Occasional pathogenic bacteria promoting ice-ice disease in the carrageenan-producing red algae Kappaphycus alvarezii and Eucheuma denticulatum (Solieriaceae,Gigartinales, Rhodophyta)

The bacterial isolates from normal and diseased branches of Kappaphycus alvarezii and Eucheuma denticulatum in the Philippines were examined for possible role in the development of the ice-ice disease. The numbers of bacteria on and in ice-iced branches were 10–100 times greater than those from normal, healthy ones. Gram-positive bacteria predominated in almost all branch sources, but with an increasing proportion of agar-lysing bacteria in branches suffering from the ice-ice disease. These agar-lysing bacteria were composed of yellow and non-pigmented, spreading colonies identified to the Cytophaga-Flavobacterium complex and the Vibrio group. Among isolates which mainly appeared on ice-iced branches, two strains, designated as P11 (Vibrio sp.) and P25 (Cytophage sp.), which showed pathogenic activity, were obtained. These strains caused early ice-ice whitening of K. alvarezii especially when subjecting branches to environmental stress, such as reduced salinity and light intensity, suggesting that these bacteria were occasionally pathogenic. This paper offers new evidence of bacterial role in the development of so-called ice-ice disease among farmed species of Kappaphycus.     

Specific bleaching of phycobiliproteins from cyanobacteria and red algae at high temperature in vivo

Exposure of blue-green or red algal cells to temperatures exceeding 60–65°C for several minutes resulted in bleaching of all phycobilin absorption in the visible range, with virtually no alteration in chlorophyll or carotenoid absorption. Difference spectra of non-bleached vs bleached cells appeared identical to absorption spectra of purified phycobilisomes isolated from the same cell culture in high phosphate medium. All phycobilin chromophores were bleached at approximately the same rate during heating. There were no changes in apparent molecular weights or relative amounts of the phycobilisome apoproteins during chromophore bleaching. Phycobilisomes in cell extracts from Anacystis nidulans resisted bleaching when suspended in medium of high phosphate concentration, but were bleached at 60–65°C within a few minutes when placed in diluted medium. The results indicate that phycobilisomes in vivo are stabilized by a mechanism other than high osmotic and ionic strength. This represents a rapid and quantitative method to characterize the phycobiliprotein content of cyanobacteria and red algae in vivo.Abbreviations Chl chlorophyll - APC allophycocyanin - PC phycocyanin - PE phycoerythrin - SPM medium, 0.2 M sucrose, 15 mM MgCl₂, 0.75 M Na/KPO₄, pH 7.8     

Life history and reproductive potential of the agarophyte Gelidium robustum in California

The reproductive potential of the tetrasporangial phase of Gelidium robustum was studied for 16 months at two sites off Santa Barbara, California. In all samples tetrasporangial thalli were always more abundant than gametangial ones. Tetratrasporangial sori were present throughout the duration of the study but relative fecundity was highest [300–400 sori g^–1 (w. wt)] in spring/summer samples of consecutive years, as a result of increasing numbers both of tetrasporangial branchlets per plant and of sori per branchlet. On the other hand, laboratory experiments showed that tetraspore release per sorus was highest (150–250 spores sorus^–1 d^–1) in winter. Inferring from these field and laboratory data plants released up to ± 34 000 tetraspores g^–1 (w. wt) d^–1 in the spring/summer of the second study year. Tetraspore germination, under defined culture conditions, also showed a marked seasonality increasing sharply from less than 10% in winter up to almost 60% in spring/summer, thus coinciding with the period of maximal spore output per plant. These results suggest that although relatively high numbers of tetraspores may be released by G. robustum plants all year round these might not always have the potential to germinate and recruit.     

Laboratory-induced development of the ice-ice disease of the farmed red algae Kappaphycus alvarezii and Eucheuma denticulatum (Solieriaceae,Gigartinales, Rhodophyta)

The most common perception of unfavorable environmental factors causing the ice-ice disease in the farmed seaweeds, Kappaphycus and Eucheuma, was demonstrated in this study for the first time using stressful conditions of abiotic factors in a continuous culture system. Light intensity of less than 50 mol photon m^–2 s^–1 and salinity of 20% or less induced ice-ice whitening characterized by short segments at midbranches which were similar to those observed in the Philippine seaweed farms, while temperatures of up to 33–35 °C resulted in wide-scale whitening leading to complete damage of the branches. These effects were preceded by slow growth rates from an optimum of 3.7% d^–1 to almost –2.0% d^–1. Mechanical stress by wound injury did not result to ice-ice whitening similar to the above. Environmental factors observed to trigger ice-ice in the laboratory, although may not necessarily parallel those in the field, may act synergestically to produce similar effects.     

