Морской биологический журнал (Nov 2022)
Growth dynamics of the benthic diatom Ardissonea crystallina (C. Agardh) Grunow, 1880 (Bacillariophyta) under copper ions effect
Abstract
Increasing anthropogenic load on coastal ecosystems of the Black Sea determines the need for regular assessing the state of planktonic and benthic communities. Planktonic microalgae contributing up to 20–25 % of global primary production are traditionally used as test objects; however, the contribution of microphytobenthos is comparable to that of phytoplankton. Benthic diatoms are close-associated with bottom substrate, and most of them are highly sensitive to the effect of technogenic pollutants accumulating in sediments. The changes in physiological indicators of benthic Bacillariophyta may objectively reflect the negative effect of various toxicants; accordingly, benthic diatoms can be used as test objects in the indirect assessment of the marine environment quality. We aimed to study the growth dynamics of abundance of clonal strain cells for a new biotesting object – the diatom Ardissonea crystallina (C. Agardh) Grunow, 1880 (Bacillariophyta) – under the effect of various CuSO4·5H2O concentrations during 10-day laboratory experiments. This species is widespread in the Black Sea sublittoral and highly sensitive to the effect of different technogenic pollutants, inter alia heavy metals. As shown, at copper ions concentrations of 32–128 μg·L−1, A. crystallina growth dynamics generally corresponds to the dose–response curve in a toxicological experiment. The correlation was found between a decrease in intensity of the culture growth and increase in toxicant concentration in the experimental medium. At copper ions concentration of 256–320 μg·L−1, the ratio of alive cells in the clonal strain decreases gradually from 62–66 % (the 1st day) to 34–37 % (the 10th day); the indicators of an increase in cell abundance in the clonal strain are characterized by a negative trend – from −0.01 (on the 2nd day) to −0.34 (on the 10th day). At Cu2+ concentrations of 384 μg·L−1 and higher, drastic inhibition and subsequent death of A. crystallina cells were revealed. At 448–1,024 μg·L−1, complete cell mortality was registered already on the 3rd day of the experiment. Statistical comparison of the ratio variability of A. crystallina alive cells and the specific growth in their abundance for the control and Cu2+ concentrations of 64–128 μg·L−1 showed as follows: at 32–128 μg·L−1, the differences between the mean values of the test indicators were significant (P = 0.002…0.020). At 256 μg·L−1, the changes in total abundance and alive cells ratio in the test culture significantly differ (P = 0.002…0.014) from those both at lower and higher copper concentrations. This fact allows to consider the toxicant level of 256 μg·L−1 as a critical one for A. crystallina: its exceeding will result in a sharp increase in cell mortality. Based on the results obtained, this benthic diatom can be recommended for use as a suitable test object in toxicological experiments, as well as for monitoring and indirect environmental assessment of coastal water areas subjected to technogenic pollution.
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