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Exposed riverine sediments, or ERS, are composed of silt, sand and gravel deposited by streams but exposed as water level falls. Other terms for ERS include river shingle, point bars, berms and shoals and they are most common in actively meandering and braided rivers. Adrian Fowles of the Countryside Council for Wales and members of the UK Environment Agency in 1993 coined ‘exposed riverine sediments’ as a term to describe the full scope of these related microhabitats. Their aim in-so-doing was to reduce confusion and pull together the conservation and scientific investigation of these habitats. Bates and Sadler (2005)〔Bates, A.J., and J.P. Sadler. 2005. ''The ecology and conservation of beetles associated with exposed riverine sediments''. CCW Contract Science Report No.688.〕 have since further defined exposed riverine sediments as:
Therefore, eroding river banks are ERS because they are usually composed of fluvially deposited sediment. Whereas areas of the stream bed and over-bank deposits are not ERS because they are only exposed when water levels are unusually low and are more elevated than the bankfull level respectively. The term ERS is slowly becoming more common and has now been used in a large number of published papers, for example: *(Petts et al. 2000 ) *(Eyre et al. 2001 ) *(Sadler et al. 2004 ) *(Looy et al. 2005 ) *(Tockner et al. 2006 ) *(Bates et al. 2006 ) ==ERS habitat== A casual glance at ERS would suggest a harsh, relatively un-inhabited habitat with little value. However, ERS habitats are of considerable conservation importance because of their high species diversity, high degree of species specialisation, and large number of rare and endangered species. ERS are of substantial importance for a small number of vertebrate species, such as the rare little ringed plover, but for the most part their value lies in their invertebrate fauna. The United Kingdom Biodiversity Action Plan, for example, lists eight species of beetle: *(''Bembidion testaceum'' ). ''See also'' Bembidion ''in Wikispecies''. *(''Lionychus quadrillum'' ) *(''Perileptus areolatus'' ). ''See also'' Perileptus ''in Wikispecies''. *(''Meotica anglica'' ). ''See also'' Meotica ''in Wikispecies''. *(''Thinobius newberyi'' ). ''See also'' Thinobius ''in Wikispecies''. *(''Hydrochus nitidicollis'' ). ''See also'' Hydrochus ''in Wikispecies''. *(''Dyschirius angustatus'' ). ''See also'' Dyschirius ''in Wikispecies''. *(''Bidessus minutisimus'' ). ''See also'' Bidessus ''in Wikispecies''. and two species of stilleto fly: *(Southern silver stiletto-fly ) ((''Cliorismia rustica'' )) *(Northern silver stiletto-fly ) ((''Spiriverpa lunulata'' )). that are associated with ERS. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Exposed riverine sediments」の詳細全文を読む スポンサード リンク
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