MEPS 135:215-222 (1996)  -  doi:10.3354/meps135215

New production and production of large phytoplankton (>5 um) on the Scotian Shelf (NW Atlantic)

Dauchez S, Legendre L, Fortier L, Levasseur M

New phytoplankton production (Pnew; nitrate uptake) and production of large phytoplankton (>5 um, PL; carbon fixation) were monitored on the Scotian Shelf (Northwest Atlantic) every month for 1 yr. On a daily basis, Pnew and PL were seldom the same. When nitrate uptake accounted for less than 20% of total primary production (f-ratio < 0.2), PL was generally higher than Pnew. Above this threshold, Pnew was higher than PL. This was true independently of actual production, i.e. the difference between Pnew and PL depended on the f-ratio and not on the level of primary production (high or low). When averaged over periods of 6 mo or more, PL and Pnew were roughly balanced. Over the year, Pnew and PL were equivalent, i.e. 121.8 and 115.2 mg C m-2 d-1, respectively. Assuming that the system was in steady state, which implies a balance between new and exported production, these results lead to the conclusion that at time scales of 6 mo or more, exportable production (PL) was equivalent to new production.

New production . Nitrate uptake . Carbon uptake . Phytoplankton . Size fractionation

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