Date of Award

Fall 11-18-1985

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Department of Oceanography and Coastal Sciences

First Advisor

Gambrell, Robert P.

Second Advisor

Thompson, Bruce A.

Third Advisor

Fleeger, John W.

Abstract

Analysis of the level of mercury contamination within the sediments and fish associated food chain of Lake Charles, Louisiana, an area located within the Calcasieu River system, were assessed. Sediment levels were found to be slightly elevated (0.33µg Hg/g) from natural background levels (0.20 µg Hg/g). Levels found within the fish of the region were also found to be slightly elevated (0.287 µg Hg/g) from natural levels. This is below the hazardous level designated by the Food and Drug Administration (0.50 µg Hg/g). The statistical analysis of the pathway of mercury through a food chain composed of eight different species was found to be strongly influenced by the factors of percent piscivory, a quantitative measure of trophic level, body length (measured as standard length) and condition factor, measured as weight/body length~3. The predictive model developed for evaluating the mercury level in an individual fish within Lake Charles is: Hg= Bo +B1(PER)+ B2(CF) + B3(BL) + B4( BL2) + B5(BL3) + Bs(CF*BL) + B7(CF*BL2) + Ba(CF*BL3) where 130 • 7.740 X 10-1 131 • 6.525 X 1o-3 132 • -4.637 X 1o2 134 • 2.066 X 1o-3 a5 • -1.42 x 1o-s 135 • 5.466 X 101 B7 • -1.536 X 1QO a8 • 1.109 x 10-2

This model is highly predictive with a A-square value of 0.53 and indicates that mercury accumulation does not follow a perfectly linear trend as it increases through the food chain but is highly correlated with trophic position. Values for mercury within the sampled areas of Lake Charles are not sufficient to cause concern for possible health risks in the area. xi

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