doctoralThesis
Qualidade da água e dinâmica temporal da biomassa fitoplanctônica em açudes do Semiárido: uma abordagem ótica
Fecha
2018-12-21Registro en:
VENTURA, Dhalton Luiz Tosetto. Qualidade da água e dinâmica temporal da biomassa fitoplanctônica em açudes do Semiárido: uma abordagem ótica. 2018. 121f. Tese (Doutorado em Ecologia) - Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, 2018.
Autor
Ventura, Dhalton Luiz Tosetto
Resumen
All over the world, scientists, managers and policy-makers have been challenged by
several ecological and economic issues caused by the artificial eutrophication of lakes,
whose most visible effect is the excessive phytoplankton biomass, commonly represented
by the chlorophyll a concentration (chla). While nutrients play a primary role in the
temporal dynamics of the phytoplankton biomass, the lakes’ hydraulic regime can exert
an external control over such dynamics. In this study, we assessed the influence of the
hydraulic regime on the temporal dynamics of the phytoplankton biomass in man-made
lakes of the Brazilian semiarid region. Lakes are a crucial source of water resources for
human consumption and irrigation in that region, but they are frequently affected by
eutrophication and lack an adequate limnological monitoring. To overcome this data
deficiency, we assessed the relationships among water quality and optical properties in
13 lakes of the study region, validated an algorithm for estimating chla from images of
the MODIS orbital sensor, and generated a 15-year time series for the three largest study
lakes: Orós (OROS), Castanhão (CAST) and Eng. Armando Ribeiro Gonçalves (EARG).
Because lakes in the Brazilian semiarid region are subject to a seasonally marked
hydraulic regime, we hypothesized that it would be reflected on the temporal variation of
chla. The comparison between the time series of chla and lakes’ volume supported such
hypothesis. The concentrations steeply dropped with intense rainfall-driven water
renewal and kept high during the dry periods. The intense rainfall of 2004 abruptly
reduced the phytoplankton biomass in EARG and OROS lakes and, for the latter, its
effects even extended to the subsequent years. Our results encourage the exploration of
the MODIS archived imagery for further studying the temporal dynamics of the
phytoplankton in natural and man-made lakes, at both seasonal and interannual scales.