Chemical pollution is one of the main causes of degradation and biodiversity loss in aquatic ecosystems.
But why are chemicals such a problem for salmon, trout and their waters?
More than 300,000 inventoried/regulated chemicals are currently used in industry, household and agriculture - which ultimately end up in our waters.
While European water bodies are contaminated with complex mixtures of ten thousands of chemicals, chemical status is defined on the basis of only 45 substances.
Concentrations of chemicals in the water may not reflect the true burden on river life, as chemicals may accumulate in tissues and be passed up the food chain.
Chemicals can harm river life lethally, where exposure causes direct death, and/or sublethally, where physiological pathways and natural behaviours are disrupted.
The Bakkavor Story
Concerning chemical signatures coupled with low Gammarus numbers and mayfly species richness (identified from our Riverfly Census project) led us to investigate below the Bakkavor salad washing factory on the River Itchen.
The bed of the stream should have shown clear, un-sedimented gravel. Instead the dominant and major composition of the biological growth covering metres of the bed was filamentous algae, with some fungal component.
It was clear from our evidence that the current discharge permits were not fit for purpose to protect the river.
We took this case study on as part of our Water Action project, as we felt it highlighted a national problem. If policy is not stopping deterioration from chemicals on a protected SAC, SSSI river - what hope is there for other rivers?
We were concerned about two things:
The overnight factory wash discharge
The day time salad washing discharge
Bakkavor progress so far
Chemicals - a national problem
We believe that businesses should not be allowed to damage the environment- they should return water in at least the same state as they receive it
Many historic discharge permits, for businesses still operating today, have not been revised and as a result are not fit for purpose to protect our waters.
Current monitoring* covers only a tiny fraction of the chemicals entering our waterways, ignoring biological impacts and mixture effects
SPEAR is a way of calculating chemical impact on rivers by looking at the presence and absence of water invertebrate species. Currently SPEAR is not used in the UK, but proposed boundaries to incorporate it into Water Framework Directive calculations do exist. Using our data, we are encouraging the use of SPEAR nationally in monitoring our watery places for chemicals.
*of priority substance-based chemical status according to the Water Framework Directive (WFD)
Chalkstreams should have their own classification under the Water Framework Directive
Our Bakkavor case study has demonstrated the value of invertebrate data - but for chalkstreams it has highlighted that current designations are not good enough to protect them from chemical damage.
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