Molluscan diversity in tidal marshes along the Scheldt estuary (The Netherlands, Belgium)

The mollusc fauna of 64 sites in 31 tidal marshes was surveyed along a salinity gradient from freshwater to marine conditions in the river Scheldt (Belgium–The Netherlands). A total of 10649 specimens involving 31 taxa were identified. Salinity turned out to be a major factor in mollusc assemblages in the Scheldt estuary, but other factors can not be excluded. In the marine part five species were common, compared to the brackish part where only Assiminea grayana was abundant. In the freshwater zone species richness was highest (24). There was a significant correlation between flooding frequency and species richness in the tidal freshwater marsh `Durmemonding'. Finally, the survey confirmed the distribution of the amphibious hygromiid snail Pseudotrichia rubiginosa, a species which in Belgium only occurs in the marshes of the tidal freshwater part of the Scheldt and its tributaries.     

Mackerel from the northern indian ocean and the red sea arescomber australasicus, notscomber japonicus

The population ofScomber from the Red Sea and northern Indian Ocean (gulfs of Aden and Oman) is identified asS. australasicus rather thanS. japonicus based on having 30–33 vs. 26–29 interneural bones under the first and second dorsal fins and the combination of interneural bone counts of 16–20 under the first dorsal fin (vs. 13–16) and first dorsal fin spine counts of 10–13 (vs. 9–10). These are the best morphological characters to distinguish these two species. This change in identification constitutes a major range extension forS. australasicus which was thought to be restricted to the Pacific Ocean and the southeastern Indian Ocean around Western Australia.     

Feeding chronology and habits of Alosa spp. (Clupeidae) juveniles from the lower Hudson River estuary, New York

Synopsis Feeding habits of juvenile alewife, A. pseudoharengus, blueback herring, A. aestivalis, and American shad, Alosa sapidissima, were examined over a 24 h period at an inshore location on the lower Hudson River. Feeding periodicity differed by species: alewives showed no diel differences, whereas shad fed least intensively near dawn and herring least intensively at night. Alewives fed primarily on chironomids and the amphipod Corophium lacustre, shad on Formicidae and larval chironomids, and herring on chironomids and copepods. Diel variation in prey selection was evident. Dietary overlap was generally greatest between alewife and herring and least between shad and herring.     

Temporal dynamics and spatial variation of algae in relation to hydrology and sediment characteristics in the Okefenokee Swamp,Georgia

In a 20-month study, phytoplankton and periphyton chl a, and dry mass of macroscopic algal aggregates in four marshes and a lake within the Okefenokee Swamp (Georgia, USA) were comparable to other wetlands and lake littoral areas. Chlorophyll levels in two marshes were inversely related to water level and phytoplankton at three marshes developed unimodal maxima following macrophyte dieback. Standing stocks in a vernally inundated marsh were greater than a nearby marsh which was permanently inundated; chlorophyll levels displayed longer blooms in the inundated marsh during periods of low rainfall or after drought. Field dynamics, sediment sorption characteristics and algal bioassays suggest that evaporative drawdown stimulates algae by release of nutrients from exposed peat, while high water levels reduce nutrient release from sediments and disperse phytoplankton through flushing. Equilibrium phosphate concentrations of sediments and algal levels were higher at an abandoned rookery than a nearby non-rookery area, indicating nutrient enrichment from residual guano deposits.     

The effect of dung beetle activity on the discharge ofPilobolus (Fungi,mucorales) sporangia in cattle,sheep and horse faeces

The effect ofAphodius sphacelatus andA. ater activity in cattle faeces andSphaeridium bipustulatum in sheep and horse faeces on the discharge ofPilobolus sporangia was investigated under laboratory conditions. In five trials, the median number of sporangia produced was significantly less (P<0.01) in experimental chambers (with 1 or 2 beetles/g faeces) than in control chambers (without beetles). In addition, median percentage reduction of sporangia was significantly higher (P<0.01) forA. sphacelatus (80.9%) than forA. ater (56.9%) at 1 beetle/g cattle faeces.

