INVESTIGADORES
MODENUTTI Beatriz Estela
artículos
Título:
Effect of UV-B and different PAR intensities on the primary production of the mixotrophic planktonic ciliate Stentor araucanus.
Autor/es:
BEATRIZ ESTELA MODENUTTI ; E BALSEIRO,; CRISTIANA CALLIERI,; ROBERTO BERTONI,; CLAUDIA QUEIMALIÑOS,
Revista:
LIMNOLOGY AND OCEANOGRAPHY
Editorial:
ASLO
Referencias:
Lugar: Estados Unidos; Año: 2005 vol. 50 p. 864 - 871
ISSN:
0024-3590
Resumen:
Stentor araucanus is a mixotrophic ciliate that, in Andean lakes, inhabits the upper epilimnetic levels, which are
commonly avoided by other planktonic organisms. This freshwater heterotrich has dark pigmented cortical granules
and lives autotrophically with endosymbiotic algae. The effect of photosynthetically active radiation (PAR) and
ultraviolet (UV)-B radiation on primary production was analyzed during summer 2003?2004 in Lake Moreno Oeste,
a highly transparent ultraoligotrophic lake (mean summer Kd 5 0.16 m21). Primary production (PP) was measured
in the field in the euphotic zone during both static and variable-depth incubations. Static exposure of the organisms
was examined at different depths (0.30, 10, and 20 m), and the variable depth exposure involved experimental
containers moved continuously up and down the epilimnion (0?15 m). In the static exposure closest to the surface
and in the mobile incubation, quartz tubes were incubated with and without a UV-B screen (Mylary). Additionally,
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
in the field in the euphotic zone during both static and variable-depth incubations. Static exposure of the organisms
was examined at different depths (0.30, 10, and 20 m), and the variable depth exposure involved experimental
containers moved continuously up and down the epilimnion (0?15 m). In the static exposure closest to the surface
and in the mobile incubation, quartz tubes were incubated with and without a UV-B screen (Mylary). Additionally,
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
commonly avoided by other planktonic organisms. This freshwater heterotrich has dark pigmented cortical granules
and lives autotrophically with endosymbiotic algae. The effect of photosynthetically active radiation (PAR) and
ultraviolet (UV)-B radiation on primary production was analyzed during summer 2003?2004 in Lake Moreno Oeste,
a highly transparent ultraoligotrophic lake (mean summer Kd 5 0.16 m21). Primary production (PP) was measured
in the field in the euphotic zone during both static and variable-depth incubations. Static exposure of the organisms
was examined at different depths (0.30, 10, and 20 m), and the variable depth exposure involved experimental
containers moved continuously up and down the epilimnion (0?15 m). In the static exposure closest to the surface
and in the mobile incubation, quartz tubes were incubated with and without a UV-B screen (Mylary). Additionally,
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
in the field in the euphotic zone during both static and variable-depth incubations. Static exposure of the organisms
was examined at different depths (0.30, 10, and 20 m), and the variable depth exposure involved experimental
containers moved continuously up and down the epilimnion (0?15 m). In the static exposure closest to the surface
and in the mobile incubation, quartz tubes were incubated with and without a UV-B screen (Mylary). Additionally,
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
is a mixotrophic ciliate that, in Andean lakes, inhabits the upper epilimnetic levels, which are
commonly avoided by other planktonic organisms. This freshwater heterotrich has dark pigmented cortical granules
and lives autotrophically with endosymbiotic algae. The effect of photosynthetically active radiation (PAR) and
ultraviolet (UV)-B radiation on primary production was analyzed during summer 2003?2004 in Lake Moreno Oeste,
a highly transparent ultraoligotrophic lake (mean summer Kd 5 0.16 m21). Primary production (PP) was measured
in the field in the euphotic zone during both static and variable-depth incubations. Static exposure of the organisms
was examined at different depths (0.30, 10, and 20 m), and the variable depth exposure involved experimental
containers moved continuously up and down the epilimnion (0?15 m). In the static exposure closest to the surface
and in the mobile incubation, quartz tubes were incubated with and without a UV-B screen (Mylary). Additionally,
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
in the field in the euphotic zone during both static and variable-depth incubations. Static exposure of the organisms
was examined at different depths (0.30, 10, and 20 m), and the variable depth exposure involved experimental
containers moved continuously up and down the epilimnion (0?15 m). In the static exposure closest to the surface
and in the mobile incubation, quartz tubes were incubated with and without a UV-B screen (Mylary). Additionally,
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
Kd 5 0.16 m21). Primary production (PP) was measured
in the field in the euphotic zone during both static and variable-depth incubations. Static exposure of the organisms
was examined at different depths (0.30, 10, and 20 m), and the variable depth exposure involved experimental
containers moved continuously up and down the epilimnion (0?15 m). In the static exposure closest to the surface
and in the mobile incubation, quartz tubes were incubated with and without a UV-B screen (Mylary). Additionally,
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanus
y). Additionally,
PP was measured in the laboratory with and without previous exposure to a UV-B lamp (290?315 nm). S. araucanusS. araucanus
was present throughout the summer with highest abundances at or above 15 m in depth. A high proportion of the
ciliate population (80%) was, therefore, exposed to UV radiation, and between 30% and 60% of the population
occupied depths at which UV-B (305 nm) exceeded 1% of surface incidence. PP values were higher in the epilimnion
than below it and were not reduced by exposure to high irradiances of PAR1UV-A and PAR1UV-A1UV-B. The
laboratory experiments showed no difference between UV-B and PAR preexposure treatments. The variable-depth
epilimnetic incubations gave similar PP values and did not differ from the static incubations. The average PAR
irradiance of the epilimnion was high, around 600 mmol photons m22 s21, which was the value at which S. araucanus
laboratory experiments showed no difference between UV-B and PAR preexposure treatments. The variable-depth
epilimnetic incubations gave similar PP values and did not differ from the static incubations. The average PAR
irradiance of the epilimnion was high, around 600 mmol photons m22 s21, which was the value at which S. araucanus
1UV-A and PAR1UV-A1UV-B. The
laboratory experiments showed no difference between UV-B and PAR preexposure treatments. The variable-depth
epilimnetic incubations gave similar PP values and did not differ from the static incubations. The average PAR
irradiance of the epilimnion was high, around 600 mmol photons m22 s21, which was the value at which S. araucanusmmol photons m22 s21, which was the value at which S. araucanus
reached a saturation level in the laboratory. In contrast, the incubations at 20 m differed significantly from those
in the epilimnion, exhibiting lower values, except when PAR irradiance was higher than 100 mmol photons m22mmol photons m22
s21. These results indicate that pigmented mixotrophs like S. araucanus achieve high population densities in the
epilimnion because they receive sufficient irradiance (PAR between 100 and 1,600 mmol photons m22 s21) to allow
endosymbiotic algae to produce.
endosymbiotic algae to produce.
epilimnion because they receive sufficient irradiance (PAR between 100 and 1,600 mmol photons m22 s21) to allow
endosymbiotic algae to produce.
endosymbiotic algae to produce.
21. These results indicate that pigmented mixotrophs like S. araucanus achieve high population densities in the
epilimnion because they receive sufficient irradiance (PAR between 100 and 1,600 mmol photons m22 s21) to allow
endosymbiotic algae to produce.
endosymbiotic algae to produce.
mmol photons m22 s21) to allow
endosymbiotic algae to produce.