Significance of advection for the carrying capacities of fjord populations

Advective rates of nutrients, phytoplankton and zooplankton were estimated for theMasfjord, western Norway, in June and October 1985. The advective contribution to the phytoplanktonbiomass formation was dearly less than the local growth. Advection of nutrients, even below the photiczone, 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 renewalwas due to water advection alone, 80 % was due to the combined effect of the current profile and thevertical distribution of the mesozooplankton. Thus transport of mesozooplankton may exceed localgrowth significantly. The deep basin (494 m) of the fjord serves as a refuge for resident macrozooplanktonand rnicronekton populations predating on mesozooplankton. Analysis suggests that such predatorsmay 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 predatorsin fjords