bluuebunny/crossref_metadata_2025 huggingface dataset:
Topsoil Handling and Storage Effects on Woodland Restoration in Western Australia
Authors: Rokich Deanna P. , Dixon Kingsley W. , Sivasithamparam K. , Meney Kathy A.
Published: March 2003

An analysis of the effects of topsoil handling and storage methods was undertaken to optimize the potential rehabilitation of southwest Western Australian Banksia woodland species present before site disturbance. An increase in the depth of topsoil stripped from the Banksia woodland, from 10 to 30 cm, correlated to decreasing seedling recruitment from the soil seedbank by a factor of three following in situ respreading in an area to be restored. There was no significant difference in total seedling recruitment in situ at two depths of spread, 10 cm and 30 cm. These results concur with an ex situ trial on the effects of depth of seed burial on seedling recruitment that showed most species failed to emerge from depths greater than 2 cm. In situ stockpiling of the woodland topsoil for 1 or 3 years demonstrated a substantial and significant decline in seedling recruitment to 54% and 34% of the recruitment achieved in fresh topsoil, respectively. Stripping and spreading during winter substantially depressed seedling recruitment, compared with autumn operations, as did in situ stockpiling followed by spreading in the wet season, or stockpiling in winter followed by spreading in spring. No loss in total seedling recruitment occurred when replaced topsoil and subsoil were ripped to 80 cm following spreading of topsoil in sites to be restored. Conclusions from this study are that (1) topsoil provides a useful source of seeds for rehabilitation of Banksia woodland communities in the southwest of Western Australia, (2) correct handling of the topsoil, stripped and replaced fresh and dry (autumn direct return) to the maximum depths of 10 cm, can be used to optimize revegetation of species‐rich plant communities with this type of seedbank, and (3) ripping of topsoil and subsoil to ease compaction of newly restored soils does not diminish the recruitment potential of the soil seedbank in the replaced topsoil.
Design and Implementation of Monitoring Studies to Evaluate the Success of Ecological Restoration on Wildlife
Authors: Block William M. , Franklin Alan B. , Ward James P. , Ganey Joseph L. , White Gary C.
Published: March 2003

Restoration projects are often developed with little consideration for understanding their effects on wildlife. We contend, however, that monitoring treatment effects on wildlife should be an integral component of the design and execution of any management activity, including restoration. Thus, we provide a conceptual framework for the design and implementation of monitoring studies to understand the effects of restoration on wildlife. Our underlying premise is that effective monitoring hinges on an appropriate study design for unbiased and precise estimates of the response variables. We advocate using measures of population dynamics for response variables given that they provide the most direct measures of wildlife status and trends. The species to be monitored should be those constituting an assemblage of umbrella species that represent the range of spatial and functional requirements of wildlife in a restored ecological system. Selection of umbrella species should be based on strong empirical evidence that justifies their usage. We also advocate that monitoring be designed as true experiments or quasi‐experiments rather than as observational studies to allow for stronger inferences regarding the effects of restoration on wildlife. Our primary message is that if monitoring is to be done, it must be scientifically based.
Microbial Biomass‐C in Reclaimed Soil of the Rhineland (Germany) and the North Bohemian Lignite Mining Areas (Czech Republic): Measured and Predicted Values
Authors: Růžek L. , Voříšek K. , Sixta J.
Published: March 2003

This article compares reclaimed soils in the Rhineland lignite mining area, Germany (RA) and in the north Bohemian brown coal basin, Czech Republic (NBB). Because of highly significant differences of physical and chemical characteristics (RA was characterized by lower content of sand, clay, soil organic carbon, and total nitrogen) between both analyzed areas, the content of microbial biomass carbon (CMB) differs significantly (p < 0.01): RA: 241.17 ± 96.50 μg C/g dry soil; NBB: 424.42 ± 136.23 μg C/g. Extracellular microbial carbon (CEX) was also significantly higher in RA than NBB. The measured CMB values from both mining areas were verified using two empirical mathematical models. Because our former model (used for evaluation of NBB) did not fit soils with low organic carbon content (0.10–0.80%), a new model was proposed. For evaluation of RA reclaimed sites the measured, model‐predicted, and calculated values were used. The best site in RA was Dürwiss Deponie (site 18 near Eschweiler), reclaimed in 1965 and characterized by good soil physical parameters (sand 4%, silt 77%, and clay 19%). In NBB undisturbed soils were the best, together with the site of Úžín (site 2 near Ústí and Labem), reclaimed in 1964, where high‐quality reclamation management resulted in high biological activity. According to biological criteria, the best management practice in NBB was use of high‐quality loam overlaying montmorillonite clayey subsoil. In RA direct reclamation of high‐quality loess with low content of sand also gave good results.
Does Weeding Promote Regeneration of an Indigenous Tree Community in Felled Pine Plantations in Uganda?
Authors: Chapman Colin A. , Chapman Lauren J. , Zanne Amy , Burgess Matthew A.
Published: March 2003

The use of plantations to manage extensive tracks of deforested lands in the tropics is a conservation strategy that has recently received considerable attention. Plantation trees can promote seed dispersal by attracting dispersers and creating favorable site conditions, leading to increased germination and establishment of indigenous trees. Subsequently, plantation trees can be harvested for profit or left to senesce, leaving a native tree community. We evaluated the effect of vine, grass, and shrub cutting (weeding) over a 3‐year period on regeneration of indigenous trees subsequent to the removal of plantation softwoods in Kibale National Park, Uganda. Counter to what would be expected if weeding released trees from competition, we found no difference in the total number of stems or in the stems greater than 10 cm diameter at breast height between control and weeded plots; there were more stems greater than 1 cm diameter at breast height in the control plots. For species found in both control and weeded plots, the maximum size of individuals did not differ. At the end of the study, 61 species were found in the control plots and 43 species were found in the weeded plots, and in both types of plots the three most abundant species were the same. The number of species and stems classified as early or middle successional species did not differ between weeded and control plots. The fact that weeding did not promote regeneration of indigenous trees after the removal of plantation trees illustrates the importance of evaluating and field‐testing potential management options.
Current Loads of Coarse Woody Debris on Southeastern Australian Floodplains: Evaluation of Change and Implications for Restoration
Authors: MacNally Ralph , Parkinson Amber , Horrocks Gregory , Young Matthew
Published: March 2003

