INVESTIGADORES
DE TEZANOS PINTO paula
artículos
Título:
Eco-physiological responses of nitrogen-fixing cyanobacteria to light.
Autor/es:
DE TEZANOS PINTO, PAULA; LITCHMAN, ELENA
Revista:
HYDROBIOLOGIA
Editorial:
SPRINGER
Referencias:
Año: 2010 vol. 639 p. 63 - 68
ISSN:
0018-8158
Resumen:
The eco-physiological responses of three nitrogen-fixing cyanobacteria (N-fixing cyanobacteria), Aphanizomenon gracile, Anabaena minderi and Anabaena torques-reginae, to light were assessed under nutrient saturation. The N-fixing cyanobacteria were isolated into monocultures from a natural bloom in a shallow colored lake and their growth irradiance parameters and pigment composition were assessed. The different ecological traits related to light use (µmax, alpha, Ik) suggest that these N-fixing cyanobacteria are well adapted to low light conditions at sufficient nutrients, yet interspecific differences were observed. Aph. gracile and An. minderi had high relative growth rates at low irradiances (ca. 70% of those in high light), low half saturation constant for light-limited growth (Ik < 9.09 μmol photon m-2 s-1) and high efficiency (alpha< 0.11 d-1μmol photon-1 m2 s). Conversely, An. torques-reginae showed poorer light competitiveness: low relative growth rates at low irradiances (ca. 40% of those in high light), low alpha (0.009 d-1μmol photon-1 m2 s) and higher Ik (35.5 μmol photon m-2 s-1). Final densities in Aph. gracile and An. minderi reached bloom densities at irradiances above 30 μmol photon m-2 s-1 with different hierarchy depending on irradiance, whereas An. torques-reginae never achieved bloom densities. All species had very low densities at irradiances below 17 μmol photon m-2 s-1, thus no N-fixing blooms would be expected at these irradiances. Also, under prolonged darkness and at lowest irradiance (0 and 3 μmol photon m-2 s-1) akinetes were degraded, suggesting that in ecosystems with permanently dark sediments, the prevalence of N-fixing cyanobacteria should not be favored. All species displayed peaks of phycocyanin, but no phycoeritrin, probably due to the prevailing red light in the ecosystem from which they were isolated.