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Résumé L'effet de l'activité d'Aphodius spacelatus et deA. ater dans les bouses de vaches et deSphaeridium bipustulatum dans les fèces de moutons et de chevaux, sur la libération de sporanges parPilobolus a été étudié en conditions de laboratoire. Sur 5 essais le nombre médian de sporanges libérés dans des cellules expérimentales (avec 1 ou 2 bousiers/g fèces) était significativement inférieur (P<0.01) à celui obtenu dans des cellules témoins (sans bousier). De plus, le pourcentage médian de réduction des sporanges est significativement plus élevé (P<0,01) pourA. sphacelatus (80,9%) que pourA. ater (56,9%) à la densité de 1 bousier/g de bouse.

     

Seawater adaptability of underyearling coho,chinook and chum salmons in the estuary of Avacha River (Kamchatka)

Synopsis The 96 h LC50 tests were conducted with chum, coho and chinook salmon alevins caught in the Avacha River (Kamchatka) estuary. Coho and chinook alevins exhibited very low seawater a adaptability when compared with chum. It is likely that coho and chinook young were pulled downstream by high velocity flow during the summer freshets.     

Seasonal changes in situ grazing of the mesoherbivores Idotea baltica and Gammarus oceanicus on the brown algae Fucus vesiculosus and Pylaiella littoralis in the central Gulf of Finland, Baltic Sea

The in situ grazing experiments were performed in the shallow water rocky habitat of the northern Baltic Sea during ice-free season 2002. In the experiments the effects of algal species and choice on the grazing of the mesoherbivores Idotea baltica (Pallas) and Gammarus oceanicus Segerstråle were tested. Salinity, temperature, concentration of nutrients in water and macroalgae and net production of macroalgae were considered as random effects in the analysis. The invertebrate feeding rate was mainly a function of the net photosynthetic activity of Pylaiella littoralis (L.) Kjellman and Fucus vesiculosus L. Feeding rate increased significantly with decreasing algal photosynthetic activity. When the two algal species were incubated together invertebrates fed primarily on P. littoralis. Low selectivity towards P. littoralis coincided with its high photosynthetic activity. The presence of F. vesiculosus did not modify the invertebrate feeding on P. littoralis. The results indicated that (1) the grazing on F. vesiculosus depended on the availability of P. littoralis, (2) the photosynthetic activity of algae explained the best the variation in grazing rate and (3) the grazers are not likely to control the early outbreak of filamentous algae in the northern Baltic Sea by avoiding young and photosynthetically active algae. The likely mechanism behind the relationship is that the increased photosynthetic activity of macroalgae coincides with their higher resistance to herbivory.     

A fish kill of massive proportion in Kuwait Bay, Arabian Gulf, 2001: the roles of bacterial disease, harmful algae, and eutrophication

In August and September 2001, Kuwait Bay, a semi-enclosed embayment of the Arabian Gulf, experienced a massive fish kill involving over >2500 metric tons of wild mullet (Liza klunzingeri), due to the bacterium Streptococcus agalactiae. In the Bay, this event was preceded by a small fish kill (100–1000 dead fish per day) of gilthead sea bream (Sparus auratus) in aquaculture net pens associated with a bloom of the dinoflagellate Ceratium furca. Sea bream were found to be culture positive for S. agalactiae, but did not show any visible signs of disease. Unusually warm temperatures (up to 35 °C) and calm conditions prevailed during this period. As the wild fish kill progressed, various harmful algae were observed, including Gymnodinium catenatum, Gyrodinium impudicum, and Pyrodinium bahamense var. compressum. Cell numbers of G. catenatum and G. impudicum exceeded 10⁶ l⁻¹ in some locations. All fish tested below the limits of detection for paralytic shellfish poisoning (PSP) and brevetoxins. Clams (Circe callipyga) were positive for PSP but at levels below regulatory limits. Nutrient concentrations, both inorganic and organic, were highly variable with time and from site to site, reflecting inputs from sewage outfalls, the aquaculture operations, a high biomass of decomposing fish, and other sources. It is hypothesized that many factors contributed to the initial outbreak of the bacterial disease, including unusual warm and calm conditions. The same factors, as well as enriched nutrient conditions, also apparently were conducive to the subsequent HAB outbreaks. The detection of PSP, while below regulatory limits, warrants further monitoring to protect human health.     

