Atrazine effects on estuarine macrophytes Spartina alterniflora and Juncus roemerianus

Two dominant estuarine marsh plants, Juncus roemerianus and Spartina alterniflora, were exposed for 35 d to three dose levels of atrazine with measured concentrations of approximately 0.03, 0.25, and 3 mg/L to assess peroxidase (POD) activity, lipid peroxidation, chlorophyll changes, and growth rates. The objective of the study was to evaluate toxicity of atrazine and to measure multiple endpoints to assess their value as biomarkers of atrazine stress or resistance. In S. alterniflora, exposure to 3.1 mg/L of atrazine did not significantly inhibit growth, generated no lipid peroxidation products, and did not affect chlorophyll production, but did significantly enhance POD activity. In contrast, in J. roemerianus, atrazine exposure significantly inhibited growth at 3.8 mg/L, produced lipid peroxidation products and inhibited chlorophyll production in a dose-response fashion, and did not elicit a POD response. In combination, POD activity and lipid peroxidation are useful indicators of atrazine stress to these plants. Results of the study indicate that J. roemerianus would decline or die off if exposed to chronically high environmental concentrations of atrazine, whereas minimal damage would occur to S. alterniflora.