GROWTH, METABOLISM AND GROWTH EFFICIENCY OF A EUPHAUSIID CRUSTACEAN EUPHAUSIA-PACIFICA IN THE SOUTHERN JAPAN SEA, AS INFLUENCED BY TEMPERATURE

Growth (assessed from intermolt period and molt increment) and metabol ism (oxygen consumption) of the post-larva of Euphausia pacifica from the southern Japan Sea were determined at seven graded temperatures ra nging from 1 to 25 degrees C. The intermolt period shortened progressi vely as temperature increased from 1 to 20 degrees C, but an effect of temperature on molt-to-molt growth increment was not seen. Oxygen con sumption rates were accelerated by the increase in temperature up to 2 0 degrees C. Beyond 20 degrees C, E.pacifica exhibited reduced oxygen consumption and died within 1 day without molting. After removing the effect of body size, the relationships between growth rate and tempera ture, and between oxygen consumption rate and temperature, were establ ished. The carbon budget was calculated as a function of temperature. Because of differential effects of temperature on growth and metabolis m, the net growth efficiency [K-2: growth x 100/(growth + metabolism)] changed with temperature. The optimum temperature at which Epacifica attained the maximum K-2 was 11.4 degrees C, which was derived from ca lculation of cumulative carbon invested in growth and metabolism in th is animal. Tn an alternative method, the optimum temperature was obtai ned mathematically by solving a set of differential equations. The bio logical and ecological significance of the optimum temperature which l eads to the maximum K-2 is discussed.