Membranoptera Alata Research Articles

Cell size influences inorganic carbon acquisition in artificially selected phytoplankton.

Cell size influences the rate at which phytoplankton assimilate dissolved inorganic carbon (DIC), but it is unclear whether volume-specific carbon uptake should be greater in smaller or larger cells. On the one hand, Fick's Law predicts smaller cells to have a superior diffusive CO2 supply. On the other, larger cells may have greater scope to invest metabolic energy to upregulate active transport per unit area through CO2 -concentrating mechanisms (CCMs). Previous studies have focused on among-species comparisons, which complicates disentangling the role of cell size from other covarying traits. In this study, we investigated the DIC assimilation of the green alga Dunaliella tertiolecta after using artificial selection to evolve a 9.3-fold difference in cell volume. We compared CO2 affinity, external carbonic anhydrase (CAext ), isotopic signatures (δ13 C) and growth among size-selected lineages. Evolving cells to larger sizes led to an upregulation of CCMs that improved the DIC uptake of this species, with higher CO2 affinity, higher CAext and higher δ13 C. Larger cells also achieved faster growth and higher maximum biovolume densities. We showed that evolutionary shifts in cell size can alter the efficiency of DIC uptake systems to influence the fitness of a phytoplankton species.

Taxonomic assessment of North American species of the genera Cumathamnion, Delesseria, Membranoptera and Pantoneura (Delesseriaceae, Rhodophyta) using molecular data

Evidence from molecular data supports the close taxonomic relationship of the two North Pacific species Delesseria decipiens and D. serrulata with Cumathamnion, up to now a monotypic genus known only from northern California, rather than with D. sanguinea, the type of the genus Delesseria and known only from the northeastern North Atlantic. The transfers of D. decipiens and D. serrulata into Cumathamnion are effected. Molecular data also reveal that what has passed as Membranoptera alata in the northwestern North Atlantic is distinct at the species level from northeastern North Atlantic (European) material; M. alata has a type locality in England. Multiple collections of Membranoptera and Pantoneura fabriciana on the North American coast of the North Atlantic prove to be identical for the three markers that have been sequenced, and the name Membranoptera fabriciana (Lyngbye) comb. nov. is proposed for them. Many collections of Membranoptera from the northeastern North Pacific (predominantly British Columbia), although representing the morphologies of several species that have been previously recognized, are genetically assignable to a single group for which the oldest name applicable is M. platyphylla.

Trace metals and radionuclides in macroalgae from Moroccan coastal waters

Macroalgae species Codium sp, Bangia atropurpurea, Membranoptera alata, Plocamium cartilagineum, Dictyota dichotoma, Fucus spiralis and Stypocaulon scoparia were collected from seven stations along the north coast of Morocco. Samples were analysed to determine activities of naturally occurring radionuclides ((210)Pb, U isotopes and (40)K) and concentrations of metals (Zn, Fe, Co, Cu, Ni, Mn, Pb, Cd, As and Cr) using radiometric and ICP-OES techniques, respectively. Metal concentrations were within ranges reported in the scientific literature, and concentrations of bio-essential elements were in the order Mn>Fe> Zn>Cu in all samples. Brown algae had the highest concentrations of almost all metals, and concentrations decreased in the order brown>red>green algae. With respect to radionuclides, the red alga P. cartilagineum had the highest activities of (210)Pb, in most cases an order of magnitude higher than for the green alga Codium sp. (234)U and (238)U activities in all algae samples were in the range 0.96- 7.61 and 1.16-6.14 Bq/kg dry weight, respectively. Our analyses of radionuclide activities and metal concentrations in marine macroalgae showed large differences among taxa. These results provide insights into which algal species should be used for biomonitoring programmes.

Long-term effects of ultraviolet radiation on growth and photosynthetic performance of polar and cold-temperate macroalgae

