Current status
The lesser silver water beetle is found in exposed, richly vegetated ditches and ponds. In the Somerset Moors, this species is confined to peat areas and is frequent only on the turbary peats of Tadham and Westhay Moors. The species benefits from piecemeal, periodic ditch cleaning and high water levels that reduce peat wastage on the Somerset Moors. The Cheshire sites include some relatively undisturbed ponds. The egg cocoon`s construction necessitates the use of floating debris and, therefore, large floating plants, such as frogbit and flote-grass, are thought to be beneficial. However, access to ponds and ditches by grazing animals may be required in order to maintain an open structure. Eggs are laid in spring or early summer, and larvae occur, often floating just below the surface, from May to July. The larvae are predators of water snails. Adults emerge during the summer and overwinter, though it is not clear whether this occurs in the water or on the bank. Adults are occasionally found attracted to light or to glass, and fly readily at dusk if kept in captivity.
In Britain this species is known from 11 ten km squares since 1970. It was much more widely distributed in the 19th century, being particularly well recorded from the Hammersmith Marshes, the Cambridgeshire Fens and Askham Bog. Until recently it was thought to have become confined to ditches on the deeper turbary peats of the Somerset Moors, but the discovery in 1990 of an adult in a pond on the Cheshire Plain has been followed by the discovery of more colonies, some with egg cocoons and larvae. By 1997, it had been recorded from 7 ten km squares here.
In Great Britain this species is classified as Endangered. It is given full protection under Schedule 5 of the Wildlife and Countryside Act 1981.
Current factors causing loss or decline
Inappropriate ditch management.
Conversion of grazing marsh to arable land, resulting in steeper ditch profiles and overgrowth of ditches in the absence of grazing.
Infilling of ponds.
Agricultural improvement.
Loss of ponds to urban development.
Current action
Ponds on the Cheshire Plain have been the subject of the Pond Life Survey since 1995.
Through NE's Species Recovery Programme, additional survey has been undertaken and some ponds have been managed to improve them for this species.
Surveys for this species were undertaken in 1993 and 1994 on the Somerset Moors.
The species is present in the Somerset Levels and Moors SPA.
Action plan objectives and targets
Maintain viable populations within the Somerset Moors and the Cheshire Plain.
Proposed actions with lead agencies
Policy and legislation
Where appropriate, include the requirements of the species when preparing or revising prescriptions for agri-environment schemes. (ACTION: NE, MAFF)
Take account of this species? requirements in response to applications for water abstraction licences. (ACTION: EA)
Address the requirements of this species in the LEAP process and in relevant WLMPs. (ACTION: EA, IDBs, LAs, MAFF)
Site safeguard and management
Where possible, ensure that all occupied habitat is appropriately managed, including periodic ditch cleaning on the Somerset Moors, by 2008. This may be through SSSI or agri-environment scheme management agreements. (ACTION: EA, NE, IDBs, MAFF)
Ensure that the habitat requirements of Hydrochara caraboides are taken into account in any relevant development policies, plans and proposals. (ACTION: NE, LAs)
Ensure that the species is included in site management documents for all relevant SSSIs. (ACTION: NE)
Consider notifying as SSSIs sites holding key populations of the species, where this is necessary to secure their long-term protection and appropriate management. (ACTION: NE)
Species management and protection
None proposed.
Advisory
Advise landowners and managers of the presence of this species and the importance of beneficial management for its conservation. (ACTION: EA, NE, MAFF)
As far as possible, ensure that all relevant agri-environment project officers, and members of regional agri-environment consultation groups, are advised of locations of this species, its importance, and the management needed for its conservation. (ACTION: NE, MAFF)
Future Research and Monitoring
Undertake further surveys to determine the status of this species. (ACTION: NE)
Establish a regular monitoring programme for this species. (ACTION: NE)
Conduct targeted autecological research to inform habitat management. (ACTION: NE)
Pass information gathered during survey and monitoring of this species to a central database for incorporation in national and international databases. (ACTION: NE)
Communications and Publicity
Promote opportunities for the appreciation of the species and the conservation issues associated with its habitat. This should be achieved through articles within appropriate journals, as well as by a publicity leaflet. (ACTION: NE)
Links with other action plans
None given.
Publication details
Originally published in: UK Biodiversity Group Tranche 2 Action Plans - Volume IV: Invertebrates (March 1999, Tranche 2, Vol IV, p87)
Related links
ARKive Visit the ARKive website to view images and further information relating to this species