bluuebunny/crossref_metadata_2025_split huggingface dataset:
BIOGEOGRAPHIC ANALYSIS OF THE ARMORED PLANKTONIC DINOFLAGELLATECERATIUMIN THE NORTH ATLANTIC AND ADJACENT SEAS1
Authors: Dodge John D. , Marshall Harold G. 
Published: October 2004

ABSTRACTThe distribution of the dinoflagellate genusCeratiumSchrank (Dinophyceae) in the North Atlantic and adjacent seas was studied by a combination of new observations on a large number of plankton samples collected from the northeastern Atlantic and North Sea, data from cruises off the east coast of North America and Caribbean Sea, and reports in the literature of the past 90 years. Seventy species were recorded, and their distribution was examined by several methods. Distribution maps were plotted for all species, and from these the ranges of temperature tolerance were derived. The 240 sets of data, which took the form of lists of species present in 5° latitude / longitude blocks obtained from the new work and the published material, were analyzed by clustering and ordination multivariate techniques using the programs Twinspan and Decorana.Analysis of the individual species showed that surface water temperature is the most important factor determining distribution and the number of species in a particular area. Warm water and /or low latitudes have many more species than cold waters and/or high latitudes. For example, at 5°N there are on average 23 species per block, whereas at 60° N there are only 8 species. On the basis of this work, theCeratiumspecies are divided into Group 1, Arctic‐temperate species normally only found in water of less than 15°C; Group 2, cosmopolitan species, which are found virtually everywhere and are the species most likely to form blooms or “brown water”; Group 3, intermediate species, which extend into neither the coldest nor the warmest water; Group 4, temperate‐tropical species, which have a lower temperature boundary of 5°–12° C; Group 5, warm‐temperate‐tropical species with a lower temperature boundary of 14°–15°C; and Group 6, tropical species, which are rarely found in water of less than 20° C.Analysis of the sample sites also confirmed the predominant influence of temperature, and the Atlantic Ocean was divided into four biogeographical zones of which the boundaries follow isotherms of surface water temperature. Zone 1 consists of the Arctic and subarctic area, with the southern boundary closely following the 10° mean annual temperature (MAT) line. Zone 2 is an intermediate or cold‐temperate zone, of which the southern boundary follows the winter 10° C MAT isotherm or the similarly placed summer 15° isotherm. Zone 3 is the warm‐temperate or subtropical zone, which is very broad. The southern boundary closely follows the 25°C summer isotherm. Zone 4 is the tropical zone, where water temperature is never likely to be much less than 23°C. These findings are discussed in relation to experimental work and environmental observations. We suggest that the genusCeratiumprovides an excellent tool for defining ocean currents and temperature changes and may become of value in studies of global change.
BUOYANCY REGULATION IN THE COLONIAL DIAZOTROPHIC CYANOBACTERIUM TRICHODESMIUM TENUE: ULTRASTRUCTURE AND STORAGE OF CARBOHYDRATE, POLYPHOSPHATE, AND NITROGEN1
Authors: Romans Kristen M. , Carpenter Edward J. , Bergman Birgitta 
Published: October 2004

ABSTRACT Trichodesmium tenue Wille (1904) was examined using transmission electron microscopy to determine the role of carbohydrate, phosphorus, and nitrogen storage in buoyancy regulation. Carbohydrate storage area (mean = 2.06 ± 0.61 [SE] μm2; 6.62% of total cell area) in negatively buoyant colonies (NBCs) was significantly higher (P < 0.001) than in positively buoyant colonies (PBCs) (mean = 0.38 ± 0.06 μm2; 0.73%). Distinct diel periodicity of carbohydrate content was found in NBCs demonstrated by an increase from darkness to afternoon. Polyphosphate content was significantly higher (P < 0.001) in NBCs, with a mean of 0.44± 0.10 μm2 (1.54%), as compared to PBCs, with a mean of 0.14 ± 0.05 μm2 (0.24%). Polyphosphate content increased in NBCs from morning to evening, and PBCs had a 10% decrease from morning to afternoon. Calculations indicated that averaged effects of polyphosphate on increased cell density is approximately 20% of that from carbohydrate accumulation. Density contribution due to ballast weight of carbohydrate and polyphosphate indicated that NBCs were 12 times more dense than PBCs. Mean area of cyanophycin granules (N storage) was not significantly different between PBCs and NBCs. In conclusion, Trichodesmium tenue can regulate buoyancy by carbohydrate ballasting similar to that noted in limnetic cyanobacteria. Polyphosphate storage and possibly nitrogen storage products play a significant role in buoyancy regulation.
TEMPERATURE‐DEPENDENT CHANGES IN COLONY SIZE OF THE FRESHWATER PENNATE DIATOM ASTERIONELLA FORMOSA (BACILLARIOPHYCEAE) AND THEIR POSSIBLE ECOLOGICAL IMPLICATIONS1
Authors: Hayakawa Toshiyuki , Kudoh Sakae , Suzuki Yoshihiro , Takahashi Masayuki 
Published: October 2004

