| Abstract |
Decapod larvae and early post-larvae were extracted from detailed vertically stratified samples taken during research cruises in the Irish Sea from April to early June 1988 and in the North Sea in June 1989.The total dry weight of decapods was 4 to 106 mg m(-2) which represented 0.5 to 8.6% of the total dry weight of zooplankton.The vertical distributions of abundant species were examined in relation to physical and biological variables.Nephrops norvegicus and Pagurus bernhardus were found nearer to the surface during the spring bloom in April than after the bloom in May.In the near-surface waters of the North Sea in June, larvae of Liocarcinus spp.were more abundant than those of other decapods.Diel migrations varied, apparently due to differences in the physical structure of the water column and the distribution of potential food.Conventional migrations were modified or absent in stratified areas when near-surface concentrations of chlorophyll were present and in well-mixed water.Few significant ontogenetic variations were found.The most striking case was of Liocarcinus spp.larvae during the day in stratified water in the North Sea, where the early zoeal stages (at a mean depth of < 6 m), the fifth zoeae (15.5 m mean) and the megalopas (26.7 m mean) occupied different positions in the water column. |
Lindley, J.A., R. Williams, and D.V.P. Conway (1994) Variability in dry weight and vertical distributions of decapod larvae in the Irish Sea and North Sea during the spring. Marine Biology 120(3): 385–395. 