Long-term effects of artificial ultraviolet radiation (UV) and natural solar radiation on growth and photosynthetic activity, as measured by chlorophyll fluorescence, were investigated in 13 different polar and cold-temperate macroalgal species. Isolates of five different species from the Arctic and Antarctic were exposed to different light treatments of photosynthetically active radiation (PAR), PAR+UVA and PAR+UVA+UVB. Eight different species collected on the island of Helgoland, North Sea, Germany, were studied in the laboratory and under natural solar radiation conditions. Increase in fresh weight and changes in photosynthetic performance were monitored over a period of 3–4 weeks. The sublittoral polar species, particularly the Antarctic red algal species Gymnogongrus antarcticus and G. turquetii, the Arctic cold-temperate brown alga Alaria esculenta and, very drastically, the Arctic-endemic Laminaria solidungula, exhibited strong inhibiting effects of artificial UVB radiation on growth. In the cold-temperate sublittoral growth of the red algae Phycodrys rubens and, to a lesser extend, Membranoptera alata was substantially inhibited by UV radiation. In contrast, eulittoral species, e.g. Fucus serratus, did not show any differences in growth with respect to artificial irradiation conditions, with or without UV radiation. In the laboratory, some individuals of the green alga Codium fragile exhibited strong morphological changes of the whole thallus, particularly under UVB exposure. In the experimental outdoor set up, growth of most of the algal species was already inhibited by the full solar UV waveband, but, apart from Polyides rotundus, no additional UVB effect could be detected. Changes of in vivo fluorescence were not always consistent with the measurable changes in growth rate, indicating that physiological processes leading to an inhibition of growth may act independently of changes in photosynthetic activity. For the polar species, a general correlation between the natural vertical distribution in the field and the individual sensitivity towards UV radiation was indicated, while for eulittoral species from Helgoland no clear relationship was found. The obtained results show that measuring growth is a good ecological parameter to monitor long-term effects of UV radiation on single macroalgal species and the possible resulting changes of whole algal communities in coastal ecosystems.

LATITUDINAL TRENDS IN THE GROWTH AND REPRODUCTIVE SEASONALITY OF DELESSERIA SANGUINEA, MEMBRANOPTERA ALATA, AND PHYCODRYS RUBENS (RHODOPHYTA)1

ABSTRACTThe seasonality of Delesseria sanguinea, Membranoptera alata, and Phycodrys rubens (Rhodophyta) was studied at Helgoland (North Sea, Germany) and Roscoff (Brittany, France). Plants were collected at bimonthly intervals, and growth and reproduction were monitored. Growth of blades was observed mainly in spring, although small blades were found on plants of M. alata and P. rubens all year round. In summer, plants started to degenerate and in autumn they became fertile. The reproductive season of D. sanguinea lasted from October to February/April at both locations, whereas reproductive plants of M. alata and P. rubens were found until April at Helgoland and until June and August, respectively, in Roscoff: Lower winter temperatures at Helgoland than at Rascoff may have caused these differences in the duration of the reproductive season. Using published data, the seasonal patterns at Helgoland and Roscoff were compared to those found at other locations (e.g. Barents Sea; Maine, USA; Isle of Man, UK) and local temperature/daylength conditions. Blade growth was synchronized across all populations and occurred in spring, when temperatures were usually still suboptimal for growth. Maximum reproduction was generally found in the colder half of the year but started earlier in autumn in the Barents Sea. Adaptive strategies in the seasonal control of growth and reproduction are discussed. Adequate timing of the history events (e.g. appearance of juveniles in spring) appears more important than maximal growth and reproduction of adults during the season with the most favorable temperatures.

Growth and Reproductive Phenology of Nine Intertidal Algae on the Murman Coast of the Barents Sea

Monthly replicate samples of 30 plants of each of nine species were collected in the intertidal zone in the Dalnezelenetskaya Inlet, Murman coast, Barents Sea. Germlings and new shoots emerged in great quantities in March when temperature was near 0 degrees C and daylength 10-13 h. All nine intertidal species on the Murman coast exhibit a period of rapid vegetative growth in early spring, at temperatures far below the optimum temperatures in at least five of them for which experimental evidence from the literature is available. The increasing light level in early spring is probably responsible for this growth. In six of them (Ulvaria obscura, Monostroma grevillei, Chorda filum, Chordaria flagelliformis, Stictyosiphon tortilis, Dumontia contorta) summer peaks of reproduction are apparently responsible for the summer decline of the thalli. The last five of these six have heteromorphic life histories in which microthallus stages are thought to ensure approximate synchronization of early spring recruitment (for instance by short day induction of microthallus development at autumnal temperatures, as in D. contorta and M. grevillei). In one species (Membranoptera alata), with an isomorphic diplohaplontic life history, early spring recruitment is thought to be ensured by the release of tetraspores and carpospores in winter. Earlier expectations that southern species would shift their reproduction to the summer near their northern distribution boundary were not confirmed. The general conclusion is that each of the nine species has approximately the same seasonal cycle of growth and reproduction in various parts of its geographic range, with only minor shifts from spring towards summer (but precise data on seasonal cycles elsewhere are scarce). This suggests that there may be subtle differences in temperatures and photoperiods triggering the onset of reproduction; this aspect needs further experimental testing of strains from the Murman coast.