We evaluated the status of coarse woody debris (CWD, fallen wood) on floodplains of the southern Murray‐Darling basin of southeastern Australia. The floodplains are dominated floristically by the river red gum Eucalyptus camaldulensis. Aerial survey techniques were used to estimate the amounts of woody debris within 200 m of the channels along 2,442 km of 11 rivers of the system, including the Murray and Darling Rivers and the Darling Anabranch. Aerially based indices were converted into wood volumes by using ground‐truthing at a selection of sites; there was a strong correlation between index values and measured wood volume densities. For thickly forested sites such as Barmah, Gunbower Island, and the Ovens floodplains, the aerial method was not useful, so ground measurements at randomly positioned sites within the forests were used. Volumes were translated into mass by using conversion factors drawn from the literature. We estimated that total tonnage on approximately 221,000 ha of floodplain forests was 4.175 ± 0.579 × 106 tonne. In the larger forested blocks (>7,000 ha), mean wood densities ranged between approximately 12 tonne/ha on the lower Goulburn up to approximately 24 tonne/ha at Barmah State Forest. The area‐weighted mean for the entire area was approximately 19 tonne/ha. A main purpose of the research was to place these figures into an historical perspective to evaluate implications for restoration. A thorough search of historical documentation revealed that there are no extant data upon which to estimate pre‐European settlement levels. We used information from an apparently undisturbed “unmanaged” site in the Millewa forests of southern New South Wales as a basis. Wood density there corresponded to a mean figure of 125 tonne/ha wood‐mass density. By using this figure we estimate that CWD levels on the southern Murray‐Darling basin may be of the order of 15% of pre‐European settlement levels. Full restoration of the 221,000 ha surveyed would require 23.5 ± 0.579 × 106 tonne, which is equivalent to about 600,000 mature (1 m diameter at breast height) river red gum trees or the amount of timber derived from clear felling about 115,000 ha of river red gum forest at current stocking levels. We discuss the implications of this massive deficit and possible short‐ and long‐term solutions.
Early Responses of Fishes and Crustaceans to Restoration of a Tidally Restricted New England Salt Marsh
Authors: Raposa Kenneth
Published: March 2003

Nekton (fishes and decapod crustaceans) is an abundant and productive faunal component of salt marshes, yet nekton responses to tidal manipulations of New England salt marshes remain unclear. This study examined nekton use of a tidally restricted salt marsh in Narragansett, Rhode Island relative to an unrestricted marsh during summer. In addition, a before‐after‐control‐impact design was used to examine early responses of nekton to the reintroduction of natural tidal flushing. Species richness and densities of Cyprinodon variegatus, Lucania parva, Menidia beryllina, and Palaemonetes pugio were higher in the restricted marsh compared with the unrestricted marsh. The unrestricted marsh supported higher densities of Menidia menidia and Fundulus majalis. Mean lengths of Carcinus maenas and P. pugio were greater in the restricted marsh. Tidal restoration resulted in increased tidal flushing, salinity, and water depth in the restricted marsh. Densities of Fundulus heteroclitus, F. majalis, and Callinectes sapidus were higher after 2 years of restoration. Density of L. parva decreased after restoration, probably in response to a loss of macroalgal habitat. Species richness also decreased after 2 years, from 20.9 species when the marsh was restricted to 13.0 species. Total nekton density did not change with restoration, but shifts in community composition were evident. In this study restoration induced rapid changes in the composition, density, size, and distribution of nekton species, but additional monitoring is necessary to quantify longer‐term effects of salt marsh restoration on nekton.
Effects of Differences in Prescribed Fire Regimes on Patchiness and Intensity of Fires in Subtropical Savannas of Everglades National Park, Florida
Authors: Slocum Matthew G. , Platt William J. , Cooley Hillary C.
Published: March 2003

Abstract We investigated effects of fire frequency, seasonal timing, and plant community on patchiness and intensity of prescribed fires in subtropical savannas in the Long Pine Key region of Everglades National Park, Florida (U.S.A.). We measured patchiness and intensity in different plant communities along elevation gradients in “fire blocks.” These blocks were prescribed burned at varying times during the lightning season and at different frequencies between 1995 and 2000. Fire frequency, seasonal timing, and plant community all influenced the patchiness and intensity of prescribed fires. Fires were less patchy and more intense, probably because of drier conditions and pyrogenic fuels, in higher elevation plant communities (e.g., high pine savannas) than in lower elevation communities (e.g., long‐hydroperiod prairies). In all plant communities fires became increasingly patchy and less intense as the wet season progressed and moisture accumulated in fuels. Frequent prescribed fire resulted in increased patchiness but a wider range of intensities; higher intensities appeared to result from regrowth of more flammable vegetation. Our study suggests that frequent early lightning season prescribed fires produce a wider range of post‐fire conditions than less frequent late lightning season prescribed fires. Our study also suggests that natural early lightning season fires readily carried through pine savannas and short‐hydroperiod prairies, but lower elevation long‐hydroperiod prairies functioned as firebreaks. Natural fires probably crossed these firebreaks only during drier years, potentially producing large landscape‐level fires. Knowledge of how patchily and intensely fires burn across a savanna landscape should be useful for developing landscape‐level fire management.
HIV‐associated neuropathies: role of HIV‐1, CMV, and other viruses
Authors: Kolson Dennis L. , Gonzalez‐Scarano Francisco
Published: March 2003