ABSTRACTChanges in colony size (cell number per colony) of Asterionella Formosa Hass. were experimentally evaluated in relation to water temperature using two types of clones having colony sizes of four or eight cells. The clones were isolated from two different temperate freshwater lakes. Both clones showed the same general trend with changing temperature. Most of the colonies were normal in size at low temperatures, but colony size was twice as large at high temperatures. Variable colony sizes were present at low percentages. Colony separation occurred at the oldest connection within the colony after cell division. Culture experiments showed that the rates of specific growth and colony separation were balanced except for a rather short period of time when the temperature was changed. Optical and scanning electron micrography did not show any distinctive morphological structure at the point of connection except for porelli and mucilage pads. Seasonal changes in colony size of A. formosa observed in a freshwater lake are discussed based on these temperature results.
IDENTIFICATION OF MARINE DINOFLAGELLATES USING FLUORESCENT LECTINS1
Authors: Costas Eduardo , Rodas Victoria López 
Published: October 2004

ABSTRACTToxic and nontoxic species of marine dinoflagellates were characterized using fluorescent lectins. Lectin binding was detected by epifluorescence as well as spectrofluorometry. The binding assay of fluorescent lectins readily differentiated between morphologically similar species (i.e the toxic dinoflagellate Gymnodinium catenatum and the nontoxic Gymnodinium sp.). Lectins appear to be a useful tool to distinguish among different clones of the same species and, thus, possibly as a tool in dinoflagellate identification. Moreover, the lectins used show that thecate species have more binding sites and diversity in glycan moieties than athecate species.
MORPHOLOGY, PLOIDY, PIGMENT COMPOSITION, AND GENOME SIZE OF CULTURED STRAINS OFPHAEOCYSTIS(PRYMNESIOPHYCEAE)1
Authors: Vaulot Daniel , Birrien Jean‐Louis , Marie Dominique , Casotti Raffaella , Veldhuis Marcel J. W. , Kraay Gijsbert W. , Chrétiennot‐Dinet Marie‐Josèphe 
Published: October 2004

ABSTRACTWe examined cell morphology, ploidy level, cell size, pigment composition, and genome size in 16 cultured strains ofPhaeocystisLagerheim. Two strains originated from the Antarctic, 3 from the tropical Western Atlantic, and 11 from temperate regions (Eastern Atlantic, English Channel, North Sea, and Mediterranean Sea). Thirteen strains made colonies morphologically similar toP. glo‐bosaScherffel, whereas three never formed colonies under any circumstances. Five‐rayed star‐like structures with filaments were observed in 11 strains. In several strains, two ploidy levels were observed, one (haploid) linked to flagellates and one (diploid) linked to colonies. Cell size did not appear to be a very good criterion for distinguishing strains since size distributions overlapped. Pigment analysis by reversed‐phase‐high‐performance liquid chroma‐tography allowed the strains to be grouped into three clusters that differed from each other mainly by the relative proportions of three carotenoids: fucoxanthin, 19′‐hex‐anoyloxyfucoxanthin, and diadinoxanthin. All strains contained low levels of 19′‐butanoyloxyfucoxanthin. Differences in genome size measured by flow cytometry delimited at least five groups. On the basis of both pigment composition and genome size, six clusters were defined, one corresponding to an Antarctic species (possibly P. antarc‐tica), one toP. globosa, and the rest probably to several yet‐undescribed species or subspecies. Two main conclusions emerge from this study. First, the taxonomy of the genusPhaeocystisneeds to be clarified through a combination of morphological, biochemical, and molecular studies. Second, sexuality is a prevalent phenomenon inPhaeocystis, but controls of the sexual cycle are most likely strain‐dependent.
PSEUDO‐NITZSCHIA AS A GENUS DISTINCT FROM NITZSCHIA (BACILLARIOPHYCEAE)1
Authors: Hasle Grethe Rytter 
Published: October 2004