Ecotypic Differences between Baltic and North Sea Populations of Delesseria sanguinea and Membranoptera alata

Article Ecotypic Differences between Baltic and North Sea Populations of Delesseria sanguinea and Membranoptera alata was published on January 1, 1993 in the journal Botanica Marina (volume 36, issue 1).

Photoinhibition of Photosynthesis and its Recovery in Red Algae

AbstractIn different marine red algae (Chondrus crispus, Delesseria sanguinea, Membranoptera alata, Phycodrys rubens, Phyllophora truncata, Polyneura hilliae) photoinhibition of photosynthesis has been investigated by means of both fluorescence and oxygen measurements. Measurements of absolute oxygen production show that photoinhibition causes a decline in the initial slope and in the rate of bending of the fluence rate‐response curve (i.e. the photosynthetic efficiency at non‐saturating fluence rates), as well as a decline in the photosynthetic capacity (Pm) at saturating fluence rates. Fluorescence data (Fv/Fm) were consistent with the results of oxygen measurements. Under excessive light photoinhibition protects photosynthesis against photo‐damage in red algae. However, an increase in the initial fluorescence (Fo) after photoinhibitory treatment indicates that it could not prevent photodamage entirely.Action spectra of photoinhibition demonstrate that the main photoinhibition site in Polyneura hiliae is PS II, because far red light absorbed by PS I was ineffective. The strong increase of Fo in the blue wavelength range and the slight and partial recovery in weak blue light indicate that blue light especially causes photodamage.Recovery of photosynthesis requires dim white light conditions. Experiments with monochromatic light also show a wavelength dependence of recovery. Moreover, the recovery of photosynthesis after a photoinhibitory treatment is strongly temperature dependent, indicating participation of enzymatic processes. The comparison of fluorescence and oxygen measurement of the recovery shows different results in some species. The rate of oxygen production in red control light increased immediately after photoinhibited algae were exposed to weak light conditions. Surprisingly, the ratio of variable to maximum fluorescence (Fv/Fm) of Phyllophora truncata and the maximum fluorescence (Fm) of Polyneura hilliae show first a delay of the recovery under weak light conditions. Thus, in recovery experiments fluorescence and oxygen data are not quite consistent.

Plant size and reproductive phenology of six species of rhodophyta in subtidal isle of man

Following a quantitative study of the reproductive phenology of some subtidal red algae, the aim of the investigation was to separate the influence of plant size from the direct effect of season on their reproduction. Quarterly samples were taken from about 2 m below lowest astronomical tide (LAT) on Port Erin breakwater and, in each species, thallus length was measured before noting fertility. In most of the species there were fewer plants near their maximum length in the spring than in the summer or autumn. In epilithic Plocamium cartilagineum, Cryptopleura ramosa and Callophyllis laciniata fertility in classes of shorter plants increased from a spring minimum to an autumn maximum. High fertility in autumn was therefore only partly due to the greater abundance of large plants at that time. In Plocamium the largest plants were always fertile. In epiphytic Palmaria palmata, Membranoptera alata and Phycodrys rubens peak reproduction occurred in spring and all length classes showed reduced fertility at othe...

Temperature tolerance and biogeography of seaweeds: The marine algal flora of Helgoland (North Sea) as an example

Temperature tolerance (1 week exposure time) was determined at intervals during two successive years in 54 dominant marine benthic algae growing near Helgoland (North Sea). Seawater temperatures near Helgoland seasonally range between 3°C (in some years 0°) and 18°C. All algae survived 0°C, and none 33°C. Among the brown algae,Chorda tomentosa was the most sensitive species surviving only 18°C, followed by theLaminaria spp. surviving 20°, however not 23°C.Fucus spp. andCladostephus spongiosus were the most heat-tolerant brown algae, surviving 28°C. Among the red algae, species of the Delesseriaceae(Phycodrys rubens, Membranoptera alata) ranged on the lower end with a maximum survival temperature of 20°C, whereas the representatives of the Phyllophoraceae(Ahnfelitia plicata, Phyllophora truncata, P. pseudoceranoides) exhibited the maximum heat tolerance of the Helgoland marine algal flora with survival at 30°C. The latter value was also achieved byCodium fragile, Bryopsis hypnoides andEnteromorpha prolifera among the green algae, whereas theAcrosiphonia spp. survived only 20°C, andMonostroma undulatum only 10°C, not 15°C. Seasonal shifts of heat tolerance of up to 5°C were detected, especially inLaminaria spp. andDesmarestia aculeata. The majority of the dominant marine algal species of the Helgoland flora occurs in the Arctic, and it is hypothesized that also there the upper lethal limits of these species may hardly have changed even today. The data presented should provide a base for further analysis of the causes of geographical distribution of the North Atlantic algal species, but have still to be supplemented with similar investigations on other coasts, and supplemented with determinations of temperature requirements throughout the life cycle.

