Chemical, isotopic and enzymatic monitoring of free and enclosed seawater implications for primary production estimates in incubation bottles

Abstract

Enclosing seawater samples in incubation bottles had 3 main effects on the phytoplankton: first, a large (5-fold in 12 h) increase of phytoplankton biomass, due to the release of grazing pressure by herbivores. Second, an increase (2-fold in 6 h) in ribulose biphosphate carboxylase specific activity (per unit chlorophyll a ) , which could be due to a smaller dependence on regenerated production (less heterotrophy on excreted compounds). This was also supported by a tight relationship between phosphoenol pyruvate carboxykinase activity and dissolved ammonium. Finally, the large changes in the carbon isotopic composition of the incubated particulate matter, which were highly dependent on the dissolved inorganic nitrogen concentrat~on, were due mainly to physiological processes such as biochemical fractionation rather than physical processes such as CO, limitation. For environments with high phytoplankton growth rate and high grazing pressure, a duration of incubation greater than 3 h may significantly change the physiology of the organisms and lead to different estimates of carbon assimilation by autotrophs than bulk water estimates.

High‐frequency measurements of productivity of planktonic algae using rugged nondispersive infrared carbon dioxide probes

“…Among the methodological constraints are, for instance, the long incubation period required in most aquatic environments making it difficult to judge whether the obtained results are from net or gross production. Collos et al (1993) point out that in certain particular circumstances-e.g., when growth is vigorous-the upper time limit for the useful in situ incubation is only 3 h, which is short in comparison to the 24 h incubation of the monitoring program in Lake Valkea-Kotinen. The precision and accuracy of the oxygen method have been improved through developments in measuring techniques, but their widespread use is still limited (Roland et al 1999;del Giorgio and Bouvier 2002).…”

Evaluation of primary production in Lake Erie by multiple proxies

“…Artifacts associated with the [ 14 C]-NaHCO 3 incubation method include bottle effects (growth of bacteria and phytoplankton on bottle walls, lack of stirring or advection, exclusion of grazers, and so on), loss of label as CO 2 and/or dissolved organic carbon, and assimilation of unlabeled respired CO 2 (Irwin 1991; Collos et al 1993;Howarth and Michaels 2000). For these reasons, the consensus of the scientific community appears to be that short-term incubations (several hours or less) provide a reasonable estimate of gross primary production; however, the [ 14 C]-NaHCO 3 estimate of primary production ( 14 C-PP) lies somewhere between gross and net production (Peterson 1980;Collos et al 1993).…”

Short-term and seasonal variation in metabolic balance in Liverpool Bay

“…The two methods used to estimate NCP here are, however, not directly comparable for several reasons. The chlorophyll a regression is the result of bottle incubations, which, by their very nature, exclude much of the water column community and minimise the effects of turbulence and light limitation (Collos et al 1993). In contrast, the NCP estimated from the Smartbuoy O 2 data includes the entire water column community in an open system (Gazeau et al 2005).…”