Action spectra and spectral quantum yield of photosynthesis in marine macroalgae with thin and thick thalli

Net photosynthesis at 10mol photons m^-2 s^-1 in each of 24 wavelengths was measured in absolute units by an O₂-electrode and corrected for dark respiration to construct action spectra for gross photosynthesis in nine species of algae, which included plants with thin and thick thalli from each of four major pigment groups. The photosynthesis of green and brown algae with thin thalli decreased in green light, but species with thick thalli from these two groups had action spectra which were almost flat, and matched the optical blackness of the thalli but did not reflect the pigment differences between the species. Among the red algae, on the other hand, there was little difference between the action spectra for thin and thick algae. Only wavelengths absorbed by the phycobilin pigments were effective in photosynthesis, even in species (e.g. Chondrus, Phyllophora) which absorbed all visible wavelengths strongly. Maximal quantum yields of 0.10 to 0.12 O₂ molecules per absorbed photon were recorded for thin green and brown algae, but thicker algae in these two groups had lower values. Red algae exhibited maximal values close to 0.10 O₂ molecules per absorbed photon, irrespective of thallus thickness or phycocyanin content, but the quantum yields of phycoerythrin-rich species in the 600 to 650 nm waveband were lower than those of phycocyanin-rich species.     

Saturated and unsaturated hydrocarbons in marine benthic algae

Saturated and olefinic hydrocarbons were determined in 24 species of green, brown and red benthic marine algae from the Cape Cod area (Massachusetts, USA). Among the saturated hydrocarbons, n-pentadecane predominates in the brown and n-heptadecane in the red algae. A C₁₇ alkyleyclopropane has been identified tentatively in Ulvalactuca and Enteromorpha compressa, two species of green algae. Mono-and diolefinic C₁₅ and C₁₇ hydrocarbons are common. The structures of several new C₁₇, C₁₉ and C₂₁ mono-to hexaolefins have been elucidated by gas chromatography, mass spectrometry and ozonolysis. In fruiting Ascophyllum nodosum, the polyunsaturated hydrocarbons carbons occur exclusively in the reproductive structures. The rest of the plant contains n-alkanes from C₁₅ to C₂₁. A link between the reproductive chemistry of benthic and planktonic algae and their olefin content is suggested. An intriguing speculation is based on Paffenhöfer's (1970) observation that the sex ratio of laboratory reared Calanus helgolandicus depends upon the species of algae fed to the nauplii. The percentage of males produced correlates with our analyses of heneicosahexaene in the algal food. Our analyses of the hydrocarbons in benthic marine algae from coastal environments should aid studies of the coastal food web and should enable us to distinguish between hydrocarbon pollutants and the natural hydrocarbon background in inshore waters.Contribution No. 2582 of the Woods Hole Oceanographic Institution; and Contribution No. 227, Systematics-Ecology Program.     

Reproduction,growth and photosynthesis of gametophytes of Laminaria saccharina grown in blue and red light

The induction of reproductive activity by blue light in female gametophytes of the brown alga Lamnaria saccharina has been investigated and related to other effects of red and blue light on these plants. Although germination of zoo-spores is slightly delayed in red light, female gametophytes grow at similar rates in blue and red light of the same quantum irradiance up to an age of 8 to 10 days, when plants in blue light begin to form eggs. The percentage of plants forming eggs is proportional to the total quanta of blue wavelengths received up to a saturating value of about 400 μE·cm^-2; a 50% response is induced by 200 μE·cm^-2. The action spectrum for the induction of fertility has a main peak at 430 to 450 nm, with two subsidiary peaks in the blue and one in the near-ultraviolet light, but the action spectrum for photosynthesis is quite different, with peaks in the red, green and blue regions. These results indicate that egg formation in female gametophytes occurs as a specific morphogenetic response to blue light, which is independent of photosynthesis and growth, and trial experiments with male gametophytes of L. saccharina and gametophytes of other species of Laminariales indicate that these plants react similarly.     

