Turbulence, watermass stratification and harmful algal blooms: an alternative view and frontal zones as “pelagic seed banks”

Watermass stratification has been considered the essential physical condition that dinoflagellates require to bloom because of their relative inability, unlike diatoms, to tolerate the elevated shear-stress associated with water-column mixing, turbulence and high velocity, coastal currents. The swimming speeds of 71 flagellate taxa, with a focus on dinoflagellates, are compared to the turbulence fields and vertical velocities that develop during representative wind conditions, upwelling and at frontal zones. The results suggest that the classical stratification–dinoflagellate bloom paradigm needs revision. Tolerance of turbulence, growth within well-mixed watermasses and survival and dispersal while entrained within current systems are well developed capacities among dinoflagellates. Their secretion of mucous, often copious during blooms, is suggested to be an environmental engineering strategy to dampen turbulence. Biophysical tolerance of turbulence by dinoflagellates is often accompanied by high swimming speeds. Motility speeds of many species exceed in situ vertical current velocities; this also allows diel migrational patterns and other motility-based behavior to persist. Species belonging to “mixing-drift” life-form assemblages can increase their swimming speeds through chain formation, which helps to compensate for the increased turbulence and vertical water-column velocities of their habitats. The ability of dinoflagellate species to tolerate the vertical velocities of offshore, frontal zones, where abundant populations often develop, suggests that fronts may serve as “pelagic seed banks”, occurring as pelagic analogues of nearshore seed beds, from which seed stock is dispersed. The different ecologies associated with the hypothesized, “pelagic seed banks” of vegetative cells and the “seed beds” of resting stage cells deposited onto sediments are discussed. There is a contradiction in the stratification–HAB paradigm: the quiescent conditions of a stratified watermass, with its characteristic nutrient-poor conditions are expected to promote stasis of the population, rather than growth and blooms. The analyses suggest that dinoflagellate blooms do not preponderate in stratified watermasses because the bloom species are biophysically intolerant of the higher velocities and turbulence of more mixed watermasses. The watermass stratification that often accompanies flagellate blooms is probably a secondary, parallel event and less essential than some other factor(s) in triggering the observed bloom.     

Kryptoperidinium foliaceum blooms in South Carolina: a multi-analytical approach to identification

Observations following the discovery of Kryptoperidinium foliaceum blooms in South Carolina (SC), USA, suggest that a multi-analytical approach, using a standard, minimal set of criteria, should be adopted for determining dinoflagellate species identity and taxonomic placement. A combination of morphological, molecular, and biochemical analyses were used to determine the identity of this “red tide” dinoflagellate, first documented in SC waters in the spring of 1998. Results from thecal plate tabulations (based on scanning electron and epifluorescence microscopy), gene sequence data, species-specific PCR probe assays, and microalgal pigment profiles were analyzed and compared to reference cultures of K. foliaceum. Comparative data showed marked inconsistencies among the K. foliaceum reference culture isolates. In addition, the SC bloom isolate was shown to be mononucleate, contrary to previous reports for K. foliaceum, suggesting a more transient endosymbiotic association than previously considered.     

Hydrology of winter–spring “red tides” in Bahía de Mazatlán, Sinaloa, México

“Red tide” events are frequent and periodical in Bahía de Mazatlán, Sinaloa, México. Yet, the ones observed from 4 February to 4 June 2000, showed some distinctive features: First, the dinoflagellates Prorocentrum balticum (85%), P. mexicanum (5%), and Ceratium furca (5%), dominated the composition of the blooms; Second, the average cell abundance by date was 1.3×10⁶ cells l⁻¹, with a range of 3.5×10³ to 24,500 × 10³ cells l⁻¹, well above previous records; Third, the temperature registered at 10–20 m deep was unusually cold (19 °C), below the normal average of 21.5 °C observed over the last 10 years. Salinity was high (35.9 psu) and showed very little influence on the water density gradient. A mean thermal stratification index (TSI), of 3.4, with a maximum of 7 °C, was observed throughout the period, in spite of a weak upwelling activity and intermittent strong NW winds which were unable to break up water column stratification. Temperature fluctuations at the surface and at the bottom layers showed a 30-day periodicity, suggesting some association with the lunar cycle. To explain the characteristics of the “red tides” registered in Bahía de Mazatlán during the winter–spring period of year 2000, it is proposed that the temperature and density stratification, stabilized further by internal waves that compensated for the weak upwelling activity and provided the necessary nutrients to the surface layer, favored the persistence and intensity of the harmful algal bloom events then observed.     

