Metabolic characteristics involved in the tolerance of bivalves to marine hypoxia: Verification by inter-and intraspecific comparisons of species with different hypoxia tolerance

Abstract

Bivalves survive exposure to hypoxic water through anaerobic metabolism. However, the characteristics of anaerobic metabolism that determine the differences in hypoxic tolerance observed between and within species remain unclear. In this study, we examined three species belonging to the superfamily Arcoidea (Anadara kagoshimensis, Tegillarca granosa, and Estellacar olivacea) with differences in hypoxia tolerance as well as one species (A. kagoshimensis) with differences in hypoxia tolerance between the locations. The species were exposed to hypoxic water in a laboratory manipulation experiment to compare temporal changes in metabolites involved in anaerobic metabolism. Comparison of anaerobic metabolic processes showed that the rate of decrease in aspartic acid was strongly correlated with the hypoxia tolerance (LT₅₀) of the target species. Aspartic acid appears to be the main source of energy production during anaerobic metabolism, and the slow rate of its consumption is an indicator of the strength of hypoxia tolerance in Arcoidea bivalves.

Keywords: Anaerobic metabolism; Aspartic acid; Bivalve; Marine hypoxia; Tolerance.