The Natural History of Chessel Bay Local Nature Reserve, Southampton © Southampton Wildlife Link Chaimlan: Julian Crel110na B.Sc.. C. BioI.. F.R.E.S.. PGc.E. Supported by: Report First published January 1993 Produced by the Southampton Wildlife Link British Gas­ Southern The Southampton Wildlife Link is a voluntary body which meets monthly at the Civic Centre. It consists of representatives from the chiefecological and natural history groups in the area. Those groups are: English Nature Southampton Schools Conservation Corps Southampton Natural History Society Southampton Commons and Parks Protection Society Hampshire & IOW Wildlife Trust Royal Society for the Protection of Birds British Trust fOf Ornithology Broadlands Valley Conservation Group British Butterfly Conservation Society Hawthoms Wildlife Association Sholing Valleys Study Centre Association Friends of Shirley Pond ENVIRONMENT Correspondence to the Hon. Sec. Mrs. P. Loxton. 3 Canton Street. Southampton Also available is a Slide Pack. This consists ofapproximately 30 colour transparencies with notes describing the ecology of Chessel Bay CONSCIOUS 1 1 A Report on the Natural History of Chessel Bay Local Nature Reserve Southampton . by The Southampton Wildlife Link 1993 CONTENTS Litter................................................ Aims . 3 21 Introduction . 4 Bait digging . 21 Woodland . 5 Seaweed collection . 21 Pressures on the Woodland .. 6 Trawling . 21 Mudflats . 8 Planting in woodland . 21 Id' IM .. Macroalgae . 8 n ustna onttonng .. 21 Microalgae. 8 Promote responsibility-education . 21 Invertebrates . 9 Scientific monitoring . 22 Birds . 11 Appendix 1: Flora ofChessel Bay . 23 Shingle . 13 Appendix 2: Insects . 26 Appendix 3: Vertebrates . 28 Appendix 4: Mudflat Community . 29 Marsh .......................................................... 16 Pressures on the Bay Shoreline .. 17 Appendix 5: Birds found around Chessel Bay 30 Development & Reclamation . 18 Results ofBird Counts . 31 Wave action and wash from boats . 18 Litter . 19 Bait digging . 19 Bird disturbance .. 19 Fishing from the shore . 20 Commercial trawling . 20 Oystercatcher Seaweed collections .. 20 Ships going aground on mud . 20 Nutrients and fertilisers . 20 Spillage from industry along river. 20 Recommendations . 21 Formation ofbye laws . 21 Oppose any planning permission . 21 Encroachment by land reclamation . 21 SQuthampton Wddhfe Link 2 AIMS OF THIS REPORT The principle aim of this report is to highlight the wildlife communities that exist in Southampton's first Local Nature Reserve and express their importance in the region. This inevitably raises the problem of pressures that are currently imposed on the organisms that inhabit the Reserve and we make recommendations that will help to maintain the Bay as a quiet backwater along the River Itchen. This report is intended to assist:- • Teachers - to help as resource material • City Planners - when making future decisions • The Public - to increase their interest in the Bay Southampton Wildlife Link 3 INTRODUCTION 12% of the city of Southampton comprises river and tidal area. September 1991 the area was officially opened by Southampton They are as such an essential habitat. The River Itchen is of City Council as a Local Nature Reserve and is now a Site of international importance and used by Butcher (1933) as a type Special Scientific Interest (SSSI) along with the rest of the river of chalk. Within the City boundary the river has extensive upper Solent region. areas of intertidal mudflats but only one part is unaffected by seawalls and/or industrialisation. This single stretch of estuarine The Nature Reserve is now managed by a Management seashore and adjoining land has been referred to as Chessel Bay Committee which meets quarterly. Representatives come from since before the 18th century, when the Chessel House was various interested parties including the City Council (landscape built. It is located to the south ofNortham Bridge where the R. architect and ecologist), Southampton Wildlife Link, Itchen meanders to produce a very wide loop and is situated on Southampton Schools Conservation Corps, English Nature and the depositing side. Thus, not only sediment and shingle collects the Headmaster ofBitterne Manor Primary School. but also man-made debris most ofwhich is non-biodegradable. The Reserve area is approximately 14 hectares and has been The principle ecological habitats within the reserve are protected from development in the past by the railway line that runs to the back ofthe Reserve and isolating it from the Chessel • Woodland estate. At either end of the Reserve there are industrial estates • Mudflat which, through land reclamation, have steadily encroached the • Shingle mudflats. These, along with the railway line, mark the • Saltmarsh boundaries of the Reserve. Not only is it the only semi-natural shore remaining on the R. Itchen but also because within its confines is the point where the Common Reed (Phragmites communis) merges into Cord Grass (Spartina sp.). This highlights the region at which freshwater changes