bluuebunny/crossref_metadata_2025_split huggingface dataset:
LATITUDINAL TRENDS IN THE GROWTH AND REPRODUCTIVE SEASONALITY OF DELESSERIA SANGUINEA, MEMBRANOPTERA ALATA, AND PHYCODRYS RUBENS (RHODOPHYTA)1
Authors: Molenaar F. J. , Breeman A. M. 
Published: October 2004

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.
FLOW VISUALIZATION AROUND SINGLE‐ AND MULTIPLE‐BLADED SEAWEEDS WITH VARIOUS MORPHOLOGIES1
Authors: Hurd Catriona L. , Stevens Craig L. 
Published: October 2004

ABSTRACTWater flow was visualized around 10 seaweeds with various morphologies to determine the onset of turbulence and to estimate the scales of motion generated by the seaweeds themselves. For single‐bladed specimens of the kelps Laminaria setchellii, Costaria costatum, Macrocystis integrifolia, and Alaria marginata, the transition from a laminar to turbulent velocity boundary layer occurred at mainstream velocities of 1.5 cm.s−1. Transition to turbulence fm multiple‐bladed specimens of M. integrifolia, Nereocystis luetkeana, Egregia menziesii, and Fucus gardneri occurred at 2.5–3 cm‐s−1 and at 5 cm.s−1 for the coarsely branched red seaweed, Gelidium coulteri. Flow features such as separation, recirculating eddies, and Von Kánncán vortex streets were observed around various morphologtcal features. We suggest that in the field, flow around larger macroalgae such as kelp is mostly turbulent and that many seaweeds will lie within the wakes of neighboring macroalgae. For small, branched seaweeds such as G. coulteri, however, the meshlike structure may damp turbulence within the thallus, thereby increasing the mainstream velocity at which the transition to turbulence occurs.
PHOTOINHIBITION AND RECOVERY AFTER HIGH LIGHT STRESS IN DIFFERENT DEVELOPMENTAL AND LIFE‐HISTORY STAGES OF LAMINARIA SACCHARINA (PHAEOPHYTA)1,2
Authors: Hanelt Dieter , Wiencke Christian , Karsten Ulf , Nultsch Wilhelm 
Published: October 2004

ABSTRACTThe capacity to cope with high light stress was investigated in different life‐history and developmental stages of Laminaria saccharina Lamour. sporophytes and gametophytes. Changes in photosynthetic efficiency and in the level of photoinhibition were measured by in vivo fluorescence changes of photosystem II. Pigment content was studied using high performance liquid chromatography. Additionally, the morphology of the various developmental stages during the life cycle was studied by light microscopy in relation to the photosynthetic parameters.High light stress (2 h, 500 μmol.m‐2.s−1) induced photoinhibition of photosynthesis with fast kinetics in older sporophytes and gametophytes. In contrast, the absolute degree of photoinhibition after light stress was higher in younger than in older sporophytes. Photosynthesis recovered faster in older sporophytes and gametophytes compared to young sporophytes. In very young sporophytes, photosynthesis did not recover fully even after 12 h exposure to low light, indicating severe photodamage. Kinetics of recovery in old sporophytes and in gametophytes showed a fast and a slow phase, whereas younger sporophytes recovered only with a slow phase, The fast phase is indicative of a decline of the photoprotective process, whereas the slow phase indicates a recovery from photodamage. The capacity to cope with high light stress in Laminaria sporophytes increased with increasing age of the thalli. The gametophytes are less sensitive to high light stress and may be selected to endure unfavorable white light conditions.Investigation of the xanthophylls showed that the higher resistance to high light is not caused solely by a higher content of xanthophyll cycle pigments. Additionally, changes in the thallus structure during the development of the sporophytes seemed to cause a higher resistance to high light. The observed changes in the ability to cope with high light in the different life‐history and developmental stages of Laminaria saccharina may influence the distribution of the species on the shore.
THE SIGNIFICANCE OF INTRACELLULAR SELF‐SHADING ON THE BIOOPTICAL PROPERTIES OF BROWN, RED, AND GREEN MACROALGAE1
Authors: Orzymski Joe , Johnsen Geir , Sakshaug Egil 
Published: October 2004