Quantification and characterization of nuclear genomes in commercial red seaweeds (Gracilariales) from the Philippines

Eight species of Gracilariaceae from the Philippines, representing the generaGracilaria, Gracilariopsis andHydropuntia, were investigated to quantify and characterize their nuclear genomes. DNA reassociation kinetics were used to determine nuclear genome organization and complexity in six of these species. Results indicate the presence of three second order components corresponding to fast, intermediate and slow fractions. Repetitive sequences varied from 13–74% and unique DNA ranged from 26–84%. Microspectrophotometry with the DNA-localizing fluorochrome DAPI was used to quantify nuclear DNA contents. Comparisons of mean nuclear DNA (I _f ) values to chicken erythrocytes (RBC) resulted in an estimate of 0.38–0.43 pg/2 C genomes for seven of the species investigated. Preliminary analyses of agar content and quality confirm the economic potential ofGracilaria firma, Gracilaria sp. 2 from Sorsogon andGracilariopsis bailinae. Nuclear genome profiles developed from data for genome size, organization and complexity are compared with data for agar quantity and quality. Gel quality and quantity do not appear to be correlated with either large repetitive fraction DNA or a high degree of genome complexity.Author for correspondence     

Microalgal biotechnology: Carotenoid and glycerol production by the green algae <Emphasis Type="Italic">Dunaliella</Emphasis> isolated from the Gave-Khooni salt marsh,Iran

In this study, carotenoid and glycerol production in two unicellular green algae (Dunaliella salina and D. viridis) isolated from the Gave-Khooni salt marsh grown in media containing five different salt concentrations (0.17, 1, 2, 3, and 4 M NaCl) were evaluated under sterile conditions. Algae growth decreased as the medium salinity increased. Optimum growth of D. salina and D. viridis were obtained at 2 and 1 M NaCl, respectively. As salinity increased, glycerol and carotenoid production were increased in D. salina, whereas lower values for these products were produced in D. viridis under the same conditions. Furthermore, the cell color of D. salina changed from green to orange-red following accumulation of carotenoid, but the color of D. viridis was not changed. Thereby, it seems that the Iranian D. salina may be suitable for carotenoid production (betacarotene) on a large scale. In addition, since carotenoid compounds enhance the efficiency of photosynthesis and glycerol synthesis, it appears that the pathway for glycerol production and mechanisms of salt tolerance in D. viridis are unique from those of D. salina.     

Effects of white,blue, red light and darkness on pH of the apoplast in the Samanea pulvinus

Leaflet movements in Samanea saman (Jacq.) Merrill are driven by fluxes of K⁺, anions, and water through membranes of motor cells in the pulvinus (R.L. Satter et al., 1974, J. Gen. Physiol. 64, 413–430). Extensor cells take up K⁺ and swell in white light (WL) while flexor cells take up K⁺ and swell in darkness (D). Excised strips of extensor and flexor motor tissue acidify their bathing medium under conditions that normally promote increase in K⁺ in the intact tissue, and alkalize the medium under conditions that normally induce decrease in K⁺ (A. Iglesias and R.L. Satter, 1983, Plant Physiol. 72, 564). To obtain information on pH changes in the whole pulvinus, we measured effects of light on pH of the apoplast, using liquid membrane microelectrodes sensitive to H⁺. We report the following: (1) The pH of the extensor apoplast was higher than that of the flexor apoplast in WL and in D (pH gradient of 1.0 units in WL and 2.0 units in D). Apoplastic pH might affect K⁺ transport through the plasma membranes of Samanea motor cells, since the conductance, gating, and selectivity of ionic channels in other systems depend upon external pH. (2) Extensor cells acidified and flexor cells alkalized their environment in response to irradiation with WL, while the reverse changes occurred in response to D. These results are consistent with the results of Iglesias and Satter (1983), and support the physiological relevance of data obtained with excised tissue. (3) The pH changes in response to irradiation with red light were similar to those obtained with D; also, the pH changes in response to blue light were similar to those obtained with WL. The pulvinus closed in red light as in darkness and opened in WL, but failed to open in blue light. The advantages and limitations of apoplastic pH measurements for assaying H⁺ transport are discussed.Abbreviations BL blue light - D darkness - RL red light - WL white light     

