Abstract
Sediment samples were collected at low tide from eight sandy and muddy shores around Southampton Water on one occasion in July and one occasion in September. The temperature and pH of the sediments were measured at the time of collection, the water content of the sediments was determined and samples subjected to granulometric analysis. The population densities of bacteria and microflagellates were determined and the ciliates in sub-samples were identified to genus level and enumerated. The concentrations of cadmium, copper, lead, mercury and nickel in the interstitial water and in the dried sediments were measured by the dithizone and atomic absorption methods, respectively. These metal concentrations were compared with literature values for other British estuaries. Ciliates belonging to 23 genera were found in the sediments, the diversity of ciliates varying widely between stations. Bacterial numbers (mean ∼5×10
8
cm
−3) at the various stations correlate with the surface area of the sediment particles and also correlate weakly with flagellate numbers (mean ∼2×10
4
cm
−3). Total ciliate numbers (mean ∼1×10
3
cm
−3) correlated quite strongly with flagellate numbers, but not with bacterial numbers.
Euplotes,
Strombidiumand
Uronemawere common at all stations and generally dominated;
Didinium,
Mesodinium pulexand
Pleuronemawere also found at all stations, and the latter two were often numerous;
Uronychiawas found at seven stations. The distributions of
Acinetopsis,
Blepharisma,
Lacrymaria,
M. pulex,
Paramecium,
Spirostomum,
Strombidiumand
Vorticellashowed similar correlations to one another, and tended to favour sites nearer to sources of freshwater; these ciliates also showed a correlation with pH, river waters locally being alkaline. None of the ciliates showed correlations with any physical characteristics of the sediments. There were no negative correlations of ciliate distributions with metal pollutants. The levels of metal pollutants found in water drained from the sediments do not exceed concentrations to which laboratory cultures of
Euploteshave been found to acquire tolerance.