Abstract  The role of the human immunodeficiency virus (HIV) and other viruses in the development of neuropathies associated with HIV infection is controversial. Distal symmetric polyneuropathy (DSP), the most common subtype of HIV‐associated neuropathy, is characterized by an abundance of reactive macrophages within the peripheral nerve, but HIV replication is limited to a small percentage of the macrophages. Thus, the pathological destruction may be mediated by pro‐inflammatory signals amplified by activated glial elements within the nerve, similar to the proposed mechanism of damage caused by HIV within the central nervous system. In contrast, in mononeuropathy multiplex (MM) and progressive polyneuropathy (PP), cytomegalovirus (CMV) replication in the peripheral nerve is consistently demonstrable, and this replication likely results in direct damage to the infected cells (neurons and glia). The rarest form of HIV‐associated neuropathy, the diffuse infiltrative lymphocytosis syndrome (DILS), is characterized by an intense CD8+ T lymphocyte infiltration into the nerve and abundant HIV infection of macrophages. Finally, while other viruses (varicella zoster, herpes simplex) are associated with myelitis in HIV‐infected individuals, there is little support for a role for these viruses in HIV‐associated neuropathy.
Multifactorial Neuropathy
Authors: Gemignani F , Ferraris A , Grosso R , Alfieri S , Melli G , Marbini A.
Published: March 2003

It is well known that in a small proportion of patients with peripheral neuropathy a cause is not found; on the other hand, it is also possible that extensive investigations reveal more than one possible cause of peripheral neuropathy, especially in older patients, raising a different kind of diagnostic problem. The aim of this study was to investigate the occurrence of “multifactorial neuropathy” in a population of patients with peripheral neuropathy, and the modalities of interaction when various causes are implicated in determining the features of neuropathy. In a series of 62 consecutive patients with peripheral neuropathy who underwent an extensive diagnostic work‐up, more than one possible cause for a single patient was found in 24 patients (38.7%), and at least 3 causes in 9 patients (14.5%). Common causes of neuropathy, such as diabetes, alcohol, drugs, Charcot‐Marie‐Tooth disease, and cryoglobulinemia were more often implicated in multifactorial neuropathy. In 8 additional patients, neuropathic motor and sensory impairment was complicated by coexistent diseases (Parkinson's disease, osteoarthrosis, lumbal stenosis). Patients with multifactorial neuropathy were older than patients with neuropathy due to a single cause (mean age: 66.8 ± 9.6 vs. 62.2 ± 11.9), and had a significantly greater disability on Rankin scale (28/32 with Rankin grade 2 or more, vs. 15/30; p = 0.002). Possible mechanisms of interaction between two or more causes of neuropathy are the following: a primary neuropathic condition is worsened or revealed by an additional superimposed cause; two coexisting causes concur to determine the features of neuropathy, for instance influencing respectively motor and sensory symptoms; a unique cause produces neuropathic damage through different mechanisms (this is typically the case of malignancies, and in particular lymphoma); the significance of some potential factors of neuropathic damage, such as monoclonal gammopathy, may be difficult to be ascertained, thus their role as a cause of neuropathy remains elusive. In addition, the disability due to neuropathy may be complicated by other concurrent neurologic or non‐neurologic conditions causing additional motor or sensory impairment. Thus it is also advisable to have a complete screening in patients with an obvious cause of peripheral neuropathy, as it could be made worse by another coexistent cause, and in older patients this evenience is not uncommon. This is especially important when a treatable additional cause is revealed.
Radial tunnel syndrome in an elite power athlete: a case of direct compressive neuropathy
Authors: Dickerman Rob D. , Stevens Qualls E.J. , Cohen Anders J. , Jaikumar S.
Published: March 2003

Abstract  Radial tunnel syndrome (RTS) is thought to result from intermittent and dynamic compression of the posterior interosseous nerve (PIN) in the proximal part of the forearm associated with repeated supination and pronation. The diagnostic criteria encompassing RTS are purely clinical and the term “radial tunnel syndrome” has become controversial because of the lack of focal motor weakness in the majority of patients diagnosed with RTS. Retrospective cadaveric and surgical studies have revealed several areas within the forearm in which the PIN may become entrapped. Recent studies have suggested that the PIN is “fixed” in the supinator muscle and that wrist pronation is the actual movement that places the most stress on the PIN. The patients most often afflicted with RTS appear to be those who perform repetitive manual tasks involving rotation of the forearm and athletes involved in racket sports. Surgical exploration with decompression of the PIN is often required in patients with RTS. We present the first case of RTS occurring in an elite power athlete and believe this case represents a direct compressive sensory neuropathy. The optimum nonsurgical treatment plan for the elite athlete in training for competition and the cause of this compressive neuropathy in power athletes will be discussed.
STEROLIC BIOMARKERS IN MARINE PHYTOPLANKTON. II. FREE AND CONJUGATED STEROLS OF SEVEN SPECIES USED IN MARICULTURE
Authors: Véron Benoît , Dauguet Jean‐Claude , Billard Chantal
Published: March 2003