Freezing and desiccation injury resistance in the filamentous green alga Klebsormidium from the Antarctic, Arctic and Slovakia

The freezing and desiccation tolerance of 12 Klebsormidium strains, isolated from various habitats (aeroterrestrial, terrestrial, and hydro-terrestrial) from distinct geographical regions (Antarctic — South Shetlands, King George Island, Arctic — Ellesmere Island, Svalbard, Central Europe — Slovakia) were studied. Each strain was exposed to several freezing (−4°C, −40°C, −196°C) and desiccation (+4°C and + 20°C) regimes, simulating both natural and semi-natural freeze-thaw and desiccation cycles. The level of resistance (or the survival capacity) was evaluated by chlorophyll a content, viability, and chlorophyll fluorescence evaluations. No statistical differences (Kruskal-Wallis tests) between strains originating from different regions were observed. All strains tested were highly resistant to both freezing and desiccation injuries. Freezing down to −196°C was the most harmful regime for all studied strains. Freezing at −4°C did not influence the survival of studied strains. Further, freezing down to −40°C (at a speed of 4°C/min) was not fatal for most of the strains. RDA analysis showed that certain Antarctic and Arctic strains did not survive desiccation at +4°C; however, freezing at −40°C, as well as desiccation at +20°C was not fatal to them. On the other hand, other strains from the Antarctic, the Arctic, and Central Europe (Slovakia) survived desiccation at temperatures of +4°C, and freezing down to −40°C. It appears that species of Klebsormidium which occupy an environment where both seasonal and diurnal variations of water availability prevail, are well adapted to freezing and desiccation injuries. Freezing and desiccation tolerance is not species-specific nor is the resilience only found in polar strains as it is also a feature of temperate strains. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia. This paper is dedicated to the memory of the late Dr. Bohuslav Fott (1908–1976), Professor of Botany at the Charles University in Prague, to mark the centenary of his birth.     

Studies on the age and growth of the bata,Labeo bata (Ham.) (Cyprinidae,Teleostei) from the river Kali,India

Age and growth of Labeo bata (Ham.) was studied by the analysis of annuli found on the scale and by length-frequency distribution. The fish attained lengths of 131, 194, 236, 277, 314, 341 and 364 mm at the end of the 1st, 2nd, 3rd, 4th, 5th, 6th and 7th years of life respectively. The increase in length of scale bears a constant relationship with the increase in length of fish, and regression analysis yielded a straight line between scale and body length. Calculated values could be expressed as: Y = –2.534 + 0.064 XThe growth rate of the fish was found high during the 1st and 2nd years and decreased gradually afterwards till the 7th year. Both sexes showed more a or less similar growth rate and attained a similar longevity. Growth trend of the fish confirmed the von Bertalanffy growth equation: Lt = 450(l–e^{–0.2165(t+0.5963))} The seasonal growth curve was chiefly influenced by feeding intensity in fishes of 1st year class while in adults it was affected by feeding intensity as well as by maturation of the gonads.     

A new pelagic marine rotifer from the southern Benguela,Synchaeta hutchingsi,n. sp., with notes on its temperature and salinity tolerance and methods of culture

A new species of marine rotifer is described from the S.E. Atlantic off Cape Town. Synchaeta hutchingsi n. sp. is unique among the approximately 36 recognized Synchaeta species in exhibiting the following combination of characters: single sharply pointed toe; slender bristle along ventral midline of foot: single lateral antenna on left side near foot base; spur on dorsal side of foot used to carry egg; total length 165–200 µm. Salinity tolerance experiments showed the new species to be obligate brackwater/marine; a temperature of 35 °C could be tolerated for a short period of time. The new species has been mass-cultured for use as an experimental live food for rearing marine fish larvae.