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While molecular methods have begun to transform ecology, most algal biodiversity is still studied using the classical approach of identifying microalgae by light microscopy directly in sample material or using cultures. In this study, we compare both approaches (light microscopy and metagenomics as a molecular approach) using the freshwater ponds of the Eifel National Park in Germany as a case study. The ponds were found to be rich in desmids by light microscopy. A total of 299 species representing 81 genera were identified by light microscopy. While the molecular method does not currently allow species identification in most cases, we were able to identify 207 different algal genera. In total, 157 genera were detected only by metagenomics, 50 genera were found with both methods, and 31 genera were found by light microscopy, highlighting the need to continue using light microscopy in addition to a molecular approach. The metagenomics method has several advantages over the light microscopy method: (1) deeper assessment of alpha biodiversity, (2) better abundance numbers, and (3) complete coverage of all living matter. The latter is also a significant improvement over metabarcoding, as universal PCR primers are not available. [ABSTRACT FROM AUTHOR]

Increases in stressors associated with climate change such as ocean acidification and warming temperatures pose a serious threat to intertidal ecosystems. Of crucial importance are the effects on foundational species, such as fucoid algae, a critical component of rocky intertidal shorelines around the world. The impact of climate change on adult fronds of fucoid algae has been documented but effects on early developmental stages are not as well understood. In particular, ocean acidification stands to impact these stages because zygotes and embryos are known to maintain internal pH and develop a cytosolic pH gradient during development. To assess the effects of seawater acidification on early development, zygotes of Fucus gardneri were exposed to artificial seawater (ASW) buffered to conditions that approximate current global averages and extend largely beyond future projections. Exposure to acidic seawater had significant effects on embryonic growth. Specifically, rhizoid elongation, which occurs by a process known as tip growth, was significantly reduced with each 0.5 unit drop in pH. When pH was decreased from 8.0 to 7.5, which is similar to levels that have been observed in Burrard Inlet, there was reduction in rhizoid growth rate of almost 20%. Under more extreme conditions, at pH 6, rhizoid growth rates were reduced by 64% in comparison to embryos exposed to seawater at pH 8.0. On the other hand, acidic seawater had no effect on earlier processes; zygotes became multicellular embryos with well-formed rhizoids on a similar time course within the first 24 h of development, even when exposed to pH 6, an extreme pH well below what is expected in the future. This suggests that zygotes can maintain an internal pH that allows germination and cell division to occur. Tip growth, however, depends on the extended maintenance of an internal pH gradient. It is therefore possible that disruptions to this gradient could account for the observed reductions in rhizoid elongation. Under acidic conditions proton influx into the cell becomes energetically more favorable than at pH 8, and expulsion would be more difficult. This could disrupt the cytosolic pH gradient and in turn affect rhizoid growth.

Vanadium-dependent haloperoxidases (V-HPO) are specific enzymes involved in the metabolism of reactive oxygen species in marine algae. These enzymes contribute to early embryogenesis of algae in the order Fucales, catalyzing the reactions which result in phlorotannin incorporation into the newly forming zygote cell wall and adhesive material. In this study we showed that early embryogenesis in Fucus vesiculosus is accompanied by synchronous changes of V-HPO activity, hydrogen peroxide content and content of cell-wall-associated phlorotannins. Phlorotannin incorporation into the cell wall of Fucus zygotes had already begun 1 h after fertilization, and this process was accompanied by rapid increase of H2O2 content and V-HPO activity. We suggest that altogether this initiates polymerization of phenolics and their cross-linking with the major cell wall constituent, alginic acid. Presumably, de novo phlorotannin biosynthesis is involved in this process, as GC-MS analysis showed dramatic changes in content of intracellular phloroglucinol and low-molecular-weight phlorotannins during the first 9 days of F. vesiculosus embryogenesis. [ABSTRACT FROM AUTHOR]

Hexavalent chromium (Cr(VI)) is highly soluble in water, but is widely used in industrial sectors for many purposes. The effluent from these industrial activities is often released to the environment posing a threat to aquatic life and to humans. Conventional methods of treating Cr(VI) often require the use of pump and treat methods followed by the use of harmful toxic chemicals that are hard to dispose of and usually are expensive. The study explores reduction of Cr(VI) to Cr(III) using biological means (a popular issue of bioremediation of contaminated aquifer) in columns; control with aquifer media, system 1 inoculated with CRB (chromium reducing bacteria) dried sludge, system 2 further amended with saw dust and system 3 amended with vegetative material from target site as carbon source. CRB are essential and were inoculated in the columns (system 1-3) as dried sludge, previously isolated (Enterococcus casseliflavus, Pseudomonas putida, C.istrobacter sedlakii, Enterobacter cloacae and Enterobacter hormaechei) and tested in a batch system. The column reactors were run for 60 days at concentrations 40, 60 and 80 mg/L. Culture isolates in the effluent of the reactors were isolated and identified. Complete reduction was observed from all columns under different concentrations, with some failures at certain periods before quasi steady state (determined after 40 d). At 40 mg/L more than 95% of Cr(VI) was reduced across the spectrum. System 3 best reduced Cr(VI) compared to other treatment column reactors at high concentrations of 80 mg/L. System 2 carbon source didn't enhance Cr(VI) reduction compared to Syetem 1 with no carbon material. Algae growth was observed in the columns after operating for 40 d at 40 mg/L. Using 18s rRNA the dominant algae was identified as Chlamydomonas debaryana. As Cr(VI) concentration was increased, both CRB and the algae were assumed to be in synergy as Cr(VI) was reduced at influent concentration as high as 80 mg/L (double the concentration from the site). Further investigation was done in the study to identify Cr(VI) reducing potential by algae. The use of vegetative material from the target site in the presence of algae proved to enhance Cr(VI) reduction by CRB even though saw dust did not perform as expected. This method has potential to be used in Cr polluted sites in South Africa with careful application. [ABSTRACT FROM AUTHOR]

Parthenogenetic development of unfused gametes is commonly observed in laboratory cultures among various brown algal taxa. There is, however, little information on the contribution of parthenogenesis to the reproduction of field populations. In this study, we investigated whether parthenogenesis is present in a sexual population of the isogamous brown alga Scytosiphon with a 1:1 sex ratio. In culture, both female and male gametes showed higher mortality and slower development compared to zygotes. More than 90% of surviving partheno‐germlings formed parthenosporophytes irrespective of the culture conditions tested. Therefore, if parthenogenesis occurs in the field, most unfused gametes are expected to form parthenosporophytes. Contrary to this expectation, parthenosporophytes were rare in the field population. We collected 126 sporophytic thalli and isolated and cultured a unilocular sporangium from each of them. We confirmed that cultures of 120 unilocular sporangia produced both female and male gametophytes by the observation of zygotes or amplification of PCR‐based sex markers indicating that these sporangia originated from zygotic sporophytes. Only females were detected in cultures from two sporangia and only males from four sporangia suggesting that these sporangia originated from parthenosporophytes. In the Scytosiphon population, although parthenogenesis is observable in culture, our results demonstrate that the contribution of parthenogenesis to reproduction is small (≤4.8%) compared to sexual reproduction. Unfused gametes may not survive to form mature parthenosporophytes in significant numbers in the field partly due to their higher mortality and slower development compared from zygotes. [ABSTRACT FROM AUTHOR]