Glucose biosensor based on nano-SiO2 and “unprotected” Pt nanoclusters

The “unprotected” Pt nanoclusters (average size 2 nm) mixed with the nanoscale SiO₂ particles (average size 13 nm) were used as a glucose oxidase immobilization carrier to fabricate the amperometric glucose biosensor. The bioactivity of glucose oxidase (GOx) immobilized on the composite was maintained and the as-prepared biosensor demonstrated high sensitivity (3.85 μA mM⁻¹) and good stability in glucose solution. The Pt–SiO₂ biosensor showed a detection limit of 1.5 μM with a linear range from 0.27 to 4.08 mM. In addition, the biosensor can be operated under wide pH range (pH 4.9–7.5) without great changes in its sensitivity. Cyclic voltammetry measurements showed a mixed controlled electrode reaction.     

Antagonistic effect of enterocin CCM 4231 from Enterococcus faecium on “bryndza”, a traditional Slovak dairy product from sheep milk

“Bryndza” is a traditional Slovak dairy product (type of soft cheese) made from sheep cheese which was ripened for 14 days. Because its manufacture, transporting and/or storing represent conditions which facilitate contamination, the effect of enterocin CCM4231 in “bryndza” was investigated with the aim to reduce the contaminant agents. “Bryndza” was divided into equal portions (50 g). The experimental sample (ES) as well as the control sample one (C1) were inoculated with Listeria innocua Li1 strain. The other control samples C2 and C3 were without Li1 strain. C3 control was selected as a reference control. ES and C2 portions were treated with purified enterocin CCM4231 in a concentration of 6400 AU/ml. Before the experimental inoculation, “bryndza” was checked for the presence of contaminant agents. The experiment lasted 1 week and the samples were stored in the refrigerator at 4 °C. Sampling was performed on day 1, on day 4 and on day 7. The control samples C2 and C3 were checked only on day 1 and then after 1 week. The following contaminant agents were detected in “bryndza” before its experimental inoculation with L. innocua Li1 strain: Escherichia coli in the amount 10³ cfu/ml/g, Staphylococcus aureus (10² cfu/ml/g) and enterococci (10⁴ cfu/ml/g). In the control sample C2, the number of E. coli was reduced to 10² cfu/ml/g. Enterococci and staphylococci were totally eliminated there. Concerning C3 control, natural decrease of bacteria was found and/or their unchanged counts. The value of pH (5) was stable during the whole experiment. In the experimental sample inoculated with Li1 strain, its counts were decreased immediately after enterocin CCM4231 addition approximately by one order of magnitude. This inhibitory effect was also detectable on day 4 by the difference of one order of magnitude between ES and C1. On day 7, 10³ cfu/ml/g of Li1 strain were detected in both samples (ES, C1). The difference by one order of magnitude indicated, an inhibitory effect of enterocin CCM4231 in “bryndza”. However, bacteriocin activity was not determined by laboratory analyses.     

