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BRISTOL AVON RIVERS TRUST
"A Clear Future for our River"

Research

We have reached 60 Riverfly monitors!

We have reached 60 Riverfly Partnership monitors! These volunteers each sample their site once a month, monitoring invertebrates as indicators of water quality. They help us to gain a long term dataset on the health of rivers, as well as identifying pollution incidents to enable response by the Environment Agency.

Click here to find out more about our Riverfly monitoring.

A massive thank you to all our dedicated volunteers! If you are interested in being trained, please get in touch with jess@bristolavonriverstrust.org

BART electrofishing surveys

BART are pleased to announce that we now own our own set of electrofishing kit. BART has been conducting electrofishing surveys for some time with partners, however we have now been able to raise sufficient funds for our own equipment.

Electrofishing is a fish surveying technique combining a mixture of electrical current with a known water conductivity to temporarily stun fish in order to measure and document the population and community fish statistics at a freshwater location. BART ensures that all members of their electrofishing team have adequate training and experiential learning to ensure that fish receive good animal husbandry and are returned to the watercourse in good health with zero impact upon the population as a result of the survey.

BART electrofishing surveys

We hope to use this around the catchment to monitor fish populations to determine sites in need of improvement works and also to follow the success of future restoration works. We have already been out to survey the Norton Brook to guide future restoration plans there, and were pleased to find a good number of juvenile trout.

A juvenile trout from the Norton Brook, Bath

2019 Bristol Avon Waterblitz – the results!

Thank you to all of our 424 wonderful volunteers for your efforts in monitoring for us this year. You can find out the results of the 2019 Waterblitz below!

You can also explore the data further on the interactive map.

What do the results show?

What do these results mean for our freshwater environments?

Elements such as phosphates and nitrates occur naturally in freshwater and are nutrients for plants and important for wildlife. However, at unnaturally high levels they are pollutants, impacting the freshwater ecosystem in detrimental ways. Excess nutrients cause algae, fungi, bacteria and some tolerant water plants to grow more rapidly and become more abundant than they would naturally. The consequences of this are that intolerant species are smothered, outcompeted or directly poisoned resulting in many species becoming rarer. Toxic algal blooms harm aquatic invertebrates and fish by reducing the amount of oxygen in the water and can lead to increased costs of drinking water treatment downstream. In the United Kingdom around 90% of lowland surface freshwaters like rivers, streams and ponds have ecologically damaging levels of either nitrogen, phosphorus or both (Biggs et al. 2014).

The data collected during the 2019 WaterBlitz shows that pollutant levels are high in many parts of the Bristol Avon catchment and have either stayed consistently high or increased in the past 3 years. It demonstrates a greater need to address the causes and decreasing the movement of pollutants into local watercourses, particularly though sewage effluent, fertiliser run-off and from urban surfaces. The WaterBlitz data you collected is being used to identify pollution hotspots where action needs to be taken.

How can you help?

  • Volunteer with your local Rivers Trust or community group. Get involved in river cleans, restoration projects and community initiatives to decrease pollution.
  • Reduce pollution by only flushing the 3 P’s, avoid pouring fats and oils down the sink, compost food waste and limit the use of household detergents and garden fertilisers.
  • Collect data during future WaterBlitz. Look out for- and report- pollution incidents when out for a walk (24/7 to the Environment Agency on 0800 807060) and get involved in citizen science events.

These above results are available as a PDF which is available on request from harriet@bristolavonriverstrust.org

Forgotten Landscape Project: Identifying the barriers to eel migration

BART are investigating the migratory passage of European eels in the Lower Severn Vales as part of the Forgotten Landscape Project. We are aiming to assess the success of eel passability into the project area by looking at where eel passage is detrimentally affected by the presence of barriers and establishing the priority barriers for more detailed fish passage investigations.

The Severn Estuary

The European eel (A.anguilla) has recently been classified as ‘critically endangered’ on the IUCN red list after populations have declined by 90-95% since the 1970s (IUCN, 2014). This decline is in spite of their extensive ecological and socio-economic importance, with approximately 25,000 people generating income from eel fisheries and aquaculture in Europe alone during the 1990s (Moriarty & Dekker 1997). Multiple factors have contributed to the decline including the exploitation and trade of glass, yellow and silver eels, habitat loss, pollutants, parasites, disease and predation. Once in freshwater, hydraulic schemes constitute a physical barrier to free upstream and lateral migration and, unless alterations for passage are considered, limit the areas where eels are present, as well as their densities.

European eels have a fascinating life history that sees them migrate from the Sargasso Sea near Bermuda to European freshwaters and back again. They begin their lives on the far side of the Atlantic as eggs and drift towards Europe with the Gulf Stream, hatching into leaf-shaped larvae as they travel. When they arrive in Europe they transform into the transparent fish known as glass eels, taking on the recognisable cylindrical shape before making their way into freshwater through estuaries and rivers. Having completed 7,000 kilometres of their migration, eels darken in colour and become known as elvers and attempt to migrate upstream where they can remain for more than 20 years. During this time the “yellow eels” will feed on invertebrates and fish until they are ready to reproduce and migrate back to the sea as silver eels to spawn. It has been noted that larger eels are more effective swimmers and better suited to traversing barriers such as weirs and dams in both directions so their ability to find food and suitable habitat on UK rivers is crucial for their spawning success.

It is important to recognise the physical barriers to eel passage because they must be able to swim upstream to feed and grow for a significant part of their lives before they are able to make the long journey back to their spawning grounds. There are many natural and human-made structures that can prevent eels (and other fish) from migrating. These include: tidal gates, dams, weirs, barrages and sluice gates. Eels and elvers are robust creatures and are able to travel along damp surfaces to reach a water course, however the barriers are often too steep, the water too fast flowing or surface too smooth for them to negotiate. This initial research will identify the presence of these barriers and establish the priority barriers for more detailed fish passage investigations and the available options to enable more successful eel migration (downstream and upstream) in the Severn Vale.

Tidal gate: an immediate barrier to eel migration

Bristol Avon Waterblitz 2019

Bristol Avon Rivers Trust are excited to announce the 2019 Bristol Avon WaterBlitz; a yearly campaign to collect as many water quality samples as possible in a week from across the Bristol Avon Catchment, between Saturday 1st June – Friday 7th June.

Join hundreds of people in using the free and simple to use water testing kit to sample your chosen river or stream in the Bristol Avon catchment (Bristol, Bath, South Gloucestershire, Wiltshire and North East Somerset).

To register and take part, please follow the link below to sign up and you will then receive a free water quality sampling pack in the post. Sampling kits are limited so please register by Friday 24th May to ensure you can participate:

https://tinyurl.com/waterblitz

Thanks to Bristol Water and the Avon Frome Partnership for supporting this year’s Waterblitz!