ABSTRACTThe spectral light absorption and fluorescence excitation spectra from thalli (in vivo) and thylakoid micelles (no intracellular self‐shading) from the macroalgae Laminaria digitata (L.) Edmonson, Palmaria palmata (L.) Kuntze, and Ulva sp. were examined. In all the examined species, the intracellular self‐shading (i.e. the package effect) was highly significant to the extent that absorption peaks related to individual pigments were significantly suppressed. Thus, for studies related to taxonomy and physiology, “unpacked”spectra may be more informative. Thylakoid micelle preparations offer opportunities to examine more closely species‐specific differences in the packaging effect, light harvesting and utilization, and pigmentation. As well, the thylakoid micelles, when analyzed with biochemical assays or fluoromtry, may provide insight into components of the photosynthetic machinery that are specific to different classes of mncroalgne. We present the Chl a‐specific absorption coefficients and the corresponding fluorescence excitation spectra of macroalgal thylakoid micelles for the three species.
PHACOTUS LENTICULARIS (CHLAMYDOMONADALES, PHACOTACEAE) ZOOSPORES REQUIRE EXTERNAL SUPERSATURATION OF CALCIUM CARBONATE FOR CALCIFICATION IN CULTURE1,2
Authors: Hepperle Dominik , Krienitz Lothar 
Published: October 2004

ABSTRACTIn nature, zoospores of the chlamydophycean genus Phacotus Perty usually have a calcified lorica. The only cultured species, Phacotus lenticularis (Ehrenberg) Stein, did not readily calcify in artificial media. To overcome this deficiency, we developed an artificial culture medium (N‐HS) in which Phacotus lenticularis formed mineralized loricae, as under natural conditions. Calcification of Phacotus (strain Krienitz 91/1) was achieved in a medium containing the ionic concentrations found in natural habitats (i.e. Lake Haussee and Lake Stechlin), hard‐water lakes of the Baltic Lake District (Germany). The N‐HS medium contained extremely low phosphate concentrations and high calcium and magnesium concentrations compared with common culture media, but the concentrations were similar to those in the lakes. Calcium carbonate in N‐HS medium was dissolved up to the saturation concentration (saturation index = 1). Supersaturation was achieved by the addition of ultra‐alkaline compounds (Na2SiO3 or NaOH). The medium with the highest super‐saturation had a saturation index of 118 and was extremely supersaturated with respect to calcium carbonate. In that medium and in modified media with less of the sodium compounds (lower supersaturations), calcification of zoospores was observed. To determine the effects of sodium and silicon compounds on calcification, various other silicon and sodium compounds were tested but were shown to be ineffective. In conclusion, calcification of Phacotus lenticularis depends directly on the degree of calcium carbonate supersaturation of the medium, but the fundamental mineralization pattern does not. Our study shows that calcification in Phacotus lenticularis can be triggered and controlled by supersaturation of calcium carbonate.
SOURCES OF INORGANIC CARBON FOR PHOTOSYNTHESIS BY THREE SPECIES OF MARINE DIATOM1
Authors: Korb Rebecca E. , Saville Peter J. , Johnston Andrew M. , Raven John A. 
Published: October 2004

ABSTRACTThe utilization of inorganic carbon by three species of marine diatom, Skeletonema costatum (Grev.) Cleve. Ditylum brightwellii (West) Grun., and Chaetoceros calcitrans Paulsen was investigated using an inorganic carbon isotopic disequilibnum technique and inorganic carbon dose‐response curves. Stable carbon isotope data of the diatoms are also presented. Observed rates of photosynthetic oxygen evolution were greater than could be accounted for by the theoretical rate of CO2 supply from the uncatalyzed dehydration of HCO3− in the external medium, suggesting use of HCO3− as an inorganic carbon source. Data from the isotopic disequilibrium experiment demonstrate the use of both HCO3− and CO2 for photosynthesis. Carbon isotope discrimination values support the use of HCO3− by the diatoms.
CHARACTERIZATION OF MORPHOSPECIES AND STRAINS OFMICROCYSTIS(CYANOBACTERIA) FROM NATURAL POPULATIONS AND LABORATORY CLONES USING CELL PROBES (LECTINS AND ANTIBODIES)1
Authors: Lópa‐Rodas Victoria , Costa Eduardo 
Published: October 2004

