Publications
A study of the diatoms of the Ouse Estuary, Sussex I. The movement of the mud-flat diatoms in response to some chemical and physical changes, by J. T. Hopkins, published November 1963 in Journal of the Marine Biological Association of the United Kingdom (vol. 43, no. 3, article, p.653, ISSN: 0025-3154) View Online
Abstract:The analysis shows that the diatom community resides mainly in the top 2 mm of the mud and when in bright light the community moves less than 1 mm towards the surface of the estuarine mud, although the colour of the mud changes noticeably. The fine mud supports more diatoms than the coarse mud, and the community in fine mud is nearer to the mud surface, but this is probably caused by the more rapid extinction of light in fine mud than in the coarse mud, while also large spaces between the coarse mud particles may offer less protection from the effect of tidal scour than in fine mud, this giving contributory explanation for the less abundant community in coarse mud.
A Study of the Diatoms of the Ouse Estuary, Sussex II. The Ecology of the Mud-Flat Diatom Flora, by J. T. Hopkins, published June 1964 in Journal of the Marine Biological Association of the United Kingdom (vol. 44, no. 2, article, p.333, ISSN: 0025-3154) View Online
Abstract:By estimating samples of diatoms taken from 0.2 m contour lines, over a horizontal range of about 85 m in the months of July 1953 a nd February 1954 the ecological factors influencing the distribution of eleven species of mud-flat diatoms were investigated. The three important factors were considered to be: the resistance to desiccation near the M.H.W.L., the ability to live under short periods of illumination near to the M.L.W.L., and the ability to tolerate the organic materials present in the black sulphureous layer. Table 7 summarizes the results for the eleven species.
A Study of the Diatoms of the Ouse Estuary, Sussex III. The Seasonal Variation in the Littoral Epiphyte Flora and the Shore Plankton, by J. T. Hopkins, published October 1964 in Journal of the Marine Biological Association of the United Kingdom (vol. 44, no. 3, article, p.613, ISSN: 0025-3154) View Online
Abstract:Analyses have been made of some of the constituents of the coastal sea water and the river water, and the results have been correlated with the growth phases of some planktonic diatom species and littoral epiphytes, although for most species the sea-water temperature and light intensity were limiting factors. The factor determining the death of an epiphytic diatom community in the littoral zone has been considered to be the air temperature in conjunction with desiccation and a summary of the limiting temperatures for each of the four substrata is given in Table 7. Table 10 is a summary of all the distribution and temperature records. The heat itself is not lethal in many cases but the desiccation of the epiphyte in the littoral zone is accelerated at higher temperatures. Diatoms in damp situations were found to occur at temperatures which in a dry site were limiting, and further work indicating the relationship between relative humidity and lethal temperatures is needed. The ability of a diatom to survive depends upon the water-retaining ability of the substratum. Chalk and large algae favoured the growth of most solitary epiphytes, and filamentous epiphytes grew particularly well on algae except the filamentous Navicula, which were best suited by chalk. The Achnanthes blue-green community was most frequent on wood. Concrete makes a firm substratum and allows rapid growth in winter but it is easily dried and most diatoms on it are destroyed in the summer. Four diatom genera ( Fragilaria, Grammatophora, Biddulphia and Melosira ) are able to exist in the epiphyte flora and the shore plankton and the term facultative epiphyte is suggested to describe the behaviour of at least some of the species of these genera.