EditorialThree articles have been contributed to this issue. Our Town Council representative Kevin Stevens introduces another important part of the river invertebrate life – mayflies. Also appended is an account of mass emergence from an old natural history book. Whilst adults are above water for such a short time, the young or nymphs with their 3-pronged tails and external gills are a regular find especially under stones on northern Wey wardening stretches all year. Kevin introduces us to their life cycle. Will anyone see the adults this summer?

Another invertebrate to make an appearance in the catchment of the northern Wey is an Australian Landhopper. This introduced species is described and illustrated by Dr Martin Angel of the Bourne Conservation Group in Farnham. If anything jumps when a log is turned by the river bank, it could be one of these. Martin gave an exhibit on this at the recent meeting of the Surrey Biodiversity Information Centre (SBIC) and he has been attending Wey Valley Catchment Project meetings . We hope to arrange a field visit with the Bourne group this summer.

Gill Glover has put some of her water level data into bar diagrams for the three years 2001-3 and we look at the trends, ask questions and come to tentative conclusions. It will be interesting to follow up the gauging station data run by the Environment Agency. Following on from this is a look at the springs feeding the northern Wey as well as the surface run-off that have both been plentiful this winter. It is amazing to see the high levels of water in the northern Wey through Alton when the channels were dry not so long ago (see earlier NWT Newsletters).

Only two years on from the major pollution event of New Year 2011 comes another one from domestic sewage, again at Paper Mill Lane. Repeated pollution events are not good news for the river. It was toilet paper in the river that first

drew attention to the problem and closer inspection revealed discoloured water concentrated at the bank by the source of the pollutant. The Environment Agency Hotline was rung and the Environment Agency responded very quickly to remedy this one the next day. Interestingly my animal sampling at Newman Lane steps for February picked up its effect with the abundance of red annelid worms and red fly larvae, both living in oxygen-depleted water. Life was normal in December.

There was a further Steering Group meeting of the Wey Valley Catchment Project in December 2012 and another is forthcoming. Jim Jones of Surrey Wildlife Trust is setting up wardening in other parts of the catchment along the lines of NWT and he outlined this at the SBIC meeting.

Our AGM is still in preparation but we hope to attach papers with the Newsletter.

June Chatfield

Northern Wey Trust NewsletterSpring 2013 Membership Newsletter No. 40

Field meetingThe Alton Natural History Society have a field meeting along the Caker Stream and balancing pond behind Omega Park in Wilsom Road, Alton on the evening of Thursday 20th June. NWT members welcome. Meet in the car park for King’s Pond, Ashdell Road at 7.30pm.SU/723395. Plants, insects and water life.

Mute Swan cygnet from 2012 at King’s Pond moulting its juvenile brown feathers. February 2013.

A mallard speaks for itself alongside. Phot: J. Chatfield

An Australian immigrantLandhoppers ahoy!During a Bourne Conservation Group’s woodland management session in Paradise Wood in South Farnham in January, when a log was rolled over numerous dark flea-like animals were seen jumping away. They looked like the sandhoppers that are common in amongst the seaweed washed up along the strandline on beaches. According to all literature, there are no native terrestrial hoppers (amphipods) in Britain. The hoppers in Paradise Wood have turned out to be Arcitlatirus dorrieni an invasive species from Australia, which was first described scientifically from specimens collected in the Abbey gardens at Tresco in the Scillies in 1924, and only later found to be imports from Australia. Their subsequent spread in Britain has been associated with subtropical gardens and have been found as far north as the Island of Colonsay where they can reach densities of 600 per square metre. They have also been recorded from Kew and Wisley, and even from the wildlife garden at the Natural History Museum in London and the subtropical garden at Inverurie in N.W. Scotland. Even so, its discovery in South Farnham was a surprise. It has since been found at another five woodland sites in Surrey. So it is probably far more widespread than we realise. Who is going to be the first to find it in Alton? They can consume up to 25% of the leaf litter in deciduous woodland. So are they likely to out-compete our native decomposers, like woodlice, millipedes and earthworms? They need it to be damp, only surviving if the relative humidity stays above 95%, but do not survive being flooded. So has the abnormally high rainfall in 2012 favoured their spread in Surrey, or have they been living quietly here without being noticed for

many years? Experimental evidence suggests that the spread of hoppers in Britain is inhibited both by low winter temperatures and by a low availability of sodium ions in leaf litter. If they are exposed to freezing temperatures they die, but they can survive by burrowing deep into the leaf litter. Recently they have been discovered in Norwich and Newcastle, so have they begun to adapt physiologically to life in Britain? It has now been adopted by the Woodlice and Waterlice Recording Scheme as an honorary woodlouse see - http://www.bmig.org.uk/page/woodlice-waterlice-recording-scheme

