Light acclimation strategies of three commercially important red algal species (original) (raw)
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Aquaculture, 2005
The photosynthetic performance and pigment content of Gracilaria chilensis Bird, McLachlan, and Oliveira were measured under natural solar radiation in the Quempillen river estuary (southern Chile) in order to assess the short-term acclimation of this species to the current levels of ultraviolet (UV) radiation during midsummer. The effect of the tidal fluctuation was evaluated in algae exposed for 3 days to two light climates in cages suspended at two depths (0.5 and 1.5 m from the bottom). Responses to high solar radiation at noon were also assessed to gain insights into rapid photochemical kinetics and the degree of photoinhibition. Results indicated that G. chilensis is a shade-adapted species with a high content of photosynthetic pigments (Chl a and phycobilins), high quantum efficiency (a), and low light saturating point (E k ) between 60 and 170 Amol m À2 s À1 reflecting the high turbidity and marked light attenuation (K d ) of both UV and photosynthetically active radiation (PAR): 1% of the UVB radiation (280-320 nm) reaches 1.8 m depth only during high tide, whereas during ebb tide, UVB can only be detected at 30 cm depth. In the case of PAR, 1% penetration depth was close to 2.7 m during low tide. Under these conditions decreases in rates of photosynthesis at noon did not exceed 23%, even in the presence of UVB. When algae were exposed to full solar radiation at noon for 3 h and then incubated under shaded conditions for recovery, evidence for photoinhibition was observed: in algae exposed to PAR+UVA+UVB, photosynthesis decreased by 16%, while recovery was close to 88% of the control. In treatments deprived of UVB, recovery was close to 100%. These results suggest that G. chilensis is not commonly exposed to high irradiances in the field and that UVB is potentially detrimental for photosynthesis when algae are maintained close to the surface, at least during summer. This was corroborated by the low content of UV-absorbing compounds (mycosporine-like amino acids, or MAAs; between 0.89 and 1.75 mg g DW).
Phycological Research, 2001
The responses of relative growth rate (% day -1 ) and pigment content (chlorophyll a, phycocyanin and phycoerythrin) to temperature, irradiance and photoperiod were analyzed in culture in seven freshwater red algae: Audouinella hermannii (Roth) Duby, Audouinella pygmaea (Kützing) Weber-van Bosse, Batrachospermum ambiguum Montagne, Batrachospermum delicatulum (Skuja) Necchi et Entwisle, 'Chantransia' stages of B. delicatulum and Batrachospermum macrosporum Montagne and Compsopogon coeruleus (C. Agardh) Montagne. Experimental conditions included temperatures of 10, 15, 20 and 25°C and low and high irradiances (65 and 300 µmol photons m -2 s -1 , respectively). Long and short day lengths (16:8 and 8:16 LD cycles) were also applied at the two irradiances. Growth effects of temperature and irradiance were evident in most algae tested, and there were significant interactions among treatments. Most freshwater red algae had the best growth under low irradiance, confirming the preference of freshwater red algae for low light regimens. In general there was highest growth rate in long days and low irradiance. Growth optima in relation to temperature were species-specific and also varied between low and high irradiances for the same alga. The most significant differences in pigment content were related to temperature, whereas few significant differences could be attributed to variation in irradiance and photoperiod or interactions among the three parameters. The responses were species-specific and also differed for pigments in distinct temperatures, irradiances and photoperiods in the same alga. Phycocyanin was generally more concentrated than phycoerythrin and phycobiliproteins were more concentrated than chlorophyll a. The highest total pigment contents were found in two species typical of shaded habitats: A. hermannii and C. coeruleus. The expected inverse relationship of pigment with irradiance was observed only in C. coeruleus. In general, the most favorable conditions for growth were not coincident with those with highest pigment contents.
Acclimation of Red Sea macroalgae to solar radiation: photosynthesis and thallus absorptance
Aquatic Biology, 2009
Thallus absorptance, daily courses of maximal quantum yields of chlorophyll fluorescence of photosystem II (F v /F m ) and electron transport rates (ETR) were determined in 3 macroalgae (Hypnea spinella, Rhodophyta; Sargassum vulgare, Phaeophyta; and Ulva lactuca, Chlorophyta) collected from a low nutrient supply (LNS) ecosystem (Red Sea, Gulf of Aqaba, Eilat, Israel). In addition, U. lactuca grown previously in high nutrient supply (HNS) fishpond effluents was used to evaluate the effect of nutrient enrichment on photosynthesis. Short-term (2 d) and mid-term (5 d) effects of both photosynthetically active radiation (PAR) and full solar irradiance (PAB: PAR+UVA+UVB) at 3 solar irradiance treatments (no neutral filters, no NF; 2 neutral filter layers, 2NF; and 4 neutral filter layers, 4NF simulating levels of irradiance at 5, 10 and 20 m depth respectively) were evaluated in algae incubated with running seawater. Significant effects of time (variation throughout the day) and irradiance (number of neutral filters) on both F v /F m and ETR were observed. Photoinhibition occurred at noon under the no NF (up to 40% decrease) and 2NF (up to 30% decrease) treatments; however, full recovery in all treatments was reached in the afternoon (dynamic photoinhibition) except in H. spinella. The highest maximum ETR was observed in the no NF treatment despite its strongest photoinhibitory effect. The decrease in F v /F m at noon was similar to or higher under the PAB than under the PAR treatment alone, depending on the species. Photoinhibition was lower and the maximum ETR was higher in HNS than in LNS U. lactuca, indicating positive effects of nutrient supply on both photosynthesis and photoprotection. The maximum ETRs exhibited by different algae may be related to their zonation in the field and the resulting energy supply.