ABSTRACTMorphologic, diagnostic characters of the subgenus Nitzschia, genus Nitzschia Hassall 1845, and the marine planktonic genus Pseudo‐nitzschia H. Peragallo in H. & M. Peragallo 1900 were compared. Colony formation by overlap of cell ends; weakly silicified, shallow, and flattened valves; an extremely eccentric raphe, not elevated above the general level of the valve; lack of con‐opea; and striated girdle bands characterize Pseudo‐nitzschia as a natural group and a genus separate from Nitzschia.
ULTRAVIOLET‐B RADIATION EFFECTS ON INORGANIC NITROGEN UPTAKE BY NATURAL ASSEMBLAGES OF OCEANIC PLANKTON1
Authors: Behrenfeld Michael J. , Lean David R. S. , Lee Henry 
Published: October 2004

ABSTRACTUltraviolet‐B radiation (UVBR: 290‐320 nm) inhibited ammonium uptake (pNH4) and nitrate uptake (pNO3) in natural plankton assemblages collected during a transect from 37° N to 55° N in the Pacific Ocean. Comparison of responses in pNH4to ambient solar‐ and lamp‐enhanced UVBR spectra allowed calculation of an action spectrum for pNH4inhibition. The slope of the action spectrum for Pnh4is half as steep as action spectra for UVBR inhibition of photosynthetic carbon uptake. Consequently, WBR‐induced photoinhibition of pNH4extends to greater depths than inhibition of carbon fixation due to the greater relative effect of longer UVBR wavelengths. Inhibition of pNH4was dependent upon UVBR dose when doses were weighted by the pNH4action spectrum. Dependence of WBR inhibition of pNH4on dose rate was not apparent. We found that near‐surface pNH4and pNO3can be overestimated in excess of 50% when measured using standard incubation vessels made of UVBR‐absorbing materials such as polycarbonate.
EFFECTS OF SMALL‐SCALE TURBULENCE ON PHOTOSYNTHESIS, PIGMENTATION, CELL DIVISION, AND CELL SIZE IN THE MARINE DINOFLAGELLATE GOMAULAX POLYEDRA (DINOPHYCEAE)1
Authors: Thomas William H. , Vernet Maria , Gibson Carl H. 
Published: October 2004

ABSTRACT Several experiments were conducted to understand better the physiological mechanisms underlying growth inhibition of the dinoflagellate Gonyaulax polyedra Stein due to small‐scale turbulence shear. To measure photosynthetic 14C uptake, a “phytoplankton wheel” device for rotating cultures in closed bottles was used. Turbulence was quantified biologically in the bottles by comparing growth inhibition with that in cultures with constant shear between a fixed cylinder and an outer concentric rotating cylinder (a stable Couette flow). At saturating irradiances, particulate photosynthesis (Psat) or photosynthesis per unit chlorophyll (PBsat) were not inhibited completely at the highest turbulence level (26.6 rad.s−1), and photosynthesis was less sensitive than growth. Photosynthesis per cell (PCsat) was increased by turbulence. In three experiments on the effects of turbulence on photosynthesis versus irradiance curves, the slope of the curve, α, for particulate photosynthesis at limiting irradiances did not change. Photosynthesis per unit chlorophyll per unit irradiance (αB) decreased at high (but not intermediate) turbulence levels. Photosynthesis per cell per unit irradiance, αC, increased with turbulence, suggesting an increase in photosynthetic efficiency in turbulent cultures. In two of the three experiments, respiration rates increased with turbulence, and in one experiment excretion of photosynthetically fixed 14C was not affected by motion. Ratios of accessory pigments to chlorophyll a did not change with turbulence, but pigments per cell and per dry weight increased with turbulence. These findings suggest little or no disruption of the photosynthetic apparatus. When turbulence was applied for 1 week, β‐carotene increased while peridinin and diadinoxanthin decreased, suggesting inhibition of synthesis of these latter pigments by prolonged turbulence. Since cell numbers did not increase or decreased during turbulent 72–h incubations, cell division was inhibited and also the cells were very much enlarged. Increases in αC per cell suggest that, in the sea, photo synthetic metabolism can persist efficiently without cell division during turbulent episodes. After turbulence ceases or reaches low levels again, cells can then divide and blooms may form. Thus, blooms can come or go fairly rapidly in the ocean depending on the degree of wave‐ and wind‐induced turbulence.
PERIPHYTIC DIATOM ASSEMBLAGES FROM HIGH ARCTIC PONDS1
Authors: Douglas Marianne S. V. , Smol John P. 
Published: October 2004

