Changes in carotenoid composition in different developmental stages of copepods: Pseudocalanus acuspes Giesbrecht and Acartia spp.

Carotenoid contents and composition were studied in three successivedevelopmental groups of copepod populations from the southernBaltic Sea. Samples were collected with >80% prevalence ofany one of three developmental groups: (i) nauplii, (ii) copepodidsI–III and (iii) copepodids IV–V and also adultsof Pseudocalanus acuspes Giesbrecht and Acartia spp. (Copepoda:Calanoida). Samples were collected over the years 1991–1999from May to September at six sampling sites in the southernBaltic Sea. The carotenoids were analyzed by means of reverse-phasehigh-performance liquid chromatography (RP-HPLC). The mean totalcarotenoid concentrations (astaxanthin, astaxanthin esters,canthaxanthin and other carotenoid unidentified and derivedfrom the diet) found in three groups of developmental stagesfor P. acuspes were 556 µg g^-1 dry weight (d.w.) in naupliarstages, 791 µg g^-1 in copepodids I–III, and 868µg g^-1 in copepodids IV–V and adults. The averagecarotenoid concentrations in Acartia spp. were 619, 764 and872 µg g^-1 d.w., respectively. Significant changes wereobserved in the proportion of carotenoids of separate developmentalgroups. Astaxanthin and canthaxanthin occurred in all developmentalgroups, with the evident dominance of astaxanthin. However,copepodid groups I–III, and especially IV–V includingadults, showed an increased proportion of astaxanthin esters.This suggests that astaxanthin is the main active carotenoidin copepod metabolism. It acts most probably as an efficientfree radical quencher and may be involved in rapid metabolismof stored lipids in mostly unfeeding young nauplii. The feedingstages (late nauplii and copepodids I–III and IV–V)are evidently able to metabolize this pigment by esterificationand further degradation.