Lipid absorption and utilization in the Norwegian lobster, Nephrops norvegicus (L.)

Abstract

The role of the digestive (mid-gut) gland in absorption, distribution, and utilization of lipids was investigated in Norwegian lobsters, Nephrops norvegicus (L.) during summer. Glycerol tri[1- 14C]palmitate was incorporated into food pellets and the subsequent distribution of label followed throughout the body. Digestion and absorption from the foregut was completed 8–12 h after ingestion, but label began leaving the digestive gland after only 4 h and became distributed in tissues and organs in direct proportion to their lipid content, there being no evidence that lipid was accumulated in the digestive gland in preference to other tissues. 75% of the lipid ingested appeared to have been oxidized within 24 h of feeding. Analysis of organs and tissues showed that the digestive gland was the only potential fat depot in males (lipids 8.89 ± 1.36% of body wet wt), the levels in the rest of the body being only ≈ 1% wet wt). No significant decrease in any lipid concentrations occurred during 18 days starvation of males or 35 days starvation of females, but in males the non-lipid dry matter decreased 6% of the total wet wt (other solids were not measured in the females). It was concluded that this was due mainly to loss of muscle protein and it is suggested that the large abdominal muscle mass of macrurous Reptantia, used principally for emergency escape swimming, could provide a reserve that may be partly metabolized without serious detriment to the animal. The concept that the decapod digestive gland has a key role in general lipid metabolism is critically reviewed. In many Decapoda, digestive gland lipid could provide for only a short period of total starvation, but the lipid may have a principal role in the moulting cycle, with perhaps a secondary function in oogenesis.