Iridaea cordata (Gigartinales, Rhodophyta): responses to artificial UVB radiation

The effects of UVB radiation on the different developmental stages of the carrageenan-producing red alga Iridaea cordata were evaluated considering: (1) carpospore and discoid germling mortality; (2) growth rates and morphology of young tetrasporophytes; and (3) growth rates and pigment content of field-collected plant fragments. Unialgal cultures were submitted to 0.17, 0.5, or 0.83 W m(-2) of UVB radiation for 3 h per day. The general culture conditions were as follows: 12 h light/12 h dark cycles; irradiance of 55 mu mol photon. per square meter per second; temperature of 9 +/- 1 degrees C; and seawater enriched with Provasoli solution. All UVB irradiation treatments were harmful to carpospores (0.17 W m(-2) = 40.9 +/- 6.9%, 0.5 W m(-2) = 59.8 +/- 13.4%, 0.83 W m(-2) = 49 +/- 17.4% mortality in 3 days). Even though the mortality of all discoid germlings exposed to UVB radiation was unchanged when compared to the control, those germlings exposed to 0.5 and 0.83 W m(-2) treatments became paler and had smaller diameters than those cultivated under control treatment. Decreases in growth rates were observed in young tetrasporophytes, mainly in 0.5 and 0.83 W m(-2) treatments. Similar effects were only observed in fragments of adult plants cultivated at 0.83 W m(-2). Additionally, UVB radiation caused morphological changes in fragments of adult plants in the first week, while the young individuals only displayed this pattern during the third week. The verified morphological alterations in I. cordata could be interpreted as a defense against UVB by reducing the area exposed to radiation. However, a high level of radiation appears to produce irreparable damage, especially under long-term exposure. Our results suggest that the sensitivity to ultraviolet radiation decreases with increased algal age and that the various developmental stages have different responses when exposed to the same doses of UVB radiation.

Life history, morphological variability and growth rates of the life phases of Gracilaria tenuistipitata (Rhodophyta: Gracilariales) in vitro

Gracilaria tenuistipitata, a species of commercial interest, is becoming a model organism for studies on red algal physiology and molecular biology as it can be grown easily in vitro under a broad range of conditions. Most of the experiments carried out around the world have been based on a tetrasporophytic clone isolated in our laboratory from a specimen collected in China. Here we describe the life history of this species, give anatomic details of the reproductive structures, illustrate the morphological variability of tetraspore progeny and compare the growth rate of gametophytic and sporophytic thalli. Tetrasporophytic branches showed higher growth rates than gametophytic branches.

Fungal community associated with marine macroalgae from Antarctica

Filamentous fungi and yeasts associated with the marine algae Adenocystis utricularis, Desmarestia anceps, and Palmaria decipiens from Antarctica were studied. A total of 75 fungal isolates, represented by 27 filamentous fungi and 48 yeasts, were isolated from the three algal species and identified by morphological, physiological, and sequence analyses of the internal transcribed spacer region and D1/D2 variable domains of the large-subunit rRNA gene. The filamentous fungi and yeasts obtained were identified as belonging to the genera Geomyces, Antarctomyces, Oidiodendron, Penicillium, Phaeosphaeria, Aureobasidium, Cryptococcus, Leucosporidium, Metschnikowia, and Rhodotorula. The prevalent species were the filamentous fungus Geomyces pannorum and the yeast Metschnikowia australis. Two fungal species isolated in our study, Antarctomyces psychrotrophicus and M. australis, are endemic to Antarctica. This work is the first study of fungi associated with Antarctic marine macroalgae, and contributes to the taxonomy and ecology of the marine fungi living in polar environments. These fungal species may have an important role in the ecosystem and in organic matter recycling.

The seaweed flora of Admiralty Bay, King George Island, Antarctic

Admiralty Bay is located on the western side of King George Island. Although several research teams of different nationalities have carried out surveys in the region for decades, there are only two publications dealing with the seaweed flora of the bay. Here, we report on a taxonomic survey of the seaweeds we collected during the 25th Brazilian Antarctic Expedition (December 2006/November 2007). We discovered 42 species (21 Rhodophyta, 14 Phaeophyceae, and 7 Chlorophyta), corresponding to an increase of about 31% in the seaweed biodiversity hitherto known for the region. Considering that the Antarctic Peninsula, adjacent to King George Island seems to be one of the most rapidly warming spots on the planet, this kind of survey may provide a valuable tool for detecting eventual changes in seaweed biodiversity.

