River Reflector January 2019

By Richard Holmes 

Have you ever wondered why maggots are different colours? or why killer shrimp are the most damaging invasive species in Western Europe? Read the lastest of the River Reflector for an overview of our current projects and events coming up!

Rivers Team January 2019 Project Update!

The Rivers Team have hit the ground running this year- whether that be the huge amount of interest in our River Health Training Programme or planting hedges and trees to Slow The Flow. Read our project overviews to find out more!

River Health Training Programme

This January the river health training programme was held at a very wintery Carding Mill Valley. Despite the cold weather there was an amazing turnout, including a group from Harper Adams University who used the session to find out more about river health monitoring for their university project. There were also positive results with the average score for our invertebrate sample (7.2/10) being one of the best scores collected in our river health training sessions. In addition, River Rangers which involves river health monitoring with children, has begun and we are now receiving bookings for schools within Shropshire. Go to Events to find out when are next training session will be! 

River Reflector

River health training at Carding Mill Valley

Black Poplar Recovery Scheme 

Most people are unaware that the Black Poplar is the most endangered native tree in the UK. There are only 7,000 specimens remaining in Britain, including only 400 female species. Shropshire has the best habitat for these species due to them favouring lowland floodplains and river banks. These trees provide an abundance of food for the caterpillars of many moths, including the hornet, wood leopard, poplar hawk and figure of eight. In addition it provides an early source of pollen and nectar for bees and other insects.

The Black Poplar Recovery Scheme is hoping to increase the population of these trees and the species that thrive on them. Dedicated volunteers and farmers have planted 82 trees so far at several farms as well as National Trust Estates including Attingham Park, Dudmaston Estate and Long Mynd . The Rivers Team would like to say a big thank you to our sponsor John Hutchinson and to Severn Trent for their support. Also, Thank you to everyone who has put in their time and effort to planting these worthy trees. 

Black Popular Planting

Carole Bickerstaff, John Hutchinson, John Bowen and Cath Edwards planting Black Poplar alongside the River Roden 

Slow the flow In Shropshire

Shropshires Slow The Flow project has received support from a National charity, 10:10 Climate Action in a  tree planting project along the River Corve to help prevent flooding by slowing water flow and absorbing carbon from the atmosphere.  Corvedale has become a flooding hotspot, which has brought problems to downstream communities. This along with Hedgerow planting to intercept rainfall as well as installing debris dams will create more habitats and help tackle the flooding issue. You can see debris dams in action at Wilderhope Manor, Shropshire. 

Want to do your bit to combat climate change? Come along to New House Farm, Shipton, TF13 6LB on Saturday 2nd of February between 10am and 15:00pm to learn about trees, flooding and to get your hands dirty and plant a tree.  Everyone's welcome.  Click on the link to out more on Shropshire's Slow the Slow https://www.shropshirewildlifetrust.org.uk/rivers/slow-flow


Planting trees in the Corvedale 



Depave UK 

The Rivers Team have been supporting an ongoing campaign called Depave UK. This not only encourages water management in the countryside but also in urban areas such as Telford. Depave UK aims to remove unwanted hard paving  to prevent contaminated surface water reaching our rivers and ponds. It does this through creating rain gardens (a small depression that holds and soaks up water) and replacing impermeable surfaces to permeable. 

Currently the Rivers Team are working with  Hub on the Hill in Telford to improve biodiversity and solve surface water problems. There are current plans to install raised beds to capture runoff from the roof, remove unwanted tarmac and plant more plants to improve biodiversity. 

Come to Hub on the Hill from 12th to the 15th of February between 10:00am and 16:00pm to transform it into a biodiversity haven! For more details contact kpiercy@shropshirewildlife.org.uk

hub on the hill

Help to Improve Hub on the Hill 

Is there more to Freshwater Shrimp than we think?

Freshwater shrimp (Gammarus pulex), native to Great Britain , are one of the most common creatures in our rivers. The abundance of them often means they are overlooked amongst other invertebrates but they play a crucial role in the underwater ecosystem. Shrimps are detrital feeders (eat decomposing plant and animal parts) and have a curved greyish body that enables it to propel itself through water and under rocks. This strategy enables it to protect itself from predators such as trout, bullhead and dippers.

Unfortunately for the freshwater shrimp, it has many predators but certain adaptations enable them to keep the population strong and sustained. For example, big compound eyes give them 360o vision so that they can see predators all around them. They also have well developed antenna which allow them to navigate and find food on the riverbed.  

