Acclimation to a dynamic irradiance regime changes excessive irradiance sensitivity of Emiliania huxleyi and Thalassiosira weissflogii

Abstract

Effects of fluctuating irradiance regimes on excessive photosynthetically active radiation (PAR) and ultraviolet (UV) radiation sensitivity were assessed for Emiliania huxleyi (Lohman) and Thalassiosira weissflogii (Grunow) Fryxell and Hasle. Cultures acclimated to low irradiance were subjected to two irradiance regimes of equal daily dose: dynamic irradiance simulating vertical mixing within the water column and constant irradiance. For each regime two irradiance levels were studied. Growth was monitored for 3 d, after which pigment composition was determined. Next, excessive PAR and UV sensitivity was measured by studying viability loss during 4-h exposure to simulated surface irradiance (SSI). Furthermore, the effects of inhibition of D1 reaction center protein turnover were investigated by incubating samples with lincomycin prior to exposure. Dynamic irradiance reduced growth rates of both species as compared to constant irradiance. Pools of light-harvesting pigments increased in dynamic irradiance, whereas the protective pigment pools decreased compared to constant irradiance. Excessive irradiance sensitivity was enhanced in cells grown in fluctuating irradiance. Furthermore, viability loss was most pronounced in UV treatments combined with lincomycin. E. huxleyi was more sensitive to excessive irradiance than T. weissflogii, which coincided with a lower ratio between protective and light-harvesting pigments in the former species. Irradiance modulation by deep vertical mixing influences growth, pigment composition, and excessive PAR and UV sensitivity within days.

Importance of deep mixing and silicic acid in regulating phytoplankton biomass and community in the iron-limited Antarctic Polar Front region in summer

“…This suggests that during the mixing process, phytoplankton at deep mixed layer stations were exposed to a range of irradiance intensities and acclimating to lower levels of irradiance. Laboratory experiments have shown that diatoms and haptophytes exposed to fluctuation in irradiance are acclimating to lower irradiances than cells grown under constant irradiance (van de Poll et al, 2007(van de Poll et al, , 2009). This could explain the lower ratios of DDþDT to TChl-a at these stations.…”

“…In contrast, under low iron high light conditions, photoinhibition or photodamage may occur as iron limitation decreases the synthesis of cytochrome b 6 f complexes, an enzyme required in the activation of photoprotective mechanisms (Strzepek and Harrison, 2004;van de Poll et al, 2009). Thus, iron-limited cells are less efficient at coping with an environment with rapid irradiance fluctuations than iron-replete cells (Strzepek and Harrison, 2004;van de Poll et al, 2009;Alderkamp et al, 2012). In addition, under iron-Si(OH) 4 colimitation conditions, growth of non-silicious, iron-efficient phytoplankton species such as eukaryotic picoplankton and cyanobacteria often dominate over larger cells (Hutchins et al, 2001).…”

“…photosystem II and photosystem I) is constrained by iron availability (Sunda and Huntsman, 1997). In contrast, under low iron high light conditions, photoinhibition or photodamage may occur as iron limitation decreases the synthesis of cytochrome b 6 f complexes, an enzyme required in the activation of photoprotective mechanisms (Strzepek and Harrison, 2004;van de Poll et al, 2009). Thus, iron-limited cells are less efficient at coping with an environment with rapid irradiance fluctuations than iron-replete cells (Strzepek and Harrison, 2004;van de Poll et al, 2009;Alderkamp et al, 2012).…”

Temperature-dependent growth and photophysiology of prokaryotic and eukaryotic oceanic picophytoplankton

“…and Pelagomonas calceo lata were transferred to 500 ml glass Erlenmeyer flasks and incubated in triplicate at 16, 20 and 24°C. Experiments were carried out in a temperature-controlled U-shaped lamp setup as described by Van de Poll et al (2007). The temperature in the setup was maintained at 16, 20 and 24°C by a thermostat (RK 8 KS, edition 2000, Lauda Dr. R. Wobser & Co.) and deviated by less than ± 0.5°C.…”

Ocean Acidification Alters the Photosynthetic Responses of a Coccolithophorid to Fluctuating Ultraviolet and Visible Radiation

“…Fluctuation of solar radiation on cloudy days led to higher primary production in the presence of UVA (315-400 nm) as compared with the presence of UVA on sunny days . Algal acclimation to fluctuating irradiance can lead to differences in growth rates and cellular pigment content compared with the cells acclimated to constant irradiance (Van de Poll et al, 2007. On the other hand, the mixing rate in the UML is strongly controlled by wind (Denman and Gargett, 1983;MacIntyre, 1993), which may increase due to global warming (Toggweiler and Russell, 2008).…”