The response of Lemna trisulca L. to cadmium

• Published in: Environmental pollution (1987) 1993, Vol.80 (3), p.247-253
• Main Authors: Huebert, David B., Shay, Jennifer M.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; Freshwater; Fundamental and applied biological sciences. Psychology; Lemna trisulca
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/0269-7491(93)90045-P

Lemna trisulca was grown, using aseptic culture techniques in a filter-sterilized medium, a portion of which was replaced regularly during experiments. L. trisulca responded to the addition of 0·64 μM Cd with a reduction in multiplication rate (MR) 2 ± 1 days after exposure. The internal Cd content reached 1000 ± 140 μg Cd/g (dry wt) within 2 days exposure to 0·64 μM Cd. The final yield was reduced by an average of c.8% for each day of exposure to 0·64 μM Cd in a 14 day experiment. This implies that an equilibration period should be used for short-term bioassay tests before the effect of a toxicant is determined. Pretreating L. trisulca with 0·08 or 0·32 μM Cd for 6 weeks had no significant effect on MR or Cd uptake when plants were subsequently exposed to a range of Cd concentrations or grown in a control medium. This suggests that L. trisulca does not become acclimated to elevated Cd concentrations. The MR of L. trisulca fluctuated over a period of almost 600 days and the doubling time ranged from 1·6 to 2·4 days. This produced more than a fivefold difference in final yield in experiments of 14 days duration. The reduction in MR in response to 0·32 μM Cd during this same 600 days period averaged 24% with a coefficient of variation of 38%, and varied with the MR of control cultures. Fluctuations in the intrinsic growth rate and the effect of a toxicant on L. trisulca could potentially confound the assessment of toxicity and must be carefully considered when designing test protocols for aquatic plants.