Photosynthetic rates of benthic marine algae in relation to light intensity and seasonal variations

The effect of light intensity on rate of photosynthesis was measured at irregular intervals over a 12-month period for 22 benthic marine algae in the western Baltic Sea. In most species photosynthesis (mg O₂·g dry weight^-1·h^-1) was highest in spring and summer, corresponding to the seasonal growth pattern of the algae. In winter all the species showed adaptation of the light compensation point. Highest productivity was shown by algae which are: short-lived annual species rather than perennials, eulittoral rather than sublittoral, and which possess sheet-like or filamentous thalli rather than coarsely branched forms. These factors are clearly inter-related.This research was carried out while one of us (R.J.K.) was an Alexander von Humboldt fellow at the University of Kiel, and is part of the programme Sonderforschungsbereich 95, Wechselwirkung Meer-Meeresboden, Universität Kiel.     

Food habits, gut morphology and pH, and assimilation efficiency of the zebraperch Hermosilla azurea, an herbivorous kyphosid fish of temperate marine waters

Adult zebraperch, Hermosilla azurea, were found to be functional herbivores in that animal matter constituted <0.01% of the total dry weight of stomach contents of fish collected off Santa Catalina Island in southern California waters. The diet of these fish consisted mainly of red algae (88.2% by dry wt) and also small amounts of brown (7.8%) and green (4.0%) algae. The most important dietary item, the filamentous red algae Polysiphonia spp., was found in >78% of the stomachs and comprised >60% of the contents by dry weight. The digestive tract was long, on average 4.0 times the standard length of the fish, and was composed of the stomach, pyloric caeca, intestine, hindgut chamber with a blind caecum, and rectum. The mean pH of the cardiac stomach was acidic (3.9), whereas that of the intestine was nearly neutral (6.9) and that of the hindgut and blind caecum slightly acidic (6.3 and 6.6, respectively). Algal foods are apparently digested by acid lysis in the stomach and by microbial fermentation in the hindgut. Zebraperch assimilated nutritional constituents from six species of algae with varying degrees of efficiency: carbon (73.7 to 89.7%), nitrogen (72.4 to 84.5%), and protein (71.9 to 94.9%). The fish assimilated these constituents as efficiently or more efficiently from three species of nondietary brown algae as from three species of dietary red and green algae. These results show that zebraperch, like their tropical and subtropical relatives (members of the genus Kyphosus), can digest a wide variety of algae including brown algae containing defensive secondary compounds. Received: 3 November 1997 / Accepted: 19 June 1998     

Broad-band versus narrow-band irradiance for estimating latitude by archival tags

The relative effectiveness of different bands of irradiance to estimate the latitude of archival tags was evaluated. These tags are placed on fishes in order to describe their movements during long distance migrations. Measurements were recorded of broad-band irradiance with and without a cosine collector and narrow-band irradiance of seven narrow bands with 50% attenuation 30 nm on either side of their central wavelength of 400 (violet), 450 (blue), 500 (blue–green), 550 (green), 600 (yellow), 650 (orange), and 700 nm (red). A holographic, cosine collector was used to reduce the vertical transmission of irradiance to the sensor and to increase horizontal transmission of irradiance so the sensor detected more of the diffuse irradiance penetrating the water at dawn and dusk. Daily measurements were made during seven periods of 1–2 days each, beginning 28 June (after 21 June solstice) and ending on 6 October 1999 (after September 23 equinox) of submarine irradiance at 15-s intervals at a fixed depth (10 m) and location (38.31°N; 123.08°W) in Horseshoe Cove, California. Irradiance transmission at this site is intermediate between the clearest offshore waters, where blue irradiance (450 nm) penetrates farther with depth than green irradiance (550 nm) and most oceanic and coastal waters, where green penetrates farther than blue irradiance. Two algorithms were used to estimate latitude, the maximum slope method and the maximum logarithmic difference method. The broad-band, cosine-corrected light, excluding those deployments near the equinox when error is highest, produced an estimate of latitude of 38.30° for both methods and a latitudinal error of ±34.4 km for the former and ±27.2 km for the latter. The mean latitudinal error for non-cosine-collected, broad-band irradiance was ±190.9 km, using the slope algorithm and ±184.8 km using the difference algorithm. The blue band of irradiance, which attenuates least with increasing depth in clear, oceanic water, also produced a comparatively high-latitudinal error of ±163.8 km error for the former algorithm and ±170.4 km for the latter algorithm. Tag designers should consider using cosine-collectors over the irradiance sensors on their archival tags to increase the accuracy of position estimates.     

Changes in photosynthetic pigment concentration in seaweeds as a function of water depth

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.     

