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Effects of C a and M g concentrations in seawater on the growth and energy budget of juvenile P aralichthys olivaceus ( T emminck & S chlegel, 1846)
Author(s) -
Wang M. L.,
Zhang X. M.,
Gao T. X.,
Zhang P. D.
Publication year - 2015
Publication title -
journal of applied ichthyology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.392
H-Index - 62
eISSN - 1439-0426
pISSN - 0175-8659
DOI - 10.1111/jai.12477
Subject(s) - paralichthys , biology , seawater , zoology , respiration , juvenile , calcium , excretion , magnesium , dry weight , energy budget , medicine , endocrinology , fishery , ecology , chemistry , botany , fish <actinopterygii> , organic chemistry
Summary Effects of seawater calcium ( C a) and magnesium ( M g) concentrations on the growth and energy budget of juvenile P aralichthys olivaceus ( T emminck & S chlegel, 1846) were investigated at 20°C and a salinity of 30 psu. The C a/ M g ratio ( C a : M g = 1 : 3) in the experimental water was kept constant. Five treatments were set: C 1, C 2, C 3, C 4, and C 5, and the Ca and Mg concentrations were 700, 1100, 1600, 2200, and 2800 (mg L −1 ), respectively. After a 60‐day feeding trial the P . olivaceus survival rates were not affected significantly by C a or M g concentrations in the range of 700–2800 mg L −1 . However, the specific growth rates ( SGR ) and weight gain ( WG ) of all treatments decreased with ascending C a and M g concentrations. The C a and M g concentrations had a strong influence on various energy parameters, namely, energy deposited for growth ( G ), energy lost for respiration ( R ), and energy lost in excretion ( U ), but had little influence on energy lost in feces ( F ). This indicated that the growth rate differences under different concentrations of C a and M g mainly resulted from differences of assimilation efficiency and energy channeled into respiration. The highest net growth efficiency was attained at the lowest concentration of C a and M g in seawater, and the higher concentrations of C a and M g increased the energy channeled to respiration and excretion, which led to significant reduction in growth. Therefore, the optimal growth of P . olivaceus could be obtained by regulating the concentration of C a and M g at 700 mg L −1 , where the average energy budget was: 100C (100% energy consumed in food) = 47.21 (±0.63) G + 32.89 (±0.42) R + 16.71 (±0.56) F + 3.19 (±0.05) U.