Some mineral nutrient studies of a lowland mere in Cheschire, England

Seasonal variations in the vertical distribution and buoyancy of Microcystis aeruginosa Kütz. emend. Elenkin in Rostherne Mere, England

“…A general impression of turbulent mixing and stratification in Rostherne Mere may be gained from the depth distribution of isotherms, presented in Fig . 3 (see also Grimshaw & Hudson, 1970) . The mere became thermally stra-3 v 18 20 6 24 S tified during May 1973.…”

“…There, the populations also develop shortly after the onset of thermal and chemical stratification, apparently in association with the development of reducing conditions in the hypolimnion, which are known to have a stimulatory effect upon the physiological activity of the blue-green algae . In Rostherne Mere, oxygen saturation in the hypolimnion falls to less than 10% in summer (Brinkhurst & Walsh, 1967) and the establishment of reducing conditions within one month of the onset of thermal stratifications is indicated by Grimshaw & Hudson's (1970) data concerning the liberation of phosphate and ammonia . Thus, chemical stratification may well have a causal role in the promotion of the annual Microcystis growth in Rostherne Mere .…”

“…17-23, 1976 Shropshire-Cheshire Plain (Area 46 .5 ha ; max depth : 30 m) . A description of its physiographic setting, together with details of the ionic composition of its waters have been given by Grimshaw & Hudson (1970) . Its phytoplankton has been described previously by Pearsall (1932), Lind (1944) and by Belcher & Storey (1968) .…”

Algal sedimentation in relation to phytoplankton periodicity in Rostherne Mere

“…The areal equivalent of the vernal diatom maxima (units cm-3) are calculated from equation (1), thus: P = C x 13.7 × 100 (1) where C is the concentration of algal units ml-1 of integrated 4.5 m column samples. During summer, the isothermal depth can never exceed that of the epilimnion, typically less than 8 m (Grimshaw & Hudson, 1970;Reynolds & Rogers, 1976). The areal equivalents of algal concentrations are approximated from equation (2): P=Cx 8.0 × 100 (2) With the exception of those for Nitzschia, the areal catches of the diatom species are apparently overestimated by factors of 2-20 for the commoner forms, and increasing to 330 in the case of Melosira varians.…”

Notes on the phytoplankton periodicity of Rostherne Mere, Cheshire, 1967–1977

“…Brinkhurst & Walsh (I967) suggested that the establishment and subsequent development of a gull roost (predominantly of Larus ridibundus L.) since about 1910 may have led to the virtual elimination of a bottom invertebrate fauna, through "guanotrophy". Reynolds (1978b) has argued that the increase in maximum nitrate and phosphate concentrations indicated in the literature (Gorham, 1957;Grimshaw and Hudson, 1970) during the last two decades is similar in both scale and timing to those which have occurred in nearby meres, and which are largely attributable to enrichment from agricultural sources. However, neither possibility has been adequately investigated.…”