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  • 1
    Electronic Resource
    Electronic Resource
    Ecological growth strategies in the seaweeds Gracilaria foliifera (Rhodophyceae) and Ulva sp. (Chlorophyceae): Soluble nitrogen and reserve carbohydrates (1982)
    Springer
    Marine biology 66 (1982), S. 251-259 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seaweeds Gracilaria foliifera (Rhodophyceae) and Ulva sp. (Chlorophyceae) were grown in an outdoor continuous-flow system at both ambient incident light (I0) and 0.13 I0. During the winter, both species accumulated substantial soluble nitrogen reserves (up to 1020 μg-at N·g dry wt-1 in G. foliifera and 630 μg-at N·g dry wt-1 in Ulva sp.). The rate at which these N reserves were depleted was proportional to the growth rate. Seaweeds grown at 0.13 I0 had lower growth rates and higher levels of soluble tissue N than plants grown at I0. During the spring-summer growing season, peaks in tissue N followed nutrient peaks in the ambient seawater. Ulva sp. had higher nutrient uptake and growth rates than G. foliifera and showed greater fluctuations in soluble tissue N. This may characterize opportunistic seaweed species with high biomass turnover rates. At I0, the levels of starch (up to 340 mg·g dry wt-1 in G. foliifera and 170 mg·g dry wt-1 in Ulva sp.) were highest during the spring and summer. During this period, fluctuations in starch content were inversely related to growth rate and soluble tissue N. Seaweeds grown at 0.13 I0 did not accumulate starch. Neither species was found to overwinter with starch reserves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397030
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  • 2
    Electronic Resource
    Electronic Resource
    Changes in photosynthetic pigment concentration in seaweeds as a function of water depth (1976)
    Springer
    Marine biology 37 (1976), S. 223-229 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We conducted a study of the relationship between changes in photosynthetic pigment content and water depth in Great Harbor near Woods Hole, Massachusetts, USA, on the green algae Ulva lactuca and Codium fragile and the red algae Porphyra umbilicalis and Chondrus crispus. A calibrated underwater photometer equipped with spectral band filters measured light attenuation by the water column. The depth required for a 10-fold diminution of photon flux was 3.6, 5.3, 6.0 and 6.0 m for red, blue, yellow and green light, respectively. Seaweeds were attached to vertically buoyed lines and left to adapt for 7 days; then, with their positions reversed, they were allowed to readapt for 7 days. All species showed greater photosynthetic pigment content with increased depth. Further, the ratio of phycobiliproteins and chlorophyll b to chlorophyll a increased with depth. Changes in pigment content were reversible and occurred in the absence of cell division. There was a net loss of pigments near the surface (high irradiance), and subsequent synthesis when seaweeds were transferred to a position deep in the water column (low irradiance). In contrast, seaweeds which were found in intertidal habitats changed only their pigment concentration, and not pigment ratio, a phenomena analogous to higher plant sun and shade adaptation. Therefore, seaweeds modify their photon-gathering photosynthetic antennae to ambient light fields in the water column by both intensity adaptation and complementary chromatic adaptation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387607
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  • 3
    Electronic Resource
    Electronic Resource
    Correlation of changes in pigment content with photosynthetic capacity of seaweeds as a function of water depth (1976)
    Springer
    Marine biology 37 (1976), S. 231-238 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We conducted a study of the relationship between changes in photosynthetic pigment content and photosynthetic capacity as a function of water depth in Great Harbor near Woods Hole, Massachusetts, USA, on the green algae Ulva lactuca and Codium fragile and the red algae Porphyra umbilicalis and Chondrus crispus. Seaweeds were attached to vertically buoyed lines at 0.5 and 10 m and were allowed to adapt to the ambient light field. All species showed greater pigment content with depth, and the ratio of accessory pigments to chlorophyll a increased with depth. Seaweed samples from 0.5 and 10 m were placed in tandem pairs of stoppered bottles and hung at prescribed depths. The rates of O2 evolution were calculated from changes in dissolved O2 content, both as a function of biomass