Phycoperiphyton Development on an Artificial Substrate in the River Wye System, Wales, U. K. Part 2: Population Dynamics

Abstract

Summary:The temporal and spatial fluctuations of the main alg@ phyla and the constant species colonising Perspex slides were studied. Higher algal counts were noted during the warmer periods of the year and lower ones during the winter months. The Bacillariophytra dominated the other algal phyla and greatly affected the total biomass. The Chlorophyta were represented by a few speoies which were regarded as plankton fall-out.The diatom species showed various, inconsistent relationships with different environmental variables. It was concluded that not only the environmental variables affected the colonisation and growth of benthic algae, but also others, such as smoothness of the surface of the Perspex slides, duration of colonisetion period, accumulation of silt and detritus on the slide, the competition for limited spaces and selectivity of the Perspex slides for certain species.Several species colonising both the Perspex slides and stone surfaces either failed to correlate significantly between themselves or were not correlated at all. Several others were only correlated Significantly at some stations and not correlated a t others. It wa8 therefore concluded that the Perepex slides affected the algal species in an unpredictable manner a t the different sampling sibs and so rendered the method unreliable for reflecting true ecological changes.