ABSTRACTEpiphytic, epilithic, and surface sediment diatom assemblages were identified and enumerated from 35 study ponds on CapeHerschel (78°37″N, 74°42″W), east‐central Ellesmere Island, Canada. All the sites are shallow (maximum depth <2 m), clear, oligotrophic, and freshwater. The ponds freeze completely for 10 months of the year. Major ion concentrations are relatively similar among the 35 sites, although environmental gradients exist. Over 130 diatom taxa from 28 genera were identified in the periphyton samples. Marked differences in species composition were evident among the ponds. Moreover, many of the diatoms exhibited varying degrees of microhabitat specificity. Variance partitioning by canonical correspondence analysis showed that 26% of the total variance exhibited by diatom species composition could be accounted for by the measured environmental variables (i.e. 10.2% by habitat and 15.8% by water chemistry). Pondwater alkalinity best explained the distribution of taxa, and weighted averaging regression and calibration were used to develop a transfer function to infer pondwater alkalinity from the diatom assemblages. Other important environmental variables included [Na+] for the epilithic and [SiO2] for the epiphytic assemblages.
CHRYSOPHYTE POPULATION AND ENCYSTMENT PATTERNS IN TWO CANADIAN LAKES1
Authors: Agbeti Michael D. , Smol John P. 
Published: October 2004

ABSTRACT The dynamics of chrysophyte populations and the onset of encystment in relation to several physical, chemical, and biological variables were studied in two Canadian lakes, Lake Opinicon (LO) and Upper Rock Lake (URL). LO is shallow and polymictic during the ice‐free season, whereas URL is deep and dimictic. Seasonal patterns of many limnological variables, as well as species composition and seasonal dynamics of chrysophyte assemblages, were broadly similar in both lakes. Three groups of chrysophytes were recognized: 1) taxa that were more abundant during ice cover and/or early spring and occasionally in late fall (Dinobryon spp. Ehrenberg and Synura spinosa Korsh), 2) taxa that seemed to prefer moderately warm water proglena americana Calkins and Ochromonas sp. Wyssotzki) and had maximum densities in late summer and occasionally in the fall, and 3) taxa that occurred in low numbers and did not exhibit any discernible seasonality in the two lakes (Mallomonas spp. Perty). Encystment rarely occurred during ice cover in both lakes. Stomatocyst concentrations were highest shortly after ice breakup (late April or early May), declined to trace levels by June, and remained at those levels until the end of the sampling season (late November). Encystment rates (cyst concentrations) were higher in dimictic URL. Encystment in both lakes coincided with concurrent changes in physical and chemical variables and chrysophyte vegetative cell densities, but it was not possible to pinpoint the exact conditions responsible for triggering encystment. Only a small proportion of chrysophytes encysted. Cyst production within a lake may vary from year to year.
PRELIMINARY INVESTIGATIONS INTO THE STRUCTURE AND ACTIVITY OF RIBULOSE BISPHOSPHATE CARBOXYLASE FROM TWO PHOTOSYNTHETIC DINOFLAGELLATES1
Authors: Whitney Spencer M. , Yellowlees David 
Published: October 2004

ABSTRACT Ribulose bisphosphate carboxylase / oxygenase (Rubisco) from the dinoflagellates Symbiodinium sp. Freudenthal and Amphidinium carterae Hulburt rapidly loses activity following cell lysis. Evidence presented indicates that this is not due to proteolysis. Using the tight binding inhibitor [14C] carboxyarabinitol bisphosphate as a marker, the Rubisco large subunit (LSu) from Symbiodinium sp. was purified. The subunit molecular weight was 56 kDa, while non‐denaturing polyacrylamide gel electrophoresis indicated that the purified protein had a molecular weight significantly less than that expected of the intact hexadecameric protein. No trace of the small subunit was apparent. The initial loss of carboxylase activity following cell lysis may be due to instability of the quaternary structure of the enzyme. Antibodies prepared to the purified LSU cross‐reacted with LSus from other dinoflagellates but not with the LSus of higher plants, diatoms, and other chromophytic algae. This suggests that the LSu of at least some dinoflagellates is antigenically different from that of other eukaryotes.
A NEW SPECIES OF ENSICULIFERA, E. IMARIENSE (DINOPHYCEAE), PRODUCING ORGANIC‐WALLED CYSTS1
Authors: Kobayashi Satoru , Matsuoka Kazumi 
Published: October 2004

