チチブ Tridentiger obscurus T. et S. の塩分適応能力いついて-I

Abstract

1. Excepting the cold season, the adaptability for salt solution of a brakish goby Tridentiger obscurus cannot be correctly experimented because of such conditions as higher temperature of the water, maturity of gonad, acceleration of metabolisms, and others. Following results were obtained February to March, 1955 (water temperature, 10°C about). 2. In hypertonic sea water at 1.30-to 1.95-fold of normal its obtained by adding the 4.0-fold Lyman-Fleming artificial sea water, the relation between chlormity and survival time in direct transfering to hypertonic sea water from fresh water, in where fish were landlocked, is shown by the formula “W=aT ?? ” where W is chlorinity in g/L; T time in minute; a. b constant. In hypertonic sea water (at 1. 15-to 4.0-fold), their mortality is 100 per cent at end of experiments after 2.5 days. 3. In the cases of direct transfer to normal sea water or hypotonic sea water from fresh water, and to fresh water or hypotonic sea water from normal its, their mortality is 0 per cent. From these results, the chlorine concentration for survival limit seems to be the chlorinity of normal sea water or a certain one between normal sea water and 1.15-fold of its. 4. This goby could be adapted in the sea water concentrated slowly up to 1.2-fold after three months and to 1.55-fold after four months.