into a saline habitat. Its importance lies not just as a local reserve but as part of a national picture. It represents a vital feeding and over­ wintering site for migrating waders and other seabirds. In Southampton Wildlife Lmk 4 WOODLAND Maps produced over the centuries have shown the extent of So, although tiny and isolated, the woodland at Chessel Bay is woodland to the north and east of Southampton, extending part of the original ancient woodland of several centuries ago, from West End down to the edge of the Solent at West Wood. and this is borne out by the quantity and variety of species Today the ancient woodland is fragmented, leaving small found there. remnants such as exist at Frog's Copse and Hum Hole. The woodland is ofoak/birch type, growing on a sandy/clay soil In 1910, the Chessel Estate (which, until 1923, was part of and the dominant tree is Pedunculate Oak (Quercus robur). The Bitterne Manor in the Diocese of Winchester) stretched from recent establishment ofbirch is by natural succession. The piece the River Itchen to Bitterne Road (Lance's Hill) and Peartree ofwoodland nearest to Quayside Road was used for allotments Avenue down to Chine Avenue in the area of what was once during the war and the oak trees here have regenerated. Since "The Copse". Chessel House was positioned where Nos 31 ­ that time, other oaks have been planted. This part of the 39 Chessel Avenue now exist. The woodland of the estate, woodland is more open with other species of trees present fragmented from ancient forest, grew on the sand and clay of including plum, apple and cherry. The plum trees have become the Bracklesham Beds. established from the days ofthe allotments as have possibly the apple and cherry, although both of these latter are associated A map of 1826 shows woodland stretching from Bitterne Road with oak woodland. to the Chessel Bay shore but the building of the Southampton to Portsmouth rail link severed this woodland, leaving the The presence of Cow-wheat (Melampyrum pratense) and the narrow strip oftrees along the Bay shore. diversity of other plant species such as Bluebell (Hyacinthoides non-scriptlls) and the Great Willowherb (Epilobium hirsutum), Part of this ancient woodland at Hum Hole ceased to be a Wood Spurge (Euphorbia amygdaloides) and the closely functioning ecosystem with the building of the Bitterne by-pass related trees, Whitebeam (Sorbus aria) and Mountain Ash and was reduced to virtually park status. This woodland was (Sorblls allcllparia), indicate that this wood was part of an the nearest habitat to Chessel Bay from which colonisation ancient woodland. could take place; with the demise of Hum Hole, dispersal of insects and seeds has slowed down to Chessel Bay. The ground flora has been eroded by the excessive use of bicycles amongst the trees. Many plants are known to have been present in quantity but now are only represented by small Southampton Wildlife Link 5 samples such as the Bluebell, Wood Sage (Teucrium PRESSURES ON THE WOODLAND scorodonia) and Wood Anemone (Anemo11e 11emorosa). It is The site lies close to a residential part of Southampton. hoped that these and others will recolonise in greater densities Although the mudland benefits from being relatively when remedial work to the banks has been carried out. inaccessible, the linear woodland receives high usage from local people in relation to its small size. This has resulted in Erosion of soil under the mature trees has reduced the a variety ofproblems: quantities ofleaflitter and associated invertebrates. In the dense cover of the scrub, decaying organic matter is protected and • Vandalism and fire. Since the introduction of the path and insects are prolific in the late spring and early summer. directed access the incidence of vandalism seems to have Ichneumon wasps are abundant including the largest species subsided somewhat although some damage has occurred to which hunt the larvae ofbutterflies and moths. The rotting fruit the wooden rails ofthe observation platform. Bonfires have from the plum trees attract a wide range of insects and several for many years caused damage to trees, particularly those large, uncommon hoverflies, e.g. Volucella zOllaria, take refuge next to the shingle habitat. Drift wood was collected, piled here. Their larvae are parasitic on wasps and hornets. Wood up below the base of the trees and set alight. With the boring beetles disperse by flight and these are seen during early formation of the Nature Reserve this has become a rare summer evenings flying along the railway and around the wood. sight. The regular litter picks organised by the Management The Stag Beetle (Lucallus cervus) is now a declining species Committtee remove much of the combustible materials and and limited to southern England but is fairly abundant, most thus reduces this hazard yet further. years, in the Bitterne area. The larvae feed for up to four years inside a variety oftrees and it is certain that the trees ofChessel • Increasing access and footpaths. The wooded region has for Bay are important in this respect.