Derbyshire Rivers put under the microscope in flylife study

We are in process of reporting the results from the second year of our unique three-year national Riverfly Census. The census aims to assess the health of our English and Welsh rivers through monitoring the water insect communities that live below the surface.

This important research has revealed that nationally no significant improvement in the condition of our rivers and chalkstreams has occurred on the initial 12 rivers included in the study over the past two years.

Dr Janina Gray, S&TC's Head of Science says:

"The message from our Census is that 2016 was yet another worrying year for freshwater habitats across the country from Cornwall to Northumberland. Where problems exist, sediment and phosphate remain the main threats that are polluting our Census rivers."

However, the river Wye in Derbyshire has bucked this trend and the results from the Census were very good overall although there were signs of some potential problems at two of the sites tested.

In contrast the river Dove did not fare so well and is showing signs of pollution as well as being impacted by invasive species like American signal crayfish and the demon shrimp.

Nick Measham, from S&TC says:

"The results of our Riverfly Census on the Wye were encouraging. We sampled five sites at Anglers Rest, Tideswell Brook, Cressbrook Mill, Bakewell and Rowsley. In the survey Rowsley was the best site as there was no sediment or phosphate impact and the spring mayfly species count was higher than any other site tested."

However, Nick Measham adds a cautionary note. He says:

"A worrying factor is that the Wye and the Dove are both part of the Trent catchment, and so strict biosecurity is essential in order to reduce the risk of the demon shrimp and the American signal crayfish impacting on the health of the River Wye in the future."

Unfortunately, the River Dove is starting to show signs of stress from pollution. Five sites were included in the survey at Hollinsclough, Milldale, Mayfield, Rocester and Hatton. Although most of these sites were impacted in some way from the polluting effects of sediment and phosphate, the researchers also detected a worrying increase in invasive species such as the demon shrimp. The count also revealed that Gammarus shrimp, which are an important food for many aquatic species, were either present in very small numbers or completely absent. On a healthy river numbers of Gammarus should be counted in their thousands.

Dr Gray continued:

"The evidence from our Census shows phosphates and sediment are having a disastrous impact on invertebrate communities in certain reaches of our rivers. They are toxic to invertebrates in isolation and more so in combination. Loss of flylife causes major disruption to the delicate balance of the aquatic food chain, with fish, mammals and bird populations suffering as a result. Understanding why and to what extent riverfly numbers, such as blue-winged olives, or Gammarus are declining is the first step in the process of safeguarding the aquatic environment. We are using these results to help fuel real improvements on our rivers. For example, we have worked with the local Environment Agency on the Test and Itchen in Hampshire to agree bespoke targets for mayfly species and Gammarus shrimp to drive action."

Nick Measham adds:

"Our rivers and chalkstreams are wonderful places of solace. However, although these rivers may appear healthy on the surface, our research shows that many are suffering underneath."

Current monitoring largely fails to pick up the pollution pressures these rivers are facing from sources such as farming, road run-off, poorly treated sewage, septic tanks, new developments and in certain areas discharges from fish farms. We are therefore calling for local people to challenge and act for their rivers.

Nick Measham explains:

"Although the Wye is currently recording a very positive result, we do not believe there is room for complacency. It is therefore vital that local people help change the way our rivers are managed by demanding better protection and monitoring, so that rivers like the Wye are kept in pristine condition. We can suggest training for people who wish to become more 'hands on' with monitoring the condition and quality of their own river. Alternatively get in touch with us so that we can take forward issues with local MPs or the Environment Agency. This is a call to arms to everyone to help save our rivers and the important aquatic wildlife that clean water supports."

For further information on the Riverfly Census or to contact Salmon & Trout Conservation, please email: lauren@salmon-trout.org