There are six different issues here: 1.There are very many lakes around the country that are turning into meadows! This is because the efficient exit system designed and built by Victorians, that lost the dirtiest bottom-water, has been blocked up (naturally by sticks and stones, or more often by concrete!); the cleanest water – surface water - is now lost over a weir. This results in detritus building up in the lake till it breaks the surface and starts growing grass (see picture). What people usually do then is precisely the wrong thing: they dredge! What they should do is repair or reconstruct the old exit, to use the power of the water itself to take the detritus away. I have much experience with these lakes, and will be delighted to advise (I also know builders who are happy to work with watery systems). 3.Ponds – from the smallest garden feature to one acre small lakes – have special requirements, e.g. pumps, filters (dwarfs and gnomes?). There are several kinds of semi-tropical fishes that do very well in temperate ponds with an anti-freeze heater: medaka, mountain minnows, even paradise fish - while larger ponds can benefit from grass carp and odd catfish! As well as koi, of course. 4.Establishing ponds and small lakes is quite difficult. Basically, they need infecting with a variety of small crustaceans, and an eye kept on the microscopic life. 5.School ponds are a special case. They are often an Edwardian relic, useless to modern teachers who don’t know an Asellus fom a Gammarus. There are two possibilities, either making them simple and decorative with a pump and fountain, or importing books like the Observer’s Book of Pond Life to involve sixth formers – and teachers. 6.Amoeba and Hydra. In the middle years of last century, when I taught Protozoa and Coelenterates, about half of ponds had amoeba and nearly all had several hydras. Only one of more than 50 local lakes has amoeba now; hydra is more common. I have been keeping Sister Monica Taylor’s original (1932-isolated) Amoeba proteus since the middle 1970’s, and am happy to infect ponds with them. I also keep several hydras, including (hopefully, as I write) a very large Hydra pseudo-oligactis from the lake at Orielton Field Station in Pembrokeshire. . |