ABSTRACTThe genus Microcystis (cyanobacteria) includes toxic and bloom‐forming morphotypes which are usually arranged into species based on morphological features. Immunofluorescence assays using polyclonal and preadsorbed antibodies, as well as FITC‐labebd lectins were used to characterize three morphospeciesof Microcystis (M. viridis, M. wesenbergii,andM. aeruginosa)from natural populations (several lakes/reservoirs in Denmark and Spain) and laboratory clones. The cell probes used were unaffected by the different phases of the cell division cycle, growth phase, or environmental factors, such as culture medium, light, or temperature. Anhbody and lectin binding patterns were specific to each clone. In nature, the cell probes were useful tools to characterizeMicrocystispopulations. Antibodies and lectins revealed geographic differentiation within the same morphospecies. Differentiation was moderate among nearby locales and intensified among areas distant from one another. Microcystis aeruginosa from Spain has very different cell surface antigens and lectin binding sites thanM. aeruginosafrom Denmark. A taxonomy ofMicrocystisbased on cell probes reveals some discrepancies with classical morphospecies. The binding affinities were more closely related to the geographic origin of the tested material than to the morphospecies identification. Different morphospecies from the same lake in some cases were more similar than the same morphospecies from different lakes. Microcystis viridis andM. aeruginosafrom Danish lakes appeared to be closely related species, whereasM. wesenbergiiemerged as a different species.
LINKAGE OF 5S RIBOSOMAL DNA TO OTHER rDNAS IN THE CHROMOPHYTIC ALGAE AND RELATED TAXA1
Authors: Kawai Hiroshi , Nakayama Takeshi , Inouye Isao , Kato Atsushi 
Published: October 2004

ABSTRACTGene organization within the nuclear ribosomal DNA cistron and linkage of the 5S rDNA gene to the cistron were surveyed in 20 taxa of protists representing most of the Chromophyta (stramenopiles) and representatives of the Dinophyceae (alveolata) and Euglenophyceae. The intergenic spacer, which separates adjacent cistrons, was first PCR‐amplified from total DNA using primers anchored in the 3’end of the large subunit and the 5’end of the small subunit in the next downstream cistron. Presence of the 5S gene in the cistron was determined by a second round of PCR using primers anchored in the large subunit and the 5S gene. where 5S‐linked rDNA was not detected in the cistron, the presence of 5S tandem repeating units were confirmed by the PCR of 5S‐5S fragments from the total DNA. Results show that most of the Chromophyta, as well as Opalina, Proteromonas (colorless stramenopiles), Dinophyceae, and Euglenophyceae have a 5S‐linked type of rDNA organization. In contrast, only tandem repeats of 5S rDNA were detected in Bacillariophyceae and Synurophyceae. The occurrence of 5S‐unlinked rDNA is hypothesized to be the result of secondary transfer from an ancestral, linked 5S type. The 5S‐linked type of rDNA organization is apparently common in protists. Given the fact that most of these protists have mitochondria with tubular or discoid cristae, as compared with flattened cristae common in higher plants and animals, we conclude that the 5S‐linked type of rDNA diverged at a very early stage in the evolution of eukaryotes.
BIOGEOGRAPHYOF BATRACHOSPERMUM GELATINOSUM (BATRACHOSPERMALES, RHODOPHYTA) IN NORTH AMERICA BASED ON MOLECULAR AND MORPHOLOGICAL DATA1
Authors: Vis Morgan L. , Sheath Robert G. 
Published: October 2004

ABSTRACTFifteen populations of the widespread fieshwater red alga Batrachospermum gelatinosum (L.) De Candolle were sampled throughout the geographic range in North America from central Alabama, U.S.A. (33° N), to Ellesmere Island, Northwest Territories (NWT), Canada (80° N). Analysis of ribosomal DNA internal transcribed spacer (ITS) 1 and 2 sequences yielded a parsimony tree with a large polytomy consisting of most populations plus a branch with one Nova Scotia and two NWT populations. The nucleotide variation, both within the polytomy and within the branch, was small (< 1%). The sequence divergence between the branch and polytomy was 3%. The lengths of the ITS 1 and 2 sequences of B. gelatinosum, 216–229 and 448–458 base pairs, respectively, fall within the very broad ranges reported for other red algae. The cluster analysis of 11 morphometric characteristics revealed three groupings of populations, partly based on geographic distribution. All tundra, eastern boreal forest, and mid‐western hemlock‐hardwood populations were in one grouping, whereas the deciduous forest, coastal plain, and eastern hemlock‐hardwood populations were in a second. How ever, one deciduous forest population from Rhode Island, U.S.A. was unassociated. There was considerable overlap in morphometric characteristics among the three groupings. Based on this fact and the relatively small nucleotade variation in ITS sequences, we conclude that B. gelatinosum is a morphologically variable and geographically widespread species that is a valid taxonomic entity.
CELLULAR DNA CONTENT OF MARINE PHYTOPLANKTON USING TWO NEW FLUOROCHROMES: TAXONOMIC AND ECOLOGICAL IMPLICATIONS1
Authors: Veldhuis Marcel J. W. , Cucci Terry L. , Sieracki Michael E. 
Published: October 2004