Systematic implications of the sesquiterpene lactones in the “strumarium” morphological complex (Xanthium strumarium, Asteraceae) of Europe, Asia and Africa

In most populations of the “strumarium” morphological complex of Xanthium strumarium L. (sensu lato) in northern Europe and in India, a new compound, xanthinosin, is the only detectable sesquiterpene lactone. In populations of this morphological complex in Portugal and Egypt as well as in eastern Asia, USSR, Korea, Hong Kong and Taiwan, xanthinin and xanthatin occur as major constituents along with xanthinosin. Experimental F, hybrids between pistillate Indian plants which contained only xanthinosin and staminate plants from Hong Kong which contained a mixture of xanthinin, xanthatin and xanthinosin produced a mixture of compounds in which the percentage of xanthinin increased relative to its percentage in the Hong Kong parent. The sesquiterpenoid data suggest that the various taxa in the “strumarium” morphological complex can be divided into three groups: (a) X. strumarium (sensu stricto) and X. indicum König, containing primarily or exclusively xanthinosin; (b) X. sibiricum Patrin and X. brasilicum Vell., with xanthinin and xanthinosin predominating; and (c) X. inaequilaterum DC., with almost equal proportions of xanthinin, xanthatin and xanthinosin. Two other taxa of the complex. X. japonicum Widd. and X. abyssinicum Wallr., were not available for inclusion in the present study.     

Amoebophrya spp. from the Bloom‐forming Dinoflagellate Cochlodinium polykrikoides: Parasites not Nested in the “Amoebophrya ceratii Complex”

Members of Amoebophrya ceratii complex are known to infect a number of free‐living dinoflagellates including harmful algal bloom species. In August and October 2012, Amoebophrya infections during two bloom events of the dinoflagellate Cochlodinium polykrikoides were observed along southern coastal waters of Korea. Microscopic observations and molecular data revealed that two different Amoebophrya parasites infected the same host species. In addition, while one developed in the host's nucleus, the other in the host's cytoplasm. Phylogenetic analyses showed that the two parasites were not nested in the previously recognized “Amoebophrya ceratii complex clade”, which contained sequences of parasites infecting numerous dinoflagellate species. Instead, they branched as sister taxa to the isolate (possibly Amoebophrya) from radiolarians Hexacontium gigantheum. Our result indicates that the two Amoebophrya parasites infecting C. polykrikoides may be different species from those inside the “complex.”     

Phylogenetic relationships in the harmful dinoflagellate Cochlodinium polykrikoides (Gymnodiniales, Dinophyceae) inferred from LSU rDNA sequences

Phylogenetic relationships among chain-forming Cochlodinium species, including the harmful red tide forming dinoflagellate Cochlodinium polykrikoides, were investigated using specimens collected from coastal waters of Canada, Hong Kong, Japan, Korea, Malaysia, México, Philippines, Puerto Rico, and USA. The phylogenetic tree inferred from partial (D1–D6 regions) large subunit ribosomal RNA gene (LSU rDNA) sequences clearly differentiated between C. polykrikoides and a recently described species, Cochlodinium fulvescens. Two samples collected from the Pacific coasts of North America (British Columbia, Canada and California, USA) having typical morphological characters of C. fulvescens such as the sulcus located in the intermediate region of the cingulum, were closely related to C. fulvescens from western Japan in the phylogenetic tree. Cochlodinium polykrikoides formed a monophyletic group positioned as a sister group of the C. fulvescens clade with three well-supported sub-clades. These three clades were composed of (1) East Asian, including specimens collected from Hong Kong, western Japan, and southern Korea, (2) Philippines, from Manila Bay, Philippines and Omura Bay, Japan, and (3) American/Malaysian, from the Atlantic coasts of USA, the Pacific coast of México, Puerto Rico, and Borneo Island, Malaysia. Each of these clades is considered to be a so-called “ribotype” representing the population inhabiting each region, which is distinguished based on ribosomal RNA gene sequences in the species despite similarities in their morphological characters.     

