He, X.J., H.M. Yang, B.D. Lyu & J.Q. Yin. (2018). Nucleic acid proxies for ingestion rate, growth and reproduction in copepod Pseudodiaptomus annandalei. Journal of Tropical Oceanography. 37(2):26-35.

307199

He, X.J., H.M. Yang, B.D. Lyu & J.Q. Yin

2018

37(2):26-35.

Publication

Available for editors   [request]

Nucleic acid indices can indicate nutrition status and growth of copepods; yet, lack of comparison among different phylogenetic groups and indices constrains application of nucleic acid proxies in field investigation. In this study, ingestion Nucleic acid indices can indicate nutrition status and growth of copepods; yet, lack of comparison among different phylogenetic groups and indices constrains application of nucleic acid proxies in field investigation. In this study, ingestion rate, growth rate of copepodid at Stage Ⅱ and egg production rate were studied in brackish copepod Pseudodiaptomus annandalei at different food levels (0.2~2.0 μg C·mL–1 ). Biochemical indices including mass specific RNA content, DNA content, RNA∶DNA, and RNA∶ protein ratios, as well as elemental composition (mass specific phosphorus content, nitrogen content, atomic C∶P, and C∶N ratios ), were also measured and described. Ingestion rate, growth rate, egg production rate, and RNA-related indices in copepodids increased with increasing food level hyperbolically, so did RNA∶ DNA ratio in female adults. Ingestion and growth rates were significantly correlated with RNA-related indices in copepodids in a linear manner and the strength of correlation ranked as RNA∶DNA>RNA∶PRO>RNA content. Egg production rate, however, was correlated with RNA∶DNA and RNA∶PRO ratios in female adults with high and moderate significance, respectively. Our results suggested that RNA∶PRO ratio is suitable to be an indicator of growth and reproduction rate in copepod besides RNA∶DNA ratio and RNA content, which have been applied in field investigation. However, RNA∶DNA as proxy of somatic growth should be confined to the same-aged copepod. In addition, the finding of hyperbolic correlation between RNA-related indices and food concentration implied that they may help prediction of food environment for copepod, but may be confined to food levels at unsaturated phase of functional responses of variables. Key words: nucleic acid indicators; copepod; ingestion; somatic growth; reproduction

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