INVESTIGADORES
PIZARRO Haydee Norma
artículos
Título:
Top-down control on planktonic components in a hypertrophic Antarctic pond: experimental approach to the study of lowcomplexity food webs
Autor/es:
ALLENDE, L; H. PIZARRO
Revista:
POLAR BIOLOGY
Editorial:
Springer
Referencias:
Lugar: Berlin; Año: 2006 vol. 29 p. 893 - 901
ISSN:
0722-4060
Resumen:
Abstract In order to address the top-down effect on the
different phytoplankton size-fractions and ciliates, a
survey at microcosm scale was conducted in a hypertrophic
Antarctic pond, testing the hypotheses that (1)
the picophytoplankton is regulated by a top-down control
exerted by organisms of the bigger size-fractions,
and (2) the nanoplankton fraction (algae and ciliates) is
not regulated by a top-down control exerted by the
microplankton. The treatments enclosed pond water
that was filtered to obtain the different plankton sizes:
(a) through 55 lm, (b) 20 lm, and (c) 3 lm pore size
filters. The variation in the net growth rate (k¢) of the
phytoplankton size-fractions and ciliates was analysed
after 4 days. The results determined a significant difference
(P<0.011) in the k¢ value of the picophytoplankton
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
phytoplankton size-fractions and ciliates was analysed
after 4 days. The results determined a significant difference
(P<0.011) in the k¢ value of the picophytoplankton
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
filters. The variation in the net growth rate (k¢) of the
phytoplankton size-fractions and ciliates was analysed
after 4 days. The results determined a significant difference
(P<0.011) in the k¢ value of the picophytoplankton
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
phytoplankton size-fractions and ciliates was analysed
after 4 days. The results determined a significant difference
(P<0.011) in the k¢ value of the picophytoplankton
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
different phytoplankton size-fractions and ciliates, a
survey at microcosm scale was conducted in a hypertrophic
Antarctic pond, testing the hypotheses that (1)
the picophytoplankton is regulated by a top-down control
exerted by organisms of the bigger size-fractions,
and (2) the nanoplankton fraction (algae and ciliates) is
not regulated by a top-down control exerted by the
microplankton. The treatments enclosed pond water
that was filtered to obtain the different plankton sizes:
(a) through 55 lm, (b) 20 lm, and (c) 3 lm pore size
filters. The variation in the net growth rate (k¢) of the
phytoplankton size-fractions and ciliates was analysed
after 4 days. The results determined a significant difference
(P<0.011) in the k¢ value of the picophytoplankton
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
phytoplankton size-fractions and ciliates was analysed
after 4 days. The results determined a significant difference
(P<0.011) in the k¢ value of the picophytoplankton
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
filters. The variation in the net growth rate (k¢) of the
phytoplankton size-fractions and ciliates was analysed
after 4 days. The results determined a significant difference
(P<0.011) in the k¢ value of the picophytoplankton
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
phytoplankton size-fractions and ciliates was analysed
after 4 days. The results determined a significant difference
(P<0.011) in the k¢ value of the picophytoplankton
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.
when nano and micro-sized fractions where removed.
Conversely, nanophytoplankton and nanociliates were
not affected by the removal of bigger size-fractions. We
suggest that in this pond the top-down control of the
picophytoplankton is relevant, and that the grazing
impact is not a key factor in the regulation of the nanosized
(algae and ciliates) plankton components.