SS1.09 Fisheries Population Linkage Spatial and Temporal Variation in Zooplankton
Date: Wednesday, June 12, 2002
Time: 11:00:00 AM
Location: Carson C
 
RichardsonK, University of Aarhus, Aarhus, DENMARK, richardson@biology.au.dk
 
IS THE IMPORTANCE OF THE SPRING BLOOM IN PELAGIC ENERGY FLOW OVERESTIMATED?
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The spring bloom is believed to be the most important signal in annual new production occurring in stratified temperate marine waters. However, the spring bloom disappears relatively quickly from the water column and a large proportion of the material sedimenting to the bottom following the spring bloom is comprised of intact phytoplankton cells. Thus, it is difficult to argue that energy fixed during the spring bloom fuels the pelagic production occurring during summer months. Based on several studies carried out in the Kattegat, Skagerrak and North Sea, it is argued that, under certain hydrographic conditions, sub-surface blooms of phytoplankton occur throughout the period of stratification (i.e., summer months). Where this occurs, these sub-surface blooms may annually be responsible for more new production (sensu Dugdale and Goering, 1967) than the spring bloom. Accumulations of mesozooplankton and fish larvae in regions where these sub-surface blooms occur suggest that these blooms play an important role in channelling energy to higher trophic levels. Thus, the importance of the spring bloom in driving pelagic energy flow may be overestimated in the classic understanding of pelagic energy flow.