Riverfly Partnership - Species and Habitats Group

Riverfly Partnership

The Riverfly Partnership (RP) was formed in 2004 and brings together anglers, conservationists, entomologists, scientists, watercourse managers and government agencies to increase our knowledge of riverfly populations and actively conserve their habitats.

Mayfly (Ephemera vulgata) © John Mold

Riverflies include three groups of insects: mayflies (also known as upwing flies); caddisflies and stoneflies. They all have aquatic larvae and winged adults and are sensitive to pollution. They are also the flies that fly-fishermen imitate with their artificial lures.

One of the RP’s leading projects, launched in 2007, is the 'Anglers Monitoring Initiative (AMI). The AMI enables trained volunteer groups to apply a simple monitoring technique to record the presence and absence of 8 invertebrate groups, 7 of which are riverflies, to monitor the biological water quality of their rivers. The volunteer groups monitor their local rivers on a regular, often monthly, basis and if severe changes are detected a rapid response by the statutory bodies is ensured.

What are Riverflies?

Riverflies include three groups of insects mayflies (also known as upwing flies), caddisflies and stoneflies. These three group are all similar in that they have aquatic larvae and winged adults.

Mayflies (Ephermeroptera) are although they are called 'mayflies' these insects are present all year round. In the water habitats

Iron blue mayfly (Alainites muticus) © Stuart Croft

Stoneflies (Plecoptera) have some of the largest larvae of any freshwater invertebrates, growing up to 3 cm long. The larvae are distinct from mayflies as they don’t have pairs of feathery gills along their abdomen and they have two tails (cerci) rather than three. They have six large sturdy legs which allow them to move around in strong currents. As their name suggests they typically live in fast flowing stony streams. Adult stoneflies have four large wings, which they wrap around their bodies when resting.

Caddisflies (Trichoptera) are one of the most species rich groups of aquatic insects. Their larvae are caterpillar like but with six strong legs, and there are two distinct types, ‘cased’ and ‘free-living’. The cased caddis larvae make intricate shelters from a variety of materials such as small snail shells, precisely cut leaves, twigs and stones, all sewn together with a silk secretion. The adult caddisflies are moth-like in appearance but they have hairy, rather than scaly, wings. The wings are held ‘tent like’ over their body when resting. Like moths they often fly in the evening or at night.

Riverfly Partnership: Species and Habitats Groups

This group was formed was formed to deliver the Riiverfly Partnership's work on the conservation of rare and threatened riverfly species and their habitats through awareness raising, collaborative work with partner organisation, and by projects and research. The group includes representatives from Buglife - The Invertebrate Conservation Trust, the Riverfly Recording Schemes, Salmon & Trout Association, Environment Agency, Natural England, Freshwater Biological Association amongst others.

Riverfly Declines

The declines in riverfly numbers are of increasing concern as their populations reflect the health of our water environment. The health of our freshwater habitats is vital for the plants, animals and people dependent on them. Many factors threaten riverfly survival, for example:

• Habitat loss. As many ponds have been lost in recent years through in-filling or draining. Modification of river channels e.g.: straightening or widening can cause the loss of important bank-side and shallow in-stream habitat.
• Pollution. Water with high nutrient levels and other pollutants in run off from farmland. Excess nutrients can also lead to large algal growths, which smother vegetation and reduce water oxygen levels making unfavourable conditions for riverflies. Toxic insecticides can be present in run off from agricultural land or from industrial sites e.g. damaging acidic runoff from conifer plantations and disused mines. The impact of insecticides is demonstrated by the fact that just a teaspoon full of cypermethrin pesticides can devastate riverfly populations for kilometers of river.
• Soil erosion. From farmland can also lead to unnaturally high levels of silt in watercourses which can smother the river bed, clogging the gills of larvae and preventing plant growth.
• Abstraction. Reduced flow levels can effect riverflies as a reduction provides less habitat for riverflies and causes pollutants become more concentrated.
• Light pollution. As artificial light can cause adults to become disorientated and attract them away from the water.

Riverfly Biodiversity Action Plan (BAP) Project

The Partnership secured funding through the Natural Englands Countdown 2010 fund to undertake conservation work on the eight Biodiversity Action Plan (BAP) riverfly species in England. BAP status means that they are species that have been identified as priorities by the government for protection. The Species and Habitats group is gathering information and identifying the conservation work needed for the eight species. Survey work will be undertaken by specialists and by volunteers in the Angling Monitoring Initiative. There will also be delivery of conservation actions and improving understanding and knowledge of these riverflies. All work ing towards halting the decline of these eight species.

