Seasonal changes in phytoplankton distribution from Óbidos to Almerim in response to Amazon flood pulse.
Evlyn
M.
Novo, Instituto Nacional de Pesquisas Espaciais, C.P. 515-CEP 12201-970, Sa˜o Jose´ dos Campos, Brasil, evlyn@ltid.inpe.br
(Presenting)
Claudio
F.
Barbosa, Instituto Nacional de Pesquisas Espaciais, claudio@dpi.inpe.br
Ramon
M.
Freitas, Instituto Nacional de Pesquisas Espaciais, C.P. 515-CEP 12201-970, Sa˜o Jose´ dos Campos, Brazil, ramon@ltid.inpe.br
John
M.
Melack, Institute for Computational Earth System Science, University of California, Santa Barbara, CA 93106, USA, melack@lifesci.ucsb.edu
Yosio
E.
Shimabukuro, Instituto Nacional de Pesquisas Espaciais, C.P. 515-CEP 12201-970, Sa˜o Jose´ dos Campos, Brasil, yosio@ltid.inpe.br
Waterloo
Pereira Filho, Departamento de Geografia, Universidade Federal de Santa Maria, Santa Maria, Brazil, waterloo@base.ufsm.br
We report an experiment carried out to assess seasonal changes in phytoplankton distribution in the Amazon floodplain lakes. The moderate resolution imaging spectrometer sensor (MODIS) on the U.S. Terra satellite is designed to provide images at optical wavebands which are suitable for detecting phytoplankton patches. The current satellite operational algorithms are suitable for Case 1 waters, but have limited application for complex Case 2 waters such as the Amazon’s. In our study, a mixing model algorithm was applied to MODIS reflectance single date images acquired at three Amazon River stages: rising (April), high (June), falling (September). The study area is located in the floodplain reach extending from Óbidos to Almerim (Pará State). Three endmenbers were used to run the mixing model: high suspended inorganic matter (HSIM), low suspended inorganic matter (LSIM), and high Chlorophyll concentration water (Phyto). The selection of those endmembers was based on ground sampling carried almost concurrently to satellite overpasses at Lago Grande de Curuai Lake. Results showed striking changes in lake and river surface occupied by phytoplankton patches among rising, high and falling water stages. During high water phytoplankton patches are confined to lakes closer to terra firme clear water inflow, whereas during the rising and falling water stages, the patches spread all over the floodplain. Average chlorophyll concentrations range from 9.4 g/l in June (high stage) to 89 g/l at low stage (September), indicating changes in phytoplankton productivity in response to the Amazon River flood pulse.
Submetido por Evlyn Novo em 26-MAR-2004
Tema Científico do LBA: SH (Hidrologia e Química das Águas)