On the nutrition and metabolism of zooplankton XI. Lipids in Calanus helgolandicus grazing Biddulphia sinensis

Abstract

Many of the calanoid copepods contain large amounts of neutral lipid that is predominantly wax esters (Lee, Hirota & Barnett, 1971; Lee & Hirota, 1973; Sargent & Garten, 1976). The role of these compounds in the life-history of copepods is particularly well documented for the large Northern Pacific calanoid Euchaeta japonica Marukawa. These animals have their highest levels of total lipid (50% of the dry weight) at stage V, up to 80% being wax esters (Lee, Nevenzel & Lewis, 1974). Wax ester levels are lower in adult females but are high in the eggs, the contents of which are subsequently used during the naupliar stages (Lee et al. 1974). Thus, wax esters accumulated during the later developmental stages provide a fuel for the developing eggs and embryos; from which it follows that the amounts of these lipids present in mature animals are likely to be critical in determining the brood size and survival of the ensuing generation. So far, however, the factors controlling lipid levels in copepods have been poorly understood.

Lipid Composition of Some Typical North Sea Copepods

“…Especially after the spring bloom lipid concentrations were high. The maxima were due to a n increase in TG (Sargent et al, 1977) and a small increase in free FA and phospholipids. The copepods produce TG as depot lipids if the food concentration is high.…”

“…Many factors may affect the lipid composition and fatty-acid pattern, e. g. depth, temperature, salinity, geographical location, season, food availability and starvation (Lee et al, 1970;Gardner and Riley, 1972;Lee, 1974a;Mayzaud, 1976;Sargent et al, 1977). Until now, lipid composition of zooplankters has only been determined for large copepods or for mixed zooplankton (e, g. Ackman et al, 1974;Lee, 197413;Sargent and Lee, 1975).…”

Lipid storage in marine zooplankton

“…methanol and chloroform (more recently the less toxic dichloromethane), mostly based on procedures of Folch et al (1957) or Bligh & Dyer (1959). After extraction the different lipid classes can be separated by silicic acid thin-layer chromatography and quantified by thin-layer chromatography-densitometry methods (Armenta 1964, Sargent et al 1977, Olsen & Henderson 1989. Another approach used to quantify the different types of lipids is the thin-layer chromatography/flame-ionization detection (TLC-FID) method (Ackman 1981, Parrish & Ackman 1983, 1985, Fraser et al 1985, Volkman et al 1986, Parrish 1987, 1999, Bergen et al 2000, Hagen 2000.…”

“…The initial phase is the synthesis and storage of triacylglycerol droplets; the second phase is the synthesis and storage of wax esters in an oil sac (Miller et al 1998). Starvation of wax-ester-rich copepods (Calanus pacificus, C. helgolandicus, Euchaeta japonica, Gaussia princeps) resulted in preferential utilization of triacylglycerols, followed by a slower rate of wax ester utilization (Lee et al 1974, Lee & Barnes 1975, Sargent et al 1977, Håkanson 1984. Because triacylglycerols and wax esters are utilized at very different rates, 2 different lipases may be responsible for the catabolism of triacylglycerols and wax esters.…”

Egg production and energy storage in relation to feeding conditions in the subantarctic calanoid copepod Drepanopus pectinatus: an experimental study of reproductive strategy

“…The persistence of these differences even after a feeding period of 2 wk suggests a relatively slow metabolism of wax esters. This was observed in C. helgolandicus: waxes were synthesised after 1 to 4 d of exposure to concentrated food and their catabolism required 2 to 7 d of starvation (Sargent et al 1977, Håkanson 1984.…”