ABSTRACTTwo new fluorochromes, PicoGreen® and SYTOX Green™ stain (Molecular Probes, Inc.), are useful with flow cytometry for quantitative detection of cellular DNA in a variety of marina phytoplankton. The basic instrument configuration of modern low‐power flow cytometers (15 mW, 488 nm excitation) is sensitive enough to detect the DNA signal in nearly all of the 121 strains (from 12 taxonomic classes)examined. The major advantages of these dyes over others are 1)suitability for direct use in seawater, 2)green fluorescence emission of the DNA‐dye complex (wavelength 525 ± 15 nm) showing no overlap with the autofluorescence of the plankton pigments in the red band, 3) high fluorescence yield of the DNA‐dye complex with an increase in fluorescence > 100‐fold compared to the unstained cell, and 4)dyes can be used to quantify double‐stranded DNA. The high sensitivity allowed the quantification of the DNA of the smallest known phyto‐plankter (Prochlorococcus) as well as bacteria found in some of the algal cultures. Of the 12 taxonomic classes tested, only the 3 Nannochloropsis spp. (Eustagmatophyceae) stained poorly, and a few members of the Chlorophyceae and Pelagophyceae showed poor staining occasionally. In general, maximal fluorescence was achieved within 15 min after addition of the dye. Although the PicoGreen dye stained some living phytoplankton species, preservation is recommended for quantitation. SYTOX Green did not stain live cells. The combination of the dyes, therefore, allows the discrimination between live and dead cells in some algal groups (Prochlorococcus, diatoms, prasinophytes, and pelagophytes). Paraformaldehyde was preferred over glutaraldehyde for fixation to avoid (induced) green autofluorescence.Total DNA values measured in 90 algal species (ca. 121 strains) varied by a factor of 20,000. The lowest values were found in Prochlorococcus and the highest in a large dinoflagellate (Prorocentrum micans). DNA content appears to be a scaleable cell component covarying with the carbon and nitrogen contents of the phytoplankton cells. This covariation allows the total DNA content to be used as an accurate, independent estimate of total cell carbon biomass in unicellular pelagic phytoplankton.
NONDESTRUCTIVE TRACING OF MIGRATORY RHYTHMS OF INTERTIDAL BENTHIC MICROALGAE USING IN VIVO CHLOROPHYLL A FLUORESCENCE1,2
Authors: Serôdio João , Marques da Silva Jorge , Catarino Fernando 
Published: October 2004