The sterols of seven unicellular algae widely used in mariculture and belonging to different classes (Prasinophyceae, Haptophyceae, Eustigmatophyceae, and Diatomophyceae) were examined for free and combined forms. Under standard culture conditions, all synthesized free sterols and combined forms (steryl esters, acyl steryl glycosides, and steryl glycosides). Free sterols were dominant in five of the species. In contrast, sterols were mostly esterified in the eustigmatophyte Nannochloropsis oculata (Droop) Hibberd and the diatom Thalassiosira pseudonana Hasle et Heimdal, whereas in another diatom, Chaetoceros calcitrans (Paulsen) Takano, glycosylated forms represented over 60% of total sterols. The pennate diatom Haslea ostrearia (Gaillon) Simonsen synthesized large amounts of steryl glycosides consisting mainly of an unusual sterol, 23,24‐dimethylcholest‐5‐en‐3β‐ol, occurring in some dinoflagellates.
RUBISCO ADAPTATION TO LOW TEMPERATURES: A COMPARATIVE STUDY IN PSYCHROPHILIC AND MESOPHILIC UNICELLULAR ALGAE
Authors: Devos Nathalie , Ingouff Mathieu , Loppes Roland , Matagne René F.
Published: March 2003

Some properties of the ribulose‐1,5‐bisphosphate carboxylase/oxygenase (RUBISCO) from two psychrophilic Chloromonas species have been investigated in relation to their adaptation to cold environments. Contrary to the situation usually encountered with psychrophilic enzymes, the carboxylase activity of both purified “cold” RUBISCO enzymes was lower at low temperatures than that found with the enzyme of the mesophilic alga Chlamydomonas reinhardtii Dangeard. Moreover, the apparent optimal temperature for RUBISCO carboxylase activity was similar for psychrophilic and mesophilic enzymes. Psychrophilic RUBISCOs, however, showed a greater thermosensitivity than the C. reinhardtii enzyme. Genes encoding small and large subunits of RUBISCO from one psychrophilic isolate were sequenced. Comparison of the deduced amino acid sequences to those of higher plants and green algae revealed the substitution of a very highly conserved residue (cysteine247→ serine in the large subunit) that could be responsible, at least in part, for the increased thermosensitivity of the “cold” enzyme. Interestingly, the relative amount of RUBISCO subunits found in the psychrophilic isolates was about twice as high as the amount observed in C. reinhardtii and five other mesophilic algae. The high production of a key enzyme to counterbalance its poor catalytic efficiency at low temperature could constitute a novel type of adaptive mechanism to cold environments.
THE CELL WALL (THECA) OF TETRASELMIS STRIATA (CHLOROPHYTA): MACROMOLECULAR COMPOSITION AND STRUCTURAL ELEMENTS OF THE COMPLEX POLYSACCHARIDES
Authors: Becker Burkhard , Melkonian Michael , Kamerling Johannis P.
Published: March 2003

Isolated cell walls (thecae) from the scaly flagellate green alga Tetraselmis striata Butcher contain the unusual 2‐keto‐sugar acids 3‐deoxy‐manno‐2‐octulosonic acid (Kdo), 3‐deoxy‐5‐O‐methyl‐manno‐2‐octulosonic acid (5OMeKdo), and 3‐deoxy‐lyxo‐2‐heptulosaric acid (Dha). In addition, galacturonic acid, galactose, gulose, and arabinose are present. EDTA‐extraction yielded an insoluble fraction that retains the shape of the cell walls and contains no 2‐keto‐sugar acids. Methylation analysis demonstrated the presence of terminal hexose, GalA, Dha, and Kdo as well as 2‐substituted hexose, 4‐or 8‐substituted Kdo, and 4,8‐disubstituted Kdo. However, most of the carbohydrate material (about 60%) was not methylated. Periodate oxidation of the cell wall preparation showed the presence of 2‐substituted Gul, 4‐ or/and 5‐substituted and 7‐ or/and 8‐substituted Kdo, which is in agreement with the methylation analysis. Again, a significant amount of carbohydrate material was not degraded, indicating complex substitution patterns. Oligosaccharides were generated by partial hydrolysis and fractionated using gel permeation chromatography and high‐pH anion‐exchange chromatography. Oligosaccharides contained either GalA and Kdo, or Gal, Kdo, Dha, and Gul, respectively. The structure of a GalA and Kdo containing disaccharide was established using 1H NMR spectroscopy.
CLONING AND CHARACTERIZATION OF NITRATE TRANSPORTER GENES FROM THE DIATOM CYLINDROTHECA FUSIFORMIS
Authors: Hildebrand M. , Dahlin K.
Published: March 2003

We have cloned and characterized the first nitrate transporter genes in a marine organism, from the diatom Cylindrotheca fusiformis. A cDNA clone and two genomic sequences, NAT1 and NAT2, were isolated. The sequences were highly conserved, with only 9 out of 484 amino acids differing. At least four copies of NAT genes were present in C. fusiformis, and multiple copies were present in other diatom species. NAT transcript abundance was high in cultures grown in the presence of nitrate, at nearly the same level during nitrogen starvation, and also high in urea‐grown cultures. Lower mRNA levels occurred in nitrite‐grown cultures. Transcript levels were highly repressed with NH4Cl or NH4NO3 as the nitrogen source, although very low amounts were detected. NAT mRNA levels were not directly regulated by light or dark. NAT mRNA levels varied, suggesting that nitrate uptake was not continuous, during progression through the cell cycle. The results suggest that transcriptional control contributes significantly to the overall control of nitrate uptake in C. fusiformis. The cloning of the nitrate transporter genes provides a new tool for investigating diatom nitrogen uptake and metabolism. In addition, the regulation of NAT expression by nitrogen source is likely to be useful in developing techniques to specifically control the expression of genes fused to NATregulatory sequences in transgenic diatoms.
IDENTIFICATION OF ALEXANDRIUM (DINOPHYCEAE) SPECIES USING PCR AND rDNA‐TARGETED PROBES
Authors: Penna Antonella , Magnani Mauro
Published: March 2003

