Influences of salinity on the physiology and distribution of the Arctic coralline algae,Lithothamnion glaciale (Corallinales,Rhodophyta)

In Greenland, free‐living red coralline algae contribute to and dominate marine habitats along the coastline. Lithothamnion glaciale dominates coralline algae beds in many regions of the Arctic, but never in Godthåbsfjord, Greenland, where Clathromorphum sp. is dominant. To investigate environmental impacts on coralline algae distribution, calcification and primary productivity were measured in situ during summers of 2015 and 2016, and annual patterns of productivity in L. glaciale were monitored in laboratory‐based mesocosm experiments where temperature and salinity were manipulated to mimic high glacial melt. The results of field and cold‐room measurements indicate that both L. glaciale and Clathromorphum sp. had low calcification and photosynthetic rates during the Greenland summer (2015 and 2016), with maximum of 1.225 ± 0.17 or 0.002 ± 0.023 μmol CaCO ₃ · g^?1 · h^?1 and ?0.007 ±0.003 or ?0.004 ± 0.001 mg O₂ · L^?1 · h^?1 in each species respectively. Mesocosm experiments indicate L. glaciale is a seasonal responder; photosynthetic and calcification rates increase with annual light cycles. Furthermore, metabolic processes in L. glaciale were negatively influenced by low salinity; positive growth rates only occurred in marine treatments where individuals accumulated an average of 1.85 ± 1.73 mg · d^?1 of biomass through summer. These results indicate high freshwater input to the Godthåbsfjord region may drive the low abundance of L . glaciale , and could decrease species distribution as climate change increases freshwater input to the Arctic marine system via enhanced ice sheet runoff and glacier calving.     

Some effects of plant growth regulators on tissue cultures of the marine red alga Agardhiella subulata (Gigartinales,Rhodophyta)

We examined whether auxins and cytokinins, either singly or in combination, stimulate cell division in tissue cultures of a red seaweed. Our experimental model consisted of filamentous and callus-like growths that developed from cross-sectional discs cut from young branches of Agardhiella subulata. Plant growth regulators were added to the medium to give combinations of an auxin with a cytokinin over a range of concentrations (1 µg L^–1 –10 mg L^–1). Several mixtures of auxins and cytokinins, as well as some single auxins, cytokinins and phenolics, stimulated cell division and growth in the tissue cultures beyond that of controls. The treatments that were effective included: phenylacetic acid/zeatin; phenylacetic acid/6-benzylaminopurine; -naphthaleneacetic acid/zeatin; 2,4,5-trichlorophenoxyacetic acid/6-benzylaminopurine; and indoleacetic acid/kinetin. High concentrations of cytokinins (i.e. 10 mg L^–1) inhibited the regeneration of plants in some of the cell cultures. These results provide further evidence that growth regulators can be used for the tissue culture of seaweeds and for the study of developmental phenomena in these plants.     

Variation in Photosynthetic Performance Relative to Thallus Microhabitat Heterogeneity in Lithothamnion australe (Rhodophyta,Corallinales) Rhodoliths

Rhodoliths are free‐living, coralline algae that create heterogeneous structure over sedimentary habitats. These fragile ecosystems are threatened by anthropogenic disturbances that reduce their size and three‐dimensional structural complexity. We investigated how physical disturbance from boat moorings affects photosynthetic performance in the rhodolith Lithothamnion australe. Photosynthetic parameters were measured for intact rhodoliths and crushed rhodolith fragments of two sizes (ca. 1 and 2 cm diameter), while chlorophyll fluorescence was measured at the surface of rhodoliths of these two sizes, between the interior branches of the larger rhodoliths, and at the surface of 52 various sized (0.4–3.5 cm diameter) rhodoliths. Gross productivity and net productivity were 15% and 36% higher, respectively, in the smaller L. australe, while respiration was 10% higher in the larger individuals. Thallus crushing reduced gross productivity by 20% and 41%, and net productivity by 9% and 14% in the smaller and larger rhodoliths, respectively. It also reduced respiration by 33% and 60% in the smaller and larger rhodoliths, respectively. Fluorescence parameters were all greater at the surface of the larger L. australe than the smaller individuals, and greater at the surface than in the interior parts of the larger individuals. Across a range of rhodolith sizes, surface fluorescence parameters were at their maxima in 1.54 to 2.32 cm diameter individuals. These results show that L. australe’s complex structure creates heterogeneity in photosynthesis and respiration between their surface and interior parts and among rhodolith sizes. This information can help predict how rhodoliths may respond to disturbance and environmental stressors.     