The settlement of zygotes in the right place is the most critical step for the survival of young kelp sporophytes in the marine environment. The eggs of Saccharina species were connected to oogonia with two flagella projected from its basal part, and this connection lasted even after fertilisation and first cell division of the zygote. Transmission electron microscopy showed that the egg flagella have a unique structure and arrangement of basal bodies different from those of other flagella appearing throughout the life cycle. Fluorescein isothiocyanate (FITC)-lectin labelling showed that a significant modification of carbohydrate composition occurred at the surface of the zygote after fertilisation. When the eggs and zygotes were artificially detached from the oogonia at early developmental stage, most sporophytes failed to attach to a substrate and remained in two- to three-cell stage even in 15 days after fertilisation; whereas, fluorescein diacetate (FDA) staining showed that most zygotes (> 95%) detached from the oogonia were still alive and had intact cell membranes. On the contrary, zygotes connected to the oogonia developed into multicellular blades composed of hundreds of cells 15 days after fertilisation with elongated rhizoids extending from the basal portion of the blade. These results suggest that the egg flagella ensure close contact and orientation of the zygote to the oogonial wall, and later binding between zygote and oogonium occurs by means of glycoconjugates. These consecutive events appear to be essential for the survival and development of young sporophytes in Saccharina species. [ABSTRACT FROM AUTHOR]

Triparma laevis f. inornata is a unicellular alga belonging to the Bolidophyceae, which is most closely related to diatoms. Like diatoms, T. laevis f. inornata has a siliceous cell wall. The cell wall of T. laevis f. inornata consists of four round plates (three shields and one ventral plate) and one dorsal and three girdle plates. But, unlike diatoms, T. laevis f. inornata cells can grow when concentrations of silica are depleted. We took advantage of this ability, using TEM to study the ontogeny of the siliceous plate, pattern center formation, and development. Two types of pattern centers (annulus and sternum) were observed in the early and middle stage of plate formation. During their formation, the annuli were initially crescent‐shaped but eventually their ends fused to make a ring. Only outward silica deposition of the branching ribs occurred on the growing annulus until it became a ring, resulting in an unfilled circle inside the annulus. The pattern center of the shield plate was always an annulus, but in ventral plates both annulus and sternum were observed. The annuli and sterna in T. laevis f. inornata round plates were very similar to the annuli and sterna in diatom valves. These results suggested that the round plates of Parmales are homologous to diatom valves. This information on the plate ontogeny of T. laevis f. inornata provides new insights into the evolution of the siliceous cell wall in the Parmales and diatoms. [ABSTRACT FROM AUTHOR]

Main conclusion: It has been proposed that future efforts should focus on basic studies, biotechnology studies and synthetic biology studies related to algal biofuels and various high-value bioproducts for the economically viable production of algal biof uels.In recognition of diminishing fossil fuel reserves and the worsening environment, microalgal biofuel has been proposed as a renewable energy source with great potential. Algal biofuel thus became one of the hottest topics in renewable energy research in the new century, especially over the past decade. Between 2007 and 2017, research related to microalgal biofuels experienced a dramatic, three-stage development, rising, growing exponentially, and then declining rapidly due to overheating of the subject. However, biofuel-driven algal biotechnology and bioproducts research has been thriving since 2010. To clarify the gains (and pains) of the past decade and detail prospects for the future, this review summarizes the extensive scientific progress and substantial technical advances in algal biofuel over the past decade, covering basic biology, applied research, as well as the production of value-added natural products. Even after 10 years of hard work and billions of dollars in investments, its unacceptably high cost remains the ultimate bottleneck for the industrialization of algal biofuel. To maximize the total research benefits, both economically and socially, it has been proposed that future efforts should focus on basic studies to characterize oilgae, on biotechnology studies into various high-value bioproducts. Moreover, the development of synthetic biology provides new possibilities for the economically viable production of biofuels via the directional manufacture of microalgal bioproducts in algal cell factories. [ABSTRACT FROM AUTHOR]

Abstract: Increasing rates of precipitation and higher air temperatures have increased the size and frequency of retrogressive thaw slumps—large depressions of thawed permafrost that form on the landscape—in north‐western Canada. Many of these thaw slumps flow into nearby stream systems, leading to increased sediment, solute and nutrient loads. We evaluated the impacts of retrogressive thaw slumps on measurements of algal biomass accumulation and decomposition of organic materials in streams in the Peel Plateau, Northwest Territories. We predicted that increased sediment loads from thaw slumps would decrease algal standing stock and decomposition in thaw slump‐impacted streams, overriding the potential positive effects of increased nutrient concentrations. Chl‐a measurements were obtained as a proxy for algal standing stock from sites upstream and downstream of thaw slumps by performing algae scrapes and deploying artificial substrates in 2014. Cotton strips were deployed at upstream and downstream sites in 2013 and 2014, and tensile strength was measured to assess breakdown. Grab water samples were taken to measure physical and chemical parameters at each site. Thaw slumps increased total suspended solids, but not dissolved nutrients at downstream sites. Our results indicated a significant negative relationship between Chl‐a and total suspended solids. Decomposition indicated a negative relationship with total suspended solids, but displayed much stronger positive relationships with temperature, pH and dissolved phosphorus. Our findings indicated that total suspended solids were a stronger driver of change in thaw slump‐impacted stream reaches than nutrients, although nutrients may be more influential during the initiation of thaw slump disturbances. Algal biomass accumulation was found to be more sensitive to thaw slump impacts than decomposition, which may lead to a functional and structural shift in favour of allochthonous‐based food webs over autochthonous ones at thaw slump‐impacted stream reaches. [ABSTRACT FROM AUTHOR]

