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FRESHWATER INVERTEBRATE RECORDER’S ANNUAL REPORT 2010/2011 ADRIAN CHALKLEY This report covers the period from May 2010 to June 2011 and will follow the format used in previous years by dividing the freshwater invertebrate community into the major groups. Within the report wherever a common name exists for a species it is given before the Latin and the current national status, if known, is given in brackets afterwards. The Ephemeroptera (Mayflies) Undoubtedly the mayfly find of the year was made by Jo Bennett, education assistant at Flatford Mill Field Studies Centre in April 2011 who found a single larva of the Pale Watery Dun, Procloeon bifidum at Homey Bridge on the River Box. We have records of this species from only seven sites in the county. The last record was made 21 years ago and though all previous records were from the River Stour catchment, none were from the Box. She also recorded the Turkey Brown, Paraleptophlebia submarginata from the same site; an infrequent species in the River Box. At Shelley on the River Brett Jo found the Large Dark Olive, Baetis rhodani, a common species. However neither of two following expected species was present; the Small Spurwing, Centroptilum luteolum, and the Blue Winged Olive, Serratella ignita, both of which are usually locally common. The Small Spurwing was however found in a few locations in the River Stour itself at Flatford, again by Jo. Large populations of two of the largest mayflies to be found in Suffolk, the Green Drake, Ephemera danica and the Drake Mackerel, Ephemera vulgata, have been recorded for many years at the Homey Bridge and Shelley sites mentioned above. Nina Sraj a member of my April identification course located both species in good numbers in the River Box but the River Brett had only E. vulgata. Amongst other species the White Midge, Caenis luctuosa and the related Caenis horaria continue to be found at widespread locations across the county and both were taken at Elveden Forest in August 2010. C. horaria was at Carlton Marshes in June and at Bixley Decoy in August. C. luctuosa was taken at Shelley in April 2010 but not found in the same month a year later. The population of Paraleptophlebia werneri (RDB 3) in a small stream at Elmsett, is still the only one discovered in Suffolk and the only one known in Eastern Britain. I reported last year that after the winter of 2009 / 2010 the length of stream in which they were present had reduced from about 5 km in 2008 to only 1¡5 km in 2010. They also used to share a wider downstream section with the related species Habrophlebia fusca, which also could not be located last year. At the time I put this down to rather harsher winter weather and of course the winter of 2010 / 2011 was even colder! In 2011 the population of P. werneri has maintained its numbers over a slightly increased stream length. H. fusca however is still not to be found downstream. Talking to a local homeowner it seems extremely likely that the damage to these populations over the previous winter was in fact caused by the overflow of a private cess pit in Autumn 2009. This is such a shame since the stream flows through two farms, both of which are aware of the importance of the

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watercourse and take great care to avoid run off and spray drift. Hopefully recovery will continue next year. By May the stream concerned is often drying up, P. werneri larvae have all hatched, the adults have mated, laid their eggs within a single day and those eggs enter diapause until the Autumn rains refresh the watercourse. The Coleoptera (Water Beetles) In April 2010 one of the crawling water beetles Haliplus laminatus (Notable B), was taken, for the second year running, at Milden Hall Farm, this time by Meghan Finneghan. In the same month at Bower House Farm, Boxford I found two water scavenger beetles Berosus affinis and Berosus signaticollis (also both Notable B); both of these are associated with silt ponds, which describes more and more of the ponds I visit on farms these days. In the same pond the following two species were common, both listed as Local in status; Laccophilus minutus and Noterus clavicornis. However, despite this national status it should be said that within Suffolk they turn up very commonly indeed. Also in April another Local species, this time a lesser diving beetle, Hydroporus discretus turned up in a sample I took at Flowton Brook. For this species there are but seven records in the database only two of which date from the last decade and both are from Flowton Brook; the first record I have was by Claude Morley in 1911. Other beetles recorded this year which are Local but which are well represented in the database were: Enochrus testaceus, Hygrobia hermanni and Laccobius striatulus at Calves Wood, Elmsett, and Haliplus immaculatus at Carlton Marshes and Bixley Decoy. In last year’s report I mentioned the crawling water beetle, Peltodytes caesus (Notable B) was found at Orford by Stuart Warrington. This year I found P. caesus at Carlton Marshes, which is only the 12th site for it in the county database. Carlton is adjacent to Oulton Broad where the species was first found by C. Morley in 1898 and again by E. C. Bedwell in 1900. Another interesting record was sent in by Mike Marsh who found the Silver Water Beetle, Hydrophilus piceus (RDB 3) in a light trap at Orford on May 16th 2010. This is another species which turns up mainly in locations near the coast. Whilst recording from the River Stour at Flatford Mill during my April 2011 course two records of interest were made by Holly Barclay. The lesser diving beetle, Hygrotus versicolor (Local) was previously recorded twice at Flatford in the 1960’s, and there are only two other post 2000 records for this species. Also recorded at Flatford was the smaller of the two Noterus species Noterus crassicornis (Notable B). Although the larger species N. clavicornis is widespread in Suffolk there are only nine sites recorded in the county database for N. crassicornis, all of which are in the far north of the county. Previous records range from Oulton Broad in the East to Botany Bay, near Lakenheath, in the West. Holly’s Flatford record is the first from South Suffolk. The Heteroptera (Water Bugs) The major discovery of this year has been the large colony of spined pondskaters, Aquarius paludum (Notable B) at Bixley Decoy in August. This has been described in White Admiral (Chalkley, 2009a: 6) and Heteroptera

