Species-specific phytoplankton growth rates via diel DNA synthesis cycles. V. Application to natural populations in Long Island Sound

A f ~e l d expenment was conducted In Long Island Sound, USA, In July 1987 to test the a b ~l ~t y of the cell cycle analys~s method to estlmate s p e c ~e s -s p e c ~f ~c phytoplankton growth rates The growth rates of 3 specles -the d ~a t o m Leptocylindrus danlcus and the d~noflagellates Prorocentrum tnestinum and Dinophysis acuminatawere measured, and d ~f f u s ~o n (cage) cultures were used In a parallel expenment to obtain Independent estimates of growth rate Growth rates e s t ~m a t e d by the cellcycle method were 0 07 to 0 25 d-' for L danicus, 0 43 and 0 44 d-' for P tr~estinunl and 0 54 and 0 67 d-' for D acumlnata The variation was h ~g h e r for L d a n ~c u s because the degree of synchrony In t h ~s specles was low Growth rates measured by the d ~f f u s ~o n culture methods were about 0 l d -' d~fferent from the correspond~ng rates from cell cycle analysis The attempt to use the frequency of double nucleated cells as a means to check the accuracy of growth rate estimates was not successful The estimated growth rates f ~t the observed pattern of phytoplankton succession