Действие тяжёлых металлов на скорость роста микроводорослей Heterosigma akashiwo, Alexandrium affine и Prorocentrum foraminosum

Abstract

A rise in the frequency of harmful algal blooms is associated with increasing environmental pollution, in particular with a gain in heavy metal content in waters. The aim of the study was to assess the effect of heavy metals on the growth rate of microalgae causing such blooms. The effect of heavy metals on the growth rate of microalgae Heterosigma akashiwo, Alexandrium affine, and Prorocentrum foraminosum was investigated: cadmium Cd²⁺, nickel Ni²⁺, and lead Pb²⁺ at concentrations of 10 and 20 μg·L⁻¹, as well as zinc Zn²⁺ and iron Fe³⁺ at 50 and 100 μg·L⁻¹. The evaluation was carried out on the third and seventh days of the experiment. These heavy metals were found to affect all investigated algae species. On the third day, the growth rate of H. akashiwo increased with the addition of Cd²⁺, Pb²⁺, Ni²⁺, and Fe³⁺; the growth was suppressed with the addition of Zn²⁺. On the seventh day, the microalga inhibition was recorded at 10 and 20 μg·L⁻¹ of Cd²⁺, 10 μg·L⁻¹ of Pb²⁺ and Ni²⁺, and 100 μg·L⁻¹ of Zn²⁺. H. akashiwo stimulation occurred at 20 μg·L⁻¹ of Pb²⁺ and Ni²⁺, as well as at 50 and 100 μg·L⁻¹ of Fe³⁺. The growth rate of A. affine on the third day rose at 20 μg·L⁻¹ of Cd²⁺, 10 and 20 μg·L⁻¹ of Pb²⁺ and Ni²⁺, and 100 μg·L⁻¹ of Fe²⁺ and Zn²⁺. On the seventh day, the growth rate dropped because of the negative effect of 10 and 20 μg·L⁻¹ of Cd²⁺ and Pb²⁺, as well as 20 μg·L⁻¹ of Ni²⁺. Stimulation of A. affine growth was registered at 10 μg·L⁻¹ of Ni²⁺ and at both concentrations of Fe³⁺ and Zn²⁺. P. foraminosum was the least resistant to heavy metals. Its growth rate decreased when exposed to all toxicants, except for Fe³⁺: in this case, stimulation of the microalga growth occurred on the seventh day of the experiment.

Keywords: Heterosigma akashiwo, Alexandrium affine, Prorocentrum foraminosum, cadmium, nickel, lead, zinc, iron, heavy metals