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News (Chalkley, 2010b: 8). Since these articles were published I have since learnt that A. paludum was also recorded at roughly the same time at Tiptree Heath in Essex. These two sites remain the only records known in either county and yet the size of the colony at Bixley suggests a more wide spread distribution. Anglers using the Bixley lakes have told me that they have noticed these larger than normal pondskaters for some time though I have no reliable suggestion as to their arrival. Since A. paludum has been spreading in England for some time it is tempting to see the Bixley colony as part of this movement. However another explanation is that of a cross channel migration from Holland occurred, as has happened with other aquatic bugs such as Sigara iactans (Brooke, S., 2005: 4). It may be worth noting here that during this last year the other skaters recorded were those to be expected. These include the Common Pondskater, Gerris lacustris (Very common) from sites too numerous to mention here but including Bixley. The Toothed Pond Skater, Gerris odontogaster (Common) from widespread sites; occasionally from rivers such as the Stour, the Blyth and the Lark but mostly from ponds and lakes. Gerris thoracicus (Occasional) was only recorded once in a Boxford farm pond. Another skater, Gerris gibbifer was found to be common in many ponds at the SWT reserve at Grove Farm, Norton in June but no records of the two other Suffolk skaters, G. argentatus, and G. lateralis have been made in the last year. It is now some ten years since Sigara iactans was first recorded at Framlingham Mere. As stated above this was part of a migration of this lesser water boatman or corixid bug from the continent. S. iactans has become established in lakes at Elveden as has been reported in previous years. In 2010 it was recorded yet again at Elveden from two out for four lakes surveyed and seems to be doing well. One lake at this site has been completely drained, desilted and refilled, this had by far the largest numbers of corixids and also the largest number of S. iactans. Unfortunately after nearly 20 years Center Parcs has decided to stop commissioning annual freshwater surveys at their holiday parks, which will disrupt the largest, continuous source of site data in Suffolk. I reported last year’s that I had observed a colony of the Water Cricket, Velia caprai (Common) on the stream in my garden had hibernated for the first time during the coldest period of the 2009 / 2010 winter. The extended cold snap and snow of winter 2010 / 2011 also produced the same behaviour with the crickets vanishing not only from the stream but from my ponds as well. From the first snows in December until the end of March they seem to have hidden away under and between stones on the stream bank and were also found under a piece of plastic sheeting some four to five metres from the water. Numbers that appeared back on the water surface were much lower than normal this spring but the warm, dry weather of early April has seen a large hatch of water cricket nymphs and the summer population seemed to be as large as ever. Unfortunately for such a distinctive insect I receive almost no records of Velia even though it is probably present in most streams in the county.

