Relationships Between Concentration of Pollutants and Shell Growth
For lead, zinc and octacosane, clear associations were apparent between the concentration of the pollutant and the percentage increase in shell width (Fig. 5). Moderate additions of these pollutants above the background level caused increases in the shell width growth. However, exposure to the higher experimental treatments resulted in reduced levels of shell width growth. For hexadecane,there was no relationship between pollutant concentration and shell width growth.
In contrast to shell width, whereas high concentrations of lead inhibit shell length growth, there was no relationship between concentration of pollutant and shell length growth for all 4 experimental treatments.