Resumen de Chlorophyll fluorescence analysis and cadmiumcopper bioaccumulation in Ulva rigida (C. Agardh)
Jose Enrique Barraza Sandoval, Alejo Carballeira Ocaña
- español
Mediante este estudio se pretende determinar la utilidad del alga Ulva rigida (C. Agardh) para monitorizar Cd y Cu disueltos en agua de mar, así como el estrés fisiológico causado por ambos metales. Para ello, discos de dicha alga (d = 19 mm) se colocaron en diferentes soluciones de Cd y Cu, durante un periodo de 12 días, siendo las concentraciones seleccionadas: 0,1; 0,3; 0,9; 2,7 mg metal l⁻¹ de solución, así como los respectivos controles. Las lecturas de fluorescencia de clorofila se efectuaron los días 1, 2, 5, 9 y se analizó el contenido metálico de los discos mediante espectrofotometría de absorción atómica con llama (AAS). Los tratamientos de Cu y los de mayor concentración de Cd (0,3; 0,9; 2,7 mg l⁻¹) presentaron claras señales de perturbación del fotosistema II, con reducciones claras del rendimiento cuántico óptimo (Fv/Fm). De igual forma, los tratamientos de Cu redujeron la eficiencia fotosintética del alga. Los niveles corporales de Cd y Cu en U. rigida registraron incrementos sucesivos durante el periodo experimental y fueron proporcionales a los tratamientos. Las cinéticas de carga fueron modelizadas mediante ajuste a Michaelis-Menten.
- English
The objective of the present study was to determine the usefulness of the alga Ulva rigida (C. Agardh) in monitoring dissolved cadmium and copper in seawater, as well as the physiological stress caused by both metals. Discs from the alga (d = 19 mm) were cultured in different Cd and Cu growth media during a 12-day period. The concentrations established were 0.1, 0.3, 0.9, 2.7 mg metal 1⁻¹, as well as the corresponding controls. Chlorophyll fluorescence readings were performed on days 1, 2, 5, 9 and 12. Discs were frozen for later AAS analysis (Perkin-Elmer). Treatments with higher Cd concentration (0.3, 0.9, 2.7 mg l⁻¹) presented clear signs of disturbing photosystem II, since optimum quantum yields (Fv/Fm) were lower than the control responses. Similarly, Cu treatments diminished the alga's photosynthetic efficiency. Cu and Cd internal levels in U. rigida increased successively during the experiments, which also were proportional to the treatments. These levels were transformed into contamination factors (CF), calculated by dividing each concentration by its respective control and adjusting with Michaelis- Menten kinetics.
