EFFECTS OF SALINITY ON LARVAL OXYGEN CONSUMPTION RATES IN ESTUARINE AND RIVERINE POPULATIONS OF MACROBRACHIUM NIPPONESE(DE HAAN)

Abstract

Oxygen consumption rates in first-stage zoea larvae of an estuarine population of Macrobrachium nipponense, characterized by laying small eggs, was maximal at the lowest and highest salinities examined (3.6 and 32.0‰ S), and minimal in the intermediate range. Reduced oxygen consumption rate at intermediate salinities was also observed in larvae of a riverine population of this species, characterized by laying large eggs. However, larvae of the riverine population did not show any significant increment of the consumption rate at higher salinities, implying that they have lost the tolerance to high environmental salinity. The pattern of oxygen consumption at various salinities in the riverine population of M nipponense was recognized to be in the intermediate state between the estuarine population of this species and a riverine population of Palaemon paucidens De HAAN.