Materials and methods
The copepods Temora longicornis and Eurytemora sp. were sampled in two marine
hatcheries in Norway. T. longicornis was sampled from Haapollen (Bømlo, South-West
Norway) from late April to late June during 3 successive years, and Eurytemora sp. was
sampled daily during 1 week of June from Meøypollen (Lofoten, Northern Norway).
Calanus finmarchicus was sampled at one location in Vestfjorden (Northern Norway),
from May to July during 2 successive years. T. longicornis and Eurytemora sp. were
sampled from wheel filters (fraction >600 Am) from which the zooplankton for rearing of
halibut larvae was taken. C. finmarchicus was sampled from surface waters (0–35 m) by
use of a plankton net (1000 Am). The copepods were sorted according to the developmental
stage (while still alive) by using a microscope (10) and plankton net (mainly
small stages of C. finmarchicus), but in several cases, the samples contained high
concentrations of a few stages and sorting was not necessary. From all samples, a known
volume of the fractions was fixed in Lugol for later counting and determination of species
and developmental stage (>440 ind/sample).
The stability of the total lipid and n3 HUFA contents during starvation was examined
for samples taken of T. longicornis and Eurytemora sp. during a period of 96 h. Both
species were transferred to 250-l conical tanks filled with either temperature acclimated
deep water (T. longicornis) or water filtered through a Millipore filter ( < 5 Am)
(Eurytemora sp.) to eliminate the food particles in the water. The tanks were submerged