AQUATIC INVERTEBRATE REPORT
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FRESHWATER INVERTEBRATE RECORDER’S ANNUAL REPORT ADRIAN CHALKLEY Having used my report in Transactions 48 to review the Suffolk Cladocera, (Chalkley, 2012) and that of volume 49 for a survey of the Hen Reedbeds, (Chalkley, 2013) this report returns to a more traditional format. There follows then a review of the more interesting freshwater invertebrate records made between Summer 2012 and Summer 2014. Wherever a common name exists for a species it is given before the Latin. Within the report are details of nine species; two Beetles and seven Caddisflies, new to the Suffolk list. The Cladocera (Water Fleas) Following my review of Suffolk Waterfleas two years ago I was able, with the help of the BRC and colleagues in the Cladocera Interest Group, to publish a provisional Atlas for the British Isles. The maps may be viewed on line at www.cladocera.org.uk and will as time allows be followed by distribution maps for Suffolk. Below are just a few of the more notable species records made since my review. The widespread but rarely found carnivorous species The Giant Eyed Waterflea, Polyphemus pediculus was found in the Soke Dyke at Oulton Marshes during 2013 and 2014 but not in similar habitats at nearby Carlton Marshes. Other unusual finds during 2013 were Daphnia curvirostris and The Crystal Waterflea, Sida crystallina also from Oulton Marshes; Graptoleberis testudinaria from Framlingham Mere; Pleuroxus uncinatus from Framlingham Mere and Hullbecks Reservoir at the Arger Fen reserve. The freshwater invertebrate community at Hen Reedbeds was decimated by the inundation of salt water when the sea wall collapsed during the Tidal Surge of December 2013. It was interesting therefore to find that the Smallheaded Water flea Simocephalus exspinosus survived in good numbers. During my survey there in 2012 the similar Simocephalus vetulus was also found, but during a return trip in June 2014 only S. exspinosus had survived. This should not be surprising however, records from Stuart Warrington of the National Trust, show that the species is to be found on Orford Ness where all pools are within reach of sea spray, probably the most Easterly location in the UK for this species. The Coleoptera (Water Beetles) I first visited Oulton Marshes (Plate 6) back in 2012 to look at some new turf ponds which had been created and I have been carrying out a long term survey there for the SWT which will finish at the end of this year. Of the more interesting beetles found there the most surprising to me was the discovery of several specimens of Hydaticus transversalis (Plate 7) in the more open dykes across the Marshes. This diving beetle is associated with rich fen in lowland ponds and ditches. It was recently rediscovered in the Cambridgeshire Fens and the Oulton specimens are a new county record for Suffolk. The only other species of Hydaticus, the slightly larger and more common Hydaticus seminiger, is also common at Oulton and frequently they
Trans. Suffolk Nat. Soc. 50 (2014)