................................................................................................................................. 14 2.1 Reasons for Wetland losses .................................................................................................................................. 14 2.2 The State of UK Wetlands ..................................................................................................................................... 16 2.3 Historic distribution of Sussex Wetlands ............................................................................................................... 17 2.4 Distributions of Rare and Priority Wetlands in Sussex .......................................................................................... 20 2.5 Summaries of wetland habitats in Sussex ............................................................................................................ 21 PART 3 - Wetland Species ............................................................................................................................................. 49 3.1 Wetland Birds ........................................................................................................................................................ 49 3.2 UK Fish .................................................................................................................................................................. 51 3.3 Amphibians & Reptiles .......................................................................................................................................... 53 3.4 Wetland plants ....................................................................................................................................................... 55 3.5 Wetland Invertebrates ........................................................................................................................................... 60 3.6 Terrestrial Wetland Mammals ............................................................................................................................... 62 PART 4 - The Wetland Potential of Sussex .................................................................................................................. 66 4.1 The potential for Sussex wetlands ........................................................................................................................ 67 4.2 Recommended Restoration Targets for Wetland Species and Habitats in Sussex .............................................. 69 4.3 What was achieved in 2010? ................................................................................................................................ 72 4.4 What is the Wildlife Trust doing for Wetlands? ..................................................................................................... 73 4.5 Biodiversity Opportunity Areas (BOA’s) and Living Landscapes .......................................................................... 73 4.6 How can we best restore the wetlands of Sussex to their full potential? .............................................................. 75 Appendix 1 Legislative and Policy Drivers for Wetland Change .............................................................................. 78 References ....................................................................................................................................................................... 82 1 Summary Sussex County is 384,000 ha in area, with a frequently flooding floodplain covering 10 % of its land area, and naturally wet soils covering nearly half of the County. The County is host to some very rare and valuable wetland habitats such as wet heath, chalk reedbed, sandstone ghylls and acid floodplain woodland. Sussex also hosts over 135 km of internationally rare chalk streams. These wetland fragments are the remnants of what was once a much more robust and healthy wetland landscape. We have lost a staggering proportion of our wetlands from Sussex, and that which remains is fragmented, degraded and on the whole at risk of disappearing entirely. We have no means of knowing exactly how much wetland has been lost or damaged, but it is likely that between 1960 & 1980 alone, over 60% of Sussex wetlands were drained (Wildlife Trusts, 1996). Sussex is home to a variety of other nationally rare wetland habitats including fen, reedbed, ancient floodplain woodland and saltmarsh. Recent surveys confirm that the area of fen in Sussex is under 100 ha and less than 10% of the original Sussex fen estimate. Two large areas of fen at Combe Haven and Pett level in East Sussex make up nearly two thirds of the entire Sussex fen resource. Similarly the true area of reedbed has been revised to just over 230 hectares or 7% of the original estimated area in Sussex. Only two large reedbeds of over 20 hectares are found at Combe Haven and the Pannel Valley in East Sussex, with only three reedbeds over 5 ha and 38 over 1 ha in area. Sussex has 2.4% (285 km) of the coastline of Great Britain. Little is known about the overall distribution and condition of our coastal (marine) habitats, but as with its freshwater wetlands, the unique geology of the County often determines the rarity of the habitats which occur (e.g. the chalk wave-cut platform). Estuarine habitats are fairly comprehensively mapped. The total amount of saltmarsh recorded in Sussex by BRANCH (Biodiversity Requires Adaptation in Northwest Europe under a CHanging climate) is 405 hectares, approximately 92% of which is found in West Sussex, predominantly in Chichester Harbour, the largest saltmarsh site in the South-East region. Saltmarsh otherwise has a very limited