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Leptophlebia marginata (Linnaeus), 1767
Identification Elliott, Humpesch and Macan (1988) for nymphs: Elliott and Humpesch (1983) for adults.
Distribution There are British Records from England, Wales and Scotland. L. marginata occurs in pockets throughout Northern and central Europe.
Habitat and ecology Nymphs occur in ponds, lakes and slow flowing rivers. There is one generation a year, which overwinters in the larval stage and emerges between April and June. The nymphs usually, but not necessarily, emerge via stones or vegetation during daylight hours. Nymphs are seldom found in the shallower margins of lakes in any quantity until early April. As the period of peak emergence approaches, many of the nymphs move into very shallow water. Males swarm above the water throughout the day. L. marginata is reported to be able to tolerate a pH in the range of 4.0 to 5.0 (Johansson and Nyberg 1981 in Elliott, Humpesch and Macan (1988). Elliott, Humpesch and Macan (1988) classify L. marginata as a 'collector-gather', meaning it feeds by filtering or gathering fine particulate organic detritus from the sediment. The nymphs live on the surface of leaves of aquatic macrophytes or in the surface layers of fine sediments, especially mud. They are poor swimmers but are adapted for moving amongst dense stands of macrophytes, especially on the surface of the stems.
Status Known from xxxxxxxxxxxxxxxxxxxxxxx.
Threats Excessive draw down or fluctuation of water levels during the breeding season could lessen the chances of successful breeding. Eggs laid prior to a change in water level could be left stranded out of water. Removal of the marginal vegetation in which the adults of L. marginata emerge and possibly shelter is likely to lessen the chances of successful breeding. Forestry activities such as felling and re-stocking can also be detrimental, by increasing the silt load of the water for a period. This can clog the gills of invertebrates or, where it settles, bury them. This threatens a broad spectrum of aquatic life, not specifically Ephemeroptera.
Conservation Try to restrict excessive fluctuation of water levels during the period when adults are present and for at least say, 30 days following this. Maintenance work liable to damage the marginal or bankside vegetation should preferably be carried out on only short stretches of, say 50 metres in each 200 metres in any one year.
Author C.R. Macadam
References
Bratton, J.H. (1990). A review of the scarcer Ephemertoptera and Plecoptera of Great Britain. Research and survey in nature conservation No. 29, 39pp.
Elliot, J.M., Humpesch, U.H. and Macan, T.T. (1988). Larvae of the British Ephemeroptera: A key with ecological notes. Scientific Publications of the Freshwater Biological Association No. 49, 145pp.
Elliot, J.M. and Humpesch, U.H. (1983). A Key to the Adults of the British Ephemeroptera. Scientific Publications of the Freshwater Biological Association No. 47, 101pp.
Goddard, J. (1991). Trout flies of Britain and Europe - The natural fly and its matching artificial. A. & C. Black, London, 242pp.