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Dept for Environment Food and Rural Affairs

Answer

Mrs. Helen Clark: To ask the Secretary of State for Environment, Food and Rural Affairs if she will make a statement on trends in populations of invertebrates in the River Nene following the pollution incident earlier this year; what evidence is publicly available of population levels; what evidence she has collated on whether species that are restricted to the affected section of the river are now extinct; whether there has been a survey for the Red Data Book of the riffle beetle Stenelimis canaliculata; whether a survey is planned; and what plans the Environment Agency has to repair damage to biodiversity as a result of the incident. [143261] Mr. Morley: The results of the routine biological monitoring of the River Nene in spring 2003 showed that biological water quality at Cogenhoe (NGR SP 831 615) (mid reaches of the River Nene) and sites as far downstream as Orton Staunch (NGR TL 167 973) were uncharacteristically poor. In particular, there was a general absence of water hog louse, mayflies and freshwater shrimp, normally commonly occurring freshwater invertebrate species in the River Nene. In contrast, the invertebrate community at Duston Mill (NGR SP 730 597), the routine monitoring site further upstream of Cogenhoe, suggested good water quality with these taxa found in abundance. Results of a survey undertaken in September 2003 from sites along the River Nene show that biological water quality at Billing Road Bridge and Cogenhoe (mid reaches of the River Nene) is improving (although water hog louse and freshwater shrimp is still absent). In contrast, the invertebrate community at sites in the lower reaches of the River Nene has largely recovered, and these sites achieved their water quality target rating. Recently an additional survey has been undertaken at the same sites. Although sample processing is not yet completed, initial observations suggest that mid reaches of the River Nene are still impacted by the pollution incident that occurred earlier in the year. Of particular concern is the continuing absence of water hog louse and freshwater shrimp. The Environment Agency undertakes routine freshwater invertebrate surveys in spring and autumn seasons each year at specific sites along the River Nene. This information is available to members of the public upon application to the Environment Agency Customer Services Department in Lincoln (Tel. 01522 513100). Additional surveying of the River Nene and Hardingstone Dyke was undertaken to locate the source of the pollution. Data arising from these surveys is not currently available pending the outcome of the Environment Agency Special Enforcement team review of this case. Monitoring undertaken to record recovery of the River Nene and Hardingstone Dyke, is also available to members of the public, on application to the customer services department. Surveys have been undertaken at three-monthly intervals at important sites along the River Nene using standard methods which sample the accessible margins of the watercourse using a pond net. Key species (water hog louse and freshwater shrimp) which were absent at sites along the mid reaches of the River Nene remain absent. The Red Data Book riffle beetle Stenelimis canaliculata was not found in any samples taken in 2003, although it has been recorded very infrequently in the lower reaches of the River Nene in the past. It is difficult to say whether its absence is related to the pollution incident, as it is a deep-water species and unlikely to be sampled using Environment Agency standard methodology. The Environment Agency have not carried out a specific survey for the Red Data Book riffle beetle Stenelimis canaliculata and have no plans to conduct such a survey. To do so would disturb the habitat, which could be damaging to this and other deep water species. It is not normal practice to restock invertebrate populations damaged by pollution incidents; invertebrate populations usually recover through natural colonisation from tributaries and unaffected sites upstream, or natural invertebrate re-distribution. Fish were not affected directly by the pollution incident, so fish re-stocking is not necessary. However, the longer term health of fish populations in the mid reaches of the River Nene may be affected because their food source remains depleted.

Secondary information

Type

Written question

Reference

143261; 415 c825-6W

Session

2003-04

Subjects

Biodiversity Fish Insects Pollution Nature conservation Rivers Shrimps Beetles River Nene

Link

View this Written question on www.publications.parliament.uk