Coral reef systems can undergo rapid transitions from coral-dominated to macroalgae-dominated states following disturbances, and models indicate that these may sometimes represent shifts between alternative stable states. While several mechanisms may lead to alternate stable states on coral reefs, only a few have been investigated theoretically. We explore a model that illustrates that reduced vulnerability of macroalgae to herbivory as macroalgae grow and mature could be an important mechanism: when macroalgae are palatable to herbivores as juveniles, but resistant as adults, coral-dominated and algae-dominated states are bistable across a wide range of parameter space. We compare two approaches to global sensitivity analysis to rank the relative importance of the model parameters in determining the presence and magnitude of alternative stable states, and find that the two most influential parameters are the death rate of coral and the rate of maturation of algae out of the vulnerable stage. The Random Forest approach for global sensitivity analysis, recently adopted by ecologists, provides a more efficient method for ranking the relative importance of parameters than a variance-based approach that has been used frequently by computer scientists and engineers. Our results suggest that managing reefs to reduce chronic stressors that cause coral mortality and/or enhance the growth rates of algae can help prevent reefs from becoming locked in a macroalgae-dominated state. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine if extreme acidic Lake Caviahue could be used as a sentinel of atmospheric deposition hypothesizing that the physiological state of algae will be the indicator parameter. The lake was sampled from 2000 to 2015 in order to determine chlorophyll concentration, algae abundance and phytoplankton in vivo fluorescence as a way to evaluate the physiological state of algae. Development and physiological state of phytoplankton in different seasons was related to concentration and dynamics of nutrients in the lake. Laboratory experiments of Keratococcus rhaphidiodes to nitrogen (N) enrichment confirmed that an increase in nutrient content enabled a better physiological state of algae (e.g. higher chlorophyll per cell). Therefore, under the projected scenarios of climate change, the increase of available N through the increase in deposition and the increase of dissolved inorganic carbon, as consequence of higher atmospheric CO2, will compensate the natural nutrient constraints observed in the phytoplankton of the lake. The effect that the atmospheric CO2 has on the DIC, and this on algal development, as well as the influence that N has on algal growth, make Lake Caviahue an interesting sentinel of nutrient deposition at regional level. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and phosphorus (P) play a major role in the biogeochemical functioning of aquatic systems. N and P transfer to surface freshwaters has amplified during the 20th century, which has led to widespread eutrophication problems. The contribution of different sources, natural and anthropogenic, to total N and P loading to river networks has recently been estimated yearly using the Integrated Model to Assess the Global Environment - Global Nutrient Model (IMAGE-GNM). However, eutrophic events generally result from a combination of physicochemical conditions governed by hydrological dynamics and the availability of specific nutrient forms that vary at subyearly timescales. In the present study, we define for each simulated nutrient source: i) its speciation, and ii) its subannual temporal pattern. Thereby, we simulate the monthly loads of different N (ammonium, nitrate + nitrite, and organic N) and P forms (dissolved and particulate inorganic P, and organic P) to global river networks over the whole 20th century at a half-degree spatial resolution. Results indicate that, together with an increase in the delivery of all nutrient forms to global rivers, the proportion of inorganic forms in total N and P inputs has risen from 30 to 43% and from 56 to 65%, respectively. The high loads originating from fertilized agricultural lands and the increasing proportion of sewage inputs have led to a greater proportion of DIN forms (ammonium and nitrate), that are usually more bioavailable. Soil loss from agricultural lands, which delivers large amounts of particle-bound inorganic P to surface freshwaters, has become the dominant P source, which is likely to lead to an increased accumulation of legacy P in slow flowing areas ( e.g. , lakes and reservoirs). While the TN:TP ratio of the loads has remained quite stable, the DIN:DIP molar ratio, which is likely to affect algal development the most, has increased from 18 to 27 globally. Human activities have also affected the timing of nutrient delivery to surface freshwaters. Increasing wastewater emissions in growing urban areas induces constant local pressure on the quality of aquatic systems by delivering generally highly bioavailable nutrient forms, even in periods of low runoff. [ABSTRACT FROM AUTHOR]

Layer-by-layer peeling of surface molecules of native cellulose microfibrils was performed using a repeated sequential process of 2,2,6,6-tetramethylpiperidine-1-oxyl radical-mediated oxidation followed by hot alkali extraction. Both highly crystalline algal and tunicate celluloses and low-crystalline cotton and wood celluloses were investigated. Initially, the C6-hydroxy groups of the outermost surface molecules of each algal cellulose microfibril facing the exterior had the gauche-gauche (gg) conformation, whereas those facing the interior had the gauche-trans (gt) conformation. All the other C6-hydroxy groups of the cellulose molecules inside the microfibrils contributing to crystalline cellulose I had the trans-gauche (tg) conformation. After surface peeling, the originally second-layer molecules from the microfibril surface became the outermost surface molecules, and the original tg conformation changed to gg and gt conformations. The plant cellulose microfibrils likely had disordered structures for both the outermost surface and second-layer molecules, as demonstrated using the same layer-by-layer peeling technique. [ABSTRACT FROM AUTHOR]

Promoting growth performance, while limiting the proliferation of bacteria such as Campylobacter jejuni, in the post-hatch period is a key goal of the broiler industry. Therefore, the objective of this study was to evaluate the effects of supplementing the diet with Laminarin and Fucoidan extracts on growth performance, small intestinal morphology and function, immune response and Campylobacter jejuni colonisation following an experimental challenge in young chicks following dietary supplementation. The experiment consisted of three diets: 1) basal diet; 2) basal diet + 250 ppm Laminarin (LAM); 3) basal diet + 250 ppm LAM + 80 ppm FUC (LAM/FUC). Day old Ross chicks (n = 135), were housed in groups of three, with 15 replicates per treatment group. On day three, all chicks were orally gavaged with 0.1 ml 10 6 colony forming units of C. jejuni. On day 13, caecal digesta samples were collected for quantification of C. jejuni and Lactobacillus. Ileal tissue was also collected post-slaughter in order to examine small intestinal morphology and the gene expression of targets related to gut health. The mean total intake for the chicks fed the LAM, LAM/FUC and basal diets during the experiment (day 0–13) were 411 g, 411 g and 373 g respectively, with chicks fed the LAM and LAM/FUC supplemented diets having increased feed intake compared to the basal diet fed chicks (P < 0.05). Chicks offered diets containing LAM and the LAM/FUC combination had higher (P < 0.05) total weight gain (262 g and 254 g respectively) compared to the basal diet 243 g. Dietary inclusion of LAM/FUC combination increased feed conversion ratio (FCR) (1.68 g/g vs 1.77 g/g) compared to the basal diet (P < 0.05). Chicks offered the LAM and LAM/FUC diet had increased ileal villus width compared to chicks offered the basal diet, while chicks fed the LAM diet had increased villus height compared to chicks fed the basal diet (P < 0.05). Chicks offered the both the LAM and LAM/FUC supplemented diets had increased gene expression of the tight junction protein CLDN1, compared to chicks fed the basal diet (P < 0.05). The gene expression of the measured intestinal nutrient transporters was unaffected by dietary supplementation (P > 0.10). There was no effect of LAM or LAM/FUC extracts on the proliferation of C. jejuni or on Lactobacilli numbers in the caeca. In conclusion, supplementation with LAM or LAM/FUC in the post-hatch period improved growth rate, positively modified small intestinal architecture and impacted the intestinal immune response, but did not impact the extent of C. jejuni proliferation. Supplementation of the diet with LAM provided beneficial effects over supplementation with LAM/FUC in relation to FCR, villus height and aspects of the immune response. [ABSTRACT FROM AUTHOR]

Enzymatic hydrolysis of seaweed biomass was studied using xylanase produced from marine bacteria Bacillus sp. strain BT21 through solid-state fermentation of wheat bran. Three types of seaweeds, Ahnfeltia plicata, Padina tetrastromatica and Ulva lactuca, were selected as representatives of red, brown, and green seaweeds, respectively. Seaweed biomass was pretreated with hot water. The efficiency of pretreated biomass to release reducing sugar by the action of xylanase as well as the type of monosaccharide released during enzyme saccharification of seaweed biomass was studied. It was seen that pretreated biomass of seaweed A. plicata, U. lactuca, and P. tetrastroma, at 121 °C for 45 min, followed by incubation with 50 IU xylanase released reducing sugars of 233 ± 5.3, 100 ± 6.1 and 73.3 ± 4.1 µg/mg of seaweed biomass, respectively. Gas chromatography analysis illustrated the release of xylose, glucose, and mannose during the treatment process. Hot water pre-treatment process enhanced enzymatic conversion of biomass into sugars. This study revealed the important role of xylanase in saccharification of seaweed, a promising feedstock for third-generation bioethanol production. [ABSTRACT FROM AUTHOR]