However, the most crucial adaptation is their reproductive system. If you have ever caught shrimps in a net you may find two shrimps holding onto each other. This is not young but a female. The males will cling onto the chosen female for several weeks until she sheds her skin and produces eggs. This can be as many as 50 a month. After this, the young shrimp will hatch into adult form and begin to breed keeping the population high. Interestingly, freshwater shrimp are very sensitive to conditions around them. Temperature in particular can determine the sex of the offspring. For example, below 5°C it becomes a male, above this, a female.

Freshwater shrimp prefer flowing water such as streams and rivers but can be found in ponds. They are intolerant of large amounts of pollution and low dissolved oxygen levels which make them a good indicator for measuring water quality. No matter what the weather, these invertebrates can be found throughout the year making them a pretty remarkable creature. 

Freshwater shrimp has proven that there is more to them then we think but to support this even more there is a reason to why fishing bait such as maggots, boilies and fishing lures are often coloured pink. A parasite called Pomphorhynchus laevis is a common pest in crustacea such as shrimps. If ingested it can cause shrimps to change their behavioural patterns and worst make them glow a pinkish/reddish colour. This bright colour makes their predation risk go from high to inevitable and fish such as perch and trout eat them. The parasite then lives on inside the fish. 

River Reflector

Parasite Pomphorhynchus laevis living inside freshwater shrimp 

Identifying freshwater shrimp to killer shrimp

Unfortunately there are many threats to our UK’s waterways, these come in the form of invasive species such as Himalayan Balsam, Creeping Water Primrose and Signal Crayfish. However, the most feared and damaging invasive species to hit Western Europe is the Killer Shrimp (Dikerogammarus villosus). Brought here by birds, ballast water and angling equipment, these shrimps can grow to 30mm and survive in brackish condition (freshwater and saltwater). Originating from Ponto-Caspian region of Eastern Europe they have invaded majority of Europe’s waterways. In the UK they have been spotted in Grafham water in Cambridgeshire and Cardiff bay.

Unlike the freshwater shrimp (Gammarus pulex) these shrimp are known to be aggressive and a voracious predator. The killer shrimp are a major predator to native shrimp, mayflies, damselflies, leeches, snails, fish eggs and larvae. Their impacts on native populations could lead to impacts in nutrient processing and effect ecosystems dramatically. However, other species such as trout and perch may benefit from increased food. Improving biosecurity is the main measure to prevent these shrimp from accessing other parts of the UK.

The main ways to distinguish freshwater shrimp from killer shrimp is to look at the tail features. Killer shrimps have cone- shaped protrusions topped with small spines whereas freshwater shrimp have small clusters of spines but no protrusions. visit www.nonnativespecies.org to find out more. 

River Reflector

Identifying the difference between freshwater shrimp and killer shrimp 


River Health Training days  

  • Saturday 2nd of February, 10am - 12:30pm - Water Pollution event and River sampling at Reabrook. Meet at Shropshire Wildlife trust, Shrewsbury, SY2 6AH. 
  • Saturday 16th February, 10am—12pm.  River Roden, Wem. Monitoring on a Stretch of River Roden off of Mill Street towards Wellgate. Meet at Wem Mill car park , SY4 5GB.
  • Monday 18th February, 10am—12pm. River Perry, Gobowen. Monitoring a stretch of River Perry adjacent to the playing field of the Village Hall on St Martins Road.  Meet at Village Hall car park on St Martins Road.
  • Monday 18th March, 10am – 12pm. Cantern Brook, Bridgnorth. Monitoring a stretch of Cantern Brook adjacent Dingle View, WV16 4JL.

Slow The Flow

  • Saturday 2nd of February, 10:00am - 15:00pm. Tree planting in the Corvedale catchment. Meet at New House Farm, Shipton, TF13 6LB 


  • 12th- 15th of February, 10:00-16:00. Removing tarmac and creating raised beds. Meet at Hub on the Hill, Southgate, Telford, TF7 4HG. 
  • 28th February, 10:00-16:00. Planting up raised beds and rain gardens. Meet at Hub on the Hill, Southgate, Telford, TF7 4HG. 

Interesting News

2019 has been declared the International Year Of The Salmon. This means that a lot of international organisations are coming together to understand, “what humans can do to better ensure salmon and their varied habitats are conserved and restored against the backdrop of increasing environmental variability.” It’s a bold initiative, we’re supporting it and we hope you will too. Find out more and get by following this link - involved.https://yearofthesalmon.org/?dm_i=3O4M%2CI0XS%2CD6F2X%2C1Z07U%2C1