Photo synthetic characteristics of microphytobenthos in Marennes-Oléron Bay, France: Preliminary results

Blanchard, Gérard; Gall, V. Cariou-Le

doi:10.1016/0022-0981(94)90207-0

Cited by 56 publications

(44 citation statements)

References 24 publications

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“…Barranguet et al 1998, Saburova & Polikarpov 2003. However, migration of diatoms (or physical mixing) can occur without any measurable effect on the overall photosynthetic activity of the benthic community (Blanchard & Gall 1994). In the present study, the benthic activity distribution was unaffected by changes in temperature and the conclusions on activity changes were thus not confounded by any vertical migration.…”

Section: Phototrophic Temperature Responsementioning

confidence: 48%

Temperature effects on respiration and photosynthesis in three diatom-dominated benthic communities

Hancke¹,

Glud²

2004

Aquat. Microb. Ecol.

121

113

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Short-term temperature effects on respiration and photosynthesis were investigated in intact diatom-dominated benthic communities, collected at 2 temperate and 1 high-arctic subtidal sites. Areal rates of total (TOE) and diffusive (DOE) O 2 exchange were determined from O 2 -microsensor measurements in intact sediment cores in the temperature range from 0 to 24°C in darkness and at 140 µmol photons m -2 s -1 . In darkness, the O 2 consumption increased exponentially with increasing temperature for both TOE and DOE, and no optimum temperature was observed within the applied temperature range. Q 10 was calculated from the linear slope in Arrhenius plots and ranged between 1.7 and 3.3 at the respective sites. The volume-specific rate (R dark,vol ) solely representing the biological temperature response was somewhat stronger, with Q 10 values of 2.6 to 5.2. The Q 10 values were overall not correlated to the in situ water temperature or geographical position. Accordingly, no difference in the temperature acclimation or adaptation strategy of the microbial community was observed. Slurred oxic sediment samples showed a Q 10 of 1.7 and were, hence, lower than estimates based on intact sediment core measurements. This can be ascribed to changes in physical and biological controls during resuspension. Gross photosynthesis was measured with the light-dark shift method at the 2 temperate sites. Both areal (P gross ) and volumetric (P gross,vol ) rates increased with temperature to an optimum temperature at 12 and 15°C, with a Q 10 for P gross of 2.2 and 2.6 for the 2 sites, respectively. The gross photosynthesis response could be categorised as psychrotrophic for both sites and no temperature adaptation was observed between the 2 sites. Our measurements document that temperature stimulates heterotrophic activity more than gross photosynthesis, and that the benthic communities gradually become heterotrophic with increasing temperature. This has implications for C-cycling in shallow water communities experiencing seasonal and diel temperature fluctuations.

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Section: Phototrophic Temperature Responsementioning

confidence: 48%

Temperature effects on respiration and photosynthesis in three diatom-dominated benthic communities

Hancke¹,

Glud²

2004

Aquat. Microb. Ecol.

121

113

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“…The larger pool size recorded in the Tagus than in the Eden estuary also corresponds with the higher average irradiance conditions in the Tagus (Table 1). Seasonal photoacclimation patterns of microphytobenthos have been reported previously (Blanchard & Cariou-Le Gall, 1994;Barranguet et al, 1998;Kromkamp et al, 1998), but the underlying physiological mechanisms have not been well described so far.…”

Section: Discussionmentioning

confidence: 99%

“…Various studies have shown that the microphytobenthic community can withstand these fluctuating irradiances (e.g. Barranguet et al, 1998) and, despite the extremely high irradiances on sunny days, photoinhibition is rarely recorded (Blanchard & Cariou-Le Gall, 1994). In contrast to most phytoplankton, microphytobenthos are seemingly even resistant to ultraviolet-B radiation (Peletier et al, 1996;Waring et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…It has been shown that benthic diatoms can acclimate to seasonal variations in irradiance. Radiocarbon incubations (Blanchard & Montagna, 1992;Blanchard & Cariou-Le Gall, 1994) and fluorescence-based rapid light curves (Serodio et al, 2006) have shown that the maximum rate of photosynthesis and the light saturation parameter, E k , were lower in winter than in summer. The maximum rate of light-saturated photosynthesis, P max b , typically ranges between 4 and 10 mg C mg chl a À1 h À1 in microphytobenthic suspensions, which is higher than that found for planktonic diatoms (average P max b around 3; Sarthou et al, 2005), and this provides a very effective sink for absorbed light.…”

