Photophysiology and primary production of phytoplankton in freshwater

Abstract

In the last 10 years enormous progress has been made in developing new instruments to collect physiological data from natural phytoplankton. In this review we summarize the motivation which has powered this engagement and focus on new technologies used to measure fluorescence, absorption and biochemical compositions of natural phytoplankton cells from nature. Combining the knowledge of phytoplankton structure along with taxon-specific measurements of photosynthetic activity and biochemical cell composition, can lead to new models which increase the reliability of water quality prediction. Furthermore, recent progress in the analysis of photophysiological fitness of phytoplankton cells has revealed new knowledge about the phylogenetic diversity of metabolic strategies to cope with light and nutrient stress. Future progress in single cell analysing systems will be discussed.

Gross photosynthesis and lake community metabolism during the spring phytoplankton bloom

“…) versus P P (Prášil et al 1996;Geider and MacIntyre 2002;Wilhelm et al 2004): (1) electron sinks within the photosynthetic electron transfer chain, (2) photorespiratory O 2 consumption, and (3) consumption of NADPH by essential photochemical processes other than CO 2 fixation, such as nitrate reduction and assimilation. These pathways will be briefly discussed.…”

“…Several investigations have previously used FRR fluorometry to assess microalgal productivity in situ (Suggett et al 2001;Raateoja et al 2004;Smyth et al 2004) but have been limited by assuming n O2 and lack of knowledge of the fluorescence blank relative to the sample (Cullen and Davis 2003). Furthermore, implementation of FRR fluorescence as a tool for directly measuring ''productivity'' is fraught with difficulty where photosynthetic pathways uncouple absorbed light, linear electron flow, and reductant partitioning from assimilated carbon (Kromkamp and Forster 2003;Suggett et al 2004;Wilhelm et al 2004). We have demonstrated an FRR approach that overcomes uncertainties inherent to these previous P chl O2 determinations.…”

“…Typically, daily production is estimated from discrete incubations of natural material. However, this approach may give rise to considerable error because realistic environmental conditions may not be reproduced in the incubation bottles (Wilhelm et al 2004). Various techniques are now used to provide direct, in situ measures of primary productivity.…”

Photosynthetic capacity of three phytoplanktonic species measured by a pulse amplitude fluorometric method

“…Measurements of absolute values of photosynthetic parameters in phytoplankton are not completely understood (Wilhelm et al, 2004) and its discussion is beyond the scope of the present study. The purpose of this research was to estimate algal speciesspecific susceptibility to a toxicant, through relative values.…”

Application of the Long-Term Delayed Luminescence for Study of Natural Water Environments

“…Contrary to Fl Chla , long-term DL Chla intensity reflects concentration of reactive centres of photosystem II with separated charges. Findings of previous research show that in specific measurement conditions we may determine an important static relationship between DL Clha intensity and primary productivity of phytoplankton (Krause & Gerhardt, 1984;Yacobi et al, 1998, Wilhelm et al, 2004. Moreover, the use of monochromatic light of several wavelengths for exciting of Chla luminescence enables us separating algae belonging to specific taxonomic from the population of phytoplankton (Krause et al, 1982;Gerhardt & Boedemer, 2005).…”