ABSTRACTIn vivo chlorophyll (Chl) a fluorescence was measured in undisturbed intertidal sediments with the purpose of tracing the vertical migratory rhythms of benthic microalgae. A pulse amplitude fluorometer, an instrument which does not require physical contact with the sample, was used, thus allowing successive measurements to be taken on the same sample without causing any type of disturbance to the sediment structure. The basis of the method is the possibility to detect changes in the Chl a concentration near the sediment surface caused by the vertical movement of the microalgae. This requires the verification of two conditions: the possibility to follow changes in the sediment Chl a content from fluorescence intensity, and a sediment photic depth smaller than the vertical distances covered by the moving microalgae. Both conditions were experimentally verified in intertidal muddy sediments of the Tagus estuary, Portugal. In vivo fluorescence was shown to vary linearly with the sediment Chl a content, and the sediment photic depth was estimated to reach 0.27 mm, a value clearly smaller than the reported depths for microalgal migrations. Sediment samples kept under in situ conditions exhibited large hourly Variations (over 400%) in the Chl a fluorescence intensity, which were closely synchronized with the daytime periods of emersion. The rhythmic fluctuations in Chl a fluorescence were confirmed further to represent microalgal migration by (1) its endogenous nature (fluorescence continued to follow diurnal and tidal cycles after removal of environmental stimuli), (2) its dependence on the vertical distribution of the microalgal population within the sediment (vertically homogenized samples failed to display fluorescence variations), and (3) the lack of significant temperature and light effects on the fluorescence emission under in situ conditions (tested in three species representative of the main groups found in the studied microphytobenthic communities—the diatom Phaeodactylum tricornutum (Böhlin), the cyanobacterium Spirulina maxima (Setch. et Gard.), and the euglenophyte Euglena granulata (Klebs) Lemm.). The results obtained indicate that, in spite of the potential concurrent effects of factors other than the Chl a concentration on the fluorescence intensity, in vivo Chl a fluorescence can be used to trace nondestructively the migratory behavior of benthic microalgae.
GENETIC VARIABILITY AND SPATIAL SEPARATION IN THE SEA PALM KELP POSTELSIA PALMAEFORMIS (PHAEOPHYCEAE) AS ASSESSED WITH M13 FINGERPRINTS AND RAPDS1
Authors: Coyer James A. , Ohen Jeanine L. , Stam Wytze T. 
Published: October 2004

ABSTRACTPostelsia palmaeformis Ruprecht is an annual species, occuring from southern California to Vancouver Island, Canada, in upper intertidal sites exposed to extreme wave shock. Because of its limited spore dispersal, discrete and inbred populations are likely on the local scale, yet dispersal of drifting and fertile thalli raises the possibility of outbred populations on a regional scale. M13 minisatellite DNA fingerprinting and random amplified polymorphic DNA (RAPD) marks were used in a complementary fashion to investigate genetic variability among 24 individuals on scales of clusters (= coalesced holdfasts). < 1 m, 10 m, 25 m, 16 km, and 250 km. Based on M13 fingerprinting, genetic relatedness within clusters was extremely high. Three of six clusters had at hast two identical individuals, and similarity values within five clusters were ≧0.90. Similarities between two of three clusters separated by < 1 m were significantly higher than between cluster pairs separated by 25 m and 250 km: however, the similarity between two clusters separated by 25 m was equivalent to the similarity between two clusters separated by 250 km. Thus, genetic relatedness as determined by M13 fingerprinting generally decreased as distance increased to 25 m. Conversely, RAPD data easily discriminated populations separated by 16 and 250 km but were not useful in discriminating individuals from < 1 to 25 m. Results from the complementary data sets suggest that most dispersal occurs over distances of 1–5 m, individuals within a cluster are siblings, and distinguishable biogeographic populations are present along the coast.
EXCYSTMENT AND GROWTH OF CHRYSOPHYTES AND DINOFLAGELLATES AT LOW TEMPERATURES AND HIGH SALINITIES IN ANTARCTIC SEA‐ICE1
Authors: Stoecker Diane K. , Gustafson Daniel E. , Merrell Jeffrey R. , Black Megan M. D. , Baier Christine T. 
Published: October 2004

ABSTRACTExtreme environmental conditions have been thought to limit algal growth in the upper sea‐ice. In McMurdo Sound, Antarctica, chrysophyte statocysts (stomatocysts) and dinoflagellate hypnozygotes (resting cysts) overwinter in first‐ and second‐year land‐fast sea‐ice exposed to temperatures of ‐20° C or lower. In early November, when temperatures in the upper ice are < −8°C and brine salinities are >126 psu, dinoflagellate cysts activate and shortly thereafter excyst. During early November, chrysophyte statocysts also begin to excyst. Net daily primary production occurs in the sea‐ice brine at temperatures as low as −7.1° C, at brine salinities as high as 129 psu, and at average photon flux densities as low as 5 μmol photons.m−2.s−1. Dinoflagellate densities were >106 vegetative cells.L−1 of ice while temperatures in the upper ice were between −6.8 and −5.8° C and brine salinities were ∼100 psu. Chrysophyte densities reached >106.L−1 of ice by early December. High densities of physiologically active clyo‐ and halotolerant algae can occur in the upper land‐fast sea‐ice under extreme conditions of temperature and salinity.