In vivo fluorescence determinations of phytoplankton chlorophyll a

Abstract

The in vivo fluorescence yield of chlorophyll a in Chlorella pyrenoidosa is shown to vary with the availability of nitrate, trace elements, and with the presence of mercury. The fluorescence yield of Phaeodactylum tricornutum also varies with culture conditions and comparisons of Cyclotella nana and Chaetoceros galvestonensis show a species‐dependent variation. Both types of yield fluctuations are eliminated when photosynthetic electron transport is blocked by adding 3‐(3,4dichlorophenyl)‐1,1‐dimethylurea (DCMU) to phytoplankton: the in vivo fluorescence yield becomes maximal and a constant function of cellular chlorophyll a, regardless of growth conditions or of the species examined. Preliminary observations of samples from the Caribbean Sea also indicate a constant in vivo fluorescence yield in the presence of DCMU.

Fluorescence properties of the freshwater phytoplankton: Three algal classes compared

“…For four algal species in pure culture Slovacek &Hannan (1977) noted that "'fluorescence becomes maximal and a constant function of cellular chlorophyll a" upon addition of DCMU. This constancy does not appear to hold over a wide array of freshwater phytoplankton species.…”

“…V1NCENT dichlorophenyl)-l,l-dimethyl urea (DCMU) (e.g. Slovacek &Hannan, 1977). Bright light promotes a transfer of excitation energy from highly fluorescent RCII to weakly fluorescent RCI (reaction centre of photosystem I), thereby reducing R values by up to 80 ~o (Vincent, 1979); this fluorescence depression can be fully reversed by incubating the algal cells in dim light or darkness (Heaney, 1978).…”

Water-quality conditions near the confluence of the Snake and Boise Rivers, Canyon County, Idaho

“…Chlorophyll-a fluorescence response can vary between sestonic algae species and within species subjected to diverse conditions (Slovacek and Hannan, 1977). Although chlorophyll-a fluorescence data were calibrated to laboratory results each month, daily changes in sestonic algae community structure, water-quality, and light conditions likely occur.…”

Immuno flow cytometry in marine phytoplankton research

“…For instance, the red chlorophyll-a autofluorescence of immunochemically (FITC)-labelled G. mikimotoi cells has been used in cluster analysis (Vrieling et al, 1994). In living phytoplankton, chlorophyll-a fluorescence is not a simple measure of chlorophylla, because the fluorescence yield is not constant but depends on the cells irradiance history and physiological status (Kiefer, 1973;Slovacek and Hannan, 1977). For immunological purposes, the cells will be fixed and that may stabilise the fluorescence yield.…”