Is inorganic nutrient enrichment a driving force for the formation of red tides?: A case study of the dinoflagellate Scrippsiella trochoidea in an embayment

Red tides (high biomass phytoplankton blooms) have frequently occurred in Hong Kong waters, but most red tides occurred in waters which are not very eutrophic. For example, Port Shelter, a semi-enclosed bay in the northeast of Hong Kong, is one of hot spots for red tides. Concentrations of ambient inorganic nutrients (e.g. N, P), are not high enough to form the high biomass of chlorophyll a (chl a) in a red tide when chl a is converted to its particulate organic nutrient (N) (which should equal the inorganic nutrient, N). When a red tide of the dinoflagellate Scrippsiella trochoidea occurred in the bay, we found that the red tide patch along the shore had a high cell density of 15,000 cells ml⁻¹, and high chl a (56 μg l⁻¹), and pH reached 8.6 at the surface (8.2 at the bottom), indicating active photosynthesis in situ. Ambient inorganic nutrients (NO₃, PO₄, SiO₄, and NH₄) were all low in the waters and deep waters surrounding the red tide patch, suggesting that the nutrients were not high enough to support the high chl a >50 μg l⁻¹ in the red tide. Nutrient addition experiments showed that the addition of all of the inorganic nutrients to a non-red-tide water sample containing low concentrations of Scrippsiella trochoidea did not produce cell density of Scrippsiella trochoidea as high as in the red tide patch, suggesting that nutrients were not an initializing factor for this red tide. During the incubation of the red tide water sample without any nutrient addition, the phytoplankton biomass decreased gradually over 9 days. However, with a N addition, the phytoplankton biomass increased steadily until day 7, which suggested that nitrogen addition was able to sustain the high biomass of the red tide for a week with and without nutrients. In contrast, the red tide in the bay disappeared on the sampling day when the wind direction changed. These results indicated that initiation, maintenance and disappearance of the dinoflagellate Scrippsiella trochoidea red tide in the bay were not directly driven by changes in nutrients. Therefore, how nutrients are linked to the formation of red tides in coastal waters need to be further examined, particularly in relation to dissolved organic nutrients.     

Study of phytoplankton characteristics in Tolo Harbour,Hong Kong,by HPLC analysis of chemotaxonomic pigments

Spatial and seasonal characteristics of phytoplankton in Tolo Harbour, Hong Kong, were studied by microscopic observation of phytoplankton samples and HPLC analysis of chemotaxonomic pigments. Diatoms dominated the phytoplankton. Common diatoms included Skeletonema costatum and species of Cerataulina, Leptocylindrus, Pseudo-nitzschia and Thalassiosira. Dinoflagellates occurred sporadically and mainly in the inner part of the harbour. The dinoflagellate Scrippsiella trochoidea was the causative organism for the red tide occurrences in March, April and September 2001. Significant positive correlations between fucoxanthin and diatoms and between peridinin and dinoflagellates suggested that fucoxanthin and peridinin were valuable chemotaxonomic markers for diatoms and dinoflagellates, respectively. Analysis of pigment ratios revealed that red tide events caused by dinoflagellates were marked by increase in the value of PERI:chl a and decrease in the value of FUCO:chl a. Increase in the value of FUCO:chl a also revealed the presence of a dense population of Pseudo-nitzschia that was not indicated by increase in chlorophyll a and fucoxanthin concentrations. Pigment analysis also revealed the presence of cyanobacteria, silicoflagellates, cryptophytes and green algae in the surface waters of Tolo Harbour.     

A review of the molecular evidence for ballast water introduction of the toxic dinoflagellates Gymnodinium catenatum and the Alexandrium “tamarensis complex” to Australasia

The potential of ballast water to act as a major introduction vector for toxic dinoflagellates and other phytoplankton is beyond doubt; however, evidence that links the suspected introduced species with a source population is less convincing, especially without supporting historical and biochemical data, or consideration of palaeobiogeographical scenarios that may explain current species distributions. This paper presents new molecular data based on LSU-rDNA and rDNA-ITS sequences that demonstrate an unequivocal and recent link between Temperate Asian and Australasian populations of the toxic dinoflagellates Gymnodinium catenatum and toxic strains of the Alexandrium “tamarensis complex”. We integrate our data with supporting evidence from historical distribution records, sediment dating studies, toxin profiles, mating studies and previous molecular studies. We contrast the observed patterns of genetic and biochemical variation with those expected from various palaeobiogeographical scenarios explaining the evolution and natural dispersal of both species. While definitive proof is impossible, the total evidence indicates that these toxic dinoflagellates were introduced to Australasia during the past 100 years, most probably via ballast water from bulk-cargo shipping from Japan and/or south-east Asia.     

