Impact of 24-hour hypoxia on hemocyte functions of Anadara kagoshimensis (Tokunaga, 1906)

Abstract

Shellfish farms are usually located in coastal areas, where molluscs can be exposed to hypoxia. Cultivating at low oxygen levels causes general disruptions of growth rate, outbreaks of diseases, and mollusc mortality. Impact of short-term hypoxia on hemocyte functions of ark clam (Anadara kagoshimensis) was investigated by flow cytometry. A control group was incubated at 6.7–6.8 mg O2·L−1, an experimental one – at 0.4–0.5 mg O2·L−1. Exposition lasted for 24 hours. Hypoxia was created by blowing seawater in shellfish tanks with nitrogen gas. In ark clam hemolymph, 2 groups of hemocytes were identified on the basis of arbitrary size and arbitrary granularity: granulocytes (erythrocytes) and agranulocytes (amebocytes). Erythrocytes were the predominant cell type in A. kagoshimensis hemolymph, amounting for more than 90 %. No significant changes in cellular composition of ark clam hemolymph were observed. The production of reactive oxygen species and hemocyte mortality in the experimental group also remained at control level. The results of this work indicate ark clam tolerance to hypoxia.