Patterns of photosynthesis in 18 species of intertidal macroalgae from southern Chile
Marine Ecology Progress Series, 2004
Photosynthetic characteristics of 18 macroalgal species, measured as chlorophyll a (chl a) fluorescence of photosystem II (PSII), pigment contents and susceptibility of photosynthesis to solar radiation, were studied in the field in southern Chile (Niebla, Valdivia) during midsummer. Photosynthesis versus irradiance curves indicated that algae exhibited sun-adapted characteristics, with saturating points for photosynthesis (E k) ranging between 50 and 400 µmol photon m-2 s-1. Under the solar radiation conditions that prevailed during the study period at this locality (daily doses of photosynthetically active radiation, PAR, close to 14 000 kJ m-2 d-1 , with instantaneous irradiances exceeding 2000 µmol photon m-2 s-1 at noon), algae were light saturated for periods (H sat) between 11 and 14 h d-1. Daily courses of optimal quantum yield (F v /F m) of chl a fluorescence of PSII revealed the existence of photoinhibition of 46% at maximum relative to fluorescence measured in the morning. Similarly, the effective quantum yield (Φ PSII) showed a decrease at noon coinciding with the peak of solar radiation. This reduction in Φ PSII was accentuated when algae were maintained in immersion for the whole measuring period; whereas, in algae measured in situ, i.e. subject to varying tidal height, chl a fluorescence decreased less. Although algae are currently exposed to very high doses of ultraviolet (UV) radiation, short-term exposures of 2.5 h around noon using specific cutoff filters did not result in high photoinhibition of F v /F m (rates < 25%), reinforcing the idea that these intertidal species are characterized by a marked tolerance to current solar UV radiation. Differences in the rates of photoinhibition of photosynthesis as well as in the photosynthetic characteristics were not related to functional-form group (e.g. thin vs thick morphs). Instead, the photosynthetic performance of algae was determined by their position in the shore: algae growing at mid-/infra-littoral zones had lower E k and lower photoinhibition than algae from upper locations.
European Journal of Phycology, 2017
Batrachospermum turfosum Bory is one of the generalists among the few red algae that have adapted to freshwater habitats, occurring in a variety of primarily shaded, nutrient-poor microhabitats with lotic (running) or lentic (standing) waters. Seasonal variations in water level and canopy cover can expose this sessile alga to widely fluctuating temperatures, solar irradiation and nutrient availability. Here we report on the ecophysiology of B. turfosum collected from an ultraoligotrophic bog pool in the Austrian Alps. Photosynthesis as a function of photon fluence density (PFD) and temperature was studied by measuring oxygen evolution in combination with chlorophyll fluorescence. In addition, the effects of ultraviolet radiation (UVR) on photosynthetic pigments were analysed using HPLC and spectrophotometric methods, and cellular ultrastructure was studied using transmission electron microscopy. We found that B. turfosum is adapted to low light, with a light compensation point (I c) and a light saturation point (I k) of 8.4 and 29.7 μmol photons m-2 s-1 , respectively, but also tolerates higher PFDs of ~1000 μmol photons m-2 s-1 , and is capable of net photosynthesis at temperatures between 5°C and 35°C. Exposure to either UV-A or UV-AB for 102 h led to a strong transient drop in effective quantum yield (ΔF/F M '), followed by an acclimation to about 70% of initial ΔF/F M ' values. Ultrastructural changes included the accumulation of plastoglobules and dilated membranes after UVR treatment. Although all photosynthetic pigments strongly decreased upon UVR exposure and no UV-photoprotectants (e.g. mycosporine-like amino acids) could be detected, the alga was capable of recovering ΔF/F M ' and phycobiliproteins after UVR treatment. In summary, B. turfosum tolerates a wide range of irradiation and temperature regimes, and these traits may be the basis for its successful adaptation to challenging environments.