Photosynthetic characteristics of the economic brown seaweed <Emphasis Type="BoldItalic">Hizikia fusiforme</Emphasis> (Sargassaceae,Phaeophyta), with special reference to its “leaf” and receptacle

Photosynthetic responses to irradiance and temperature of “leaves” and receptacles were compared in February (vegetative stage) and May (reproductive stage) in the seaweed, Hizikia fusiforme (Harvey) Okamura (Sargassaceae, Phaeophyta) from Nanao Island, Shantou, China. Irradiance-saturated photosynthesis (P_max) was significantly higher in receptacles than in “leaves” on a fresh weight basis, and that of “leaves” was greater in May than in February at ambient seawater temperatures. The optimum temperature for P_max was 30^∘C for both “leaves” and receptacles, being 5–10^∘C higher than the ambient seawater temperature. The apparent photosynthetic efficiencies were greater in receptacles than in “leaves” within the tested temperature range of 10–40^∘C. The irradiance for saturating photosynthesis for both “leaves” and receptacles was temperature-dependent, with the highest values (about 200μmolphotonsm⁻²s⁻¹) at 30^∘C.     

The nature and affinities of the “robust” Australopithecines: a review

The fossil evidence of the “robust” australopithecines is reviewed with an emphasis on the taxonomic divisions and evolutionary relationships among this group of hominids. The hypodigms of A. robustus, A. crassidens and A. boisei are described, and the significance of morphological variation within and between these species is assessed. Phylogenetic relationships among the “robust” australopithecines are examined using maximum parsimony analysis, and evolutionary scenarios are evaluated in the light of recent discoveries in East Africa.     

香港西贡牛尾海邻近岛屿植被与植物物种多样性

牛尾海是连接香港陆地和南中国海的重要通道.作者采取全面普查和重点线路补查的方法,于1997年8月、12月和2008年6月先后3次考察了牛尾海邻近各岛屿的植被概况和植物种类.结果表明,牛尾海邻近岛屿共有维管束植物345种,隶属于108科254属.植被类型以灌丛和草灌丛为主,兼有次生性常绿阔叶林和滨海砂生植被,并有相当数量...     

“Menstrual induction” with sulproston

The PGE₂-analogue Sulproton (16-phenoxy·ω-17,18,19,20-tetranor-PGE₂-mythylsulfonylamide) was administered to 200 medically and gynecologically normal women who were 17±0.4 days beyond their expected menstrual period and who had a positive pregnancy test. The intramuscular impact dose (500 μg repeated after 4 hours) caused an immediate tonic uterine contraction which compromised the estradiol 17β, progesterone and chorionic gonadotropin production within the fetoplacental unit, and thereby allowed the evolution of cyclic uterine activity, cervical dilatation and tissue expulsion.Pregnancy termination was complete in 92% of women, 5.5% required surgical curettage and 2.5% were given a second Sulproston treatment 2–3 weeks after the first to remove retained tissue from the uterus. The medical induction of menstruation was preferred by 83% of the women who had previously experienced surgical termination of pregnancy. Normal menstruation resumed in all women after 36±0.9 days. The majority of 42 women questioned found Sulproston a satisfactory, safe, simple and effective drug regimen for “menstrual induction”.     