The potential for first-generation ethanol production from sugarcane

Ethanol production from sugarcane, mainly in Brazil, on the basis of first-generation technology (22.5 billion liters, in 2007/2008 season, in 3.4 million hectares) replaces 1% of the gasoline used in the world today and is highly competitive in economic terms with ethanol produced from other crops in the USA and Europe. In this paper we discuss the potential for sugarcane ethanol expansion from two angles: (1) productivity gains which would allow greater production in the same area and (2) geographical expansion to larger areas. The potential of first-generation technology for the production of ethanol from sugarcane is far from being exhausted. There are gains in productivity of approximately a factor of two from genetically modified varieties and a geographical expansion by a factor of ten of the present level of production in many sugar-producing countries. The replacement of 10% of the gasoline used in the world by ethanol from sugarcane seems possible before second-generation technology reaches technological maturity and possibly economic competitiveness. (C) 2009 Society of Chemical Industry and John Wiley & Sons, Ltd

Historical carbon budget of the brazilian ethanol program

This work models the carbon neutralization capacity of Brazil`s ethanol program since 1975. In addition to biofuel, we also assessed the mitigation potential of other energy products, such as, bioelectricity, and CO(2) emissions captured during fermentation of sugar cane`s juice. Finally, we projected the neutralization capacity of sugar cane`s bio-energy system over the next 32 years. The balance between several carbon stocks and flows was considered in the model, including the effects of land-use change. Our results show that the neutralization of the carbon released due to land-use change was attained only in 1992, and the maximum mitigation potential of the sugar cane sector was 128 tonnes Of CO(2) per ha in 2006. An ideal reconstitution of the deployment of the sugar cane sector, including the full exploitation of bio-electricity`s potential, plus the capture Of CO(2) released during fermentation, shows that the neutralization of land-use change emissions would have been achieved in 1988, and its mitigation potential would have been 390 tCO(2)/ha. Finally, forecasts of the sector up to 2039 shows that the mitigation potential in 2039 corresponds to 836 tCO(2)/ha, which corresponds to 5.51 kg Of CO(2) per liter of ethanol produced, or 55% above the negative emission level. (C) 2009 Elsevier Ltd. All rights reserved.

Have Biofuel, Will Travel: A Colorful Experiment and a Different Approach To Teach the Undergraduate Laboratory

The substitution of petroleum-based fuels with those from renewable sources has gained momentum worldwide. A UV-vis experiment for the quantitative analysis of biofuels (bioethanol or biodiesel) in (petroleum-based) diesel oil has been developed. Before the experiment, students were given a quiz on biofuels, and then they were asked to suggest a suitable UV-vis experiment for the quantification of biofuels in diesel oil. After discussing the results of the quiz, the experiment was conducted. This included the determination of lambda(max) of the medium-dependent, that is, solvatochromic, visible absorption band of the probe 2,6-bis[4-(tert-butyl)phenyl]-4-{2,4,6-tris[4-(tert-butyl)phenyl]pyridinium-1-yl}phenolate as a function of fuel composition. The students appreciated that the subject was linked to a daily situation and that they were asked to suggest the experiment. This experiment served to introduce the phenomena of solvation and solvatochromism.

The corrosion of austenitic 304 stainless steel in biodiesel

Fuel distribution uses 304 stainless steel containers for the storage of biofuels, however there are few reports in the literature about the corrosive aspects this. steel in biodiesel. The objective of this research is to study the corrosive behavior of 304 austenitic stainless steel in the presence of biodiesel, unwashed and washed, with aqueous solutions of citric, oxalic, acetic and ascorbic acids 0,01 mol L(-1), and compare with results obtained for the copper (ASTM D130). The employedtechniques were: atomic absorption spectrometry (AAS) and optical microscopy (OM). The results of EA A showed a low rate of corrosion for the stainless steel, the alloys elements studied were Cr, Ni and Fe, the highest rate was observed for the chrome, 1.78 ppm / day in biodiesel with or without washing. The OM of the 304 steel, when compared with that of copper has a low corrosion rate in the 304 steel/biodiesel system. Not with standing, this demonstrates that not only the 304 steel, but also the copper corrodes in biodiesel

Solvent assisted decomposition of the tetrahedral intermediate of the transesterification reaction to biodiesel production. A density functional study

B3LYP/6-31 + G(d) calculations were employed to investigate the mechanism of the transesterification reaction between a model monoglyceride and the methoxide and ethoxide anions. The gas-phase results reveal that both reactions have essentially the same activation energy (5.9 kcal mol(-1)) for decomposition of the key tetrahedral intermediate. Solvent effects were included by means of both microsolvation and the polarizable continuum solvation model CPCM. Both solvent approaches reduce the activation energy, however, only the microsolvation model is able to introduce some differentiation between methanol and ethanol, yielding a lower activation energy for decomposition of the tetrahedral intermediate in the reaction with methanol (1.1 kcal mol(-1)) than for the corresponding reaction with ethanol (2.8 kcal mol(-1)), in line with experimental evidences. Analysis of the individual energy components within the CPCM approach reveals that electrostatic interactions are the main contribution to stabilization of the transition state. (C) 2009 Elsevier Ltd. All rights reserved.

