WHY DO DINOFLAGELLATES HAVE LOWER GROWTH-RATES

Dinoflagellates have substantially lower growth rates than other taxa of similar size. These low growth rates have been suggested to reflect the lower chlorophyll a to carbon ratio (Chl a:C) in dinoflagellates, but that speculation has never been widely tested. This study tests i f the variations In growth rates among taxa are related to differences in Chl a:C using published data. I collected 92 data entries from the literature representing 31 species, mostly from two divisions (Chryso phyta and Pyrrophyta), and found a significant relation (r(2) = 0.39) between growth and Chl a:C. Since Chl a:C is almost independent of C c ontent, I also developed a growth model using both C and Chl a:C. Toge ther, the two variables explain 68% of variation in algal growth. Howe ver, a further 6.4% of the variance in growth can still be attributed to phyletic differences. Low chi a:C is only a partial explanation for the low growth rates of the dinoflagellates.