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Variation in climate determines differences in the influence of abiotic variables on the phytoplankton community in tropical ecosystems
This study shows the influence of abiotic variables on phytoplankton in two different tropical climates. Samples were taken from tropical reservoirs, including six from tropical climate (As) and five from semi-arid climate (BSh). Phytoplankton samples were identified and biomass was quantified. Climatic and physicochemical variables were evaluated. We performed canonical analyses in order to observe the influence of abiotic variables on phytoplankton. In both As and BSh ecosystems, the physicochemical variables were significant, and the synergistic effect between variables and climatic conditions were more pronounced in BSh. Micronutrients had a significant role in structuring the phytoplankton community in both As and BSh. In As climate, Cylindrospermopsis raciborskii occurred under lower concentrations of zinc and copper, while in BSh, this species was present under higher concentrations of zinc. In As climate, Geitlerinema amphibium, Cyclotella meneghiniana, Planktothrix agardhii, and Microcystis aeruginosa were also associated with higher sodium concentrations in water, while in BSh, these species experienced lower rainfall. The climate determines the influence of abiotic variables on the phytoplankton community in an isolated and synergistic way. We showed that phytoplankton in tropical and semi-arid reservoirs is mostly regulated by nutrients whose influence varies according to the climate.
MF17079 Accepted 06 September 2017
© CSIRO 2017