Colonisation by epibionts and meiofauna of real and mimic pneumatophores in a cool temperate mangrove habitat

The size and pace of change in meiofaunal assemblages suggest that meiofauna make excellent subjects for testing theories about how ecological communities change. A field experiment was performed in which the  abundance and composition of epibionts and meiofauna on natural,  transplanted and mimic pneumatophores were monitored over a 47 wk period. Meiofaunal density increased with growth of algal epibionts, both reaching maximum values after 24 wk, at the end of winter. At this time the assemblages from the 3 substrata were similar, although the combined abundances of meiofauna on transplants and mimics were only 28% of the average on natural pneumatophores. Meiofaunal abundance on all substrata decreased rapidly during spring as algal cover declined due to desiccation. Twenty-three species of nematode were recorded from mimics compared with 8 and 7 from transplants and pneumatophores, respectively. A temporal sequence of feeding groups occurred in the order of epigrowth feeders, deposit feeders, and omnivore/predators, with the latter 2 adding to rather than replacing earlier trophic groups. Scavengers were found only on natural pneumatophores. The turnover rates of nematode species between all census times were similar, peaking at 63%, but there was no trend in the turnover rates with time. We conclude that mimics are more suitable than transplanted pneumatophores for colonisation studies because of their greater persistence and more easily standardised surface area. Moreover, the composition of colonising assemblages on them closely resembled assemblages on natural pneumatophores at the time of peak meiofaunal abundance.

Meiofaunal recruitment to mimic pneumatophores in a cool-temperate mangrove forest: spatial context and biofilm effects

A field experiment was devised to test whether meiofauna that colonised mimic pneumatophores (artificial substrates) resembled the assemblage on adjacent live pneumatophores in three randomly chosen intertidal, estuarine sites. The experiment showed that the close proximity of particular biota on living pneumatophores did not reliably influence subsequent development of assemblages upon mimic pneumatophores within a scale of 10 m during a colonisation period of less than 20 weeks. There was some convergence of the composition of the colonising assemblage of meiofauna on mimic pneumatophores with the local assemblages in sites dominated by barnacles, or where the natural pneumatophores were free from macroscopic epibionts. However, tychopelagic meiofauna from algal epiphytes did not significantly colonise mimic pneumatophores during the 20-week trial, probably due a lack of growing algae. During the conditioning phase suspended in water at a marine site 20 km from the mangroves, mimic pneumatophores acquired an assemblage of meiofauna different from the estuarine assemblage that colonised mimics following implantation in the estuarine mudflat. Enhanced colonisation rates of mimics in suspended bags at the conditioning site may be explained by the absence of benthic macroinvertebrates, and the lack of intertidal exposure. Biofilms aged 2, 7, and 11 weeks had no consistent, different effect on the subsequent colonisation of meiofauna. We conclude that divergence of phytal-based assemblages of meiofauna depends upon the amount of coverage, as well as the type, of fouling macro-epibionts on the pneumatophores. Meiofaunal assemblages on artificial substrates after 20 weeks colonisation displayed less intrinsic patchiness than mature phytal assemblages on natural pneumatophores, and so present a potentially useful way of improving the power of biomonitoring applications using meiofauna.

The effect of grazing gastropods on meiofaunal colonisation of pneumatophores in a temperate mangrove

A field experiment was run to assess how grazing affects meiofaunal colonisation of mimic pneumatophores in a temperate mangrove. The effects of two manipulated factors were tested: mimics (made from wooden dowel rods) were either implanted into the sediment, or suspended just above the substratum; and in addition were either fitted with an aluminium 'snail barrier' or left without. The abundance of meiofauna was estimated on the 4 treatments after 2, 4, 8 and 16 weeks in situ in the intertidal region. After 16 weeks the meiofaunal assemblage was dominated by copepods, and the effect of suspension was highly significant on abundance of the epibiotic assemblage. Mimics suspended above the sediment, out of reach of snails, were fouled with a green algal layer whereas implanted units were not. In contrast, 'snail barriers' were found to be relatively ineffective in preventing access by the dominant herbivorous gastropod Bembicium melanostomum. Meiofaunal assemblages were more abundant on suspended units, but there was greater taxonomic richness at levels of phylum and class on implanted units than on   suspended units. The colonising meiofaunal assemblage was less abundant on implanted mimics than in previous experiments at this study site, and this was attributed to the present experiment being carried out during the dry summer period, when meiofauna on pneumatophores is in decline.

