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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />were vacuum-filtered through separate 0.45 ~m pore-size fiberglass <br />filters in the field; the filters were placed in separate labeled envelopes <br />and placed on dry ice until returned to the lab. Chlorophyll extraction <br />and analysis was performed according to methods outlined in Parsons <br />and Strickland (1963). <br /> <br />Organic material composed of living or dead suspended particulate material <br />is important to the ecosystem since it represents food for aquatic <br />fauna from zooplankton to larval fish. Total and organic suspended <br />particulate material in the river and backwaters, with a comparison <br />of two size fractions (>25 ~m and <25 ~m) were determined as follows: <br />fifty liters of water were filtered through a 25 ~m pore-size net. <br />About 10 L of the filtrate passing through the 25 ~m net was retained <br />in a clean container. The filtrate retained by the net (the >25 ~m <br />fraction) was collected and preserved with sufficient formalin to yield <br />about a 2 percent solution for subsequent laboratory analysis. From <br />the 10 L of material saved that passed through the net (the <25 ~m <br />fraction), two replicate 500 to 1500 mL volumes were vacuum-filtered <br />through separate, preweighed, preashed Gelman AlE fiberglass filters. <br />These preweighed and numbered filters were then dried in an oven, weighed, <br />ashed to burn off the organic portion of the filtered material, and <br />weighed to determine the percent of organic vs. inorganic material. <br />The same procedure was used to separate organic from inorganic <br />material >25 ~m. <br /> <br />Duplicate 25-L water samples were collected and filtered through an <br />80 ~m plankton net to identify and determine abundance of net phyto- <br />plankton and zooplankton in both the main river and backwaters. Samples <br /> <br />8 <br />