Section: Introductionmentioning

confidence: 99%

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Photoacclimation in microphytobenthos and the role of xanthophyll pigments

Leeuwe¹,

Brotas

Consalvey

et al. 2008

European Journal of Phycology

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Estuarine microphytobenthos are frequently exposed to excessively high irradiances. Photoinhibition in microalgae is prevented by various photophysiological responses. We describe here the role of the xanthophyll pigments in photoacclimation. The pigment composition of the microphytobenthos was studied in three European estuaries (Barrow, Ireland; Eden, UK; Tagus, Portugal). Using HPLC-analyses, microscale changes in biomass and pigment composition were monitored over short (hourly) and long (seasonal) time scales. In the Barrow estuary, the biomass of microphytobenthos (measured as chlorophyll a) increased significantly in the top 400-500 mm of the sediment surface within 1 h of emersion; simultaneously, the xanthophyll pool size (diadinoxanthin plus diatoxanthin, dd þ dt) almost doubled. A more gradual conversion of dd into dt was observed, with the dt:dd ratio increasing from <0.1 at the start of emersion to >0.3 after 3 h emersion. Similar trends in the dt:dd ratio were observed in the surface sediments of the Eden and the Tagus estuaries. Higher ratios were recorded in the Tagus estuary, which may be explained by higher incident irradiance. In addition, seasonal studies carried out in the Eden and Tagus estuaries showed that the xanthophyll pool size increased by 10% in the summer months. The pool size was highest in the Tagus estuary. Concurrently, high values for the de-epoxidation state were recorded, with values for dt/(dt þ dd) > 0.35 recorded in the summer. At the Eden, the ratio never exceeded 0.3. The de-epoxidation state was higher in winter than in summer, which was ascribed to the low winter temperatures. During a vertical migration study, a negative relationship between chlorophyll a and the de-epoxidation state was observed. It is suggested that this relationship originates from 'micro-migration' within the biofilm. Migration within the euphotic zone may provide an alternative means for cells to escape photodamage. In this paper, we propose that both xanthophyll cycling and 'micro'-migration play an important role in photoacclimation and it appears that these processes operate in parallel to regulate the photosynthetic response.

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“…Adaptation processes include protection and repair mechanisms. Avoidance of UV-B includes the ability to move away from the harmful radiation (Underwood et al 1999), and on community level, ''selfshading'' i.e., cells deeper in the assemblages get protection through light absorption by cells at the surface (Blanchard and Gall 1994). In a hard bottom microphytobenthic community the adaptation processes are more important because a movement deeper into the sediment is not possible.…”

Section: Introductionmentioning

confidence: 99%

Grazing and UV radiation effects on an Antarctic intertidal microalgal assemblage: a long-term field study

Zacher

Hanelt²,

Wiencke

et al. 2007

Polar Biol

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A 15 week field experiment (austral summer Nov-Mar) was carried out in an intertidal hard bottom platform in Antarctica (King George Island). To test whether grazing and ultraviolet radiation (UVR) influenced the succession of a benthic microalgal assemblage, a twofactorial design was used (1) ambient radiation, >280 nm; (2) ambient minus UV-B, >320 nm; (3) ambient minus UVR, >400 nm versus grazer-no grazer). On four sampling occasions microalgae were identified, counted and carbon contents were calculated. The assemblage was dominated by the diatom genera Navicula and Cocconeis. Biomass was generally low in all treatments but was significantly reduced by grazing throughout the experiment. No significant UV effects were found. Grazer absence particularly favoured diatoms of the genus Cocconeis. We conclude that the Antarctic microalgal assemblage was unaffected by present day UVR whereas grazers acted as important drivers on the intertidal microalgal community structure.

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Photo synthetic characteristics of microphytobenthos in Marennes-Oléron Bay, France: Preliminary results

Cited by 56 publications

References 24 publications

Temperature effects on respiration and photosynthesis in three diatom-dominated benthic communities

Temperature effects on respiration and photosynthesis in three diatom-dominated benthic communities

Photoacclimation in microphytobenthos and the role of xanthophyll pigments

Grazing and UV radiation effects on an Antarctic intertidal microalgal assemblage: a long-term field study

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