A PCR (polymerase chain reaction)‐based assay for the detection of Alexandrium species in cultured samples using rDNA‐targeted probes was developed. The internal transcribed spacers 1 and 2 (ITS1 and ITS2) and the 5.8S ribosomal RNA gene (rDNA) from cultured isolates of A. tamarense (Lebour) Taylor, A. catenella (Whedon et Kofoid) Balech, A. fundyense Balech and A. lusitanicum Balech were amplified using PCR and sequenced. Sequence comparisons showed that the 5.8S and ITS1‐ITS2 regions contain sequences specific for the Alexandrium genus, especially at the 3′ end of the 5.8S coding region. PCR primers and a radioactive 32P‐labeled DNA probe were devised for this region. The cross‐reactivity of the PCR primers and probe was tested against cultured isolates of Alexandrium and other dinoflagellates and diatoms. All the Alexandrium isolates screened reacted toward the genus‐specific probe; in contrast, the other groups of microalgae (dinoflagellates and diatoms) did not react with the probe. Furthermore, the PCR amplification technique combined with the use of the rDNA‐target probe allowed us to develop a method for the detection of Alexandrium cells in cultured samples. This PCR method might offer a new approach for the identification and enumeration of the HAB (harmful algal bloom) species present in natural phytoplankton populations.
THE FATTY ACID AND STEROL COMPOSITION OF FIVE MARINE DINOFLAGELLATES
Authors: Mansour Maged P. , Volkman John K. , Jackson Anne E. , Blackburn Susan I.
Published: March 2003

The fatty acid and sterol compositions of five species of marine dinoflagellates (Scrippsiella sp. Symbiodinium microadriaticum Freud, Gymnodinium sp., Gymnodinium sanguineum Hirasaki, and Fragilidium sp.) are reported. All contained the major fatty acids that are considered common in dinoflagellates, but the proportions were quite variable, and some species contained low contents of some polyunsaturated fatty acids. Concentration ranges for the major fatty acids were: 16:0 (9.0%–24.8%), 18:4(n‐3) (2.5%–11.5%), 18:5(n‐3) (7.0%–43.1%), 20:5(n‐3) (EPA) (1.8%–20.9%), and 22:6(n‐3) (DHA) (9.9%– 26.3%). Small amounts of novel very‐long‐chain highly unsaturated C28 fatty acids occurred in all species. Each dinoflagellate contained a complex mixture of 4‐methyl sterols and 4‐desmethyl sterols. Four species contained cholesterol, although the amounts were highly variable (from 0.2% of total sterols in Scrippsiella sp. to 45.6% in Fragilidium sp.). All but G. sanguineum contained the 4‐methyl sterol dinosterol, and all species contained sterols lacking a double bond in the ring system (i.e. stanols); in Scrippsiella sp. cholestanol composed 24.3% of the total sterols. Other common features of the 4‐methylsterol profiles were the presence of 23,24‐dimethyl alkylation and unsaturation at Δ22 in the side chain. In Scrippsiella sp., four steroidal ketones were identified: cholestanone, dinosterone, 4α,23,24‐trimethyl‐5α‐cholest‐8(14)‐en‐3‐one, and dinostanone. The structures of these corresponded to the major sterols in this species, suggesting that the sterols and steroidal ketones are biosynthetically linked. Steroidal ketones were not detected in the other species. Although fatty acid profiles can be used to distinguish among algal classes, they were not useful for differentiating among dinoflagellate species. In contrast, whereas some taxonomic groupings of dinoflagellates display similar sterol patterns, others, such as the gymnodinoids studied here, clearly do not. The combination of fatty acid, sterol, and steroidal ketone profiles may be useful complementary chemotaxonomic tools for distinguishing morphologically similar species. The identification of steroidal ketones supports earlier suggestions that certain dinoflagellates might be a significant source of such components in marine environments.
THE RESPONSE OF GROWTH AND BIOCHEMICAL COMPOSITION TO VARIATIONS IN DAYLENGTH, TEMPERATURE, AND IRRADIANCE IN THE MARINE DIATOM THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE)
Authors: Thompson Peter
Published: March 2003

The relationships between the growth rate of the marine diatom Thalassiosira pseudonana (Hustedt) and irradiance, daylength, and temperature were determined in nutrient‐sufficient semicontinuous cultures. The initial slopes of the growth versus total daily irradiance curves were not affected by temperature or daylength. Growth versus irradiance was best modeled as a hyperbolic function at short daylengths and better modeled as an exponential function at longer daylengths. The maximum or light‐saturated growth rates at each daylength were modeled as a hyperbolic function of daylength. This model was extended in a novel manner to include temperature dependence providing a framework that can be used to interpret other experimental data on growth rate versus daylength. The resulting model should be useful in global models of phytoplankton growth. Carbon, nitrogen, and chl a quotas were influenced by daylength, irradiance, and temperature. Both C and N quotas were positive exponential functions of irradiance, whereas N and chl a quotas were significantly greater for cells grown at the lower temperature. The ratio chl a:C quota (chl a:Qc) was a strong negative exponential function of total daily irradiance. Cells grown at 10° C had significantly greater chl a:Qc ratios than those grown at 18° C, and daylength also had a significant positive influence on chl a:Qc. The apparent effect of daylength on chl a:Qc was removed by standardizing chl a:Qc to growth rate (μ), resulting in a temperature‐dependent relationship between chl a:Qc·μ−1 and irradiance that accounted for 95% of the variation in the data.
ECO‐PHYSIOLOGY, BIO‐OPTICS AND TOXICITY OF THE ICHTHYOTOXIC CHRYSOCHROMULINA LEADBEATERI (PRYMNESIOPHYCEAE)
Authors: Johnsen Geir , Dalløkken Runar , Eikrem Wenche , Legrand Catherine , Aure Jan , Skjoldal Hein Rune
Published: March 2003