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The Mollusca (Freshwater Snails and Bivalve Molluscs) As well as some interesting beetles found at the SWT, Carlton Marshes Reserve the rare Little Whirlpool Ramshorn Snail, Anisus vorticulus (RDB2) was found to be present in small numbers in my samples. Although Carlton is well known for this snail it was good to confirm its continued presence. Unfortunately I also hoped to photograph the living snail but high winds blowing from Oulton Broad caused my small aquarium on a tripod to move so much the resulting blur could have been any ramshorn and so A. vorticulus was replaced safely beneath the waves and out of the wind! Other molluscs found at Carlton (all common unless otherwise stated) included: The Lake Limpet, Acroloxus lacustris River Limpet, Ancylus fluviatilis Whirlpool Ramshorn, Anisus vortex Leach’s Bithynia, Bithynia leachii (Local) Common Bithynia Bithynia tentaculata The Flat Ramshorn, Hippeutis complanatus, The Wandering Snail, Radix balthica The Great Pond Snail, Lymnaea stagnalis The Fountain Moss Bladder Snail, Physa fontinalis The Great Ramshorn, Planorbarius corneus The Keeled Ramshorn, Planorbis carinatus An unusual find this year was that of The Moss Bladder Snail Aplexa hypnorum made in October by Rob Brown of the Environment Agency in the Hundred River. This is the first record for A. hypnorum in my database but is close to sites listed by Ian Killeen (Killeen, 1992) In October 2010 I ran a weekend course on Freshwater Snails at the Flatford Mill Field Studies Centre. With the students collecting only from the freshwater around the Mill, mainly the River Stour and Cribbensgate Lake, the total list numbered 19 species which was nearly half of the freshwater species in the British Isles. The following were found, all common unless otherwise stated: Lake Limpet, Acroloxus lacustris River Limpet, Ancylus fluviatilis Whirlpool Ramshorn, Anisus vortex Contorted Ramshorn, Bathyomphalus contortus Leach’s Bithynia, Bithynia leachii (Local) Common Bithynia, Bithynia tentaculata White Ramshorn, Gyraulus albus Marsh Snail, Lymnaea fusca Great Pond Snail, Lymnaea stagnalis Fountain Moss Bladder Snail, Physa fontinalis Great Ramshorn, Planorbarius corneus Keeled Ramshorn, Planorbis carinatus Jenkins’ Spire Shell, Potamopyrgus antipodarum Ear Pond Snail, Radix auricularia

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Wandering Snail, Radix balthica The Nerite, Theodoxus fluviatilis Flat valve snail, Valvata cristata The Valve Snail, Valvata piscinalis Lister’s River Snail, Viviparus contectus (Local) Other Groups Megaloptera Adult Alderflies are a common sight near almost any water body in Suffolk. In Britain we have three species but until this year only the most common species, Sialis lutaria has been recorded in the county. At Stoke by Nayland in October Rob Brown discovered Sialis fuliginosa in a small stream which is part of the River Stour catchment. There have been reports of increasing numbers of S. fuliginosa being found in other parts of the country, so although this would seem to be the first record for Suffolk it is possible that more records will be made in future. Further records will be very welcome, both adults and larvae of S. lutaria and S. fuliginosa are easily separated and the author will be pleased to offer help with identification if required. The Cladocera (Water Fleas) The Cladocera are one of the Cinderella groups of freshwater. Everybody knows roughly what a waterflea looks like but knows little about them. Most naturalists will defer to a vague ‘Daphnia’ if prompted to think of a family, maybe Daphnia pulex at a push for a species. The last British key was published in 1966 and hence is very out of date! The group it is one of only a handful with no recording scheme and very few records listed on the NBN website. To try and rectify this situation The Cladocera Interest Group was formed in January 2011. During our first year we have published a revised species list for the British Isles (92 species) and also our first newsletter, both of which are downloadable from our website www.cladocera.org. We have attracted 45 members so far. We will soon have an on-line recording facility with the aim of increasing our knowledge of distributions across the country. In line with this aim I would like to obtain more records for Suffolk. Perhaps you have a garden pond or access to any waterbody and notice waterfleas (try looking at night with a torch). If you can catch a few (try using a flour sieve) I would welcome a sample sent to me for identification. Waterfleas can be killed and preserved in alcohol in any kind of small container (neat Vodka or Gin also works well in an emergency!) All specimens sent will be acknowledged and identified. For the location please do send an OS Ref. or your postal address with post code and if include an email address for my reply to save postage. Please send any specimens to the address at the bottom of this report. Due to the paucity of Cladocera recorders there are relatively few water flea records for the county. Claude Morley of course recorded a few, Alona quadrangularis from Fritton Lake in 1903 being an early example and a species which has not been seen since in Suffolk (Morley, 1942). Other species such as Bosmina longispina, Chydorus sphaericus, Daphnia cucullata, Eurycercus lamellatus and Scapholeberis mucronata are species

