An Investigation of the Mud Fauna of the Stour Estuary

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TRANSACTIONS AN INVESTIGATION OF THE MUD FAUNA OF THE STOUR ESTUARY T H E M O R L E Y ESSAY FOR 1 9 5 9 BY FRANCES BULL, H E L E N HONEYMAN AND SUSAN

KNOTT

INTRODUCTION

ONE of the most striking features of any estuary is the replacement of freshwater by marine animals as the river progresses towards the sea. This should be of great interest to the ecologist. In spite of the presence of numerous estuaries in the British Isles, surprisingly few accounts of their ecology have been published (notably SPOONER and M O O R E , 1 9 4 0 ) . It was decided that a study of the River Stour estuary should be made over a period of three weeks during June 1958. The scope of the investigation was limited to burrowing animals and to their distribution in relation to salinity, substrate, and their level on the shore. The estuary of the River Stour is in origin a drowned river valley, and forms part of the boundary between Suffolk and Essex. From Harwich to Manningtree, a distance of 10 miles, the estuary is about a mile wide. Above Manningtree it narrows abruptly but it is tidal for a further two miles up to Fiatford. The vertical tidal ränge varies from 13 feet at Harwich to 6 feet at Fiatford. The main Channel is relatively narrow and at low water expanses of shore are exposed. This shore is predominantly muddy but coarser material occurs locally, where there are stronger water currents, or where the shore is more exposed to wave action. During recent years, Spartina townsendii has colonised the Upper part of the shore and in many places vigorous growth has resulted in a dense turf extending downwards almost to mid-tide level. The investigation did not include a study of this specialised habitat.


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An Investigation of the Mud Fauna of the Stour Estuary by Suffolk Naturalists' Society - Issuu