ABSTRACT We describe a new organic‐walled resting cyst from surface sediments of Imari Bay in western Japan. The cysts are spherical, 23–29 pm in diameter, and their surface is covered with spinous to membranous ornaments that are 5–7 μm long and 1.5–2.2 μm wide. The ornaments vary from slender and bifurcate to membranous and multifurcate distal extremities. No archeopyle was observed. The cyst shape is variable in both natural samples and clonal cultures. Vegetative cells are small and ovoid, 17–25 μm long and 14–21 μm wide, and are yellow‐brown in color. The epitheca is conical with a conspicuous apical horn, and the hypotheca is hemispherical. The cingular transitional plate has a needle‐like spine at its anterior right corner. The plate formula is Po, X, 4″3a, 7″, 5c, 5s 5″and 2″. Although vegetative cells of the present species correspond to Ensiculifera, it is distinct from other species in producing no calcareous cysts. No species of Ensiculifera has been reported to produce cysts composed of only an organic wall. The present species is provisionally placed in the genus Ensiculifera as E. imariense sp. nov.
SEASONAL GROWTH, BIOMASS, AND REPRODUCTIVE BEHAVIOR OF THREE SPECIES OF RED ALGAE IN GODAVARI ESTUARY, INDIA1
Authors: Narasimha Rao G. Mohan 
Published: October 2004

ABSTRACT Growth and different phases in the life histories of Bos‐trychia tenella (Vohl.) J. Ag., Caloglossa leprieurii (Mont.) J. Ag., and Catenella impudica (Mont.) J. Ag. were estimated for 23 months from January 1986 to December 1987 in the Gautami Godavari estuary of lndia. Seasonal data on hydrographical conditions, biomass, and plant length were collected from three stations in this estuary. Biomass was minimum in August and September and maximum in January and February, as was frond length of tetrasporic and vegetative plants. Temperatures of 24°–27°C and salinities of 5–20 ppt coincided with optimal growth for all three algae. In all three species, tetrasporophytes were present in all months of the year without any seasonal periodicity, and nearly 50% of the plants were tetrasporophytes. The gametophytes of B. tenella and C. leprieurii and cystocarpic plants of C. impudica occurred from October to May, with greatest abundance in January. The abundance of spermatangial and cystocarpic plants in the populations of B. tenella and C. leprieurii ranged from 3 to 15%. Spermatangial plants of Catenella impudica could not be identified, and the abundance of cystocarpic plants was very low.
SUMMER DECLINE OF ULVA LACTUCA (CHLOROPHYTA) IN A EUTROPHIC EMBAYMENT: INTERACTIVE EFFECTS OF TEMPERATURE AND NITROGEN AVAILABILITY?1
Authors: Rivers Jennifer S. , Peckol Paulette 
Published: October 2004

ABSTRACT Throughout the summer, abundance of Ulva lactuca L. declined while biomass of Cladophora vagabunda (L.) van den Hoek and Gracilaria tikvahiae McLachlan increased in a New England embayment undergoing eu‐trophication (Waquoit Bay, Massachusetts). We investigated the physiological basis for the summer dieback, focusing on temporal variations in photosynthetic performance and tissue nitrogen (N). We also compared photosynthetic and N uptake capabilities of U. lactuca with other abundant species in this eutrophic system. Photosynthetic egiciency and capacity of U. lactuca declined markedly at 25°C, compared with a spring (15°C) peak in photosynthetic performance; Pmax was 4.6 ± 0.3 and 1.8 ± 0.6 μmol O2.m−2.s−1 during spring and summer, respectively. Notably, summer pmax of other abundant species of the embayment was 1.5–3 × higher than that measured for U. lactuca. Ulva lactuca showed a signifciant photosynthetic response to dissolved inorganic carbon enrichment during summer, when water‐column‐dissolved CO2 levels were 20% of spring values. Although ammonium uptake rates of U. lactuca were extremely high at both subsaturating (15μM) and saturating (75 μM) N concentrations, as predicted by the functional‐form hypothesis, tissue N fell to 1% by late summer. We suggest that a carbon imbalance, initiated by rising water temperatures and declining water‐column N; thermal stress; and biological factors (competition, grazing) all contribute to the recurrent summer decline of U. lactuca in this shallow, eutrophic embayment. Thus, while the morphology of U. lactuca might be considered a successful strategy for disturbed, or “stressed” (sensu Littler and Littler 1980), habitats, its inability to persist and flourish in this environment emphasizes the complexity of factors at work in natural systems.