Light quality in relation to growth,photosynthetic rates and carbon metabolism in two species of marine plankton algae

The effect of light quality on growth, photosynthesis and carbon metabolism in two species of marine algae,Cyclotella nana (Hustedt) andDunaliella tertiolecta (Butcher), was examined. Relative growth constants forC. nana were 0.37, 0.29 and 0.25 in blue, white and green light, respectively. Corresponding constants were 0.41, 0.31 and 0.29 forD. tertiolecta. Photosynthetic rates in both species were higher in blue light and lower in green light compared with white light of the same intensity. More than 60% of¹⁴C assimilated byC. nana orD. tertiolecta grown in blue or green light was incorporated into the ethanol-insoluble fraction, compared with 10 to 30% in this fraction in white light. The relative importance of the various components within this fraction was independent of light quality. Although less¹⁴C was assimilated into the ethanol-soluble fraction in blue or green light, there was a relative increase in some amino acids and organic acids in this fraction and a decrease in sugars and sugar phosphates relative to white light of the same intensity. These differences were independent of light intensity, photosynthetic rate and cell density in the cultures.     

Neutral lipids in macroalgal spores and their role in swimming

We followed changes in the neutral lipid content of actively swimming zoospores of the palm kelp Pterygophora californica in a laboratory experiment to investigate the degree to which spore swimming is fueled by endogenous lipid reserves. The neutral lipid content of individual zoospores during the experiment was measured by flow cytometry using Nile Red, a fluorescent stain that is specific for neutral lipid. Results showed that photosynthesis greatly influenced lipid consumption during zoospore swimming. We found no detectable change in the neutral lipid content of zoospores after 30 h of swimming under conditions where light was near the optimum for photosynthesis. By contrast, neutral lipid declined by ≃43% over 30 h in zoospores kept in the dark. To evaluate whether lipid reserves are generally related to spore motility in macroalgae, we surveyed spore lipid-content and composition in species with motile spores and non-motile spores using thin-layer chromatography (TLC), and flame-ionization detection (FID). We observed substantial differences in lipid content and composition among the 20 species examined. Spores high in total lipid (as estimated by the ratio of lipid:carbon) generally had a large amount of neutral lipid; motile spores had significantly more lipid and a significantly larger neutral lipid fraction than non-motile spores. The kelps as a group had the highest total lipid content and the largest neutral lipid fraction, while non-motile spores of red algae were generally low in total lipid and in the proportional abundance of neutral lipid. Phospholipids accounted for more than half of all lipid in 14 of the 20 species examined, while neutral lipid accounted for the majority of lipid in all five species of kelp examined. Triacylglycerols, which function primarily in energy storage, were the primary form of neutral lipid in all but one species of kelp (Agarum fimbriatum), whereas free fatty acids were the dominant form of neutral lipid in most red algae and in brown algae that had a small neutral lipid fraction. Our results are largely consistent with the hypothesis that macroalgae use endogenous lipid reserves to fuel spore-swimming. The small amounts of triacylglycerols observed in the motile spores of several species of brown and green algae, however, indicate that the amount of lipid reserves needed to fuel spore-swimming may be influenced by a variety of factors including swimming behavior, photosynthetic efficiency, and the light environment inhabited by spores. Received: 8 September 1998 / Accepted: 8 January 1999     

Occurrence and biological role of light-induced chromatophore displacements in seaweeds

The occurrence of light-induced chromatophore displacements and concomitant transmittance changes in marine algae was investigated by microscope and photometrically with an automated recording microphotometer system; 16 brown, 6 green and 20 red algae were studied. In most of the brown algae, both phaeoplast displacements and transmittance changes were found. In some red algae which are frequently exposed to direct sun light during emergence at low tide, light-induced transmittance changes were measured, but they could not unequivocally be correlated with changes in the position of rhodoplasts. Among green algae, only Ulva lactuca shows chloroplast displacements which, however, follow circadian rhythms and are consequently not light-induced in the strict sense. The dose-response curves of light-induced chromatophore displacements were measured in the following Fucus and Laminaria species: F. spiralis, F. vesiculosus, F. serratus, L. digitata, L. saccharina and L. hyperborea. While in Fucus species correlations between light-induced transmittance changes and zonation of the intertidal area seem to exist, no significant differences have been found in the Laminaria species. The physiological role and ecological importance of light-induced chromatophore displacements for seaweeds living in the intertidal belt are discussed.     

