ZOOPLANKTON DYNAMICS DURING THE ONSET OF WINTER IN A NORTHERN NORWEGIAN FJORD - VERTICAL-DISTRIBUTION AND METABOLIC-ACTIVITY IN RELATION TOPHYTOPLANKTON AND SEDIMENTATION
Kg. Barthel et al., ZOOPLANKTON DYNAMICS DURING THE ONSET OF WINTER IN A NORTHERN NORWEGIAN FJORD - VERTICAL-DISTRIBUTION AND METABOLIC-ACTIVITY IN RELATION TOPHYTOPLANKTON AND SEDIMENTATION, Sarsia, 80(1), 1995, pp. 23-32
The study was conducted at a permanent station (depth of 80 m) in Ramf
jorden (ca. 70 degrees N), a branch of Balsfjorden near Tromso, Norway
, in November/December 1989. Phytoplankton and zooplankton were collec
ted and sedimentation rates were measured every 3 to 4 days; zooplankt
on respiration was determined in the laboratory. Phytoplankton concent
rations were extremely low and tended to decrease during the investiga
tion period, while zooplankton abundance was still at about 65 % of it
s annual peak level. Depth distribution was markedly different between
copepod species. Pseudocalanus acuspes and Acartia longiremis were mo
re abundant in the surface layer while concentrations of Microsetella
norvegica and Microcalanus pusillus were higher in deep water. Weight-
specific respiration and faeces concentrations in the surface layer we
re higher than at depth. It is hypothesized that P. acuspes and A. lon
giremis remain active in winter and, by feeding, conserve part of the
biomass in the pelagial.