Thinking About Rivers

On “Springwatch” this evening, Monday, June 5th, there was an item about  the importance of rivers as a habitat and the health of the rivers to be found in Europe and Britain.

Presenter, Chris Packham, revealed that the European Water Framework had looked at the quality of rivers in Europe and found that 43% of them were ecologically good. When it came to those in Britain, however, he said, 17% were good and just 0.08% were in high order.

Problems in the rivers could be caused by a number of issues, including run-off from farms and roads, pollution from sewers and over abstraction for crops.

This riparian environment, where two types of habitat – land  and water – met, could be very rich and was of tremendous importance for biodiversity, Chris explained.

To start with, there were the plants, both those on the bank and the emergent vegetation in the water, providing food and shelter for various insects, amphibians and aquatic creatures. Water voles and water shrews could move in, as well as keystone predators such as otters, which could not live in polluted waterways.

He desribed the ideal riparian environment, which would have trees close to the river  bank and plants along the bank and in the water. These would act as a buffer to airborne or flood pollutants and provide shelter for many creatures. Remove the trees and plants and canalise the river and you had the potential for disaster as the run-off would go straight into the water and choke everything up. Chris described how in that sort of situation, creatures in the gravel of the river bed, such as young fish or insect larvae, would not be able to breathe.

The water in the Gaywood River is really clear.

This item reminded me of  a recent trip I made along with other members of the Gaywood Valley Conservation Group to a section of the Gaywood River in Derby Fen, a few miles from King’s Lynn. One of our members, Alistair, is a River Guardian, which involves him sampling the water quality on a regular basis and looking out for the different types of  plants and creatures in and around the waterway. He reported that the water quality was good and remarkably consistent along its length from its starting point in fenland right into King’s Lynn, where it eventually ran into the River Great Ouse. Water levels were also remarkably consistent.

The 11 kilometre long Gaywood River is one of nine chalk rivers in Norfolk and one of only around 200 in the world.

While at Derby Fen members of the Conservation Group saw some of the traps Alistair uses to catch samples of river invertebrates – they are later released – and helped catch others with nets. Among the samples were some small fish; three species of mayfly larvae, including a carnivorous one; shrimps;  and caddis fly larvae. He has data going back to 2003 which shows 150 different taxa have been discovered in the Gaywood.

It was an enjoyable and interesting outing even though it rained quite a bit of the time! And it showed how important our rivers are, whether they are large or small.

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