Effect of light quality on photosynthesis of the reef coral Montipora verrucosa

Pieces of the reef coral Montipora verrucosa (Lam.), collected from Kaneohe Bay, Oahu, Hawaii in 1982, were grown in four low-light treatments (11% sunlight): blue, green, red and the full spectrum of photosynthetically active radiation (PAR); and at high-intensity full PAR (90% sunlight). These acclimated corals were then tested for photosynthetic ability in blue, green, red, and white light. The photosynthetic parameters that were measured were; ligh-saturated photosynthetic rate, the initial slope of the photosynthesis/irradiance curve, the light intensity where these two lines crossed, and dark respiration. While acclimation intensity had a pronounced effect, the results also showed that the color of the acclimation treatment influenced the photosynthetic responses of the corals. The color of the light used in the measurements of photosynthesis had much less effect on the photosynthetic responses of the corals.Contribution No. 729 of the Hawaii Institute of Marine Biology     

UV-radiation can affect depth-zonation of Antarctic macroalgae

Due to depletion of stratospheric ozone over polar regions of the Northern and Southern Hemispheres UV-B-radiation has increased at the surface of the earth. Measurements of variable chlorophyll fluorescence were conducted to document UV-induced photoinhibition of photosystem II in cultivated macroalgae with different depth distributions in Antarctica. The reactions during artificial UV-exposure were observed on a short time scale (hours) and in light–dark cycles over several days. The nine species of investigated macroalgae show great differences in UV-tolerance of the photosynthetic process. Photosynthesis of the studied green algae was inhibited to a minor degree, while the brown algae showed an intermediate inhibition of photosynthesis. The response of the studied red algae varied with species. The differences in the degree of inhibition and recovery of photosynthetic efficiency and capacity indicate that UV-radiation is one important factor affecting the vertical distribution of macroalgae in nature. Received: 11 December 1997 / Accepted: 27 March 1998     

Hydrocarbons in benthic algae from the eastern Gulf of Mexico

Thirty-six samples of benthic algae were collected from the continental shelf along the eastern Gulf of Mexico. The algae contain 82.8±143 ppm aliphatic hydrocarbons by dry weight and 11.8±22.7 ppm aromatic and polyolefinic hydrocarbons. The aliphatic constituents of red algae are composed almost entirely of n-C₁₇ (70 to 95% of aliphatic weight); green algae have varying amounts of n-alkanes in the range of n-C₁₅ to n-C₁₉, with homologous series of odd carbon number n-alkenes. Phytadienes occur as high as 740 ppm dry weight in the green algae and do not appear to be related to time or place of collection or to presence of any petroleum pollutants. The single brown algal species contains predominantly n-C₁₅. About 30% of the samples have hydrocarbons resembling degraded petroleum residues, but no petroleum pollution of recent origin was detected in any specimen.     

Do correlations exist between chromatophore arrangement and photosynthetic activity in seaweeds?

In Dictyota dichotoma, as in many other plants, the chromatophores which at low intensities occupy the cell walls perpendicular to the light beam move to the side walls parallel to the light beam if exposed to high light intensities. The aim of this investigation was to find out whether or not the changes from low- to high-intensity arrangement and vice versa function as an active control mechanism to regulate photosynthetic activity in D. dichotoma under the respective light condition. Four different experimental approaches were made: (a) In white and blue light experiments the changes of the transmittance and of the rate of photosynthetic oxygen production in high- and low-intensity arrangement were compared. (b) The kinetics of the depression and recovery of the PS-rates, as well as of the transmittance changes, were determined during high- and low-intensity movement, respectively. (c) Transmittance and PS-rates of thalli under illumination with polarized and unpolarized light of the same intensity (1,000 1x) were compared. (d) PS-rates of thalli after darkening as well as after preirradiation with weak and strong red light, conditions under which the chromatophores occupy the same position in the cells, were measured. In all these experiments the photosynthetic activity was strongly influenced by pre-illumination, but was independent of the respective chromatophore arrangement. This finding was confirmed by experiments with two other algae: (1) In the brown alga Alaria esculenta which does not display light-induced chromatophore displacements and concomitant transmittance changes, pre-irradiation with high light intensities decreases the PS-rates. (2) In the green alga Ulva lactuca, which shows circadian chloroplast movements, the PS-rates depend on the pre-irradiation only, irrespective of the chloroplast position. Thus we may conclude that in these organisms the function of chromatophore displacements is not the regulation of photosynthetic activity. Other ecological functions are discussed.     

