A dinâmica do fitoplâncton em uma várzea Amazônica variações sazonal e nictimeral (Várzea do Lago Grande de Curuai Pará, Brasil)
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2011-03-28
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Universidade Federal de Goiás
Resumo
The river-floodplain systems are environments submitted a lateral overflow of river
channel due the rains and/or underground waters. They are controlled by the type of
climate, morphology and local effects. The lowland lakes are also highly productive
because of the rich sources of primary carbon. The sediments transport and suspended
and dissolved matter are done by the rivers between the land and aquatic phases. These
phases strongly influence nutrient cycling, primary and secondary production and
decomposition. The phytoplankton dynamics in tropical floodplain lakes is as variable
as the seasonal and isolation patterns of flooding. For this reason, the aims of this work
were i) to assess the rotation influence of potamophase and limnophase upon the
phytoplankton of the Curuai Lake (PA, Brazil) and about the connectivity between other
lakes, and ii) to evaluate the phytoplankton dynamics in a nictemeral cycling related to
changes in CO2 in water, and what phytoplankton groups which were most important in
this process. The phytoplankton community and environmental variables of the
floodplain lakes of the Curuai Lake were sampled in the potamophase and limnophase
(2009) and in a nictemeral cycling (2010). The informations summarized were obtained
through the principal component analysis (PCA), canonical correspondence analysis
(CCA), redundancy analysis (RDA) and nonmetric multidimensional scaling (MDS).
The community structure was different among the periods with greater richness, density
and phytoplanktonic biovolume in limnophase. There was predominance of
Cryptophyceae (mainly Cryptomonas brasiliensis Castro, Bicudo & Bicudo) in
potamophase and Cyanophyceae [Dolichospermum circinalis (formerly Anabaena
circinalis) (Rabenh. ex Bornet et Flah.) Wacklin et al.] in limnophase, both influenced
by environmental variables. In addition, the high phytoplanktonic biomass was favored
by the highs temperatures and also responsible by the CO2 depletion in water caused by
photosynthesis, which is reflected for the high carbon content in phytoplankton
organisms. Despite the entry of water in the floodplain that connects the lakes, these
environmental were distinct in relation a phytoplankton composition and a limnological
variables. The phytoplanktonic community in Curuai Lake showed daily variation of
biovolume because of high temperature and light availability. The development of
persistent cyanobacteria bloom, with species predominance of Dolichospermum genius
[functional group H1, D. spiroides (formerly A. spiroides) (Klebahn) Wacklin et al.]
and Microcystis protocystis Crow (functional group M) caused the CO2 depletion in
lake surface layer during the period of increased photosynthesis. The cyanobacteria
bloom occurred mainly due to the attributes of group, which became it expressive
competitors in relation another microalgae ones.
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Citação
ALVES, Carla Patrícia Pereira. The dynamics of phytoplankton in an Amazon fllodplain - seasonal and nictemeral variations (Lago Grande de Curuai - Pará, Brasil). 2011. 93 f. Dissertação (Mestrado em Ciências Biológicas - Biologia) - Universidade Federal de Goiás, Goiânia, 2011.