Spatial and temporal distributions of dominant epiphytes on the stipes of Laminaria hyperborea (Gunn.) Fosl. (Phaeophyta:Laminariales) in S.E. Scotland

The epiphytic flora of the stipes of Laminaria hyperborea (Gunn.) Fosl. at St. Abbs Head, Berwickshire, Scotland has been examined. Four species Palmaria palmata (L.) O. Kuntze, Ptilota plumosa, (C. Ag.) Huds., Membranoptera alata (Huds.) Stackh., and Phycodrys rubens (L.) Batt. make up > 95% of the epiphyte biomass. The species show two distinct patterns of zonation, one with depth the other with respect to position on the host stipe. Palmaria is found on the upper parts of the stipes at 1 and 2 m depth, with the three other species found lower on the stipe. At 6 m depth Ptilota occupies the position on the stipe where Palmaria had occurred in the shallower water. In the deepest samples (12m) Ptilota was absent and its position on the stipe was occupied by Phycodrys and Membranoptera. This zonation is reflected in the biomass of the epiphyte species, Palmaria is restricted to the shallow waters, Ptilota reaches its greatest biomass at intermediate depths while Membranoptera and Phycodrys are most abundant at 6 m and below. Palmaria, Membranoptera, and Phycodrys show similar patterns of seasonal changes in epiphyte biomass with a peak in September and a decline in winter. Ptilota, which in the British Isles is considered to be a species of northern distribution, shows an earlier peak biomass and a correspondingly earlier decline in abundance.

The reproductive phenology of nine species of Rhodophyta in the subtidal region of the Isle of Man

Monthly samples of about 40 separate plants of each species were collected from 1 to 3 m below lowest astronomical tide on Port Erin breakwater, Isle of Man, Irish Sea. In three species growing on rock, Plocamium cartilagineum, Cryptopleura ramosa and Callophyllis laciniata, about 90% of the plants were fertile in late summer but less than 10% in spring although some fertile plants were always present. Delesseria sanguinea and Odonthalia dentata, also epilithic, had a winter sporing season, Odonthalia extending into late spring, and all plants were sterile in summer. Three species growing epiphytically, Palmaria palmata, Membranoptera alata and Phycodrys rubens, reproduced maximally in the first half of the year at the time when the stipes of the host species, Laminaria hyperborea, grow fastest. Only Palmaria had a sterile season, late summer. The encrusting Cruoria pellita showed little seasonality. The first three species, which reproduce mainly when the sea temperature is above average, are in the nort...

Reproductive ecology of four subtidal red algae

The reproduction and stature of the red algae Callophyllis cristata (C. Ag.) Kuetz., Membranoptera alata (Huds.) Stackh., Phycodrys rubens (Huds.) Batt., and Ptilota serrata Kuetz. were recorded from subtidal populations at Appledore Island, Maine, U.S.A., with respect to time and depth. Only Membranoptera alata exhibited a conspicuous seasonal fluctuation of reproduction. A vertical gradient of reproduction was evident, with reduced levels of reproduction in shallow populations of Phycodrys rubens and Ptilota serrata, as well as deep populations of Phycodrys rubens, Membranoptera alata and Callophyllis cristata. Differential stratification of the reproductive phases of Ptilota serrata occurred with higher frequencies of tetrasporic plants in deep populations and of cystocarpic plants in shallow populations. In contrast, the haploid and diploid plants of the other three species showed similar distributional patterns. Membranoptera alata, Phycodrys rubens, and Callophyllis cristata showed a conspicuous decrease in stature during maximum reproduction.

Cystocarps and tetrasporangia on the same thallus inMembranoptera alataandPolysiphonia urceolata

Numerous plants of Membranoptera alata (Huds.) Stackh, and a single specimen of Polysiphonia urceolata (Dillw.) Grev. were found bearing both cystocarps and tetrasporangia.