A toxic phytoplankton bloom, dominated by the prymnesiophyte Chrysochromulina leadbeateri Estep, developed in the Ofotfjord–Tysfjord area (North Norway) in mid‐May and ended in late June 1991 in Vestfjorden and the adjacent fjord areas. Chrysochromulina leadbeateri dominated at total cell densities of >2 × 106 cells·L−1; at lower total cell densities, C. leadbeateri was accompanied by other Chrysochromulina species, peridinin‐containing dinoflagellates, and diatoms. Bio‐optical characteristics and pigmentation in laboratory and field strains of C. leadbeateri allowed for the interpretation of the optical signatures within the bloom. The bio‐optical data suggested healthy and actively growing cells during the bloom. About 600 metric tons of pen‐raised Atlantic salmon were killed by the C. leadbeateri bloom. A laboratory study was conducted to assess the potential impact of finfish on C. leadbeateri growth. It was found that the polyamine putrescine enhanced cell biomass and hemolytic activity. Given this, a possible scenario for the development of this bloom and the level of toxicity is hypothesized: (1) The nutrient loading in the Ofotfjord area was enhanced during the winter of 1990–1991 due to the overwintering of 1.5 × 106 metric tons of herring from a depth of 0–250 m. This may have sustained a large stock of the mixotrophic C. leadbeateri in early spring before light regime (irradiance, spectral irradiance, and day length) made net photosynthesis possible. (2) The release of polyamines during the decay of dead fish (e.g. putrescine, cadaverine, and histamine) may have acted as cofactors with ichthyotoxins making “hypertoxic complexes” with the polyamines enhancing growth in the mixotrophic C. leadbeateri.
HALOSTYLODINIUM ARENARIUM, GEN ET SP. NOV. (DINOPHYCEAE), A COCCOID SAND‐DWELLING DINOFLAGELLATE FROM SUBTROPICAL JAPAN
Authors: Horiguchi Takeo , Yoshizawa‐Ebata Junko , Nakayama Takeshi
Published: March 2003

A new genus and species of marine coccoid dinoflagellate from subtropical Japan, Halostylodinium arenarium Horiguchi et Yoshizawa‐Ebata, gen. et sp. nov., is described. The dominant stage of the dinoflagellate is a nonmotile ovoidal to spheroidal cell with a distinct stalk. The stalk consists of an upper thick tubule, a lower thin tubule, and a discoidal holdfast. The dinoflagellate possesses a yellowish‐brown chloroplast with multiple lobes radiating from a central pyrenoid. It reproduces by the formation of two motile cells, which swim for a short period and then transform directly into the stalked nonmotile cell. The stalk is produced during transformation from the apical stalk complex present in the apex of the motile cell. The apical stalk complex consists of a double‐folded apical pore plate and doughnut‐shaped holdfast‐building material. The ultrastructure of the apical stalk complex is compared with those of Bysmatrum arenicola and Stylodinium littorale. Halostylodinium arenarium possesses delicate thecal plates, and the thecal plate formula is Po, 5′, 2a, 7″, 7c, 6s, 5″′, 1p, 2″″. A phylogenetic study based on the 18S ribosomal RNA gene did not show any clear affinities between this organism and any species included in the analysis.
Distribution of rare earth elements in seaweed: implication of two different sources of rare earth elements and silicon in seaweed
Authors: Fu Feng Fu , Akagi Tasuku , Yabuki Sadayo , Iwaki Masaya , Ogura Norio
Published: March 2003

Rare earth elements (REEs) and Si in five species of seaweed, ambient surface seawaters, and suspended solid particles in the seawaters were determined separately. Inductively coupled plasma mass spectrometry (ICP‐MS) was used for REEs and inductively coupled plasma emission spectrometry (ICP‐ES) was used for Si in order to evaluate REEs as a tracer in seaweeds and to understand the source of inorganic elements, especially Si, in seaweeds. Two different REE patterns, one similar to that of the seawater solution and another resembling that of suspended particles, were observed in seaweeds, and the variation of REE patterns seems to show a clear dependence on the abundance of Si. The REE pattern and Si concentration seem to vary depending on the division: green and red algae showed REE patterns similar to that of suspended particles, but brown algae showed patterns closer to that of seawater solutions and relatively lower Si concentration. The possibility of contamination from silicate particles on the surface of seaweeds was ruled out for several reasons. Silicate particles, not dissolved silicate, have been identified as the direct source of REEs and Si in plants (Fu et al. 1998), and seaweeds are no exception. We have to consider that seaweeds can take up Si from suspended particles through their blade or branches. From the appearance of tetrad‐effect‐like variation of REEs, Si is assumed to enter a dissolved state just before the particles are taken up. From the results of a sonication experiment, REEs, once taken up as silicate particles, seem to be separated from Si in the thallus.
Development of hormosira banksii (PHAEOPHYCEAE) embryos in selected components of secondarily‐treated sewage effluent
Authors: Kevekordes Karen , Clayton Margaret N.
Published: March 2003

