Exposed riverine sediments, or ERS, are composed of

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel ...

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class ...

and

gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...

deposited by streams but exposed as water level falls. Other terms for ERS include river shingle,

point bar A point bar is a depositional feature made of alluvium that accumulates on the inside bend of streams and rivers below the slip-off slope. Point bars are found in abundance in mature or meandering streams. They are crescent-shaped and located on ...

s, berms and

shoal In oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. It ...

s and they are most common in actively

meander A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank ( cut bank) and deposits sediments on an inner, convex ban ...

ing and

braided river A braided river, or braided channel, consists of a network of river channels separated by small, often temporary, islands called braid bars or, in English usage, ''aits'' or ''eyots''. Braided streams tend to occur in rivers with high sediment ...

s. Adrian Fowles of the

Countryside Council for Wales The Countryside Council for Wales (CCW; cy, Cyngor Cefn Gwlad Cymru (CCGC)) was a Welsh Assembly sponsored body responsible for wildlife conservation, landscape and countryside access authority for Wales. It was merged with Forestry Commis ...

and members of the UK

Environment Agency The Environment Agency (EA) is a non-departmental public body, established in 1996 and sponsored by the United Kingdom government's Department for Environment, Food and Rural Affairs, with responsibilities relating to the protection and en ...

in 1993 coined ‘exposed riverine sediments’ as a term to describe the full scope of these related

microhabitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s. Their aim in-so-doing was to reduce confusion and pull together the

conservation Conservation is the preservation or efficient use of resources, or the conservation of various quantities under physical laws. Conservation may also refer to: Environment and natural resources * Nature conservation, the protection and manageme ...

and scientific investigation of these

habitats In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

. 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:

''Exposed, within channel,
fluvial In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluviog ...
ly deposited sediments (gravels, sands and silts) that lack continuous
vegetation Vegetation is an assemblage of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic charac ...
cover, whose vertical distribution lies between the levels of bankfull and the typical
baseflow Baseflow (also called drought flow, groundwater recession flow, low flow, low-water flow, low-water discharge and sustained or fair-weather runoff) is the portion of the streamflow that is sustained between precipitation events, fed to streams by d ...
of the
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of ...
.''

Therefore, eroding river banks are ERS because they are usually composed of fluvially deposited sediment. Whereas areas of the

stream bed A stream bed or streambed is the bottom of a stream or river ( bathymetry) or the physical confine of the normal water flow ( channel). The lateral confines or channel margins are known as the stream banks or river banks, during all but fl ...

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. 2000Eyre et al. 2001Sadler et al. 2004Looy et al. 2005Tockner et al. 2006Bates 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 An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

. ERS are of substantial importance for a small number of vertebrate species, such as the rare

little ringed plover The little ringed plover (''Charadrius dubius'') is a small plover. The genus name ''Charadrius'' is a Late Latin word for a yellowish bird mentioned in the fourth-century Vulgate. It derives from Ancient Greek ''kharadrios'' a bird found in ri ...

, but for the most part their value lies in their invertebrate fauna. The

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...

Biodiversity Action Plan, for example, lists eight species of beetle:
''Bembidion testaceum''
''See also''

Bembidion ''Bembidion'' is the largest genus of beetles in the family Carabidae by number of species.Carl H. Lindroth. ''The Carabidae (Coleoptera) of Fennoscandia and Denmark''. Leiden - Copenhagen: Brill - Scandinavian Science Press, 1985. . P. 129-199. ...

''in

Wikispecies Wikispecies is a wiki-based online project supported by the Wikimedia Foundation. Its aim is to create a comprehensive open content catalogue of all species; the project is directed at scientists, rather than at the general public. Jimmy Wale ...

''.
''Lionychus quadrillum''''Perileptus areolatus''
''See also'' Perileptus ''in

''.
''Meotica anglica''
''See also'' Meotica ''in

''.
''Thinobius newberyi''
''See also'' Thinobius ''in

''.
''Hydrochus nitidicollis''
''See also'' Hydrochus ''in

''.
''Dyschirius angustatus''
''See also'' Dyschirius ''in

''.
''Bidessus minutisimus''
''See also'' Bidessus ''in

''. and two species of stilleto fly:
Southern silver stiletto-fly''Cliorismia rustica''

''Spiriverpa lunulata''
. that are associated with ERS.

ERS dynamics

ERS rely on a continued supply of sediment from upstream, and periodic disturbances from

flooding A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrolog ...

to prevent

ecological succession Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades (for example, after a wildfire) or more or less. Bacteria allows for the cycling of nutrients such as car ...

to more vegetated

riparian A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks a ...

habitat.

Threats to ERS

Many of the threats to ERS act to: #reduce the supply of sediment by interrupting its downstream transfer: ## dam construction ##

construction aggregate Construction aggregate, or simply aggregate, is a broad category of coarse- to medium-grained particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregate ...

extraction ##reducing river

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...

(

river engineering River engineering is a discipline of civil engineering which studies human intervention in the course, characteristics, or flow of a river with the intention of producing some defined benefit. People have intervened in the natural course and be ...

and dam construction) #reduce the frequency and magnitude of floods (dam construction) (Plachter and Reich 1998, Sadler et al. 2005, Tockner et al. 2006). Other threats operate over smaller scales, such as livestock trampling.Bates et al. 2007
/ref>

References

Further general reference material

*Bates, A.J., J.P. Sadler, and A.P. Fowles. 2006. Condition-dependent dispersal of a patchily distributed riparian ground beetle in response to disturbance. ''Oecologia'' 150:50-60. *Eyre, M. D., M. L. Luff, and D. A. Phillips. 2001. The ground beetles (Coleoptera: Carabidae) of exposed riverine sediments in Scotland and northern England. ''Biodiversity & Conservation'' 10:403-426. *Looy, K. V., S. Vanacker, H. Jochems, G. de Blust, and Dufrêne. 2005. Ground beetle habitat templets and riverbank integrity. ''River Research & Applications'' 21:1133-1146. *Petts, G. E., A. M. Gurnell, A. J. Gerrard, D. M. Hannah, B. Hansford, I. Morrissey, P. J. Edwards, J. Kollmann, J. V. Ward, K. Tockner, and B. P. G. Smith. 2000. Longitudinal variations in exposed riverine sediments: a context for the ecology of the Fiume Tagliamento, Italy. ''Aquatic Conservation: Marine and Freshwater Ecosystems'' 10:249-266. *Sadler, J. P., D. Bell, and A. P. Fowles. 2004. The hydroecological controls and conservation value of beetles on exposed riverine sediments in England and Wales. ''Biological Conservation'' 118:41-56. {{DEFAULTSORT:Exposed Riverine Sediments Habitats