Relationship between cover of Chondrus crispus (Gigartinales,Rhodophyta) and Phymatolithon (Corallinales,Rhodophyta) on friable rock substrata

Field observations in sublittoral Prince Edward Island, Canada, indicated that on a friable sandstone substratum Chondrus crispus was more commonly associated with Phymatolithon sp. than with bare rock. Thus, a substantial proportion of the population of Irish moss along the coast of Prince Edward Island occurs on this encrusting coralline. These observation may be explained on the basis of the relative stability of the substratum in contrast to other studies in which sloughing of epithallial cells by species of both Phymatolithon and Lithothamnium has been reported to limit epiphytism by fleshy macrophytes.Issued as NRCC 31426.     

Sulfated galactans from the red seaweed Nothogenia fastigiata (Nemaliales,Rhodophyta)

Fractionation of the cetrimide salts of the sulfated polysaccharides of Nothogenia fastigiata led to the isolation of a complex galactan sulfate. This product showed compositional and molecular weight heterodispersion together with composition-, temperature-, time-, and conformation-dependent molecular associations. In this sense, the behavior of the galactan sulfate is similar to that of the mannan sulfate previously isolated from the same seaweed.Formerly classified as Chaetangium fastigiatum.     

Phenology of Gigartina skottsbergii (Gigartinaceae,Rhodophyta) in Ancud Bay,southern Chile

This study reports the variations in biomass and reproductive phenology in a natural bed of Gigartina skottsbergii over a period of a year and correlates these variations with the abiotic factors solar radiation, number of daylight hours, water temperature and salinity. The results obtained show an annual production cycle with maximum biomass values in spring-summer, correlated with high solar radiation and to a lesser extent with salinity. Sexual reproduction was maximum in autumn-winter, correlated with low temperature and short-day conditions. The population showed a large gametophytic dominance according to size and biomass, which suggests that there is not ecological equivalence between the life history phases of the species. Finally, based on the results, a restriction of harvesting to spring-summer is suggested.     

Effect of ammonium on growth and carrageenan content in Kappaphycus alvarezii (Gigartinales,Rhodophyta)

Kappaphycus alvarezii, cultured in a region deficient in nitrogen with intermittent application of 10 mM ammonium at three-day intervals for 1 hour, attained a daily growth rate of 4.6%, which was considered to be the optimum growth rate. Under such conditions, the C/N ratio was 29 with a carrageenan content of 58% and gel strength of 45–70 g cm^–2. Gel strength of carrageenan was high when nitrogen content was high and vice versa.     

Phylogenetic analysis of rhodolith formation in the Corallinales (Rhodophyta)

Although the ecological importance of rhodolith (maerl, free-living coralline algae) beds is well-known, rhodolith-forming species have been neglected in molecular phylogenetic studies. This is the first molecular systematic study aimed at understanding whether the rhodolith habit is a fixed feature in lineages and determining the relationship (phylogenetic vs. environmental) between rhodolith and crustose habits. Phylogenetic relationships of rhodolith-forming species and encrusting coralline algae at generic and species levels were analysed using SSU rDNA and psbA sequences. Extensive sampling in the European North Atlantic, Pacific and Caribbean Mexico of Phymatolithon, Lithothamnion, Lithophyllum and Neogoniolithon taxa forming rhodoliths and crusts was accompanied by examination of type or topotype material. Phylogenetic reconstruction showed that Neogoniolithon contained a monophyletic group of rhodolith-forming species whereas other rhodolith-formers were closely related to encrusting forms in the genera Phymatolithon, Lithothamnion, Mesophyllum, Hydrolithon, Spongites and Sporolithon. DNA analysis showed that the crust-forming Lithophyllum cf. incrustans/dentatum also forms rhodoliths with a stone nucleus that occur on rocky shores. In contrast, species that form beds of non-nucleate rhodoliths (e.g. Neogoniolithon spectabile, N. strictum, Lithophyllum cf. incrustans/dentatum or sp. 1 and Phymatolithon calcareum) rarely form crusts. The rhodolith habit cannot be used to delimit species for taxonomic or identification purposes. Extensive taxonomic revision will be required to deal with problems such as the position of specimens identified as Lithophyllum margaritae in two unrelated lineages.     