We investigated the effects of phosphate, ammonium, and a mixture of heavy metals as components of sewage effluent, together with the effects of reduced salinity due to sewage effluent discharge into a marine environment, on the development of Hormosira banksii (Turner) Decaisne embryos. The concentration of each effluent component tested in this study was calculated to approximate levels in the shore zone where H. banksii once occurred at Boags Rocks (Victoria, Australia) and the artificial sea medium was diluted to 20‰ S based on average salinity levels measured at this site. Newly fertilized eggs were cultured in each of these components and combinations of components for up to 7 days. Ammonium, elevated to levels that occur in the vicinity of the outfall, and fresh water, which reduces seawater salinity, were the most damaging of the effluent components tested. Osmotically stressed embryos commonly showed swollen chloroplasts, loss of cell contents, vesiculate cytoplasm, and stunted rhizoid development. Exposure to elevated levels of ammonium retarded embryo development and growth until day 7, when cellular damage became evident. The number of damaged embryos was significantly greater when exposed to elevated levels of ammonium added to artificial seawater medium diluted to 20‰ S. The adverse effects caused by elevated levels of ammonium and reduced seawater salinity on H. banksii embryo development could have contributed to the disappearance of this species from Boags Rocks.
THE MAIN NONPOLAR CHLOROPHYLLc  FROMEMILIANIA HUXLEYI(PRYMNESIOPHYCEAE) IS A CHLOROPHYLLc 2‐MONOGALACTOSYLDIACYLGLYCERIDE ESTER: A MASS SPECTROMETRY STUDY
Authors: Garrido José L. , Otero Jorge , Maestro Miguel A. , Zapata Manuel
Published: March 2003

The main nonpolar chlorophyllc ‐like pigment was extracted fromEmiliania huxleyi(Lohm.) Hay et Mohler (strain CCMP 370) cultures and isolated by preparative column chromatography and HPLC. The pigment, whose visible spectrum closely resembled that of chlorophyllc 2, was studied by low‐resolution fast atom bombardment mass spectrometry, showing a very high mass molecular ion (m/z 1313). The fragment ions, either in the direct spectrum or obtained by tandem mass spectrometry with collision‐induced dissociation of the molecular ion, were compatible with the consecutive losses of two fatty acids (14:0 and 18:4), glycerol, and a hexose, leaving a chlorophyllc 2backbone, suggesting the molecule consists of a chlorophyllc 2residue linked, via an ester bond, to the sugar moiety of a monohexosyldiacylglycerol. The identities of the two fatty acid residues (14:0 and 18:4n‐3) were subsequently corroborated by gas chromatography of the corresponding methyl esters. Chemical hydrolysis–derivatization–gas chromatography–mass spectrometry demonstrated the occurrence of glycerol and that galactose is the constituent sugar. The porphyrin obtained on acid hydrolysis showed chromatographic and visible spectral properties identical to pheoporphyrinc 2. This evidence led us to propose a tentative structure whose molecular formula, C76H96O14N4Mg, was supported by the values of exact mass measurements by high‐resolution fast atom bombardment mass spectrometry. This novel structure represents the highest molecular weight natural chlorophyll described to date.
INTRACELLULAR CYANOBACTERIAL SYMBIONTS IN THE MARINE DIATOM CLIMACODIUM FRAUENFELDIANUM (BACILLARIOPHYCEAE)
Authors: Carpenter Edward J. , Janson Sven
Published: March 2003

The diatom Climacodium frauenfeldianum Grunow was collected in the tropical Atlantic and Pacific Oceans. Observations with epifluorescence microscopy revealed that this diatom contained coccoid symbionts (2.5–3.5 μm) with a typical cyanobacterial fluorescence in addition to that of their own chloroplasts. Mean concentration of C. frauenfeldianum for 28 stations in the SW tropical Pacific Ocean was 530 x 103 (SE = 1372) cells·m−2, with highest concentration (mean 17.5 cells·L−1) at 40‐m depth. The symbiosis was only observed at water temperatures between 26.3 and 28.9° C, with highest concentrations at 27.7° C. Three almost complete 16S rDNA sequences from one sample were determined, and they were identical. The phylogenetic analysis of this 16S rDNA sequence and those from other cyanobacteria and plastids revealed that it was closely related to the 16S rDNA sequence from Cyanothece sp. ATCC 51142. Cyanothece sp. ATCC 51142 is a unicellular nitrogen‐fixing cyanobacterium isolated from a coastal marine environment and has ultrastructural features similar to the symbionts of C. frauenfeldianum. The close relationship between Cyanothece sp. and the cyanobacterial symbiont in C. frauenfeldianum suggests the potential for nitrogen fixation in the symbiosis.
INVESTIGATING THE BIODIVERSITY, ECOLOGY, AND PHYLOGENY OF ENDOSYMBIOTIC DINOFLAGELLATES IN THE GENUS SYMBIODINIUM USING THE ITS REGION: IN SEARCH OF A “SPECIES” LEVEL MARKER
Authors: LaJeunesse Todd C.
Published: March 2003

The internal transcribed spacer (ITS) regions from 47 Symbiodinium (Freudenthal) isolates cultured from 34 different host species and two populations sampled from nature were sequenced and compared. Of these, 17 distinct ITS types were identified. The described species Symbiodinium goreaui, S. kawagutii, S. pilosum (Trench and Blank), S. microadriaticum (Freudenthal), and S. (=Gymnodinium) linucheae (Trench and Thinh) had ITS sequences distinct from each other. Four of these species share identical ITS sequences with uncharacterized isolates. Sequence differences among other isolates indicate that at least seven other cultured types await formal species descriptions, whereas numerous others most likely exist in nature. The Symbiodinium phylogeny is positively correlated with cell size, mycosporine‐like amino acid production (UV protection), and host infectivity, whereas the production of water‐soluble peridinin–chl a–protein homodimer and monomer apoproteins and isoenzyme similarity do not correlate. There is evidence, based on the lack of phylogenetic congruency with allelic variability, that sexual recombination occurs at some frequency among Symbiodinium populations. Symbiodinium isolates from the Caribbean possess identical ITS sequences to isolates originating from the Red Sea or the western Pacific. These findings indicate that some Symbiodinium species may have global biogeographic distributions.
PHYLOGENETIC UTILITY OFrbcS SEQUENCES: AN EXAMPLE FROMANTITHAMNIONAND RELATED GENERA (CERAMIACEAE, RHODOPHYTA)
Authors: Lee Sang‐Rae , Oak Jung Hyun , Suh Youngbae , Lee In Kyu
Published: March 2003

