Degree Name

Master of Science (MS)

Semester of Degree Completion


Thesis Director

Charles L. Pederson


Baseline data, including diatom community structure, metal concentrations of water, sediments and periphyton of the Embarras River were determined previously (Vaultonburg, 1991). Data on diatom community structure in conjunction with efforts to identify relative sensitivity of diatoms may be useful in establishing an effective method for biomonitoring metal pollution in the Embarras River and other aquatic systems. The main objectives of this project were: i) develop a bioassay method; ii) evaluate relative toxicities of several metals towards diatoms; and, iii) evaluate relative sensitivities of diatoms toward dissolved metals.

Unialgal cultures of Cyclotella meneghiniana, Navicula vaucheriae, and Nitzschia palea were isolated from Embarras River water and associated substrata (e.g. mud, stones, twigs). Standard 14-day, non-renewal bioassay procedures were used to investigate the effects of various concentrations of Al, Cu, Ni, and Zn on diatom population growth and survival. Copper was found to be the most toxic metal to all three diatoms with EC50 values of 5-10 μM. Nickel EC50 values were 18 μM for N. palea, and 10-12.5 μM for C. meneghiniana and N. vaucheriae. Zinc was found to be less toxic than Ni with an EC50 of 17 μM for C. meneghiniana and 50-100 μM for N. vaucheriae and N. palea. Aluminum was the least toxic to all diatoms with EC50 values of 150 μM for C. meneghiniana, 360 μM for N. vaucheriae and 500-1000 μM for N. palea. All three species appear to be equally sensitive to Cu. Cyclotella meneghiniana was found to be the most sensitive to Al and Zn. Both C. meneghiniana and N. vaucheriae were more sensitive to Ni than was N. palea.

Included in

Microbiology Commons