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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 3209

A.L. Galliford and E.G. Williams; Microscopic Organisms of Some Brackish Pools at Leasowe, Wirral, Cheshire. North Western Naturalist XXIII:39-62, 1948

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The pools were artificially formed and are still subject to occasional, but irregular, influxes of seawater. The salts are derived mainly from the sea directly, but lime salts, etc. many be leached out of the soil and concentrated. From time to time high salinities and influx of strictly marine organisms are due to invasion of seawater. Salinities then begin to decrease under the influence of rainfall and drainage. The marine organisms of poor adaptability die out fairly soon, and it is probable that poor adaptability causes mortality to brackish and freshwater forms in sudden increase of salinity. Whether this mortality is 100% in either case is open to question, and we would appear to be faced with that struggle for existence to which the intertidal creatures are subjected. The composition of the macro fauna (insecta, mollusca, malacostrata, etc.) appears to be fairly constant, but that of the micro-fauna and micro-flora appears to reflet the changing conditions and comparatively few forms were active over the whole period of observation. This is, of course, the case for pieces of water generally. It would appear that many of the freshwater forms of micro-fauna and micro-flora have some tolerance of slight salinity, though some, such as the Cladocera and certain Rotifers, as usual were entirely missing from even the least saline of the pools.