Epiphytic cyanophytes Xenococcus kerneri and Chamaesiphon minutus on the freshwater red alga Paralemanea catenata (Rhodophyta)

Epiphytes of Paralemanea catenata (Kützing) Vis & Sheath (Rhodophyta) were studied on material from the River Dyje in National Park Podyjí. Longitudinal sections of the thalli were made with help of Cryo Cut Microtome techniques. The epiphytic cyanophytes Xenococcus kerneri Hansgirg and Chamaesiphon minutus (Rostafinski) Lemmermann were recognized on the cortex of the thalli. Our observations of the determined species are discussed.     

Interactions between environmental variables on growth rate and carrageenan content of Solieria chordalis (Solieriaceae,Rhodophyceae) in culture

Using vegetative propagules (ramuli) of the iota carrageenan producing red seaweed Solieria chordalis, a maximum growth rate of 6.8% d⁻¹ was achieved when cultured at 20 °C and 100 μmol photon m⁻² s⁻¹ in seawater supplemented with 20 μM NO₃-N or 10 μM NO₃-N plus 10 μM NH₄-N. Ramuli grew less well when nitrogen was supplied solely as NH ₄ ⁺ . Maximum carrageenan content was observed at the same temperature, irradiance and salinity as growth, but at lower nitrogen concentrations. These findings are discussed in relation to results obtained from studies on other iota-carrageenan producing carrageenophytes.     

The relationship between stand biomass and frond density in the clonal alga Mazzaella cornucopiae (Rhodophyta,Gigartinaceae)

The negative relationship between stand biomass and plant density observed in terrestrial plants was tested among fronds of a clonal red alga, Mazzaella cornucopiae. Stand biomass and frond density were estimated bimonthly for 1 year on 7 permanent quadrats. A positive linear correlation was found between biomass and density for the whole data set, suggesting the lack of self-thinning among fronds of this intertidal alga at natural densities. Higher frond densities could favor increased water retention among fronds, thus minimizing desiccation during low tides. In this way, stands could maintain higher production of biomass. Fronds may also be cushioned better against wave action at higher frond densities, thus decreasing the detachment of larger fronds. The temporal variation of the relationship between biomass and density was plotted separately for these 7 quadrats. Four quadrats showed positive linear correlation between both variables (the other three quadrats showed non-significant positive linear correlation). Their four slopes are statistically similar to that found for the entire data set. It is possible, then, that there is only one positive slope for the biomass-density relationship in this population. If this is true, standing biomass could be estimated from the density of fronds.     

Tank cultivation of the red alga Palmaria palmata: Effects of intermittent light on growth rate, yield and growth kinetics

Tank cultivation of marine macroalgaeinvolves air-agitation of the algal biomassand intermittent light conditions,i.e.periodic, short light exposure of thethalli in the range of 10 s at the watersurface followed by plunging to low lightor darkness at the tank bottom andrecirculation back to the surface in therange of 1–2 min. Open questions relate toeffects of surface irradiance on growthrate and yield in such tumble cultures andthe possibility of chronic photoinhibitionin full sunlight. A specially constructedshallow-depth tank combined with a darktank allowed fast circulation times ofapproximately 5 s, at a density of 4.2 kgfresh weight (FW) m^-2s^-1. Growthrate and yield of the red alga Palmaria palmata increased over a widerange of irradiances, with no signs ofchronic photoinhibition, up to agrowth-saturating irradiance ofapproximately 1600 mol m^-2s^-1 in yellowish light supplied by asodium high pressure lamp at 16 h light perday. Maximum growth rate ranged at 12% FWd^-1, and maximum yield at 609 gFW m^-2 d^-1. This shows that highgrowth rates of individual thalli may bereached in a dense tumble culture, if highsurface irradiances and short circulationtimes are supplied. Another aspect ofintermittent light relates to possiblechanges of basic growth kinetics, ascompared to continuous light. For thispurpose on-line measurements of growth ratewere performed with a daily light reductionby 50% in light-dark cycles of 1, 2 or 3min duration during the daily light period.Growth rates at 10 °C and 50 molphoton m^-2 s^-1 dropped in allthree intermittent light regimes duringboth the main light and dark periods andreached with all three periodicitiesapproximately 50% of the control , with noapparent changes in basic growth kinetics,as compared to continuous light.     

