Charity urges citizens to challenge the health of their local West Country rivers
Fisheries charity, Salmon & Trout Conservation (S&TC ) has just completed the second year of its unique three year national Riverfly Census.
The results of the Riverfly Census on the River Camel were encouraging but S&TC warns that we have to be vigilant to help keep our rivers clean and healthy and free of pollution from phosphate and sediment.
Fisheries charity, Salmon & Trout Conservation (S&TC ) has just completed the second year of its unique three year national Riverfly Census. The census aims to assess the health of our English and Welsh rivers through monitoring the invertebrate communities that live below the surface.
This important research has revealed that nationally sediment and phosphate are repeatedly causing major pollution problems and no significant improvement in the condition of the 12 rivers chalkstreams included in the study has occurred, in 2015 or 2016.
More rivers have been added to the Census in 2016 and 2017 bringing the total number of rivers in the Census to 23.
Two West Country rivers were surveyed - the Axe and Camel. The Axe showed evidence of degradation in the lower catchment. The Camel generally bucked the degradation trend but the charity warns that there is no room for complacency as without vigilance, river pollution could still pose a major problem.
According to S&TC the threat to our rivers has moved from industrial pollution to a range of more subtle but equally damaging impacts from excess phosphates and fine sediments. These enter our watercourses from sources such as agricultural and road run-off, poorly treated sewage, septic tanks, and new housing developments.
The River Axe is a rain-fed river that supports salmon, sea trout, brook and sea lamprey. It also has Special Area of Conservation (SAC) protection designation for its aquatic plants.
On the Axe, five sites were surveyed: Seaborough, Forde Abbey, Wadbrook, Cloakham Bridge and Whitford Bridge. A mixed picture was found - the upper reaches appeared relatively clean but the lower reaches indicated damage from sediment and phosphate pollution. Thus, having a detrimental impact on riverfly species in the lower catchment.
One measurement used in addition to the number of riverfly species to determine a river's health is the number of freshwater shrimp (Gammarus) in a three-minute kick sample. These were low in number on the Axe and, while this could simply be a function of habitat, it could indicate other factors at work such as pesticides, insecticides and livestock treatments such as cattle wormers.
The river Camel fared much better than the Axe. Rising in Bodmin moor, the Camel has a special conservation designation because of its otter population and bullheads. Five sites were measured in the Census including; Slaughter Bridge, Wenford Bridge, Dunmere Bridge, Nanstallon and Polbrook Bridge. The spring and autumn results identified that the Camel is a clean river and generally unimpacted by sediment or phosphate. It also has very good riverfly species richness with relatively modest Gammarus shrimp populations.
Dr Janina Gray, head of science with S&TC said, "The results from the 2016 spring and autumn counts were very encouraging on the Camel but give some cause for concern on the Axe, which is suffering from the effects of sediment and phosphate pollution in the lower reaches of the river.
Phosphate and sediment are both toxic to invertebrates in isolation and more so in combination. They damage water quality and the overall ecological health of the aquatic environment, in turn impacting wild fish. We do feel that this is a wake-up call and that prompt action should be taken to lessen the impact of pollution."
Dr Gray continued, '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 these results to help drive real improvements on our rivers, for example we have worked with the local Environment Agency on the Test and Itchen to agree bespoke targets for mayfly species and Gammarus shrimp to drive action. We will be using this as a case study to help agree similar targets for the other rivers in the study, beginning with an expert workshop in the autumn."
Nick Measham, Campaign Manager at S&TC said, "The aim of our Riverfly Census is to provide an accurate picture of water quality, to gauge the problems we are facing and to identify workable solutions to restore degraded watercourses. To do this, we analyse the invertebrates down to individual species rather than families. The increase in resolution is akin to moving from a magnifying glass to a microscope. The evidence from our Census is irrefutable. Increased phosphates and fine sediments are having a disastrous impact on invertebrate communities in our rivers. 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."
The Riverfly Census measures the number and abundance of invertebrate species in a three-minute kick-sweep sample. Different species have unique tolerances to specific types of pollution. Therefore, the presence or absence of species provides an excellent indicator of the underlying ecological condition of our rivers.
As can be seen from the results of S&TC Riverfly Census on these two West Country rivers it is imperative that people who care about their local river start to act now.
Nick Measham explains, "Our rivers and chalkstreams are wonderful places of solace. However, although these rivers may appear healthy, our research shows that there is a time-bomb lurking just below the surface."
According to S&TC, river monitoring is often not picking up the pressures these rivers face. The charity is therefore calling for local people to challenge and act for their precious rivers.
Nick Measham explains, "We would like local people to help change the way our rivers are managed by demanding better protection and monitoring. 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."