The green marine macroalgae of the class Ulvophyceae (Ulvophytes) are common algae distributed worldwide particularly in intertidal areas, which play a key role in aquatic ecosystems. They are potentially valuable resources for food, animal feed and fuel but can also cause massive nuisance blooms. Members of Ulvaceae, like many other seaweeds, harbour a rich diversity of epiphytic bacteria with functions related to host growth and morphological development. In the absence of appropriate bacterially derived signals, germ cells of the genus Ulva develop into 'atypical' colonies consisting of undifferentiated cells with abnormal cell walls. This paper examines the specificity of bacteria-induced morphogenesis in Ulva, by cross-testing bacteria isolated from several Ulva species on two Ulva species, the emerging model system Ulva mutabilis and the prominent biofouler species Ulva intestinalis. We show that pairs of bacterial strains isolated from species other than U. mutabilis and U. intestinalis can fully rescue axenic plantlets generated either from U. mutabilis or U. intestinalis gametes. This laboratory-based study demonstrates that different compositions of microbial communities with similar functional characteristics can enable complete algal morphogenesis and thus supports the 'competitive lottery' theory for how symbiotic bacteria drive algal development. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the efficient harvesting of microalgal biomass through crossflow membrane filtration. The microalgal biomass harvesting experiments were performed using one microfiltration membrane (pore size: 0.2 µm, made from polyvinylidene fluoride) and three ultrafiltration membranes (molecular weight cut-off: 150, 50, and 30 kDa, made from polyethersulfone, hydrophilic polyethersulfone, and regenerated cellulose, respectively). Initially, to minimize membrane fouling caused by microalgal cells, experiments with the objective of determining the critical flux were performed. Based on the critical flux calculations, the best performing membrane was confirmed to be the UH050 membrane, produced from hydrophilic polyethersulfone material. Furthermore, we also evaluated the effect of transmembrane pressure (TMP) and crossflow velocity (CFV) on filtration flux. It was observed that membrane fouling was affected not only by the membrane characteristics, but also by the TMP and CFV. In all the membranes, it was observed that increasing CFV was associated with increasing filtration flux, independent of the TMP. [ABSTRACT FROM PUBLISHER]

Species diversity of algal communities of sphagnum epiphyton was studied in six mountain and plain mires of the Subpolar Urals (Russia). A total of 154 species and intraspecific taxa from six divisions were identified. The highest species richness was recorded for Bacillariophyta (96 taxa) and Charophyta (33) divisions. Species Kobayasiella parasubtilissima, Tabellaria flocculosa and Eunotia lunaris had high abundance. Dominant communities were often formed by Eunotia lunaris, E. mucophila, Kobayasiella parasubtilissima and Pinnularia subcapitata. CCA analysis showed that conductivity and altitude above the sea level are the main factors affecting the development of algae in the studied mires. [ABSTRACT FROM AUTHOR]

Parasitic red algae evolve from a common ancestor with their hosts, parasitizing cousins using familiar cellular mechanisms. They have independently evolved over one hundred times within the exclusively multicellular red algal class Florideophyceae. Reduced morphology, a lack of pigmentation, and direct cell–cell connections with their hosts are markers of red algal parasitism. With so many potential evolutionary pathways, red algal parasite diversity offers a unique test case to understand the earliest stages of this lifestyle transition. Molecular and morphological investigations led to the categorization of these parasites based on their relationship to their host. “Adelphoparasites” are phylogenetically close to their hosts, often infecting a sister species, whereas “alloparasites” are more distantly related to their hosts. The differentiation of these parasites, based on their phylogenetic relationship to their host, has resulted in a simplified classification of these parasites that may not reflect the many evolutionary pathways they take to arrive at a similar endpoint. Accordingly, many parasites fall into a gray area between adelphoparasite and alloparasite definitions, challenging the established features we use to classify them. Molecular phylogenetic research has been essential in identifying gaps in knowledge, but microscopy needs to be reincorporated in order to address red algal parasite developmental variation to establish a new paradigm. The joint utilization of molecular and microscopic methods will be critical in identifying the genomic and physiological traits of both nascent and well-established parasites. [ABSTRACT FROM AUTHOR]

A comprehensive mechanistic model for describing algal growth dynamics in a photobioreactor was developed in this work with state of the art understanding and realistic assumptions for major associated processes. The model included 27 state variables related to various algal processes. This model was validated with extensive experimental data obtained from independent growth experiments in batch reactors, and was able to simulate system performance reasonably well. The comprehensive nature of the formulation also highlights the complex inter-relationship between all processes, and provides a tool for gaining more systematic insights into algal behavior in photobioreactors and other such systems. [ABSTRACT FROM AUTHOR]

Background: Culture collapse due to high temperatures can significantly impact the profitability of outdoor algal cultivation systems. The objective of this study was to model for the first time the impact of high temperatures on algal activity and viability. Results: Viability measurements on Dunaliella salina cultures were based on cytometry with two fluorescent markers (erythrosine and fluorescein di-acetate), and photosynthetic activity was measured by Pulse Amplitude Modulation (PAM) fluorometry. Kinetic studies revealed that viability and activity losses during exposure to high temperatures could be described by a Weibull model. Both mortality and activity were shown to be functions of the thermal dose received by the algae, defined as the product of duration of exposure to high temperatures and an exponential function of temperature. Simulations at five climatic locations revealed that culture collapse due to high temperatures could impact productivity of D. salina in non-temperature-controlled outdoor photobioreactors by 35 and 40% in arid and Mediterranean climates, respectively. Conclusions: The model developed in this study can be used to forecast the impact of high temperatures on algal biofuel productivity. When coupled with models predicting the temperature of outdoor cultivation systems, this model can also be used to select the best combination of location, system geometry, and algal species to minimize the risks of culture collapse and therefore maximize biofuel productivity. [ABSTRACT FROM AUTHOR]

The adaptation to a strong light is one of the essential characteristics of green algae, yet lacking relatively the information about the photophobic responses of Eukaryotic microalgae. We investigated the photophobic step-up responses of Euglena gracilis over a time course of several hours with alternated repetition of blue-light pulse illumination and spatially patterned blue-light illumination. Four distinctive photophobic motions in response to strong blue light were identified in a trace image analysis, namely on-site rotation, running and tumbling, continuous circular swimming, and unaffected straightforward swimming. The cells cultured in autotrophic conditions under weak light showed mainly the on-site rotation response at the beginning of blue-light illumination, but they acquired more blue-light tolerant responses of running and tumbling, circular swimming, or straightforward swimming. The efficiency of escaping from a blue-light illuminated area improved markedly with the development of these photophobic motions. Time constant of 3.0 h was deduced for the evolution of photophobic responses of E. gracilis. The nutrient-rich metabolic status of the cells resulting from photosynthesis during the experiments, i.e., the accumulation of photosynthesized nutrient products in balance between formation and consumption, was the main factor responsible for the development of photophobic responses. The reduction-oxidation status in and around E. gracilis cells did not affect their photophobic responses significantly, unlike the case of photophobic responses and phototaxis of Chlamydomonas reinhardtii cells. This study shows that the evolution of photophobic motion type of E. gracilis is dominated mainly by the nutrient metabolic status of the cells. The fact suggests that the nutrient-rich cells have a higher threshold for switching the flagellar motion from straightforward swimming to rotation under a strong light. [ABSTRACT FROM AUTHOR]