Acid dissociation constants and pH values for standard “bes” and “tricine” buffer solutions in 30, 40, and 50 mass% dimethyl sulfoxide/water between 25 and −25 °C

Information is given concerning two standard buffer solutions suitable as pH references in 30, 40, and 50 mass% dimethyl sulfoxide (DMSO)/H₂O mixed solvents at subzero temperatures from −20 to 0 °C, with the intention of establishing a pH (designated pH^*) scale. The two buffers selected were the ampholytes N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid (“bes”) and N-tris(hydroxymethyl)methylglycine (“tricine”), and the reference standard consisted of equal molal quantities of the buffer and its respective sodium salt. The assignment of pH^* values was based on measurements of the emf of cells without liquid junction of the type: Pt;H₂(g,1 atm) ¦Bes, Na Besate, NaCl ¦ AgCl;Ag and Pt;H₂(g,1 atm) ¦Tricine, Na Tricinate, NaCl ¦AgCl;Ag and the pH^* was derived from a determination of K₂, the equilibrium constant for the dissociation process (Buffer)^±/ai (Buffer)⁻ + H⁺.     

Flexibility versus “rigidity” of the functional architecture of AChE active center

Functional architecture of the AChE active center appears to be characterized by both structural “rigidity”, necessary to stabilize the catalytic triad as well as by flexibility in accommodating the different, high affinity AChE ligands. These seemingly conflicting structural properties of the active center are demonstrated through combination of structural methods with kinetic studies of the enzyme and its mutant derivatives with plethora of structurally diverse ligands and in particular with series of stereoselective covalent and noncovalent AChE ligands. Thus, steric perturbation of the acyl pocket precipitates in a pronounced stereoselectivity toward methylphosphonates by disrupting the stabilizing environment of the catalytic histidine rather than through steric exclusion demonstrating the functional importance of the “rigid” environment of the catalytic machinery. The acyl pocket, the cation-binding subsite (Trp86) and the peripheral anionic subsite were also found to be directly involved in HuAChE stereoselectivity toward charged chiral phosphonates, operating through differential positioning of the ligand cationic moiety within the active center. Residue Trp86 is also a part of the “hydrophobic patch” which seems flexible enough to accommodate the structurally diverse ligands like tacrine, galanthamine and the two diastereomers of huperzine A. Also, we have recently discovered further aspects of the role of both the unique structure and the flexibility of the “hydrophobic patch” in determining the reactivity and stereoselectivity of HuAChE toward certain carbamates including analogs of physostigmine. In these cases the ligands are accommodated mostly through hydrophobic interactions and their stereoselectivity delineates precisely the steric limits of the pocket. Hence, the HuAChE stereoselectivity provides a sensitive tool in the in depth exploration of the functional architecture of the active center. These studies suggest that the combination of “rigidity” and flexibility within the HuAChE gorge are an essential element of its molecular design.     

A biochemical approach toward the systematics of the Leptothorax “muscorum”Group in North America (Hymenoptera: Formicidae)

Enzyme patterns have been used to distinguish among a number of morphologically very similar ant species belonging to the Leptothorax “muscoru” group in North America. Not counting the already described species L. retractus, L. sphagnicolus and L. crassipilis, the complex apparently consists of at least three or four more different taxa.     

Silurian calcispheres (Calcitarcha) of Gotland (Sweden): Comparisons with calcareous dinoflagellates

Scanning electron microscope examinations of polished and etched surfaces of sediments from the Silurian carbonate platform of Gotland, Sweden, revealed the presence of numerous, morphologically diverse “calcispheres” (Calcitarcha). Some of these spherical calcareous microfossils display wall structures that are surprisingly similar to those of calcareous dinoflagellate cysts. In analogy to the interpretation of the biological affinities of Palaeozoic acritarchs as cysts of organisms that might have been the ancestors of organic-walled dinoflagellates, the Calcitarcha from Gotland can be compared and may possibly be related to organisms that may have been the ancestors of calcareous cyst-producing dinoflagellates that so far have not been observed before the Late Jurassic.