The eight riverflies designated as conservation priorities (BAP species) by the Government include:

• Stonefly - Northern february red; Rare medium stonefly
• Caddisflies - Small grey sedge, Window winged sedge, Scarce grey sedge, Scarce brown sedge

  Northern february red adult (Brachyptera putata) © Mike Hammett

• Mayflies - Southern iron blue, Yellow mayfly

Northern february red (Brachytera putata) This stonefly is unusual as it occurs just in Britain making it a British 'endemic' species. In Britain it mainly occurs in Scotland, with a few sites in England and Wales. This is vulnerable to acidification, chemical pollution and high nutrient levels. Survey work and research is being carried out to provide a better understanding of its life cycle.

Rare medium stonefly (Isogenus nubecula)

This stonefly occurs only on the river Dee and was last found in 1995, unfortunately the species wasn't found during recent surveys in 2004/06. Threats to this species include pollution (industrial and agricultural); it is also vulnerable to floods and droughts because it is so rare. Further surveys are required on the river Dee, in addition to research work on its behaviour and habits.

Small grey sedge (Glossosoma intermedium)

This caddisfly has been found in only four Lake District streams, however it has been lost at two of the four sites and another is in decline. It is suspected that cypermethrin sheep dips may have been responsible for one disappearance. Surveys of the sites to see if this species has survived are being carried out, and a possible re-introduction programme is being discussed, if suitable sites can be

Scarce brown sedge (Ironoquia dubia)

This caddisfly is known from two breeding sites and its habitat is scarce and declining, making it vulnerable to habitat modification. Research is needed on the biology of the larvae which might be using the damp bankside rather than the water. Once understanding of its whole life cycle has improved old sites and other potential sites will be surveyed.

Scarce grey flag (Hydropsyche bulgaromanorum)

The only recent records for the species from the river Arun in Sussex, all other records are over 100 years old. This species prefers large rivers and so is

Scarce grey flag (Hydropsyche bulgaromanorum) © Peter Barnard

Southern iron blue (Baetis (Nigrobaetis) niger)

This is a widespread mayfly lives among plants in chalk streams, but this species has declined massively in recent years. The decline has been linked to poor water quality due to pollution and inappropriate weed-cutting. Other factors effecting the species

Southern iron blue mayfly (Baetis (Nigrobaetis) niger) © Stuart Croft

Yellow mayfly (Potamanthus luteus)

This mayfly is only found on the river Wye, because it is so rare it is vulnerable to poor water quality through pollution events, changes in bankside and river vegetation and low flows caused by abstraction. Other factors thought to be contributing to its decline include: suspended silt, dredging, loss of side channels, channels with too much vegetation and excessive bankside light. Surveys of the rivers Test, Usk and Wye are being carried out, and more research is needed on the habits and nature of the species and programme of captive breeding and release.

Yellow mayfly adult (Potamanthus luteus) © Mike Hammett

Yellow mayfly nymph (Potamanthus luteus) © Mike Hammett

Window winged sedge (Hagenella clathrata)

Window winged sedge (Hagenella clathrata) © Ian Wallace

This caddisfly lives in pools that occur on bogs and heathland, and on only 10 sites in the UK. It is very sensitive to trampling and habitat loss from pools drying out when trees invade the pools. Surveys are being carried out at the sites where it occurs. This species will also benefit from the creation of new pools and the reintroductions to increase its numbers.

River Habitats

The group is also look at river habitats and how rivers can be improved for the benefit of riverfly species, this work will be undertaken through collaborative research and information dissemination to partner organisations and the River Habitat Action Plan groups.

What can you do

• If you are part of an Angling group why don't you get your group involved with the the Riverfly Partnerships Angling Monitoring Initiative, which give anglers the skills to go out and monitor their rivers. The monitoring groups will also be involved in the BAP species monitoring
• Or get involved in managing your local river by joining a local rivers group, contact your local Wildlife Trust office or the Association of Rivers Trusts to find existing groups - if you don't have one why don't you set one up
• Stand up for your local river through the 'Our rivers' campaign
• Make a pond as part of the Million pond project ponds are an important habitat for a number of mayfly and caddisfly species, for more on making ponds see the Pond Conservation website
• Don't dispose of unwanted chemicals carelessly - chemicals washed or poured into drains often end up in rivers and other water habitats

For more information on The Riverfly Partnership, its partners and current work visit www.riverflies.org