Small-scale temporal variation in propagule supply of an intertidal red alga

Information on the variability in supply of algal propagules is scarce, hindered by the difficulty in identifying propagules, but this variability may affect the distribution and abundance of algal assemblages. This study examined the small-scale (½ hourly to hourly) temporal variation in propagule supply of Chondrus verrucosus (Gigartinaceae, Rhodophyta) over a dense, isolated bed in south-eastern Japan in summer and winter of 1999. Either 0.5 litre scoop samples or 5 litre pump samples were collected ½ hourly to hourly over 13, 22.5, and 30 h on three occasions in summer (June & July) and 32 h on one occasion in winter (December). Sampling was conducted around either the new moon (two occasions in summer) or full moon (one occasion in both summer and winter) and incorporated full tidal sequences including daytime (summer) and nighttime (winter) low-low (LL) tides. Chondrus verrucosus was the only red alga with spores within the size range of 15–20 μm that was fertile in the study area and surrounds at the time of sampling facilitating identification of spores. Spores in scoop samples were settled onto Petri dishes and identified on the basis of cell shape, colour and size. Pump samples were filtered onto transparent membrane filters and identified using epifluorescence microscopy: C. verrucosus spores fluoresced bright yellow and were easily distinguished from other micro-organisms of similar size, which fluoresced red or green. Results showed that while propagules could be found in the water column at most times, propagule supply of C. verrucosus was greatest during the 1–2 h period following LL tides. Variability in propagule supply was less than in previous studies examining surface or offshore waters. Spore release is thought to be stimulated by either desiccation or salinity changes associated with periods of emersion at low tide followed by re-immersion on incoming tides.

Plastid division in mallomonas (Synurophyceae, Heterokonta)

Laser scanning confocal microscopy and TEM were used to study the morphology of secondary plastids in algae of the genus Mallomonas (Synurophyceae). At interphase, Mallomonas splendens (G. S. West) Playfair, M. rasilis Dürrschm., M. striata Asmund, and M. adamas K. Harris et W. H. Bradley contained a single H-shaped plastid consisting of two large lobes connected by a narrow isthmus. Labeling of DNA revealed a necklace-like arrangement of plastid nucleoids at the periphery of the M. splendens plastid and a less-patterned array in M. rasilis. The TEM of M. splendens and M. rasilis showed an electron-dense belt surrounding the plastid isthmus in interphase cells; this putative plastid-dividing ring (PD ring) was adpressed to the inner pair of the four plastid membranes, suggesting that it is homologous to the PD ring of green and red plastids. The PD ring did not contain actin (indicated by lack of staining with phalloidin) and displayed filaments or tubules of 5–10 nm in diameter that may be homologous to the tubules described in red algal PD rings. Confocal microscopy of chl autofluorescence from M. splendens showed that the plastid isthmus was severed as mitosis began, giving rise to two single-lobed daughter plastids, which, as mitosis and cell division progressed, separated from one another and then each constricted to form the H-shaped plastids of daughter cells. Similar plastid division cycles were observed in M. rasilis and M. adamas; however, the plastid isthmus of M. striata was retained throughout most of cell division and was eventually severed by the cell cleavage furrow.

Some aspects of photosynthetic characteristics in a set of perennial irrigation reservoirs located in five river basins in Sri Lanka

Phytoplankton primary productivity of eleven irrigation reservoirs located in five river basins in Sri Lanka was determined on a single occasion together with light climate and nutrient concentrations. Although area-based gross primary productivity (1.43–11.65 g O2 m−2 d−1) falls within the range already established for tropical water bodies, net daily rate was negative in three water bodies. Light-saturated optimum rates were found in water bodies, with relatively high algal biomass, but photosynthetic efficiency or specific rates were higher in water bodies with low algal biomass, indicating nutrient limitation or physiological adaptation of phytoplankton. Concentrations of micronutrients and algal biomass in the reservoirs are largely altered by high flushing rate resulting from irrigation release. Underwater light climate and nutrient availability control the rate of photosynthesis and subsequent areabased primary production to a great extent. However, morpho-edephic index or euphotic algal biomass in the most productive stratum of the water column is not a good predictor of photosynthetic capacity or daily rate of primary production of these shallow tropical irrigation reservoirs.