INVESTIGADORES
PEREZ Alejandra patricia
artículos
Título:
Replicated mesocosm study on the role of natural ultraviolet radiation in high CDOM, shallow lakes
Autor/es:
PATRICIA PÉREZ; MÓNICA M. DIAZ; MARCELA A. FERRARO; GABRIELA C. CUSMINSKY; HORACIO E. ZAGARESE
Revista:
Photochemical and Photobiological Sciences
Editorial:
The Royal Society of Chemistry
Referencias:
Lugar: Cambridge; Año: 2003 vol. 2 p. 118 - 123
ISSN:
1474-905X
Resumen:
The role of ultraviolet radiation on shallow, high CDOM (colored dissolved organic matter) lakes was investigated during two consecutive summers (1999 and 2000) in replicated mesocosms (rectangular fiberglass tanks). Each tank (volume: 300-liter; depth: 40 cm) was covered with a layer (~ 3 cm) of sediment from lake El Toro (40° 14? S; 70° 22? W) and filled with filtered water. The experimental design consisted of two treatments: full natural radiation (UV- exposed) and natural radiation without ultraviolet radiation (UV- shielded). UV-exposed and UV-shielded treatments differed in most studied variables as revealed by repeated measures ANOVA. UV-exposed tanks displayed lower CDOM concentration (dissolved absorbance) of lower average molecular size (absorbance ratio between 250 and 365 nm), higher bacteria biomass, and lower chlorophyll a concentration. The effect on consumers (rotifers and crustaceans) was less noticeable. The results are consistent with UV stimulation of bacteria production mediated by higher rates of CDOM photobleaching, and the photoinhibition of planktonic algae. Thus, a major effect of UVR in shallow, high CDOM ecosystems appears to be the stimulation of heterotrophic pathways and a simultaneous inhibition of photoautotrophs.