Protein and nucleic acid metabolism as proxies for growth and fitness of Oithona davisae (Copepoda, Cyclopoida) early developmental stages

► AARS activity and RNA/DNA ratio as indices of Oithona davisae growth and fitness. ► RNA/DNA ratio is more sensitive to nauplii nutritional condition than AARS activity. ► Both specific AARS activity and RNA/DNA ratio are adequate indices of somatic growth. ► RNA/DNA ratio is stage dependent and might not be useful on mixed populations. ► The two indices are useful tools to assess nutrition and growth of copepod larvae.