Didymosphenia geminata is a benthic bloom-forming diatom that is invasive in many temperate, oligotrophic freshwater ecosystems. D. geminata blooms are unusual, resulting from prolific basal stalk production stimulated by phosphorus limitation. The adaptive value of stalk production and bloom development is disputed. We examined blooms in relation to stalk biomass, biovolume and phosphatase activity. An austral summer survey of 15 sites within the Waitaki River of New Zealand compared reference communities (no detectable D. geminata), with those impacted by high and low D. geminata biomass. Sites were compared for differences in phosphatase location and activity using chromogenic substrates, community composition using morphological identifications, and overlying water and pore-water chemistry. Experimental microcosms subjected live proliferations to varied phosphate concentrations, and phosphatase rates and location were examined. Survey results identified phosphatase activity increased with D. geminata biomass, with lowest rates in reference communities. Pools of labile nutrients were detected in D. geminata mats, and in vitro hydrolysis rates were rapid in replete phosphoester conditions (~0.2 mmol l h cm at 16°C), with activity concentrated on stalks. Our results suggest D. geminata bloom development is an adaptation to maximise supply of phosphate under chronic phosphorus limitation. [ABSTRACT FROM AUTHOR]

Carrion in the form of dead seal pups and algal mats placed on soft bottom habitats at Explorers Cove and Salmon Bay, McMurdo Sound, attract scavenging invertebrates that are driven away by hydrogen sulphide produced by sulphate-reducing bacteria sequestered below a layer of Beggiatoa/Thioploca -like filamentous bacteria. This system is usually found for lipid-rich marine mammal carrion, but also occurred with natural algal mats. [ABSTRACT FROM AUTHOR]

Coral reefs are under intense conditions of stress caused by the anthropogenic activities in coastal areas and the increase of human population. Water effluents from urban and industrial areas carry large amounts of sediments and pollutants affecting corals populations, inducing bioerosion, increasing diseases and promoting the development of algae that compete for space with corals. In the Veracruz Reef System National Park (VRSNP) coral reefs are strongly affected by human activities carried out in the area. Gallega and Galleguilla reefs are among the most affected by wastewater discharges from the industrial (petrochemical and metallurgical) and urban areas in their vicinity. To assess the potential impact of this contamination on corals in the VRSNP, a chemical composition and morphology study of 76 Pseudodiploria colonies collected in reefs Gallega, Galleguilla, Isla Verde and Isla de Enmedio, was performed. Fragments of ~10 cm2 were collected and boric acid at 0.5% was used to remove tissue from the skeleton; once clean, the morphology of each sample was determined with a scanning electron microscope (SEM). Subsequently, to test the chemical composition, an energy dispersion spectroscopy of X-ray chemical microanalysis (EDSX) was performed in the SEM. We found that corals from Gallega and Galleguilla reefs, located closer to human populations, presented high levels of tungsten and the skeleton exhibited multiple perforations. In contrast, corals from the farthest offshore reefs (Isla Verde and Isla de Enmedio) exhibited lower levels of tungsten and fewer perforations in their skeleton. These results demonstrated that anthropogenic activities in the NPVRS are affecting corals skeleton, highly damaging and promoting their bioerosion. The presence of traces of tungsten in the skeleton of corals is an evidence of the damage that waste discharges are causing to coral reefs. Discharges of large amounts of contaminants promoted the growth of harmful species that grow and develop into the corals skeleton, causing its bioerosion, and making them susceptible to disease and physical damage. This study is the first evidence of the effects of contamination on these species; therefore, further studies are necessary to determine the impact of pollution on their biology and survival. Rev. Biol. Trop. 64 (3): 1077-1089. Epub 2016 September 01. [ABSTRACT FROM AUTHOR]

SUMMARY Gracilaria spp. are dominant macroalgae inhabiting the intertidal zone and are exposed to constant wave action and currents. In wild Gracilaria populations, fronds tend to occur in clusters, being grouped close to one another on the shore. It is rare to find thalli growing individually, but the reason for such a clustering development is unknown. In this study we traced the early development of tetraspores of Gracilaria sp. and examined the adhesion strength of discs. We recorded two different tetraspore-derived disc developmental patterns: in the first pattern, individual tetraspores developed into discs; whereas in the second pattern, multiple tetraspores that had attached in proximity to each other, coalesced to form a single composite disc during early development. We found that more uprights grew from coalesced discs and that the attachment areas of coalesced discs were larger compared with those of individual discs. The adhesion strengths of coalesced discs and individual discs were analyzed. The retention percentage of coalesced discs after treatment with rapid water flow was higher than that of individual discs, suggesting that coalesced discs are better able to withstand wave flow when compared with single-spore discs. Based on these results, we propose that the clustering of Gracilaria sp. plants at sites within the intertidal zone is a mechanism that enables this macroalgae to survive the wave action and currents that occur in this zone, and that plant recruitment in these areas is enhanced by the coalescence of holdfast discs during early development. [ABSTRACT FROM AUTHOR]

Field observations showed that the characteristics of chemical composition of waters and the development of plankton algae in the lakes within the delta of the Selenga river are determined by their flowage. The most open Lake Nekipelovskoe communicates with the Selenga outlets throughout a year, and Lake Zavernyaikha only at the period of an open channel. Lake Semenovskoe and Lake Khlystov Zaton are located in the islands and are isolated from the outlets. According to composition of main ions, the lakes under investigation refer to the hydrocarbonate class, the calcium group. The sum of ions in the water of Lake Nekipelovskoe approaches the one in the Selenga (86−221 mg/dm), and the highest sums of ions were recorded in the wintertime in the lakes isolated from the outlets (446−743 mg/dm). The lakes of the delta are characterized by a high trophicity. The maximum concentrations of total phosphorus in Lake Nekipelovskoe and Lake Zavernyaikha were 68 and 122 μg mg/dm, and in Lake Semenovskoe and Lake Khlystov Zaton −0.8 and −0.63 μg mg/dm, respectively. The most intense development of algae is observed in Lake Zavernyaikha, which is due to the high population of Baikal endemics. Lake Zavernyaikha showed a close negative correlation between the concentration of NO, mineral phosphorus and phytoplankton biomass; the correlation coefficient was −0.8 and −0.63, respectively. The lakes exhibited increased contents readily hydrolysable organic matter, and a decrease in dissolved oxygen concentration in winter; hydrogen sulfide was repeatedly recorded in Lake Khlystov Zaton. The water quality in the lakes during the springtime varies from 'quite clean' to 'weakly polluted'; at low-water periods, especially in winters, it can drop to the category of 'exceedingly dirty'. The water quality of the Selenga can be influenced by the lakes during spring floods when material accumulated during the wintertime is transported to the river outlets and further to Lake Baikal. [ABSTRACT FROM AUTHOR]

