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Title: Audit of priority species of rivers and wetlands : riverine and wetland molluscs in South Hampshire and the Isle of Wight
Author: Environment Agency Hampshire Area
Document Type: Monograph
The following report has been commissioned by the Environment Agency (Southern Region). It has been prepared on behalf of the Hampshire and Isle of Wight Wildlife Trust and is one of seven audits covering species of rivers and wetlands that are considered to be a priority for conservation action by the Environment Agency and its partners. The species covered by the audits are: Wetland and river molluscs (Anisus vorticuhis, Pisidium tenuilineatum, Pseitdanodonata complanata, Segmentina nitida, Vertigo moulinisiana); Freshwater Crayfish; Southern Damselfly; Marsh Fritillary; Black Bog Ant; Birds of Rivers and Reedbeds (Bittern, Kingfisher)and Water Vole. A vorticulus requires clean calcareous waters of marsh drains and a rich aquatic flora and is often associated with places where there are floating plants of ivyleaved duckweed Lemna trisulca and frogbit Hydrocharis morsusranae. It is typically found on the surface with the floating plants. Other specialized habitat demanding and rare species of mollusc which live with it are: Valvata macrostoma, Segmentina nitida and Pisidium pseudosphaerium. Freshwater pulmonates do not have gills and in the smaller species the mantlecavity may be waterfilled, and some depend on cutaneous respiration over the surface of the exposed parts of the body. Whilst large Lymnaeids come to the surface to take air (and thus have some independence from the oxygen content of the water), planorbids rely on cutaneous respiration under water. Planorbids are interesting in having invertebrate haemoglobin, perhaps an adaptation to oxygen storage. Difference species have different tolerances of anaerobic conditions, with the tolerant ones able to remove anaerobic metabolites from their tissue faster than the more sensitive species, of which A. vorticulus is almost certainly included from its requirement of clean water. In freshwater limpets the seasonal variation in oxygen consumption was correlated with reproduction and growth rates.
Publisher: Environment Agency
Publication Date: 1998
Publication Place: Winchester
Subject Keywords: Rivers; Wetlands; Wildlife management; Population survey; Nature conservation; Mollusca; Habitats
Geographic Keywords: Hampshire; Isle of Wight
Extent: n.p. [45]
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