Growth of the Riverfly census to help tackle pollution in Welsh rivers

An increase in the pollution of rivers in Wales has led to the launch of a three-year scientific monitoring programme by Salmon & Trout Conservation to find out exactly how Welsh rivers are doing health wise.

This study is an expansion of our existing Riverfly Census. The results from 12 English rivers over the past two years have showed us that many of the country’s watery places are in a perilous condition.

Richard Garner Williams, our Welsh officer, explains the science:

“Last autumn saw the start of our innovative Riverfly Census monitoring programme in Wales. This highly informative method of analysis aims to assess the health of our rivers through monitoring the diversity of freshwater insect communities. The loss of the aquatic stages in the lifecycles of bugs such as caddisflies and mayflies causes major disruption to the delicate balance of the aquatic food chain, with fish, mammals and bird populations suffering as a result.”

Different invertebrate species have unique tolerances to specific types of pollution. Therefore, the presence or absence of a species provides an excellent indicator of the underlying ecological condition of our rivers and accurately pinpoints potential pollution sources. The threat to our rivers has moved from industrial pollution to a range of more subtle but equally damaging impacts, including the pollution from some forms of intensive agricultural production, which can be toxic to river insects – a vital part of the food chain within rivers.

The three rivers included in the Riverfly Census in Wales – the Clwyd, Usk and Cleddau Ddu or Eastern Cleddau – represent a good geographical spread across the country. Over the next few years we will be able to gather crucial evidence about the condition of these rivers and, when problems are identified, to develop workable solutions to reverse the decline in biodiversity and water quality.

Richard Garner Williams continued:

“The results from the 2016 autumn sampling have formed an important baseline for measuring the condition of these rivers in subsequent years. Early results on the Eastern Cleddau and, to a lesser extent the Clwyd, indicate that agricultural pollution may be taking its toll. In contrast, the early results on the River Usk are more promising, but there is never any room for complacency and we need more data over future years to provide an accurate picture.”

Understanding why and to what extent riverfly numbers, such as blue-winged olives, are declining is the first step in the process of safeguarding the aquatic environment. We are using our results in England 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 to drive improvements. We now want to be just as forensic in Welsh rivers!

Pollution incidents are occurring far too frequently in Wales, especially in the milkfields of West Wales, where waste products from intensive dairy production are having a devastating impact on the freshwater environment. This is a major concern for all of us who care about our rivers and aquatic wildlife. However, the results from our Riverfly Census will help to provide the scientific evidence needed to identify specific problems and to develop workable solutions in order to guide meaningful restoration and avoid further incidents. We look forward to working with Natural Resources Wales, the Welsh Government and other stakeholders to ensure this happens for the benefit of our rivers and the wild fish of Wales, both now and in the future.

For further information the Riverfly Census in Wales, please contact: Richard Garner Williams on:

Leave a Reply

Your email address will not be published. Required fields are marked *