Different patterns of carotenoid composition and photosynthesis acclimation in two tropical red algae

To be able to survive, marine macroalgae in shallow coastal waters need mechanisms for short-term acclimation to fast changes in their environment. Of major importance are mechanisms that regulate the efficiency of photosynthesis by protecting PS II from photo-oxidative damage. Carotenoids, xanthophyll cycles and non-photochemical quenching (NPQ) are central constituents of such protection mechanisms. Red algae as a group do not have a universal carotenoid composition. We screened ten red algal species and selected two species, originating from similar ecological conditions but with different carotenoid compositions, for use in irradiance-acclimation experiments. We selected the tropical intertidal species Gracilaria domingensis and Kappaphycus alvarezii with antheraxanthin and lutein as major xanthophylls, respectively. Simultaneous in vivo fluorescence and O₂ evolution experiments were performed at different irradiance levels, which allowed a direct comparison of overall photosynthetic performance with NPQ. Interconversions of xanthophylls (violaxanthin, zeaxanthin, β-cryptoxanthin and one unidentified carotenoid) did occur in G. domingensis, but not in response to sudden exposure to light. Thus, NPQ was not correlated with any xanthophyll cycle during short-term acclimation to light. G. domingensis had five times higher weight-specific photosynthetic rates than K. alvarezii, which can be explained by the thicker thallus of K. alvarezii. Chlorophyll-specific gross photosynthetic rates were higher in K. alvarezii, but net rates were the same for both species. G. domingensis showed an immediate strong onset of NPQ upon exposure to irradiance, followed by downregulation to the NPQ level required. In K. alvarezii NPQ increased slowly until the required NPQ level was reached. At high irradiance G. domingensis downregulated photosynthesis while K. alvarezii continued to produce O₂ even at 2,000 μmol photons m⁻² s⁻¹ without NPQ increase. The strategy of K. alvarezii may provide short-term gains but with the risk of oxidative damage. The fast onset of NPQ in G. domingensis even at subsaturating irradiance as well as downregulation of photosynthesis when NPQ is saturated might provide this species with a competitive advantage under conditions of changing irradiance in the field.     

Photosynthetic acclimation and biochemical responses ofGelidium sesquipedale cultured in chemostats under different qualities of light

The red algaGelidium sesquipedale (Clem.) Born. et Thur. has been cultured in chemostats to assess the effects of light quality and photon-fluence rate (PFR) on growth, photosynthesis and biochemical composition. Plants under blue and red light (BL and RL) showed higher growth rates than under white light (WL) of the same PFR (40 mol m^–2 s^–1). The light-saturated rate of photosynthesis was higher for algae grown under BL and RL than for algae grown under WL. When algae were transferred to WL of moderate PFR (100 mol m^–2 s^–1), the light-saturated rate of photosynthesis decreased, being higher in previously RL-grown algae than in previously BL- and WL-grown algae. The initial slope of photosynthesis-irradiance (PI) curves () was affected by PFR but not by light quality. Pigment content was little affected by light quality. Light-quality treatments also affected the biochemical composition of the alga; previous exposure to various light treatments activate or repress several metabolical pathways that are fully expressed in the subsequent phase of WL of moderate PFR. Thus, phycobiliproteins and soluble proteins increased for previously BL- and RL-grown algae, whereas insoluble carbohydrate concentration was reduced, indicating a change of the C-partitioning between carbon compounds and organic nitrogen compounds. Inorganic nitrogen metabolism was also affected by light: under WL of moderate PFR, NO₃ ^– was totally depleted from sea water, and maximal values of NO₃ ^– uptake were recorded. In addition, neither NO₂ ^– nor NH₄ ⁺ was released. However, when algae were transferred to a low PFR, there was a drastic reduction of NO₃ ^– uptake under WL, which only partially recovered over time. It was accompanied by the release of NO₂ ^–, but not NH₄ ⁺, to the culture medium. Under BL and RL, however, there was a transient enhancement of NO₃ ^– uptake that was followed by a net release of NO₂ ^– and NH₄ ^–. Growth rates were not correlated with PFR. This could be due to the the dynamics of internal carbon mobilization and accumulation in the algae. When algae were exposed to a moderate PFR of WL, carbon requirements for growth were satisfied by photosynthesis. Thus, there was a net accumulation of carbon in the tissue. In contrast, when algae were exposed to low PFRs of either WL, BL or RL, observed growth rates could not be maintained by photosynthesis and carbon was mobilized.     

