Influence of temperature on the relationship between oxygen- and fluorescence-based estimates of photosynthetic parameters in a marine benthic diatom(Cylindrotheca closterium)

Abstract

In this paper we investigate the temperature sensitivity of the photosynthetic process of the benthic diatom Cylindrotheca closterium grown in light-limited turbidostat cultures at two different growth rates. Photosynthesis was measured as the rate of oxygen evolution and as the photosystem II (PSII) electron transport rate (ETR). The photosynthetic efficiency (a), as measured by both methods. was rather insensitive to temperature, and decreased significantly only at the extreme temperatures used (S and 3S'C). The maxImum PSII quantum efficiency (Fv/F m ) showed a small but significant trend of reduction with increasing temperature. However, the maximum rate of photosynthesis (pBmax and ETR max ) was extremely temperature sensitive. The effect of temperature on the relationship between pB and ETR was limited to the most extreme temperatures investigated; deviations from linearity were most extreme at SoC and different conversion factors were observed at Sand 3YC. A short-term change in temperature (lO-30°C), as might be experienced during emersion on a European tidal flat, will not significantly affect the relationship between pB and ETR. However, care should be taken when using a single conversion factor between pB and ETR at the extremes of the temperature range. We have also shown that algal absorption measurements are important for correct calcUlation of ETR. The facts that different species seem to have different conversion factors and that changing environmental conditions will affect the absorption capacity and growth rate of the microphytobenthos (MPH) community suggest that it is wise to perform further calibrations of the relationship in the field before use in primary production modelling. Variable fluorescence measurements are quick and non-invasive and, with knowledge of the absorption properties of the MPH community, allow the quantification of photosynthetic parameters across large areas. Hence they are potentially useful for improving our estimates of ecosystem scale primary production.Key words: microphytobenthos. PAM fluorescence. photosynthesis, PSII electron transport. temperature Introduction Benthic microalgae or microphytobenthos (MPB) form highly productive natural ecosystems in intertidal areas (Cahoon, 1999). They are an important food source for both benthic and pelagic communities (MacIntyre et al., 1996; and have also been linked to sediment stabilization (Underwood et al., 1995).Three main factors appear to regulate the rate of photosynthesis in microphytobenthos: I~ght availability (Barranguet et al., 1998; Perkms et af., 2001), mud surface temperature (Blanchard et al., 1996; and CO2 availability (Underwood & Kromkamp, 1999 and references therein). Nutrients are not generally thought to be limiting in intertidal habitats (Underwood & . Both light and temperatureCorrespondence 10· E. Morris. e-mail: E.morris(a·nioo.knaw.nl change on seasonal, daily and hourly time scales. The two factors also co-vary, making their individual effects hard to separate in field situations . In order...

Limits to productivity of the algaPleurochrysis carterae(Haptophyta) grown in outdoor raceway ponds

“…Numerous studies have also suggested that the reactions of dioxygen (O 2 ) and active oxygen species, such as the superoxide radical (O Á 2 ), the hydroxyl radical ( Á OH), hydrogen peroxide (H 2 O 2 ), and singlet oxygen (1Dg O 2 ), can cause photoinhibition of photosynthesis (Belay and Fogg, 1978;Cadenus, 2005;Foy and Gibson, 1982;Krause, 1994;Singh et al, 1995). Photosynthesis and photorespiration are also influenced by temperature, with higher temperatures increasing oxygenase and PSII activities (Belay and Fogg, 1978;Janssen et al, 2002;Morris and Kronkamp, 2003;Verity, 1981).…”

Laminaria hyperborea photosynthesis-irradiance relationship measured by oxygen production and pulse-amplitude-modulated chlorophyll fluorometry

“…A commonly used value for CF is 0.5 (Morris & Kromkamp 2003), implying that light is equally distributed between PSI and PSII. Hancke et al (2008) discuss the influence of the approach used to estimate the fraction of light absorbed by PSII when comparing PAM oxygen production estimates with those obtained from incubation experiments using different phytoplankton species.…”

“…However, some controversial results occur when P−I curves obtained from oxygen production incubation experiments are related to PAM-based estimates obtained under similar conditions e.g. with the macroalgae Porphyra columbina (Rhodophyta), Ulva australis (Chlo rophyta) and Zonaria crenata (Phaeophyta) (Franklin & Badger 2001); with the macroalgae U. rotundata, U. olivascens and P. leucosticta (Figueroa et al 2003); with the benthic diatom Cylindrotheca closterium (Morris & Kromkamp 2003); with phytoplankton (Goto et al 2008, Hancke et al 2008; with thin-and thick-leaved marine macroalgae (Nielsen & Nielsen 2008); and with phytoplankton (Blache et al 2011). The usefulness of chlorophyll fluorescence as a photosynthesis proxy depends on the existence of a predictable relationship with the quantum yield of oxygen or carbon dioxide evolution.…”

Effects of temperature on photosynthetic parameters and TEP production in eight species of marine microalgae

“…T let is the lethal temperature and the shape parameter β is a dimensionless parameter related to the Q 10 . To simplify curve fitting, Morris & Kromkamp (2003) fixed β at 1.3. We did not fix β, but we fixed T let as a function of experimental data.…”