A. A. Soldatov, Yu. V. Bogdanovich, N. E. Shalagina, V. N. Rychkova - Effect of Acute Hypoxia and Hydrogen Sulfide Contamination on the Succinate Dehydrogenase Activity and Adenylate Complex of Tissues in the Bivalve Mollusk Anadara kagoshimensis (Tokunaga, 1906)

BIOLOGIYA MORYA, 2024, Vol. 50, No. 6, pp. 417-426

Effect of Acute Hypoxia and Hydrogen Sulfide Contamination on the Succinate Dehydrogenase Activity and Adenylate Complex of Tissues in the Bivalve Mollusk Anadara kagoshimensis (Tokunaga, 1906)

¹Kovalevsky Institute of Biology of the Southern Seas, Russian Academy of Sciences, Sevastopol 299011, Russia;
²Sevastopol State University, Sevastopol 299053, Russia

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The separate effects of acute hypoxia and hydrogen sulfide load on the marker enzyme succinate dehydrogenase (SDH) of the mitochondrial respiratory chain and the adenylate status of tissues in the bivalve mollusk Anadara kagoshimensis (Tokunaga, 1906), a species tolerant to these groups of factors, were studied under experimental conditions. The study was carried out on adult individuals with a shell height of 23-34 cm. The control group of bivalves was kept in the water with an oxygen concentration of 7.0-8.2 mgO₂/L. One experimental group was exposed to acute hypoxia (0.1 mgO₂/L) and another to hydrogen sulfide load (6 mgS^2-/L). The exposure period in both cases was 48 h. The water temperature was maintained at 17-20°C. The acute hypoxia led to an increase in the SDH activity in all the studied tissues (gills, foot, and hepatopancreas). This reaction was not observed under the hydrogen sulfide load. The energy state of the tissues decreased in both cases. This was expressed as a decrease in the ATP and ADP content accompanied by an increase in the AMP content, which allows implementation of the adenylate kinase reaction. These changes were more pronounced in the presence of hydrogen sulfide. However, the adenylate pool and adenylate energy charge (AEC) values remained at a relatively high level, which indicates the ability of ark clam to exist in the near-bottom water layers with a low level of oxygen and the presence of hydrogen sulfide. It is assumed that ark clam's mitochondria have an alternative oxidase that is not sensitive to the presence of sulfides in water.

Key words: Anadara kagoshimensis, hydrogen sulfide, hypoxia, succinate dehydrogenase, adenylate complex, tissues.