Evidence of abalone (<Emphasis Type="Italic">Haliotis rubra</Emphasis>) diet from combined fatty acid and stable isotope analyses

Abalone are common herbivores throughout temperate and tropical waters, and yet the contribution of red and brown macroalgae to the diet of wild abalone remains unclear. In the northern hemisphere, adult abalone are considered to consume predominantly brown algae, but in the southern hemisphere abalone are thought to prefer red algae. Conventional methods such as gut content analysis and feeding trials provide some insight into diet choice, but the associated biases of these techniques create uncertainty surrounding the aforementioned variability in abalone diet. We use combined stable isotope and fatty acid analysis to determine the relative contribution of red algae, brown algae and detritus/microalgae to the diet of wild abalone in Tasmanian waters. Stable isotopes of carbon suggest that brown algae and/detritus are a more important source of carbon than red algae. Fatty acid analysis confirmed the larger contribution of brown algae to the diet of abalone, and also identified the bacterial and diatom component of detritus to be an important contributor to abalone diet. These results show combined use of chemical tracers to be a promising technique for resolving abalone diet, and challenge current perceptions regarding spatial variability in abalone diet choice.     

Preparative and analytical extraction of pigments from brown algae with dimethyl sulfoxide

Dimethyl sulfoxide (DMSO) rapidly extracts much of the chlorophyll c and fucoxanthin from the intact thalli of brown algae. Subsequent extraction by acetone rapidly removes most of the chlorophyll a and -carotene. An analytical procedure for these pigments has been developed, based upon this extraction sequence, followed by partition of the acetone extract between hexane and aqueous acetone. Fucoxanthin and chlorophyll c can be recovered from the DMSO extract and the aqueous acetone phase by extraction into ethyl acetate and subsequent evaporation. The DMSO-acetone extraction sequence is also effective with green algae and a few red algae, although the full scope of the method has not been investigated.     

Green and blue fluorescing dinoflagellates in Bahamian waters

At three stations in Bahamas waters, in 1989, 15 to 30% of all the dinoflagellates >20µm diameter observed in near-surface waters fluoresced green under blue excitation light, 55 to 66% fluoresced red, and the remainder did not fluoresce at all. The abundance of these green-fluorescing dinoflagellates ranged from ca 5 to 10 cells l^–1 at the study sites. Under UV excitation, however, the dinoflagellates had a blue to blue-green appearance. Almost all the blue-green fluorescing dinoflagellates appeared to be heterotrophic, except for one species,Phalacroma rapa Stein, which also contained red-fluorescing (under blue light) chlorophylla. The emission spectra from all species examined were of three basic types. Type 1 typically had two fluorescence emission peaks (ca 440 and ca 510 nm). Type 2 spectra possessed one sharp peak at 495 nm. Spectra belonging to Type 3 had a broad peak around 470 to 480 nm. The green fluorescence thus is likely caused by different substances in individual species. The attempt to reconstitute observed spectra with nicotinamide adenine dinucleotide (NADH) and riboflavin 5-phosphate (FMN) solutions was unsuccessful.     

Comparative study of heavy metal distribution in some coastal seaweeds of Alexandria, Egypt

The distribution of Cd, Cu, Fe, Hg, Mn, Ni, Pb, and Zn concentration in five algae species (Enteromorpha intestinalis, Enteromorpha linza, Ulva lactuca, Corallina mediterranea, Pterocladia capillacea) collected from three areas having different types of metal contamination along Alexandria coastal waters (Egypt) were determined by Atomic Absorption Spectrometry. The recovery study was carried out using a Certified Reference Material TORT-2. The obtained heavy metal contents indicate that different species demonstrate various degree of metal accumulation. Enteromorpha intestinalis (green algae) recorded the highest levels of Fe and Mn while Corallina mediterranea (Calcareous red algae) recorded the highest concentration of Pb, Ni, and Cd in the three areas under study. According to the present study, filamentous algae (Enteromorpha intestinalis) showed the ability to concentrate greater amount of trace elements than the foliaceous ones (Enteromorpha linza). In each area, mercury concentration has nearly the same value for all species under study.