LBA-ECO 9th Science Team Meeting Seasonal changes in phytoplankton distribution in floodplain lakes in response to Amazon flood pulse derived from MODIS images Evlyn Márcia Leão de Moraes Novo Cláudio Clemente de Farias Barbosa Ramon Moraes de Freitas Yosio Edimir Shimabukuro Instituto Nacional de Pesquisas Espaciais, John M. Melack University of California, Santa Barbara, Waterloo Pereira Filho Universidade Federal de Santa Maria

LBA-ECO 9th Science Team Meeting What we know from literature Primary production has high spatiotemporal variation within most river-floodplain systems. In the central Amazon Basin, primary productivity ranges from 50 to mg C m-2 d-1) according to location and flood stage. Macrophytes appear to be the major producers in floodplains (Bayley 1989; Melack et al.1999; Lewis et al. 2001, Melack and Forsberg 2001). Source: Winemiller K.O., 2005 Department of Wildlife and Fisheries Sciences, Texas A&M University

LBA-ECO 9th Science Team Meeting What we know from literature Analysis of stable isotopes indicates that dominant production sources for higher consumers in the Amazon river-floodplain food webs appear to be phytoplankton, periphyton and fine particulate organic matter derived from algae (Araujo-Lima et al. 1986; Forsberg et al. 1993; Thorp and Delong 1994, 2002; Thorp et al. 1998; Benedito-Cecilio et al. 2000; Lewis et al. 2001;Leite et al. 2002).

LBA-ECO 9th Science Team Meeting Why such a discrepancy? Time intensive sampling restricted to too few sample sites to grasp spatial variability. Space intensive sampling restricted to too few dates to grasp time changes. Chlorophyll distribution (mg/l) Sampling strategy constrained by access to floodplain lakes during certain phases of the hydrological cycle. Ground sampling

LBA-ECO 9th Science Team Meeting How to address the problem? Integration of field sampling and satellite analyses MODIS data advantages –synoptic view, –medium resolution (250 m x 250 m) –relatively high frequency of cloud free

LBA-ECO 9th Science Team Meeting How to derive information on phytoplankton abundance? changes in water color are related to chlorophyll concentration in case 1 water (Darecki and Stramski 2004). case 2 water optical properties are determined by a mixture of components (Mobley 1994). –phytoplankton, –inorganic particles, –colloids – dissolved organic matter MODIS IMAGE

LBA-ECO 9th Science Team Meeting How to uncouple the chlorophyll signal? Application of unmixing model to compute chlorophyll fraction images (Mertes 1990; Novo and Shimabukuro,1994). –end member selection High inorganic particle concentration(ip > 100mg/l) High phytoplankton (chl concentration > 20 mg/m 3 ) Clear/black water (< 5mg/l) Mixture Analysis

LBA-ECO 9th Science Team Meeting Experimental procedure Ground data collection concurrently to MODIS overpasses at Curuai floodplain lake. –70 sample sites chlorophyll (Chl), suspended inorganic particle (ip) dissolved organic carbon (DOC). –4 ground missions at critical phases of the hydrological cycle. Water level changes Ground data analysis –Basic statistics to define strategy for model development. Ground Sample Statistics

LBA-ECO 9th Science Team Meeting Experimental procedure Image processing –JERS-1 wetland mask –Water mask derived from SWIR band to isolate open lakes Mixing model application Empirical model development –Boundary conditions Exclusion of high inorganic matter environment Exclusion of low chlorophyll concentration water masses Model assessment

LBA-ECO 9th Science Team Meeting Empirical Model Chl = 3.9 e fphy –Standard error = 19 mg m -3 – Adjusted R 2 = 0.76, – Model predicts, with an error of around 25 %, chlorophyll concentration in the range between 10 to 120 mg m -3

LBA-ECO 9th Science Team Meeting Model extension Application of the empirical model to a time series of MODIS (MOD 09 day product) images from June 02 to December 03. Chlorophyll spatial distribution Computation of the weighed average of chlorophyll concentration from Parintins (Amazonas) to nearby Almerim (Pará). Chorophyll x Water level

LBA-ECO 9th Science Team Meeting Conclusions chlorophyll concentration is higher than reported in the literature. Human pressure on the floodplain may be a factor controlling those high concentrations. Floodplain transects Floodplain transects there is an almost six month offset between the maximum water level and the maximum weighed average chlorophyll concentration. phytoplankton peak production is achieved when the Amazon pulse recedes, and the lakes are enriched by dissolved nutrients but less turbid water.