Chlorophyll a fluorescence an alternative method for estimating primary production

• The in vivo chlorophyll a fluorescence index (F+DcM u-F-DcMu/F+DcMU) of natural waters was compared to the 14C-determined primary production, and the fluorescence intensity in the presence of 3-(3,4-dichlorophenyl)-l,l-dimethylurea (F + DCM~) was studied as a function of extracted and spectrophotometrically determined chlorophyll concentrations. Samples were taken every second week from May through October, 1979, at the station "Systrarna" situated in a coastal area of the Bottnian Sea. In addition, samples from the Archipelago Sea of the Baltic were collected on board the Finnish research vessel R/S "Aranda" during the September cruise 1979. The correlations between the fluorescence index and the 14C-determined primary production and between F+DcMu and total chlorophyll concentration were good when samples taken over short time intervals were compared. The shortcomings of both the fluorescence and the 14C methods are discussed. It is concluded that the fluorescence method is useful if it is desirable to follow with high time resolution any changes in the potential for photosynthesis (or pirmary production) in a water mass over relatively short time periods; e.g. during an algal bloom. The fluorescence method can furthermore be technically developed for automatic monitoring with a high time resolution. Efforts are being made in our laboratory to develop the method further to give information about the in situ rates of photosynthesis rather than the potential for photosynthesis in a phytoplankton population.

Ämnesord

NATURVETENSKAP  -- Biologi -- Mikrobiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Microbiology (hsv//eng)

Nyckelord

Microbiology

Mikrobiologi

Mikrobiologi

Microbiology

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