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Abstract

The ecological model of Lago Janauari is presented. The lake is a multitrophic lake where morphological dynamism is of first importance and where lake metabolism undulates in a natural synchronism with water levels. There is a lotic-lentic nature in the lake which results in the trophic level being depth dependent. Chlorophyll a (chl.a) was related to water levels (r=0.90) and ranged from 0.007 to 46.77 μgl-1. There were approximately 100 μmoles of oxygen for every 10μ moles of chl.a. D.O. war clinograde high at water periods. Primary producers were limited by turbulant flow, light and nutrients. Degradation was rapid. Pheopigments averaged 31.41 μgl-1 and were related to chl.a (r=+0.98). Total organic carbon (TOC) averaged 12.5 mg l-1 and was composed of a mean of 75% dissolved organic carbon (DOC). Particulate organic carbon (POC) was related to BOD (r=+0.86) and both were associated with allochthonous detritus. TOC was 37% labite, and the labile carbon was related to the standard plate count (r=0.77). Permanganate demand averaged 25.2 mg l-1 and was related to water levels. Patterns of total bacteria were affected by autochthonous and allochthonous sources in addition to shore-lake interactions. Densities ranged from 0.745 to 17 x 10^8 μ l-1. Total coliform averaged 81 CFU l-1 bacterial activity was shown to be an expression of primary productivity. Vmax ranged from 0.062 to 199.762 μg glucose l-1 hr-1 and gave the highest turnover times recorded in the literature.