Estimating copepod nauplii growth with biochemical tools

Abstract

Marine copepod nauplii are the most abundant multicellular organisms in the planet. They are important in the marine food web as a major food source for larvae and juveniles of commercially important fish. However, field studies are mainly focused on copepodites and adults. Due to their small size, little is known about nauplii ecology and metabolism. We present two biochemical methods, already in use for adults, adapted as indexes of in situnauplii growth: i) the aminoacyl-tRNA synthetases (AARS) activity (Yebra & Hernández-León, 2004) and ii) the RNA/DNA ratio (Berdalet et al., 2005). Once calibrated, these methods will be applied to our ongoing research, which focuses on the differential response of nauplii to physiological stress induced by temperature and contaminants (eutrophication and hydrocarbons). On the long term, we aim to simplify the study of copepod nauplii ecology, and to improve zooplankton description at oceanic scale, optimising cruises and costs. REFERENCES E. Berdalet, C. Roldán and M. P. Olivar, 2005. Quantifying RNA and DNA in planktonic organisms with SYBR Green II and nucleases. Part B. Quantification in natural samples. Sci. Mar. 69(1):17-30. L. Yebra and S. Hernández-León, 2004. Aminoacyl-tRNA synthetases activity as a growth index in zooplankton. J. Plankton Res. 26(3): 351-356