Seasonal changes in growth rate, carrageenan yield and lectin content in the red alga Kappaphycus alvarezii cultivated in Camranh Bay, Vietnam

The three color morphotypes of the red alga Kappaphycus alvarezii (brown, red and green) were cultured in Camranh Bay, Vietnam, using the fixed off-bottom monoline culture method to evaluate the growth rate, carrageenan yield, 3,6-anhydrogalactose, gel strength and lectin content. The brown morphotype was cultivated over a 12-month period; the red and green morphotypes were over a 6-month period. At the 60-day culture timepoint, the brown morphotype showed a higher growth rate (3.5–4.6% day⁻¹) from September to February, and lower growth rate (1.6–2.8% day⁻¹) from March to August. Significant (P < 0.05) differences in growth rate between culture months were found with the brown morphotype. High growth rates for the red (3.6–4.4% day⁻¹) and green (3.7–4.2% day⁻¹) morphotypes were obtained from September to February. The carrageenan yield, 3,6-anhydrogalactose and gel strength of the three morphotypes showed little variation, with the highest values obtained in November–December. At the 30-day sampling point, the brown morphotype had a higher lectin content (167–302 μg g⁻¹ dry alga) from August to March and a lower lectin content (23–104 μg g⁻¹ dry alga) from April to July. High lectin contents were recorded for the red (139–338 μg g⁻¹ dry alga) and green (124–259 μg g⁻¹ dry alga) morphotypes from September to February. This study shows that the different morphotypes of K. alvarezii can be grown in the tropical waters of the Camranh during the northeast monsoon, and part of the southwest monsoon, especially the brown morphotype, which can be grown during any season.     

Seasonal variations in sterol composition of Delesseria sanguinea (Ceramiales,Rhodophyta)

On Normandy coasts, the red alga Delesseria sanguinea perennates by its stipe; fronds grow in January and disappear in June. Seasonal variations in sterol composition in relation to the biology of D. sanguinea are reported. Sterols in cellular membranes are free or conjugated by esterification with fatty acids, heterosides or lipid complexes like phospholipids. Both kinds of sterols were analyzed by GC-MS. The major sterol (80%) found in fronds was cholesterol whereas in stipes, cholesterol was also the major sterol in spring, but in September, an important reduction in cholesterol yield was noted with proportional increase in sitosterol content. It appears that cholesterol is synthesized in fronds in spring, then transferred to the stipe, which loses an important amount of cholesterol with loss of the blades.     

The system of xylogalactans from the red seaweed Jania rubens (Corallinales, Rhodophyta)

The main acidic polysaccharides from the red seaweed Jania rubens share the general characteristics of corallinans (agar-like xylogalactans). After fractionation by ion-exchange chromatography, ten fractions were separated and characterized by sugar composition, other components, methylation, ethylation, desulfation-methylation, and NMR analyses. The main group of fractions carry the agaran disaccharidic repeating unit [-->3)-beta-d-Gal-(1-->4)-alpha-l-Gal-(1-->] substituted mainly on O-6 of the beta-d-Gal unit by beta-xylosyl side stubs, and less with sulfate or methoxyl groups, and also on O-2 of the alpha-l-Gal unit with methoxyl or sulfate, or less on O-3 of the same unit with methoxyl groups. These features are somehow common to the four members of the order already studied. However, a sugar uncommon to the order appears in moderate proportions for all the fractions: it is 3,6-anhydro-l-galactose (partly sulfated or methoxylated on O-2) replacing the l-Gal unit. Besides, several other structural features never found in the order (and uncommon in any polysaccharide) appear in some minor fractions: the presence of side stubs of 2,3-di- and 3-O-methyl-d-galactose, and also part of the 3-O-methyl-l-galactose acting as side stubs. These results show that, although the main features of the corallinean xylogalactans are common to all the species studied, each one has minor characteristics of its own.     

Influence of tissue source and growth rates on dry weight and carrageenan composition of Chondrus crispus (Gigartinales,Rhodophyta)

Carrageenan analyses were conducted on vegetative female clones of Chondrus crispus that were cultured to provide tissues with differing growth rates. Tissue dry weights increased from apex to base of fronds. Total carrageenan contents were lower in apical 1 to 2 cm segments than elsewhere in the frond, except when the alga was grown at high photon irradiances. Clone 373A contained more carrageenan than clone G8. The proportion of 0.3 M KCl-soluble polymers in the total native carrageenans varied from 44 to 92%, being highest in older tissues of fronds cultured at high photon irradiances. The apical 1 cm segments contained less KCl-soluble carrageenans than other tissues from the corresponding fronds. The KCl-soluble carrageenans, when alkali-modified and refractionated, afforded the expected kappa-iota carrageenan in > 79% yields. The remainder consisted of a polymer containing 23.1% SO₃Na and 8.4% 3,6-anhydrogalactose. Lambda carrageenan was not detected. Variations in carrageenan distribution between the apical region and other parts of the frond may reflect the increasing influence of medullary tissue developed as the immature cells differentiate.     