and chlorophyll a concentration. Our results indicate that intensity and/or chromatic adaptation enhance the photosynthetic capacity of a seaweed in limiting light conditions. The strategy of seaweeds in manipulating their photon-gathering antennae is not to maximize photosynthetic rate, but rather to optimize the photosynthetic rate. They can change pigment rations, or simply increase the total amount of pigment, or both. Further, if a seaweed is optically thick, as are Codium fragile and Chondrus crispus, it does not matter what color it is. We conclude that the red algae are phylogenetically no better adapted to utilize the ambient light at great depth than their green counterparts. The ambient light conditions alone do not determine the limit for the vertical distribution of the red algae relative to the green algae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387608
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  • 4
    Electronic Resource
    Electronic Resource
    Fluorescence quenching during photosynthesis and photoinhibition of Ulva rotundata blid. (1993)
    Springer
    Planta 190 (1993), S. 97-106 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll fluorescence ; Photoinhibition ; Photoprotection ; Ulva (photosynthesis)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationships between photoinhibition and photoprotection in high and low-light-grown Ulva were examined by a combination of chlorophyll-fluorescence-monitoring techniques. Tissues were exposed to a computer-controlled sequence of 5-min exposures to red light, followed by 5-min darkness, with stepwise increases in photon flux. Coefficients of chlorophyll fluorescence quenching (1−qP and NPQ) were calculated following a saturating pulse of white light near the end of each 5-min light treatment. Dark-adapted chlorophyll fluorescence parameters (F0 and FV/FM) were calculated from a saturating pulse at the end of each 5-min dark period. Low-light-grown Ulva showed consistently higher 1−qP, i.e. higher reduction status of Q (high primary acceptor of photosystem II), and lower capacity for nonphotochemical quenching (NPQ) at saturating light than did high-light-grown plants. Consequently, low-light plants rapidly displayed photoinhibitory damage (increased F0) at light saturation in seawater. Removal of dissolved inorganic carbon from seawater also led to photoinhibitory damage of high-light-grown Ulva at light saturation, and addition of saturating amounts of dissolved inorganic carbon protected low-light-grown plants against photoinhibitory damage. A large part of NPQ was abolished by treatment with 3 mM dithiothreitol and the processes so inhibited were evidently photoprotective, because dithiothreitol treatment accelerated photoinhibitory damage in both low- and high-light-grown Ulva. The extent of photoinhibitory damage in Ulva was exacerbated by treatment with chloramphenicol (1 mM) without much effect on chlorophyll-quenching parameters, evidently because this inhibitor of chloroplast protein synthesis reduced the rate of repair processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195680
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  • 5
    Electronic Resource
    Electronic Resource
    Photosynthetic response of Ulva rotundata to light and temperature during emersion on an intertidal sand flat (1992)
    Springer
    Oecologia 89 (1992), S. 516-523 
    Details
    ISSN: 1432-1939
    Keywords: Chlorophyll fluorescence ; Photoinhibition ; Photosynthesis ; Temperature stress ; Ulva
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have investigated the diurnal response of photosynthesis and variable photosystem II (PSII) chlorophyll fluorescence at 77 K for thalli of the chlorophyte macroalga, Ulva rotundata, grown in outdoor culture and transplanted to an intertidal sand flat in different seasons. The physiological response in summer indicated synergistic effects of high PFD and aerial exposure, the latter probably attributable to temperature, which usually increased by 8 to 10° C during midday emersion. Except at extreme emersed temperatures in summer (38° C), the light-saturated photosynthesis rate (Pm) did not decline at midday. In contrast, light-limited quantum yield of photosynthetic O2 exchange (τ) and the ratio of variable to maximum fluorescence yield (Fv/Fm) reversibly declined during midday low tides in all seasons. Shade-grown thalli exhibited a fluorescence response suggestive of greater photodamage to PSII, whereas sun-grown thalli had greater photoprotective capacity. The fluorescence decline was smaller when high tide occurred at midday, and was delayed during morning cloudiness. These results suggest that the diurnal response to PFD in this shallow water species is modified by tidal and meteorological factors. U. rotundata has a great capacity for photoprotection which allows it to tolerate and even thrive in the harsh intertidal environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317158