DOAJ (DOAJ: Directory of Open Access Journals), 2009
For the first time, the photosynthetic performance of field-grown macroalgae from the Magellan Strait was evaluated with respect to their photoadaptation in the field and acclimation potential to ultraviolet radiation. Five macroalgal species were collected in the eulittoral and the upper sublittoral: Ulva intestinalis, Porphyra columbina, Adenocystis utricularis, Desmarestia confervoides and D. ligulata. Photosynthesis vs. irradiance (P-I) curves of macroalgae cultivated in the laboratory under low white light intensities more than a week were used to assess the acclimation potential to irradiance conditions in the field. Both, photosynthetic parameters referred to as maximum electron transport rate (ETRmax) and light saturation points of photosynthesis (I k) were species-specific and did not correlate with the position on the shore. I k ranging between 80 and 215 μmol photons m-2 s-1 was indicative of moderate sun-adaptation in all studied species. The acclimation potential to UV-radiation was determined as the extent and the rates (m inh) of PSII inhibition (resulting from decreased maximum PSII-quantum yield (Fv/Fm)) after four hours of UV-exposure and as the subsequent rates of recovery (m rec) in dim PAR. The results suggest that photosynthesis of each species during UV-exposure was transiently down regulated rather than damaged. Furthermore, no reductions in ETRmax were detected after 4 h exposure to UV-A and UV-B-radiation, and consequently the Calvin cycle could not be affected. Thus, Fv/Fm was a more sensitive parameter than ETRmax explaining the photosynthetic UV acclimation. Both, the rates of inhibition and the rates of recovery were not correlated with the morpho-functional groups of macroalgae nor to their vertical distribution. Thus, although the capacity to acclimate to UV-radiation varied among the different species, data suggest that such responses are based on metabolic adjustments or possibly photoprotective strategies. In conclusion and taking into account the light adaptation characteristics, all species collected in the midlittoral and the upper sublittoral at the Strait of Magellan seem to be well acclimated to UV-B doses occurring at their habitat, which might be a prerequisite to withstand enhanced solar UV-B during ozone depletion or summertime irradiance conditions.
Marine Ecology Progress Series, 2011
We address the question of whether seaweed zonation can be characterized in terms of light absorption, pigmentation, photosynthetic parameters, photoinhibition, and thallus structure. Based on 32 seaweed species from the Pacific coast of southern Chile, intertidal assemblages exhibited higher light requirements for photosynthesis (E k) and lower thallus light absorptances than subtidal algae. E k values were lower than the highest measured irradiances at the corresponding natural depths, suggesting that photosynthesis in these organisms could potentially occur at lower depths. During summer, 1% of photosynthetically active radiation (PAR) reached a depth of 23 m, while UV-B and UV-A wavelengths were completely attenuated at < 3 and 6 m, respectively. Overall, the photobiological adaptations were associated with depth, morphology, and taxonomic group. Photoinhibition was similar in algae from different depths, although recovery was higher in upper littoral algae than in infra-and sublittoral species. The characteristics conferring competitive abilities in light use and light stress tolerance were not, or only partially, related to the classical Littler form-function model. The filamentous and foliose forms were able to acclimate rapidly to changing light and physical stress in the supralittoral zone. For infralittoral kelps living in a highly dynamic environment, higher cross-sectional area and enhanced in vivo light absorption were coupled with morphological features (e.g. massive thallus) that are advantageous in withstanding e.g. water movement. By contrast, the rapid physiological adjustments that allow algae to endure solar stress (e.g. photochemical down-regulation) were strongly dependent on the position on the shore but not on gross morphology.
Polar Biology, 1998
In ®eld studies conducted at the Kongsfjord (Spitsbergen) changes of the irradiance in the atmosphere and the sublittoral zone were monitored from the beginning of June until the end of August 1997, to register the minimum and maximum¯uxes of ultraviolet and photosynthetically active radiation and to characterise the underwater light climate. Measurements of photosynthesis in three abundant brown algal species (Alaria esculenta, Laminaria saccharina, Saccorhiza dermatodea) were conducted to test whether their photosynthetic performance re¯ects changing light climate in accordance with depth. Plants sampled at various depths were exposed to controlled¯uence rates of photosynthetically active radiation (400±700 nm), UV-A (320± 400 nm) and UV-B (280±320 nm). Changes in photosynthetic performance during the treatments were monitored by measuring variable chlorophyll¯uorescence of photosystem II. In each species, the degree of inhibition of photosynthesis was related to the original collection depth, i.e. shallow-water isolates were more resistant than plants from deeper waters. The results show that macroalgae acclimate eectively to increasing irradiance levels for both photosynthetically active and ultraviolet radiation. However, the kinetics of acclimation are dierent within the dierent species. It is shown that one important strategy to cope with higher irradiance levels in shallow waters is the capability for a faster recovery from high light stress compared to isolates from deeper waters.