The best way to tell if a river is healthy is to monitor its invertebrates. These are little animals without backbones and they make up an amazing 97% of all life on earth. The most important invertebrates in a river are tiny creatures like Mayflies, Stoneflies, Caddis Flies and Freshwater Shrimps. If a river is full of all these, then there’s a good chance it’s healthy. If they’re not there in large numbers – or if some of them are missing – then something is probably wrong.
Old monitoring
The Cain Valley River Group (CVRG) started monitoring the Cain’s invertebrates back in 2008. At first we were trained and equipped by the Environment Agency and then by the Riverfly Partnership. We ‘kick-sampled’ a bit of river-bed into nets which we transferred to trays full of water. Then we crouched on the river bank, counting the target species. How many mayflies? How many shrimps? Looks good. Then we’d tip the creatures back into the river, fill in a form and send it off to a central record. CVRG monitors did this at up to six selected spots between the start of the Cain just outside Bodfach Park and its conclusion about nine miles away in Llansanffraid.
New monitoring
Then along came the Wildfish ‘SmartRivers’ project which offers river monitoring which is far more sophisticated than anything we’ve done before. Now our kick-sampling in the river is more precise and instead of crouching on river banks, we sit at tables in the Llanfyllin Institute. We separate the creatures into families and then separate the families into species. Take Caddis flies. There are six families of Caddis flies and in the Cain there are twenty-two species! With this sort of analysis you can also learn about the river flow, the levels of chemical and organic pollution and how much the river is under stress from sediment and phosphorus. This is real science!
Close-up knowledge
Of course this sort of monitoring is far beyond a group of amateurs, but here in the Cain Valley we’re really lucky. The Severn Rivers Trust (SRT) with whom we’ve worked for many years, has taken over much of the SmartRivers analysis and our role now is therefore to support them by providing volunteers to kick-sample and help with the sorting and counting of invertebrates. This sorting needs strong lights and microscopes but the SRT has great equipment. We’ll be doing this twice a year – in Spring and Autumn – and the result will be a really fantastic close-up knowledge of the Cain. We’ll know precisely what’s good and what isn’t and then we’ll be able to take action to improve things if we need to.
If you’d like to spend a few hours in the fascinating world of river invertebrates, then become a SmartRivers monitor. Contact Charlotte Davies for more details.
You can also join the next session on Tuesday 29th July at 10am. Click here for more details.