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found by Morley which continue to be common today. E. lamellatus recorded from Carlton Marshes, the River Box and the River Brett in the last year. B. longirostris was present in many lakes such as those at Elveden and Bixley Decoy as well as in a few farm ponds. C. sphaericus is frequently abundant in lakes and ponds as it was this year at Elveden, Bixley, Lavenham and Boxford. D. cucullata was taken by Morley at Fritton Lake in 1903 and Breydon Water in 1920; it first turned up in lakes at Elveden in July 2008 and has persisted through 2009 and 2010. Scapholeberis mucronata (Plate 14) was taken at Elveden and Bixley and has in fact been common at Eleveden since 1992. Polyphemus pediculus is one species of water flea I have only ever found once in Suffolk, at Lound Lakes in 2006. This is a large, unusual, easily identified cladoceran which is a highly mobile predator (Chalkley, 2007). This April during the Flatford FSC course a very large swarm of P. pediculus was discovered by one of the students, Robert Morgan, in the River Stour right outside the laboratory. The majority of these were parthenogenetic females who obligingly produced young under our very eyes, which the whole course observed under the microscope. This is then only the second record for the county despite my recording water fleas wherever I sample. That these two records are so widely spaced by geography and date says a great deal about our patchy knowledge of these creatures. I should add that when making a return visit to Flatford a fortnight later I had a quick look in the river and the swarm was still there, both in the same spot and still in similar numbers albeit on a river with a fair flow rate. The Hydracarina (Water Mites) The water mites are another one of the Cinderella groups. There are, as far as I know, no modern available keys. The group is represented in almost all waterbodies, caught in all samples and yet my freshwater database contained no records until this year. However in a box of old specimen tubes with perished cork stoppers found and given to me by Jo Bennet from Flatford Mill I found a collection of nearly one hundred water mites. These were all taken in the local area in the 1960’s and identified by Ceri Hopkins the Assistant Director of Flatford Mill in the days when Jim Bingley ran the centre. I am now in the process of re-tubing the samples and listing the species. Without a national recorder it hard to know who to contact to look at the species list and I certainly am unable to verify them myself. Luckily the Freshwater Biological Association has been able to help in this respect and I await a response from the contact they have given me. Perhaps more may be known by the time for next year’s report. References Brooke, S. (2005). Sigara iactans Jansson, 1983. Het News, 2nd Series, no.5, Spring 2005: 4. Chalkley, A. K. (2007). Freshwater Invertebrate Recorder’s Annual Report 2007. Trans. Suffolk Nat. Soc. 43: 59–62. Chalkley, A. K. (2010a). Aquarius paludum, A new county record for Suffolk. White Admiral 77: 6–7.

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Chalkley, A. K. (2010b). Aquarius paludum, New to Suffolk. Het News, 2nd Series, no.16, Autumn 2010: 8. Killeen, I. J. (1992). The Land & Freshwater Molluscs of Suffolk. Suffolk Naturalists’ Society, 49–50.

Morley, C (1942). Proceedings. Trans. Suffolk Nat. Soc. 5: 78–70.

A. Chalkley

Adrian Chalkley 37 Brook Hall Road, Boxford Suffolk. CO10 5HS Email: aquatics@sns.org.uk

Plate 14: Scapholeberis mucronata forma cornuta, a parthonogenetic female; the picture is the right way up - it crawls underneath the surface film (p. 70).

Trans. Suffolk Nat. Soc. 47 (2012)

FRESHWATER INVERTEBRATE RECORDER’S ANNUAL REPORT 2010/2011  

Adrian Chalkley

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