Pond Dipping at Glen Fern – 25 July 2008

The pond at Glen Fern is now four years old. It’s lined with butyl which should last for many years. Various water plants — Canadian Pondweed, Curly Waterweed, and Hornwort, were planted and now occupy much of the pond, in spite of major thinning and trimming every winter. There is a good clump of waterlilies and emergent Dwarf Bulrush and Flowering Rush. There are (deliberately) no fish.

Only two people came to dip in the pond on a fine sunny morning. The first instruction is always to look carefully at the water before plunging the net in. ‘What’s that large worm?’, he said. When netted out and placed in a dish, it began to ‘loop’ in characteristic leech fashion — but when stretched out it was a good 25 cm long. It was a Horse Leech. Apparently these do not suck blood from horses (or humans), but live on earthworms that fall into the pond and, it is said, also creep out and hunt them in the wet grass.

Apart from the leech there were dragonfly and damselfly larvae, water mites, snails of several kinds, and mayfly larvae. The microscope revealed another well-populated world, with water fleas, tiny worms, and lots and lots of ostracods (a kind of waterflea that lives within two shells like a miniature and very mobile cockle. A good haul and an interesting morning; we shall repeat it and hope for more participants!