We have experienced extensive invasions by non-native species of both plants and animals. Many of these appear to be having relatively small effects on the ecology of our countryside. So far the spread of land hoppers appears to be relatively benign. Other aliens are known to be undesirable and are having serious impacts. You can find out more about some of these undesirable aliens at https://secure.fera.defra.gov.uk/nonnativespecies/home/index.cfm

Martin Angel

Arcitlatirus dorrieni, an Australian Landhopper in Farnham, Surrey. Phot: Martin Angel

This is a repeated occurrence in parts of the northern Wey in the urban part of Alton seen as a buff-coloured fluffy “gunge” attached to bottom stones, brick sides of channels and vegetation but there is little reference to it in books on freshwater life. However it has merited some coverage in “Fungi” by B. Spooner and P. Roberts in the Collins New Naturalist Series (2005) in the chapter on freshwater fungi (pages 237-239).

Over 200 species of aquatic microfungi have been recorded from sewage works. Many of them are water moulds of which the best known is Leptomitus lacteus characteristic of polluted water: it is often known as sewage fungus as it forms extensive masses in sewage plants that block filters. Polluted rivers with a high concentration of organic nutrients offer similar conditions to sewage works for the fungi which may have important roles in nutrient breakdown and remediation of such pollution. In our rivers however they are unsightly. Many of the aquatic fungi are useful in breaking down toxins and even DDT. Sewage fungus

with bacteria, that also absorb and digest organic nutrients, is to some extent nature’s way of handling the problem. Sewage fungus can only thrive with a nutrient supply so to prevent the unsightly growth the best attack is to locate and stem the source of the nutrient or pollutant and ring the Environment Agency Hotline 0800 80 70 60. There is a smell when the nutrient supply is depleted and the fungus dies and rots but with a good flow, remaining nutrients are diluted and eventually the fungus disintegrates and is washed away. We seek prevention rather than cure.

June Chatfield

Sewage fungus

This newsletter has been compiled by Dr June Chatfield. Any news items or other features of interest should be sent to June Chatfield, Anglefield, 44 Ashdell Road, Alton, Hampshire GU34 2TA or to the Secretary by e-mail: glovermgr@aol.com

Subscriptions Adults: £5 Family: £10 Corporate: £25 Treasurer/Membership Secretary: Jacqueline Martin, 15 Finches Green, Alton, Hants, GU34 2JU. Cheques payable to: The Northern Wey Trust . Website – www.northernweytrust.org.uk

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Springs in the Wey catchment

The official source of the River Wey is from springs arising in the meadow of Will Hall Farm along the New Odiham Road, Alton. The river then flows along the side of our Secretary’s garden before following the edge of Flood Meadows, a public open space on the lower part of the former Amery Farm and behind Tan House Lane. The most interesting part of this open space is the river and old watercress beds alongside that sometimes attract passing Water Rail. Supporting the cress beds is a spring line at the foot of the steep bank topped by a hawthorn hedgerow. Here spring water emerges and keeps areas clear of vegetation but further away are banks of flourishing watercress (an annual perpetuating from seeds in the mud).

Following the wet weather this millennium, Stream Water-crowfoot has established below the bridge at the back of the cress beds and near the weir where the water from the cress beds starts to enter the Wey approaching

Tan House Lane. This plant is typical of chalk streams requiring clean, permanently cool running water and a gravel bed in which to anchor. It also occurs in the stretch of the Wey in the Banks car park, Alton. Identification is not easy due to the branches varying with water speed as well as with species, but the one here is deemed to be Spring Water-crowfoot (Ranunculus penicillatus)

and is in the same genus as buttercups. It is a typical plant of the Wessex chalk streams and does not take kindly to silt.

Further downstream where the Wey emerges from under the railway embankment at Ashdell Road it then flows for a stretch shaded by trees before running through King’s Pond as an “on-line stream”. Here its flow is augmented by more springs from under Windmill Hill that make the south bank scalloped. When I first came to Alton in 1979 I noticed spring water issuing from the bank by white washed chalk below and a slight curvature in the line of the bank. Over 30 years later this has led to a distinct gully or tributary showing a textbook example of headward erosion of streams. This winter the section of the river has been bankfull and flowing fast obscuring the shape of the gully. Rivers and their courses are constantly changing because this is what they do: they do not appreciate being made to stay in the same place. Wardening activities show that there are active streamside springs all through Alton and Holybourne – developers beware!

