Photosynthesis, excretion, and growth rates of Phaeocystis colonies and solitary cells

[摘要] Unialgal cultures of the prymnesiophyte, Phaeocystis cf. pouchetii, were isolated from Norwegian and United States coastal waters. Manipulation of the nutrient medium resulted in populations overwhelmingly dominated by either colonies or solitary cells of Phaeocystis.Both morphotypcs were grown under a range of irradiances at 0°, 2°, 5°, 10° and 20°C. Photosynthesis was measured as incorporation of H14CO3- and excretion as accumulation of DO14C during 24-hour incubations; growth rates of solitary cells were determined concurrently from changes in abundance. Both morphotypes exhibited temperature-dependent asymptotic increases in pigment-specific photosynthesis with irradiance. Saturation intensities increased with temperature. Cell division by Phaeocystis solitary cells exhibited a functional response similar to photosynthesis, although growth apparently saturated at lower irradiances. C:Chla ratios were positively correlated with irradiance and inversely related to temperature, while C:N ratios were inse...

[学科分类] 自然科学（综合）