An infra-red sensitive video-recording technique was used to study the effects of darkness and light intensities from 0.0001 to 270 photopic lx on the feeding behaviour of herring (Clupea harengus L.). When offered natural zooplankton, consisting of a mixture of Calanus finmarchicus, Euchaeta norvegica, Oithona similis, Balanus sp. nauplii, and crustacean nauplii as prey, the fish fed by biting (snapping) at light intensities above a threshold of 0.001 lx and were size-selective, taking the larger organisms first. When fed on pure cultures of California Artemia sp. nauplii (San Francisco Bay brand), the threshold light intensity was 0.01 lx. Swimming speed increased with increasing light intensity when the fish were actively feeding by biting. When the fish were filterfeeding on high densities of Artemia sp. nauplii in the light, they continued to school and swimming speed was not related to light intensity.

Advective rates of nutrients, phytoplankton and zooplankton were estimated for the Masfjord, western Norway, in June and October 1985. The advective contribution to the phytoplankton biomass formation was dearly less than the local growth. Advection of nutrients, even below the photic zone, may have large implications for the new production of the fjord. The highest renewal rate (13.6 % d l ) due to advection was obtained for the mesozooplankton in June. While 20 % of this renewal was due to water advection alone, 80 % was due to the combined effect of the current profile and the vertical distribution of the mesozooplankton. Thus transport of mesozooplankton may exceed local growth significantly. The deep basin (494 m) of the fjord serves as a refuge for resident macrozooplankton and rnicronekton populations predating on mesozooplankton. Analysis suggests that such predators may be more sensitive to a change in the advective rate than to a similar change in the prey growth rate. Advection may be an important factor underlying the carrying capacity of mesozooplankton predators in fjords.

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HAEDRICH 1991 0710. A comparison of the macrozooplankton faunas in two Newfoundland fjords differing in physical oceanography. -Sarsia 76:41-52. Bergen. ISSN 0036-4827.The macrozooplankton faunas were compared between two Newfoundland fjords containing predominantly different deep-water masses; Bay d'Espoir contains warm, saline, Modified Slope Water while Fortune Bay contains cold, low-salinity, Labrador Current Water. Samples were collected in May 1982 and June 1983 using a 3-m Isaacs-Kidd Midwater Trawl. Data are presented on the species composition, relative abundance and vertical distribution of macrozooplankton. The fauna in both fjords consisted largely of the euphausiids Thysanoessa raschii, Thysanoessa inermis, Meganyctiphanes norvegica and the chaetognath Sagitta elegans. Eleven species occurred only in Fortune Bay while nine species occured only in Bay d'Espoir. Twenty species were common to the fjord faunas although eight of these occurred in low numbers. Catch rates were significantly different between fjords for eight species, but not for four species including T. raschii the most abundant species in both fjords. Differences in species composition and relative abundance could be attributed, in part, to the differing deep-water properties of the fjords. However, bottom depth and substrate type appeared to be important for some species.