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  • 6
    Electronic Resource
    Electronic Resource
    Analysis of blue-green and red algal ribosomal-RNAs by gel electrophoresis (1971)
    Springer
    Archives of microbiology 76 (1971), S. 292-298 
    Details
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ribosomal-RNAs of two species of red algae (Porphyridium aerugineum and Griffithsia pacifica) and a blue-green alga (Phormidium persicinium) were examined by the method of polycrylamide gel electrophoresis. The results of this study indicate that red algal cytoplasmic rRNAs have molecular weights (1.21 m and 0.54–0.58 m) which are the lowest of any other known for an eukaryotic organism; but a 130,000 dalton gap remains between these values (for the heavy rRNA component) and those for prokaryotic rRNAs (1.06–1.08 m and 0.56 to 0.59 m). Although the cytoplasmic rRNAs of the red algae are distinctly “eukaryotic” in size, the chloroplast rRNAs of these organisms exhibit physical characteristics (molecular weights and mode of breakdown) which make them more like blue-green algal rRNAs than like the rRNAs of other chloroplasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408526
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of temperature on nitrogen-limited growth rate and chemical composition of Ulva curvata (Ulvales: Chlorophyta) (1989)
    Springer
    Marine biology 100 (1989), S. 143-150 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ulva curvata (Kutz.) de Toni growing in shallow estuaries experiences a highly variable supply of dissolved inorganic N, which can limit growth rates. The effects of N supply variability and annual temperature and light variation on growth rates and chemical composition were assessed in plants grown in outdoor tanks supplied with running seawater and either pulsed or continuous N additions for 8 d. Environmental variables were measured every 12 h, growth rates every 2 d, and plant nitrogenous constituents every 4 d. The experiment was repeated 7 times over the course of a year. The slopes of growth rate-tissue N and growth rate-N supply plots increased with temperature and varied at periods at least as short as 2 d. Temperature explained 44% of variation in growth rate, and temperature, light, and N supply together explained 53% of variation in growth rate. N-limitation occurred only above 20°C, the approximate temperature for the maximum growth rate. Growth rate and tissue N were not affected by N supply frequency. Tissue N, ribulose-bisphosphate carboxylase activity, and chlorophyll contents were correlated with each other and with environmental variables but not with growth rate. U. curvata thus does not maintain balanced growth in the strict sense, but rather stores nutrients supplied as pulses for use when they become growth-limiting. Since the relative importance of any single growth-limiting factor is highly dynamic, assessing the importance of multiple limiting factors requires longterm, high-frequency sampling of principal limiting factors and seaweed growth rates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391953
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  • 8
    Electronic Resource
    Electronic Resource
    Optimization of pigment content and the limits of photoacclimation for Ulva rotundata (Chlorophyta) (1989)
    Springer
    Marine biology 103 (1989), S. 267-274 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two vegetative clones (designated 11/85 and 7/86 in accordance with month/year of collection) of the chlorophyte macroalga Ulva rotundata were collected in the vicinity of Beaufort, North Carolina, USA. Each was grown in an outdoor continuous-flow system in summer (〉-20°C) of 1986 and late winter (10° to 17°C) of 1987 in graded scalar quantum irradiances ranging from 9 to 100% of full sunlight, with and without NH 4 + enrichment. The pigment content of plants from each irradiance was determined following 4 to 8 d sunny weather. Chlorophyll (chl) and carotenoid content were inverse curvilinear functions of irradiance. The chl a:b and carotenoid: chl ratios were positively related to irradiance. The close nonlinear relationship between chl (a+b) and the chl a:b ratio was independent of clone, temperature or NH 4 + -enrichment. Chl (a+b) content was linearly correlated with light-regulated growth rate in the summer, but showed a marked hysteresis in the relationship in winter due to photoinhibition. The photon growth yield (PGY, i.e., the biomass yield per unit absorbed light) was maximal for plants grown at slightly subsaturating irradiances, and dropped off sharply at lower irradiances. At higher irradiances, PGY declined gradually in summer and markedly in winter. Light absorption exceeded growth needs at full sunlight, suggesting that U. rotundata was incapable of further reducing its pigment content when growth rate was light-saturated. This, along with the linear chlgrowth relationship, is consistent with photosynthetic feedback regulation of chl content. Regardless of the mechanism, chl regulation may operate within the constraints of a resource tradeoff between light harvesting and carboxylation capacities, such that pigmentation must be optimized rather than maximized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00543357
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  • 9
    Electronic Resource
    Electronic Resource
    Photoacclimation of Ulva rotundata (Chlorophyta) under natural irradiance (1989)
    Springer
    Marine biology 103 (1989), S. 261-266 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two vegetative clones (designated 11/85 and 7/86 in accordance with month/year of collection) of the green macroalga Ulva rotundata were collected in the vicinity of Beaufort, North Carolina, USA. Each was grown in an outdoor continuous-flow system in summer (≥20°C) of 1986 and late winter (10° to 17°C) of 1987, in irradiances ranging from 9 to 100% of full sunlight, with and without NH 4 + enrichment. Continuous enrichment of influent estuarine water (dissolved inorganic nitrogen ∼2 μM, N:P≤5) to 8–12 μM NH 4 + had only a slight effect on growth rate. Temperature changes of 2 to 3°C had a much greater effect. Prolonged exposure to a given daily irradiance resulted in acclimation, exposure to a given daily irradiance resulted in acclimation, indicated by faster growth of conditioned plants relative to those transferred from a different irradiance. Most of the difference in growth rates between transferred and control plants was attributed to differences in thallus absorptance. Growth was photoinhibited above 40% sunlight at temperatures below ∼15°C, but not above ∼20°C. Following interday irradiance transfers, thallus percent dry weight changed in a manner that suggests different response times for photosynthesis and cell division.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00543356
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  • 10
    Electronic Resource
    Electronic Resource
    Adaptation of light-harvesting pigments to downwelling light and the consequent photosynthetic performance of the eulittoral rockweeds Ascophyllum nodosum and Fucus vesiculosus (1977)
    Springer
    Marine biology 42 (1977), S. 293-303 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We compared the effect of habitat and water depth on the light-harvesting pigment content for Ascophyllum nodosum and Fucus vesiculosus at two near-shore stations in Long Island Sound (USA). Excised pieces of seaweeds were attached at depth intervals to a vertically buoyed line, and left in situ for 7 days. For comparison, fronds were collected from sun and shade habitats in the littoral zone. The three major antenna (light-harvesting) pigments increased in concentration with depth or shade. Chlorophyll c to a ratios remained stable at about 0.2. Fucoxanthin to chlorophyll a ratios decreased by 20 to 30% with depth or shade. Although pigment composition for the two rockweed species was equivalent, the maximum photosynthetic performance of F. vesiculosus exceeded that of A. nodosum by a factor of 2, while the compensation depths for 4 m-adapted A. nodosum and F. vesiculosus under natural limiting light conditions were equivalent. Plants held at 4 m had higher photosynthetic rates compared with plants held at 0 m, no matter the depth of measurement. Indirect evidence indicates that the enhanced photosynthesis of 4 m-adapted plants is due not only to higher concentrations of antenna pigments but to other physiological factors as well. We conclude that the clearly delineated vertical distribution of these two canopy species, the F. vesiculosus zone over the A. nodosum zone, is not determined by light quantity or quality, but by biotic factors as evidenced by the experiments of Menge which are cited herein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402191
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