Current status
Lophopus crystallinus is one of 11 freshwater bryozoans found in the UK, and is the only member of its family in this country. Bryozoans feed on minute organisms suspended in the water column. L. crystallinus lives in lakes, ponds, ditches and slow rivers, where it has been found growing on a variety of substrata including water plants, rocks, shells, wood and dead leaves. Bryozoans are hermaphrodites. Sexual reproduction produces a short-lived free-swimming stage. They also reproduce asexually in two ways: by 'budding' from the mature colony; and by producing statoblasts, a seed-like resting stage which is able to withstand environmental extremes and can remain dormant for several years. The characteristic floating statoblasts of L. crystallinus are the most likely means of long-distance dispersal.
Since 1970 L. crystallinus has been found at only four sites: Bagmore Pit, Norfolk; Chil Brook, Oxfordshire; Barton Blow Wells, South Humberside; and near Westhoughton, Lancashire. There are older records from: near Port Meadow, Oxfordshire; several of the Norfolk and Suffolk Broads and waterways; Langmere, Norfolk; Hartwell, Buckinghamshire; Little Baddow, Essex; and Chelsea, Middlesex. A record from the River Ravensbourne, Kent, is undated. It is typical for records of this species at any particular site to be for a short period only; this may be a natural aspect of its ecology or because continual occurrences tend not to be reported. Lophopus crystallinus has been widely recorded in Europe but its current status outside Britain is not known.
In Great Britain this species is classified as Rare.
Current factors causing loss or decline
Eutrophication of water bodies.
Water abstraction.
Over-tidying of waterbodies, especially the removal of fallen wood.
Current action
Barton Blow Wells are within Barton & Barrow Clay Pits SSSI.
Action plan objectives and targets
Maintain all long-term populations of Lophopus crystallinus.
Facilitate natural increase in the number of populations by 2010.
Proposed actions with lead agencies
Policy and legislation
Address the requirements of this species in the LEAP process and in relevant WLMPs. (ACTION: EA, IDBs, LAs, MAFF)
Take account of the species? requirements in response to applications for water abstraction licences. (ACTION: EA)
Site safeguard and management
By 2004, reduce water abstraction from Barton Blow Wells aquifer and Breck aquifers. (ACTION: EA).
Where possible, ensure that all occupied habitat is appropriately managed, including the reduction and elimination of sources of eutrophication or pollution, by 2008. (ACTION: NE).
Ensure that this species is included in site management documents for all relevant SSSIs. (ACTION: NE).
Consider notifying as SSSIs sites holding viable populations of this 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 the species and the importance of beneficial management for its conservation. (ACTION: EA, NE)
Future Research and Monitoring
By 2004, assess the possibility of surveying for Lophopus crystallinus by examining sediments for statoblasts, using pollen concentration techniques. (ACTION: NE).
Conduct targeted autecological research to inform habitat management. (ACTION: NE, EA)
By 2000 start long-term surveillance of one or more populations, possibly using artificial substrata to allow quantitative population studies, in order to study natural fluctuations in population size. (ACTION: EA, NE)
Trawl for unpublished records through appeals in appropriate literature, and undertake surveys to determine the status of this species, by 2004. (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 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, p437)
Related links
ARKive Visit the ARKive website to view images and further information relating to this species