SOME STUDIES ON BLUE-GREEN ALGAE

Abstract

167 samples of algae were collected from Wessex Estate (Singapore 0513) and various other locations in Singapore. With the exception of a very low occurrence of diatome(Bacillariophyta), all the algae collected belong to either blue-green (Cyanophyta) or green (Chlorophyta) algae. Only seven species of filamentous blue-green algae (five non-heterocystous, two heterocystous) were collected. The five non-heterocystous species were Schizothrix ca1cico1a, S. mexicana, Oscillatoria lutea, Microco1eus vaginatus and Porphyrosiphon notarisii, while the two heterocystous species were Scytonema hofmannii and Nostoc commune. S. hofmannii was found to be consistently associated with a rich variety of coccoid blue-green algae. A non-heterocystous blue-green alga, Porphlrosiphon notarisii, was used for various motility studies. Linear translation of trichomes of P. notarisii during gliding was associated with rotational movement about the long axis, with any point on the trichome surface describing a left-handed helix. In addition, the slightly curved terminal of a mature trichome traced a little Cone in space at the same time. Either end of a trichome with one blunt and one tapering terminal could be leading during gliding. Reversals occurred unpredictably and spontaneously during gliding, but could not be induced by impact with an obstacle. Short trichomes showed a higher reversal frequency and may display rapid and incessant jerks during gliding. Free ends of attached trichomes displayed significant f1exional movement. Trichomes were capable of rapid dispersion and aggregation depending on circumstances. Trichomes from about 0.2 - 2.0 mm showed a significant correlation between length and gliding rate, with the longer trichomes moving faster than the shorter. Different types of trichomes with respect to terminal morphology did not show any significant difference in gliding rate. Tetracaine, a local anaesthetic, inhabited motility in P. notarisii. It also induced the breaking up of the trichomes into shorter pieces.