Ecology of a deep-living Oscillatoria (= Plankto-thrix) population in the sulphide-rich waters of a Spanish karstic lake.
Camacho, A.; Vicente, E.; Miracle, M. R.
published: Jun 14, 2000
ArtNo. ESP141014803007, Price: 29.00 €
In a three-year field survey which included some ecophysiological studies, the ecology of a deep living Oscillatoria (= Planktothrix) cf. ornata population at the chemocline and in the hypolimnion of the sulphate-rich karstic Lake Arcas was studied. This cyanobacterium, together with the phototrophic sulphur bacterium, Chromatium weissei, develops dense populations in the anoxic waters of the lake during the summer stratification (maximal cyanobacterial population densities were around 1,300 filaments/ml), both being absent from the water column during the mixing period. O. cf. ornata from Lake Arcas shows several adaptative features which help to explain the development of these dense populations. Phycoerythrin, the main light-harvesting accessory pigment, allows this cyanobacterium to collect efficiently the yellow-green light reaching the chemocline, which can only be used via photosystem II. Oxygen-evolving photosynthesis in this species is sulphide-resistant, it can be sustained at the sulphide concentrations found at the chemocline of the lake. In addition, buoyancy regulation mediated by gas-vesicle formation and carbohydrate accumulation substantially overcomes sinking losses in the population.