The Wey’s largest tributary is the Caker Stream that is much more branched than the northern Wey and has a different character. One stretch of the Caker is parallel with Truncheants Lane and along this is Caker Bridge that takes a footpath and BOAT (byway

open to all traffic) which was the main road from Selborne to Alton up until the nineteenth century. A modern

footpath runs along its top from which a good view of the hollow lane is obtained as well as the entrance looking directly up it from the bridge. It is called Water Lane for the very good reason that in winter it is underwater as run-off from the malmstone fields drains into the lane and rushes down the slope to feed into the Caker Stream. Winter flow scours out the bottom exposing bare rock and particles carried along further erode the surface. These lanes were graphically described by the Reverend Gilbert White, the Selborne naturalist, as “one of the singularities of this place” and were worn down by “the fretting of water and the traffic of ages”, the latter being horse traffic with iron shoes. The very heavy rain last Christmas gave a dramatic view of a tributary with small waterfalls over outcrops of harder rock (White’s blue rag).

Photos and text:June Chatfield

A cold day on 27th March 2013: I was surprised to see a lone white flower of Stream Water Crow-foot above the water. Is this a sign of Spring or seasons in a muddle?

Water Lane between West Worldham and Truncheants in December 2012.

The bridge over the cress beds in Flood Meadow, Alton was constructed by the Environment Group of the Alton Society.

Water rushing down a tributary ravine into Water Lane, thence draining into the Caker Stream.

Stream Water-crowfoot below the bridge over cress beds, Alton.

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Water levels from wardening at the source of the northern Wey.The height of the water in the river or stream is a part of the data recorded monthly by Northern Wey Trust river wardens. The uppermost warden stretch is from the source at Will Hall Farm downstream to the western edge of Flood Meadows in Alton. The measurement is taken from a fixed point on the parapet of the road-bridge on the B3349 down to the surface of the water. The approximate depth of the water is obtained using an estimate of the position of the river bed.

Table 1: Water level comparison 2001 to 2003 The comparative chart – Table 1 -shows water height for the years 2001 to 2003. In 2001 (blue), water was present in each month of the year, an unusual occurrence in this particular stretch. Here the river is a winterbourne and naturally dry for several months. The present wardens have data from 1998 to 2012 and during that period water has been present for the whole year only in 2001.

Table 2: Rainfall in Alton, Hampshire – 2001 to 2003

Table 3: Frank Tait’s annual rainfall totals 2001-2003.

It is interesting to look at these results and to postulate on the influencing factors. We obtained monthly rainfall data from Frank Tait of Alton Natural History Society who keeps a rain-gauge in his garden at Huntsmead, Alton and his data for 2001-3 is shown in Table 2 while Table 3 gives yearly totals of rainfall and the numbers of months each year when the river in New Odiham Road had water in the channel. Looking at the results we then

posed questions and set one set of data against the other to look for a correlation. Rainfall is quite a complex study, as the weather forecasters often refer to “the wrong sort of rain”. Table 3 showed that 2001 in which the Wey had water in the channel all year was not necessarily the one with the highest total rainfall. What other factors are operating? Is it the time of year that the rain comes, or is it the gardener’s delight of “all night steady rain” or the opposite of cloudburst and heavy rain when rivers swell, land and roads flood and then levels fall again? The latter sort of weather we seem to be having more often causing flash floods.

We used the data set to compare winter and summer rain. When rain comes in winter the roots of the trees and many other plants are dormant and not intercepting the rain on its passage down through the soil and subsoil to the ground water table. Conversely in the summer the deciduous trees in particular will be absorbing water from their roots, transporting it around the tree and some will be evaporated out from the leaves via the pores or stomata (transpiration flow) so that only a certain amount of the rain falling on the ground reaches the water table in summer to support river flow. There is considerable movement and passage of water through the ground that is powered by gravity vertically and aided by fissures in the rocks to flow laterally and sometimes hindered by geology as clay layers or pockets. We therefore considered rainfall and river data not for calendar years but for respective winters (November to March) and summers (May to September).

There was no direct correlation between total winter rain and the river but there is a lag effect between rain falling and the ground water entering the river. Looking at the total summer rainfall:

Table 5: Summer rain, when leaves are on the trees and functioning: May to September.

There was a direct relationship in 2001-2003 between the total summer rainfall and water in the source of the river. Sometimes one notices after a flash flood when the river is dry that water may remain in the channel after the wet period is over but there is no flow as the river is just storing the run-off like a pond.

What other factors might therefore have been involved?