Characterization of an agar fraction extracted from Gracilaria dura (Gracilariales,Rhodophyta)

The evaluation of biopolymers of biotechnological interest has stressed the importance of renewable sources from the northern Adriatic Sea. In the frame of this research program, the red alga Gracilaria cf. dura, has been studied. Agar was obtained from Gracilaria cf. dura by means of alkali treatment and hot water extraction. In order to purify the extracts, amylase and isopropyl alcohol were used. Analysis of sugars was carried out by means of gas chromatography on alditol acetate derivatives; sulfate content was evaluated by means of infrared spectroscopy. An analysis of molecular weight distribution was carried out by means of high performance gel permeation chromatography coupled with a low angle laser light scattering device as detector. Analytical data were examined in terms of specificity of the algal source utilized, and the agar fractions extracted by means of this procedure were compared with a commercial sample.     

Expansion of the red alga Grateloupia doryphora along the coasts of Brittany (France)

Grateloupia doryphora (Montagne) Howe (Halymeniales, Halymeniaceae) has previously been reported for two locations along the Brittany coastline (France). Important ecological and morphological traits of the species in the breton populations are detailed here. Because of the impressive size it can reach, G. doryphora can be considered as the largest red alga in the world. G. doryphora has the tendency to dominate the algal flora once installed. At Lorient, in addition to the marginal extension of the population, a progressive colonisation of the whole intertidal zone has been noted for 2 years. The species actually preferentially develops in currents and pools where it is abundant between early winter and mid summer. An interesting development is the recent spreading from the mid and lower eulittoral towards the upper rocky pools. The seasonality of the life-cycle has also been studied over 2 years. In addition, this work reports on the first identification of G. doryphora near the Loire estuary in South Brittany, at Concarneau and in the Bay of Brest in western Brittany, and on the coasts of Normandy, at Granville and Cherbourg. The occurrence of attached specimens on ship hulls and pontoons suggests a distant transport of the species by navigation. Considering the rapid geographical propagation of G. doryphora, and its tendancy to proliferate in settling locations, the species can be regarded as potentially invasive on the north–west coasts of Europe.     

Cell suspension culture from Porphyra linearis (Rhodophyta) a multicellular marine red alga

A cell-suspension culture suitable for continuous propagation was established from protoplasts of the red alga Porphyra linearis Grev., an edible, winter annual species of nori. Protoplast-derived cells that did not regenerate into thalli were used to establish a culture line of uniform-sized (average about 25 μm diam.) cells, which resembled the vegetative cells of this species in the leafy thallus phase. Cell division occurred about once per 24 to 30 h in uncrowded (1–2 cells per culture well) culture. This cell-suspension culture has now been maintained as continuously growing subcultures for more than four years without formation of organized thalli; however, the latter can be obtained at will by altering culture conditions (lowering temperature from 20° to 10 °C, lengthening photoperiod from 10: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% aIXaGaaGinaaaaaaa!3777!\[\overline {14} \] or 8 : % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% aIXaGaaGOnaaaaaaa!3779!\[\overline {16} \] to 14: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% aIXaGaaGimaaaaaaa!3773!\[\overline {10} \] or 16: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaaca% aI4aaaaaaa!36C0!\[\overline 8 \] and increasing irradiance from 10 to ≥ 30 μmol m^-2 s^-1). This appears to be the first continuous non-clonal cell-suspension culture developed for a multicellular alga. NRCC No. 30272.     

Saldanha Bay,South Africa: recovery of Gracilaria verrucosa (Gracilariales,Rhodophyta)

Since World War II the greater Saldanha Bay lagoon system, South Africa, has been an important Gracilaria producer. Two agar factories, built in the 1960's, used Gracilaria from Saldanha Bay as their raw material. In the early 1970's the industry was destroyed as a result of dredging and marine construction operations to establish a harbor in the bay for loading ore. These environmental changes destroyed stocks and prevented the previously significant beachings of the seaweed from occurring. After a few years of no or very low commercial production, the resource slowly started to recover. The size of Gracilaria drifts increased over the following eight years to approximately one-third of the original output. This trend seems to continue. Although the stocks and resultant drifts are unlikely to recover fully to their original quantity, current production is already sufficient to ensure re-establishment of a seaweed industry in Saldanha Bay. This could have considerable socio-economic impact on the area.