Lipid changes during life cycle of marine copepod,Euchaeta japonica marukawa

Abstract

All stages from egg to adult of the North Pacific copepod,Euchaeta japonica contained wax esters in their lipid stores, while triglycerides were important only in the eggs, early naupliar stages, and adults. The large lipid reserves of the eggs were wax esters and triglycerides (58% and 19% of the lipid, respectively), both of which were used rapidly during the early stages of development. Wax esters continued to decrease after triglycerides had been utilized completely for energy. The slow metabolism of lipid during starvation indicated that lipid stores in adult females may be conserved for egg production. The dominant alcohols of the wax esters of all stages were tetradecanol (24–42% of the total) and hexadecanol (25–65%). Only minor amounts of polyunsaturated alcohols were observed. There was, however, a high proportion of polyunsaturation in the wax ester fatty acids, even though octadecenoic was generally predominant (16–46% of the total wax ester fatty acids). The polyunsaturation of the wax esters fatty acids and the presence of 21∶6 hydrocarbon suggest phytoplankton in the diet of adults and in the younger stages. Cholesterol was the main sterol, but there were minor amounts of desmosterol (1–12% of the total sterols) present. The latter sterol has not been found previously in copepods, although reported from Cirripedia and Decapoda.

Effect of total organic content of eggs on hatching success and naupliar survival in the copepod Calanus helgolandicus

“…The lipid composition of the egg in copepods varies among species. In the case of C. helgolandicus, the main lipid class present in eggs is triacylglycerol, and there is no detectable wax ester (Lee et al 1972;Gatten et al 1980). The sources of triacylglycerol in C. helgolandicus eggs are either wax esters accumulated by the females in spring-summer when food is abundant or the triacylglycerol ingcstcd in the diet (Gatten et al 1980).…”

“…However, in this study the lipid content of particulate food was a poor predictor of egg size (Table 3). Because of the marked reduction in lipid content of stage 1 nauplii compared with eggs (Lee et al 1972), triacylglycerol would seem to be metabolized during embryonic development in C. helgolandicus. WC were not able to obtain information about the lipid consumption of eggs.…”

Lipid storage in marine zooplankton

“…In contrast, the eggs of the copepods Euchaeta japonica and C. plumchrus are full of lipid droplets, and feeding does not begin until the late naupliar stages, i.e. after 20 to 30 d (Lee et al 1974, Saito & Tsuda 2000.…”

“…The egg yolk allows development without feeding through all naupliar stages and the first copepodite stage (Fig. 9) (Lee et al 1974). E. norvegica females decreased from 1800 to 600 µg lipid/individual after spawning with each egg sac containing 500 µg lipid, while E. japonica females used most of their lipids for reproduction, since an egg sac and a gravid female had 560 and 600 µg lipid, respectively (Table 3) (Båmstedt & Matthews 1975 Lee et al (1971a), Lee (unpubl.…”

“…However, some species, e.g. Neocalanus cristatus and Euchaeta japonica, have larval forms with large lipid stores to withstand long starvation periods (Lee et al 1974, Saito & Tsuda 2000 …”