Floating debris provides substrates for dispersal of organisms by ocean currents, including algae that thrive on plastics. The 2011 earthquake and tsunami in Tohuku, Japan resulted in large amounts of debris carried by the North Pacific Current to North America from 2012 to 2016. In 2015-2016, the plastics in the debris bore a complex biota including pink algal crusts. One sample (JAW4874) was isolated into culture and a three-gene phylogeny (psbA, rbcL, and SSU) indicated it was an unknown member of the red algal class Stylonematophyceae. It is a small pulvinate crust of radiating, branched, uniseriate filaments with cells containing a single centrally suspended nucleus and a single purple to pink, multi-lobed, parietal plastid lacking a pyrenoid. Cells can be released as spores that attach and germinate to form straight filaments by transverse apical cell divisions, and subsequent longitudinal and oblique intercalary divisions produce masses of lateral branches. This alga is named Tsunamia transpacifica gen. nov. et sp. nov. Sequencing of additional samples of red algal crusts on plastics revealed another undescribed Stylonematophycean species, suggesting that these algae may be frequent on drift oceanic plastics. [ABSTRACT FROM AUTHOR]

The Vendian (Ediacaran) beds of the Zavkhan Basin, in the upper part of the Tsagaanolom Formation (<632 ± 14 Ma), yielded a new 'Zavkhan' association of algae, microfossils, and problematic organisms, which is established in the series of alternating chert-carbonate shale with phosphorite interbeds. This association is distinct in the predomination of large (250 μm and over) sphaeromorphic microfossils of the genera Tasmanites, Archaeooides, and Leiosphaeridia, whereas acanthomorph acritarchs are represented by rarely found Cavaspina sp. and Tanarium sp. Multicellular algae included fragments of encrusting or foliate thalli with pseudoparenchymatous structure of polygonal cells characteristic of Rhodophyta algae ( Thallophycoides sp.), and cordlike thalli of Vendotaenid algae Tyrasotaenia podolica. These layers of siltstone contain imprints of the problematic Vendian macrofossil Beltanelliformis brunsae. In their stratigraphic position, chemostratigraphic data, and fossil assemblage, the 'Zavkhan' association can be assigned to the Upper Vendian. [ABSTRACT FROM AUTHOR]

Open-cut mining operations can form pit lakes on mine closure. These new water bodies typically have low nutrient concentrations and may have acidic and metal-contaminated waters from acid mine drainage (AMD) causing low algal biomass and algal biodiversity. A preliminary study was carried out on an acidic coal pit lake, Lake Kepwari, in Western Australia to determine which factors limited algal biomass. Water quality was monitored to obtain baseline data. pH ranged between 3.7 and 4.1, and solute concentrations were slightly elevated to levels of brackish water. Concentrations of N were highly relative to natural lakes, although concentrations of FRP (<0.01 mg/L) and C (total C 0.7-3.7 and DOC 0.7-3.5 mg/L) were very low, and as a result, algal growth was also extremely low. Microcosm experiment was conducted to test the hypothesis that nutrient enrichment will be able to stimulate algal growth regardless of water quality. Microcosms of Lake Kepwari water were amended with N, P and C nutrients with and without sediment. Nutrient amendments under microcosm conditions could not show any significant phytoplankton growth but was able to promote benthic algal growth. P amendments without sediment showed a statistically higher mean algal biomass concentration than controls or microcosms amended with phosphorus but with sediment did. Results indicated that algal biomass in acidic pit lake (Lake Kepwari) may be limited primarily by low nutrient concentrations (especially phosphorus) and not by low pH or elevated metal concentrations. Furthermore, sediment processes may also reduce the nutrient availability. [ABSTRACT FROM AUTHOR]

Grateloupia ramosa Wang & Luan sp. nov. (Halymeniaceae, Rhodophyta) is newly described from Hainan Province, southern China. The organism has the following morphological features: (1) purplish red, cartilaginous and lubricous thalli 5-10 cm in height; (2) compressed percurrent axes bearing abundant branches with opposite arrangement; (3) claw-like apices on top, constricted to 2-4 cm at the base; (4) cortex consisting of 3-6 layers of elliptical or anomalous cells and a medulla covered by compact medullary filaments; (5) reproductive structures distributed throughout the thallus, especially centralized at the bottom of the end portion of the branches; and (6) 4-celled Carpogonial branches and 3-celled auxiliary-cell branches, both of the Grateloupia-type. The morphological diff erences were supported by molecular phylogenetics based on ribulose-1, 5-bisphosphate carboxylase/oxygenase ( rbcL) gene sequence analysis. There was only a 1 bp divergence between specimens collected from Wenchang and Lingshui of Hainan province. The new species was embedded in the large Grateloupia clade of the Halymeniaceae. The pairwise distances between G. ramosa and other species within Grateloupia ranged from 26 to 105 bp, within pairwise distances of 13-111 bp between species of the large genus Grateloupia in Halymeniaceae. Thus, we propose this new species as G. ramosa Wang & Luan sp. nov. [ABSTRACT FROM AUTHOR]

A hydrodynamic model and an aquatic ecology model of Dianshan Lake, Shanghai, were built using a hydrodynamic simulation module and the water quality simulation module of Delft3D, which is an integrated modelling suite offered by Deltares. The simulated water elevation, current velocity, and direction were validated with observed data to ensure the reliability of hydrodynamic model. The seasonal growth of different algae was analyzed with consideration of observed and historical data, as well as simulated results. In 2008, the dominant algae in Dianshan Lake was Bacillariophyta from February to March, while it was Chlorophyta from April to May, and Cyanophyta from July to August. In summer, the biomass of Cyanophyta grew quickly, reaching levels much higher than the peaks of Bacillariophyta and Chlorophyta. Algae blooms primarily occurred in the stagnation regions. This phenomenon indicates that water residence time can influence algal growth significantly. A longer water residence time was associated with higher algal growth. Two conclusions were drawn from several simulations: reducing the nutrients inflow had little effect on algal blooms in Dianshan Lake; however, increasing the discharge into Dianshan Lake could change the flow field characteristic and narrow the range of stagnation regions, resulting in inhibition of algal aggregation and propagation and a subsequent reduction in areas of high concentration algae. [ABSTRACT FROM AUTHOR]

Gloiopeltis furcata (Postels et Ruprecht) J. Agardh is a commercial red alga with high value in nutraceuticals and pharmaceuticals. To enrich information on its life history, the early developmental process of G. furcata from northern China was investigated using free-hand section and microexamination methods. Early life stage development includes the formation of carpogonial branch, spermatangia, cystocarp tetrasporangia, and spores germination. Results showed that one auxiliary cell and one adjacent supporting cell constituted an ampulla. Auxiliary cell was usually near the basal part of the ampulla and generated several two to three celled carpogonial branches. One spermatangial mother cell originated in the superficial cortical cell and produced single spermatangia. After fertilization, carpogonium formed a connecting filament which fused with the auxiliary cell ultimately. Many branched gonimoblast filaments were produced from auxiliary cell and generated into carpospores. Mature cystocarps protruded on the thalli surface showing some subspherical-shaped structures. Tetrasporangium developed from the inner cortical cell generated four tetrasporangia by cruciform division. Mature tetraspores and carpospores were released, attached to the bottom of Petri dishes through the stickum within 12 h, and then divided through regular binary fission. Undergoing a month of cultivation, the spores grew up to discoid crusts with diameters ranging from 55 to 60 µm. Growth of G. furcata was initiated with the domeshaped apical cell division to form the central axial structure, being the first to confirm the occurrence of apical growth of this species. [ABSTRACT FROM AUTHOR]

The article discusses the development and optimization of algal growth inhibition test for hazard identification of chemicals. It mentions that the algal toxicity testing is part of the standard information requirements under the European Union (EU) chemical legislation Registration, Evaluation, Authorization and Restriction of Chemicals (REACH). It examines the shading effects of nanoparticles on algal growth.

