Ecology and physiology of photosynthetic organisms in highly acid streams

Abstract

Two surveys of the water chemistry and photosynthetic flora were carried out in England, for waters with a pH of 3.0 or less. Of the 16 sites located, fourteen were associated with coal mining, one with a barytes mine and one with an industrial effluent. One coal mining site (Site 16) and the industrial effluent (Site 15), were found to run intermittently below pH 3.0. Samples collected from 95 10 m reaches, showed that the waters were characterized by high levels of heavy metals, silicate and sulphate and that most carried moderately large levels of phosphate and combined inorganic nitrogen. The total flora from the 16 sites consisted of 24 algal species, two mosses and two flowering plants. Of the 8 species which occurred in over 20% of the roaches sampled, Euglena mutabilis was the most widespread and abundant species. One stream with a pH gradient of 2.6 - 7.0 (Brandon Pithouse Acid Stream) was studied in greater detail. Observations were made in respect to seasonal variation and to changes in chemistry and flora along the pH gradient. In addition, monthly estimations of the maximum standing crop of algae and moss protonema were carried out for one year. Analysis of these data suggests that over a large pH range, H+ concentration has the greatest influence on the number of species present in the stream; although other factors (eg. precipitation of ferric hydroxide) may also affect the presence and abundance of some algae. in addition to field studies, laboratory experiments were conducted on five species of algae isolated from Brandon Pithouse Acid Stream. These included an examination Of the effect pH had on growth and morphology and also the relationship between low pH and heavy metal toxicity.