Photosynthetic rate of the marine diatom Cylindrotheca closterium

Abstract

Photosynthesis in Cylindrotheca closterium was greatest in 1-day-old cells (2-4 � O2 per 106 cells per hour), declining to about 50% of this at 3 days and to about 10 % at 14 days. Due mainly to a decrease in the intensity of photosynthesis the ratio of photosynthesis to respiration fell from 6-8 at 1 day to 34 at 3 days, and to 0.6-1.6 at 14 days. The decline in photosynthesis started before phosphate or nitrate in the culture medium was exhausted, but was accompanied by a pH change from 7.4 before inoculation to 8.4 at 1 day and 9.2 at 3 days and thereafter. White light of 1000-1500f.c. (6.4-9.6 mW/cm2) saturated photosynthesis, the compensation point varying from 50 to 100 f.c. (0.3-0.6 mW/cm2). In blue light similar in spectral composition to that found at 10m below the surface of the ocean, the compensation point was 0.5-0.6 mW/cm2.

Effects of Environmental Perturbations on Short-Term Phytoplankton Production off Lawson's Bay, A Tropical Coastal Embayment

“…During the blooms, the magnitude of the standing crop is high as indicated by the microscopic examination and the plant pigment units . Further, these dredging blooms gave high ratios (10-13) of photosynthesis : respiration which are characteristic of log phase culture populations (HUMPHREY & SUBBA RAO 1967 ;SUBBA RAO unpublished) and natural populations (EPPLEY & SLOAN 1965 ;SUBBA RAO 1969 ;PLATT & SUBBA RAO 1970a, 1970b . Gross production values during the dredging blooms were higher than those summarized by STRICKLAND (1960), RAGHU PRASAD & NAIR (1963) from the inshore waters in the Gulf of Mannar, India and SUBBA RAO (1969) on Asterionella japonica bloom off Waltair .…”

Vat incubator with immersion core illumination — a new, inexpensive setup for mass phytoplankton culture

“…One ml was settled for 24 h in a 25 ml chamber and counted by the Utermohl method using a Nikon Diaphot-TMD, inverted microscope (Phase Contrast-2 ELWD turret). Live samples from VIICI were enumerated using a Neubauer haemocytometer (Humphrey & Subba Rao, 1967).…”