Effects of electrolysis by low-amperage electric current on the chlorophyll fluorescence characteristics of Microcystis aeruginosa were investigated in order to reveal the mechanisms of electrolytic inhibition of algae. Threshold of current density was found under a certain initial no. of algae cell. When current density was equal to or higher than the threshold (fixed electrolysis time), growth of algae was inhibited completely and the algae lost the ability to survive. Effect of algal solution volume on algal inhibition was insignificant. Thresholds of current density were 8, 10, 14, 20, and 22 mA cm at 2.5 × 10, 5 × 10, 1 × 10, 2.5 × 10, and 5 × 10 cells mL initial no. of algae cell, respectively. Correlativity between threshold of current and initial no. of algae cells was established for scale-up and determining operating conditions. Changes of chlorophyll fluorescence parameters demonstrated that photosystem (PS) II of algae was damaged by electrolysis but still maintained relatively high activity when algal solution was treated by current densities lower than the threshold. The activity of algae recovered completely after 6 days of cultivation. On the contrary, when current density was higher than the threshold, connection of phycobilisome (PBS) and PS II core complexes was destroyed, PS II system of algae was damaged irreversibly, and algae could not survive thoroughly. The inactivation of M. aeruginosa by electrolysis can be attributed to irreversible separation of PBS from PS II core complexes and the damage of PS II of M. aeruginosa. [ABSTRACT FROM AUTHOR]

Growth and survival of two populations ofFucus vesiculosuswere studied at its southern limit of distribution on the eastern Atlantic coast. Experimentally denuded areas at an estuarine and a semi-exposed site in an upwelling area (NW Spain) were followed for 17 months. Three different cohorts were detected during the sampling period. Differences among the three cohorts in terms of growth, reproduction and survival were detected. These differences may be due to the different time of appearance of the different cohorts or the presence of the previously established individuals when the second and third cohorts were recruited. Although growth of the cohorts recruiting in autumn was faster than for the cohorts recruiting in spring and summer, individual growth was represented in all cases by a logistic function, as the fastest rates of increase in length occurred during the first 6 months of life, and maximum length was attained after the thallus reached 1 year in age. In the same way, production was maximum for the first cohort, recruiting in autumn, even when it had the lowest survival rate, because of the rapid growth of survivors during spring and summer. For both populations, reproduction was continuous through the year but it was maximal during spring and summer. Protection from waves might have been thought to favour higher production and standing stock biomass values at the estuarine site compared with the semi-exposed site, while turnover rates of biomass were higher at the latter. Contrary to expectations, most of the nutrients available for the studied populations were not related to upwelling. Despite the fast initial growth of new recruits, both populations appeared to be very sensitive to clearance. [ABSTRACT FROM PUBLISHER]

Understanding how the impact of different herbivores varies spatially on coral reefs is important in qualifying the resistance of coral reefs to disturbance events and identifying the processes that structure algal communities. We used assays of six common macroalgae ( Acanthophora spicifera, Caulerpa taxifolia, Galaxaura rugosa, Laurencia sp. Sargassum sp., and Turbinaria ornata) and remote underwater video cameras to quantify herbivory in two habitats (reef crest and slope) across multiple sites on Orpheus Island, Great Barrier Reef. Rates of herbivory varied among macroalgal taxa, habitats, and sites. Reductions in algal biomass were greatest for Sargassum sp. (36 % 4 h), intermediate for A. spicifera, Laurencia sp., C. taxifolia, and T. ornata (17-33 % 4 h) and lowest for G. rugosa (6 % 4 h). Overall, rates of herbivory were generally greater on the reef crest (30 % 4 h) than the reef slope (21 % 4 h). This difference in rates of herbivory coincided with a marked shift in the dominant herbivores between habitats. Kyphosus vaigiensis, despite only feeding on three species of macroalgae ( Sargassum sp., T. ornata, and A. spicifera), was responsible for 34 % of all bites recorded on the reef crest yet did not take a single bite from algae on the reef slope. In contrast, Siganus doliatus took bites on every species of algae in both habitats, accounting for 40 % of bites on the reef crest and 74 % of all bites recorded on the reef slope. This difference in the number of macroalgal species targeted by herbivores and the habitat/s in which they feed adds another dimension of complexity to our understanding of coral reef herbivore dynamics. [ABSTRACT FROM AUTHOR]

Seasonal and interannual variability in sinking flux of biogenic particles was reported by the multi-year bottom-tethered sediment trap measurements in the Northwind Abyssal Plain (Station NAP: 75°N, 162°W, 1975m water depth) of the western Arctic Chukchi Borderland. Whereas the trapped particle flux had an obvious peak with the dominance of sea ice-related diatom valve in August 2011, the observed particle flux was considerably suppressed throughout the summer season in 2012. In the present study, response of ice algal production and biomass to wind-driven changes in physical environments was addressed using a pan-Arctic sea ice-ocean modeling approach. Sea ice ecosystem with ice algae was newly incorporated into the lower-trophic marine ecosystem model, which was previously coupled with a high-resolution (i.e., horizontal grid size of 5 km) ocean general circulation model. Seasonal experiments covering two year-long mooring periods indicated that primary productivity of ice algae around the Chukchi Borderland depended on basin-scale wind pattern through various processes. Easterly wind in the southern part of distinct Beaufort High supplied high abundance of nutrient for euphotic zones of the NAP region via both surface Ekman transport of Chukchi shelf water and vertical turbulent mixing with underlying nutricline water as in 2011. In contrast, northwesterly wind flowing in the northern part of extended Siberian High transported oligotrophic water within the Beaufort Gyre circulation toward the NAP region as in 2012. The modeled ice algal biomass during the summer season certainly reflected the differences in nutrient distribution. The sinking flux of Particulate Organic Nitrogen (PON) was comparable with the time series obtained from the sediment trap data in summer 2011. On the other hand, lateral advection of shelf-origin ice algal patch during a great cyclone event might have caused a model bias on the PON flux in 2012. The extension of year-long measurements is expected to help the illustration of more general features on the Arctic marine biological pump. [ABSTRACT FROM AUTHOR]

Microhabitat-level spatial variations in diatom and isotope compositions of epilithic periphyton in the littoral zones of Lake Malawi were examined using periphyton samples collected from seven regions of the lake. Discriminant analysis revealed a clear difference in diatom composition among the slopes of the rocks from which the samples were collected. This difference may be associated with interspecific variation in the adhesive power of diatoms. The slope of the rocks also strongly affected the stable carbon isotope ratios of periphyton, together with subsidiary effects of algae size class, sampling site, depth, and some of their interaction terms. The effect of slope can be explained by the decrease in photosynthetic activity along the slope, which originates from the decline in sunlight. Thus, the diatom composition and carbon isotope ratios may be good indicators of microhabitat and have the potential to be powerful tools for quantitative measurement of microhabitat utilization of epilithic algae-feeding consumers of this lake, including territorial cichlids. [ABSTRACT FROM AUTHOR]