2001 2002 2003 Year

965 1085 678 total Rain mm. 912

12 9 6 Water in source months

2001 2002 2003 Year

330 313 162 Total Rain May to Sept

12 9 6 Water in source months

Previous Nov - Dec 2000 162mm +123 mm rainfall Jan - Mar 2001 84mm + 98mm +141mm Total 608mm (12 wet months)

Nov - Dec 2001 42mm + 23mm Jan - Mar 2002 96mm + 110 mm + 48mm Total 319mm (9 wet months)

Nov– Dec 2002 197mm + 170mm Jan - Mar 2003 83mm +30mm +27mm Total 507mm (6 wet months)

Table 4: Winter rainfall and the river

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Mayflies – Fisherman’s Friend

Well known to fly fishermen the world over - ‘duns’ and ‘spinners’ are cryptically mimicked on fishing hooks as an aid in attracting freshwater fish, particularly trout. Mayflies (Order: Ephemeroptera) are complex and unique insects on many levels, and their use as a fishing model amply demonstrates their importance in freshwater food chains: they are useful components of freshwater ecology.

They are considered the oldest, winged insect order and are thought to have originated during the hot and moist tropical era of the Carboniferous, approximately 330 million years ago. They are also unique amongst insects in having a pre adult winged stage known as a sub adult, or sub imago. They are the only insects that moult after developing functional wings.

The name for their taxonomic Order – Ephemeroptera, derives from the Greek ephemeros – lasting a day, and pteron – a wing. Most species are literally on the wing for only a day, some only manage a few hours or even minutes! Adults do not feed and have very reduced, non functional mouthparts; their sole purpose is to take to the air and reproduce.

Their life journey actually starts several years before; like other freshwater insects such as the dragonfly and caddis fly, as a young hatched nymph, or naiad, released from one of the many laid eggs beneath the surface of water. Naiads moult regularly and numerously (up to 35 times in some species), over an approximate two year period. Unlike the adults, these do feed and have chewing mouthparts; most are detrivores and herbivores, feeding on submerged plant material and the detritus found along the bottom of their aquatic habitat, though some are carnivorous. They possess a closed tracheal system with lateral abdominal gills, and usually three feathery abdominal tails. Evolution has allowed them to utilise various types of habitats from still ditches, ponds and lakes to fast flowing streams and rivers.

Mayflies have an incomplete metamorphosis and do not pass through a pupal stage. Once fully grown as a naiad, they will rise to the water’s surface and moult into a dull winged sub adult, or dun. This rather drab stage can last a day, or less than an hour, and will see the ‘juveniles’ test their wings by flying to nearby vegetation. Once settled, the final moult will take place and shows off a much more vibrant coloured adult, or spinner, with a shiny, soft bodied abdomen and large wings. These cannot be folded back along the body – the only insect order unable to do

so along with Odonata (dragonflies and damselflies). The adults also usually have two very long cerci, and a tail between them which give mayflies their distinctive shape. Mayflies are split into two distinct sub orders – Schistonota (split back mayflies) and Pannota (fused back mayflies). Both sub-orders are easiest to tell apart as larvae – Schistonotan species have wing pads free along the back midline, Pannotan species have their wing pads fused along the back midline.

Ephemera danica (Family: Ephemeridae) showing anatomical detailing (McGavin: Essential Entomology (2007) Pg 70)

Firstly water abstraction from Weysprings Pumping Station was operative until shut down in March 2003. The distribution of the rain over time and its intensity would be revealed by the Environment Agency’s gauging stations, in this case the Banks Car Park outside the Community Centre in Alton and at the end of King’s Pond. This data picks up the sharp rise and fall of flash floods, an effect influenced also by urban activities on ground permeability. This limits the areas of bare soil or natural vegetation available for rainfall absorption or sustainable drainage. The

whole nature of the vegetation of the river catchment area can also have its effect, hence the current Wey Valley Catchment Project focusing not just on the river corridor but its supporting landscape.

June Chatfield and Gill Glover

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May Flies from “Life in Ponds and Streams”,

1919 by W.Furneaux

Large numbers of mayflies will emerge together and form distinctive swarms which rise and fall rhythmically, often at dawn or dusk. Both the males and females are able to recognise swarms of their own species, and the females enter these swarms for the sole purpose of mating, jostling into position with the males. The males are assisted in such a competitive environment with the aid of bi - focal compound eyes which are divided into linear zones, with enlarged facets in the upper zone. It is thought that this gives an ability to see potential mating females above them in the ebb and flow of the swarm.

Once fertilised, the female will lay her numerous eggs by depositing over water during flight, singly in small groups, or in one drop in a large packet. Her life purpose completed, she will then drop to the water surface exhausted and eventually die, if she is not eaten first. The males, having completed mating, will also do the same. Mayflies are very important constituents of the aquatic food chain and are eaten by both invertebrates and vertebrates, and are a staple food source for freshwater fish such as trout. They are also sensitive to pollution and are thus useful as water quality indicators.

Kevin Stevens.Mayfly nymphs: the aquatic stage

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