The aim of this chapter was to determine the influence of zooplankton organisms on carbon cycling within reservoirs and lakes from Northern Quebec. The first part of the paper presents results from LG-2 reservoir where zooplankton dynamics were followed from 1 year prior to impoundment to 6 years after flooding. In terms of community structure, flooding was associated with an increase in zooplankton biomass with the strongest effects observed for cladocerans and rotifers. This increase was related to changes in the physical characteristics of the sampled sites (water residence time, temperature and turbidity), chemical characteristics of the water (total phosphorus) and the abundance of resources (Chl. a).
The second part of the chapter is a comparison of zooplankton community structure expressed as limnoplankton (AFDW) for several reservoirs of different age (1 to 35 years old). We related the average size of organisms to the algal biomass and finally to the carbon fluxes measured between the water and the atmosphere. We found that part of the larger carbon fluxes observed in young reservoirs compared to older reservoirs may be explained by a top-down control of primary producers by zooplankton.