Unusual allometry between in situ growth of freshwater phytoplankton under static and fluctuating light environments: possible implications for dominance

Author： Mitrovic Simon M.

Publisher： Oxford University Press

ISSN： 1464-3774

Source： Journal of Plankton Research, Vol.25, Iss.5, 2003-05, pp. : 517-526

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Abstract

The effects of fluctuating light fields on the growth of phytoplankton are not well understood and conclusions in the literature have been equivocal. Most studies have examined responses such as productivity and chlorophyll a content (laboratory culture and field tests) or growth rates (laboratory culture tests). In this study we examined the in situ growth rates of different types of phytoplankton within two natural populations. Comparisons were made between populations grown in a static environment (suspended in a fixed position in the water column) and an equivalent population moving through the water column simulating the mixing of entrained phytoplankton. Growth under fluctuating light fields in this experiment only significantly (P < 0.05)="" increased="" the="" growth="" of="" the="" diatom="" skeletonema="" and="" decreased="" the="" growth="" of="" anabaena="" circinalis,="" microcystis="" aeruginosa="" and="" scenedesmus="" sp.="" all="" other="" phytoplankton,="" including="" the="" genera="" nitzschia,="" fragilaria="" and="" dactylococcopsis,="" did="" not="" have="" growth="" rates="" that="" were="" significantly="" different="" between="" static="" and="" fluctuating="" light="" treatments.="" a="" general="" pattern="" where="" diatoms="" grew="" best,="" followed="" by="" chlorophytes="" with="" the="" toxicogenic="" cyanophytes="" m.="" aeruginosa="" and="" a.="" circinalis="" growing="" least="" well,="" was="" distinguished="" under="" fluctuating="" irradiance.="" this="" seems="" consistent="" with="" the="" common="" occurrence="" of="" these="" groups="" of="" phytoplankton="" in="" the="" natural="" environment.="" the="" cyanophytes="" dactylococcopsis="" and="" aphanothece="" did="" not="" follow="" this="" pattern,="" with="" the="" former="" growing="" better="" under="" fluctuating="" light="" and="" the="" latter="" exhibiting="" an="" unusual="" growth="" pattern="" where="" growth="" was="" higher="" under="" lower="" light="" intensities.="">