Remarks on a Bloom of Microcystis aeruginosa Kützing
Parra, O.O.; Ugarte, E.; Mora, S.; Liberman, M.; Aron, A.; Balabanoff, L.
Nova Hedwigia Band 33 Heft 1-4 (1980), p. 971 - 1004
40 references
published: Feb 26, 1980
DOI: 10.1127/nova.hedwigia/33/1980/971
ArtNo. ESP050003300036, Price: 29.00 €
Abstract
The appearance and persistence of a bloom of Microcystis aeruginosa Kütz., a blue-gren alga considered in the literature as toxic for man as well as for domestic animals, are analyized. The quantitative variations in the population, observed between April and August, 1977, are analized, using samples taken at depths of 0, 5 and 10 meters. At the same time, the habitat factors that have a role in the development of blooms of Microcystis are measured. The accompanying phytoplankters and the quantitative fluctuations of those that were more abundant, are also determined. The results of the measurements are compared with those obtained in previous research work for another body of water in the same region (lake Lo Mendez), and with the requirements indicated by laboratory cultures, especially those determined by Gerloff et al. (1952). In Laguna Grande de San Pedro the bloom occurred when the orthograde distribution of O2 and the uniformity in the thermic outline indicated circulation in the water column. Low values for water transparency were detected and the pH remained low and close to the optimum for the growth of M. aeruginosa. The bloom appeared in Laguna Grande de San Pedro under conditions of water hardness that were quite different from those determined in lake Lo Mendez. The Ca and Mg values were always above the minimum requirements of the alga. The P-PO4 concentrations proved to be much under the “surprisingly low” requirements determined by Gerloff et al. Likewise, N-NO2 and N-NO3 were present in concentrations that were under the minimum requirements determined in the cultures. The S-SO4 was occasionally low and Na and K were always in more than satisfactory concentrations. The silicate concentration was constant in the period under study; a drop was registered at the end of this period, which coincided with a rise in the number of Melosira granulata, a diatom that became the dominant species in the phytoplankton.
Keywords
bloom • alga • habitat factors • phytoplankters • quantitative fluctuations • orthograde distribution • thermic outline • lake Lo Mendez • Laguna Grande de San Pedro • Chile