We report the potential phylogenetic utility of the small RUBISCO subunit (rbc S) sequences from a sampling ofAntithamnionand related genera in ceramiacean algae. The size ofrbc S was 417 bp for all taxa examined. Analyses of the DNA sequence data indicated that pairwise divergences ofrbc S sequences were 3.3%–9.8% among species ofAntithamnion, and ranged from 13.6% to 18.0% betweenAntithamnionand related genera. Phylogenetic analyses fully resolved relationships at the intrageneric level with statistical significance supported by high bootstrap values. Two subgenera ofAntithamnion,PterotonandAntithamnion, were clearly distinguished in the molecular tree. In the clade of subgenusPteroton,A. aglandumwas allied withA. callocladumand separated fromA. nipponicum.In the pairwise distance comparison of sequence variation,Ceramiumshowed the greatest genetic distances among genera examined in the study. All phylogenetic trees generated by the maximum parsimony, neighbor joining, and maximum likelihood were completely congruent in topology with high confidence.
PIGMENT COMPOSITION ANDrbcL SEQUENCE DATA FROM THE SILICOFLAGELLATEDICTYOCHA SPECULUM: A HETEROKONT ALGA WITH PIGMENTS SIMILAR TO SOME HAPTOPH Y TES
Authors: Daugbjerg Niels , Henriksen Peter
Published: March 2003

Monophyly of plastids in the morphologically diverse heterokont algae has rarely been questioned. However, HPLC analysis revealed that the pigment composition of the silicoflagellateDictyocha speculumEhrenberg is similar to that observed in a group of haptophytes (“type 4”sensuJeffrey and Wright 1994.Dictyocha speculumand type 4 haptophytes possess acylfucoxanthins (19′‐butanoyloxy‐ and 19′‐hexanoyloxyfucoxanthin) in addition to fuco‐, diadino‐, and diatoxanthin and chla,c, andc3. The pigment composition of two pedinellids (Apedinella radians[Lohmann] Campbell andMesopedinella arcticaDaugbjerg), a sister group toD. speculum, deviates fromD. speculumby lack of chlc 3and acylfucoxanthins. The distinct pigment composition suggested that plastid evolution inD. speculumdiffers from that of other heterokont algae. This prompted determination of the plastid‐encodedrbcL gene fromD. speculumto gain further insight into the evolutionary history of plastids in heterokont algae and haptophytes. A phylogenetic inference based on parsimony, maximum likelihood, and LogDet transformation methods included 35 heterokonts, 19 haptophytes, 8 red algae, and 1 cryptomonad. Three proteobacteria possessing type I RUBISCO were used to root the tree. In phylogenetic analyses,D. speculumwas closely related toRhizochromulinasp. and pedinellids, despite the latter possessing a different pigment composition. Surprisingly, the Dictyochophyceae clustered outside the lineage of heterokont algae but not within the haptophytes. Hence, analyses deduced fromrbcL sequences indicated that the plastids in heterokont algae might have a more complex evolutionary history and that the shared pigment composition inD. speculumand type 4 haptophytes could be explained by convergent evolution or gene transfer. The pigment composition inD. speculummay have implications for pigment‐based characterization of phytoplankton community structure in natural samples.
SNOW ALGAE OF THE WINDMILL ISLANDS, CONTINENTAL ANTARCTICA: DESMOTETRA AUREOSPORA, SP. NOV. AND D. ANTARCTICA, COMB. NOV. (CHLOROPHYTA)
Authors: Ling Hau U.
Published: March 2003

Two cryophilic Desmotetra species, D. aureospora, sp. nov., and D. antarctica (Fritsch) Ling appear to be unique to the southern hemisphere snow ecosystem, or at least to the Windmill Island region, Antarctica. They have not been encountered in previous extensive studies of the Arctic and northern alpine regions. Also unusual are the higher pH (6.8 and 7.8) and conductivities of 279 μS·cm−1 and 426 μS·cm−1 for habitat conditions of D. antarctica that can be attributed to the influence of penguin guano. Both species are characterized by cells enveloped in individual mucilage layers, 1–3 contractile vacuoles, and a cup‐shaped chloroplast containing a diffuse pyrenoid. The cells divided in three planes to form cubical loosely aggregated green cell packages embedded in mucilage. Vegetative cells of the two species cannot be distinguished with certainty; however, their zygospores are very different. Desmotetra aureospora has spherical, smooth‐walled, golden zygospores, whereas D. antarctica has pale, yellow green, aereolate zygospores. Mucilage stalk morphology of cells in stationary‐phase cultures can also be used to separate the two species. Zygospores of D. antarctica have previously been identified as the snow alga Trochiscia antarctica Fritsch. Both species are currently maintained in culture at the Australian Antarctic Division. The cultures did not grow at temperatures above 15° C. The two species are compared with the soil alga D. stigmatica (Deason) Deason et Floyd, the only other species in the genus, and also with Chlorosarcina stigmatica Deason strain T105. Results show that the three Desmotetra species form a natural group and that the absence or presence of a wall on the zoospore is of dubious value in classifications of green algal taxa above the species level.