L. Mousseau et al., Assessing the trophic pathways that dominate planktonic food webs: an approach based on simple ecological ratios, J PLANK RES, 23(8), 2001, pp. 765-777
It was recently proposed that there is, in the pelagic environment, a conti
nuum of trophic pathways ranging from the herbivorous food web to the multi
vorous,food web, the microbial food web and the microbial loop. It was also
suggested that combining specific ecological ratios could provide a way of
assessing the dominance of planktonic food webs by specific trophic pathwa
ys. Three large data sets, collected in different but adjacent marine syste
ms (the Scotian Shelf, off eastern Canada; the Gulf of St Lawrence; and nea
rshore waters of the Baie des Chaleurs, in the northwestern Gulf), are used
to compute two ratios: small-sized (<5 <mu>m) to large-sized (>5 mum) part
iculate phytoplankton production, and phaeopigments in small- to phaeopigme
nts in large-sized particles. By combining the two ecological ratios it is
possible to delineate successfully, in each studied system, coherent period
s during the year; to interpret the combined ratios in terms of dominance b
y specific trophic pathways; and to show that the interpretation is consist
ent with additional information collected in the three systems.