Spetter, C.A.; Popovich, C.A.; Arias, A.; Asteasuain, R.O.; Freije, R.H., and Marcovecchio, J.E., 2015. Role of nutrients in the phytoplankton development during a winter diatom bloom in a eutrophic South American estuary (Bahía Blanca, Argentina). The Bahía Blanca Estuary is considered highly eutrophic. Long-term studies have shown that the winter-early spring bloom can be considered the development of a diatom assemblage with Thalassiosira curviseriata as the dominant species. Since 2003, several changes have been observed in the annual pattern of nutrients and phytoplankton. To assess the availability of nutrients and their relationship with phytoplankton development, nutrient variability was studied during a winter bloom in 2003 (April 22-September 4). Nitrite, nitrate, ammonium, phosphate, silicates, chlorophyll- a, phytoplankton abundance, particulate organic matter, and physicochemical parameters were measured in surface water at Cuatreros Port. In the Sauce Chico River mouth, we determined the concentration of nutrients to estimate the input of this river. The results of this study were compared with those of a previous usual diatom bloom from 2002. In 2003, the bloom was dominated by the Cyclotella sp. with high chlorophyll- a concentrations (26.5-40.4 μg L−1). Thalassiosira curviseriata was present only at three sampling dates, reaching up to 19% of the total abundance. Mean values of dissolved oxygen, nitrate, oxygen saturation percentage, and salinity were significantly higher in 2003 than in 2002, while N:P ratios were significantly lower. Si was never limiting. A shift in the limiting nutrient between the years (N in 2003 and P in 2002) could have lead to a change in species dominance during the blooms. Results suggest that the nutrients levels in the coastal ecosystems at Cuatreros Port play an important role in the control of phytoplankton dynamics during the productive period and partially explain its interannual variability. El estuario de Bahía Blanca es considerado altamente eutrófico. Los estudios anteriores han demostrado que la floración invernal del fitoplancton se caracteriza por el desarrollo de una asociación de diatomeas con Thalassiosira curviseriata como la especie dominante. Desde el 2003, se han observado cambios en el patrón anual de nutrientes y fitoplancton. La variabilidad de los nutrientes fue estudiada en Puerto Cuatreros durante una floración invernal (22 Abril-4 Septiembre 2003) con el fin de evaluar la disponibilidad de nutrientes y su relación con el desarrollo del fitoplancton. Se determinó la concentración de nitrito, nitrato, amonio, fosfato, silicatos, clorofila a, materia orgánica particulada, la abundancia del fitoplancton y los parámetros fisicoquímicos en agua superficial. Para estimar el aporte del Río Sauce Chico se determinaron las concentraciones de los nutrientes en su desembocadura. Los resultados de este estudio se compararon con los de una floración típica previamente estudiada durante el 2002. En 2003, la floración estuvo dominada por Cyclotella sp. presentando altas concentraciones de clorofila a (26.5-40.4 μg L−1). Thalassiosira curviseriata alcanzó el 19% de la abundancia total y se detectó solo en tres fechas del muestreo. Los valores promedios de oxígeno disuelto, nitrato, porcentaje de saturación de oxígeno, y salinidad fueron significativamente mayores en 2003 que en 2002, mientras que la relación N:P fue significativamente menor. El Si nunca fue limitante. Se sugiere que un cambio en el nutriente limitante (N en 2003 y P en 2002) puede haber conducido a un cambio en la dominancia de la especies durante la floración invernal. Los resultados evidencian que los niveles de nutrientes en sistemas costeros como Puerto Cuatreros cumplen un rol importante en el control de la dinámica del fitoplancton durante un período productivo y podrían explicar en parte su variabilidad interanual. [ABSTRACT FROM AUTHOR]

A major limiting factor in the development of algae as a feedstock for the bioenergy industry is the consistent production and supply of biomass. This study is the first to access the suitability of the freshwater macroalgal genus Oedogonium to supply biomass for bioenergy applications. Specifically, we quantified the effect of CO2 supplementation on the rate of biomass production, carbon capture, and feedstock quality of Oedogonium when cultured in large-scale outdoor tanks. Oedogonium cultures maintained at a pH of 7.5 through the addition of CO2 resulted in biomass productivities of 8.33 (±0.51) g DW m−2 day−1, which was 2.5 times higher than controls which had an average productivity of 3.37 (±0.75) g DW m−2 day−1. Under these productivities, Oedogonium had a carbon content of 41-45% and a higher heating value of 18.5 MJ kg−1, making it an ideal biomass energy feedstock. The rate of carbon fixation was 1380 g C m−2 yr−1 and 1073.1 g C m−2 yr−1 for cultures maintained at a pH of 7.5 and 8.5, and 481 g C m−2 yr−1 for cultures not supplemented with CO2. This study highlights the potential of integrating the large-scale culture of freshwater macroalgae with existing carbon waste streams, for example coal-fired power stations, both as a tool for carbon sequestration and as an enhanced and sustainable source of bioenergy. [ABSTRACT FROM AUTHOR]

Our objective was to select setae ultrastructure characteristics as identification criteria for Chaetoceros subgenus Hyalochaete. We sampled 53 Korean coastal water locations and three Chukchi Sea, Arctic Ocean sites, and we studied 22 species using light microscopy and scanning electron microscopy. We selected 12 criteria for species-specific identification: (1) point of fusion of the sibling setae, (2) spine form, (3) poroid shape, (4) spine arrangement, (5) poroid arrangement, (6) number of poroid rows per pm along the setae, (7) special intercalary setae, (8) connecting bridge-like structure on the basal part of the intercalary setae, (9) siliceous capilli on the basal part of the setae, (10) setae crosssectional shape, (11) silicification of the setae wall and (12) direction of setae to the chain axis. Using these criteria, we constructed a dichotomous key to aid species-specific identification in the subgenus Hyalochaete. [ABSTRACT FROM AUTHOR]

The airborne algae of Oahu, Hawaii was studied along a transect crossing from the leeward to the windward side of the Koolau Mountain Range in summer 2013. Algae were collected on agarized medium in petri dishes from a car window as the vehicle drove from Honolulu to Kailua, Oahu, through an elevation gradient of > 360 m and a rainfall gradient of c. 900-3150 mm yr-1. Light microscopy and molecular methods [18S ribosomal (r)RNA gene, 16S rRNA gene, and UPA sequences] were used to characterize a total of 97 operational taxonomic units from the transect. The airborne algal flora of the transect was dominated by cyanobacteria, followed by chlorophycean green algae, diatoms, and ferns and liverworts. This study is the first in Hawaii to incorporate molecular techniques into the identification of airborne algae. [ABSTRACT FROM AUTHOR]

We isolated 17 strains of Chrysotila stipitata and 10 strains of Chrysotila lamellosa from samples collected at exposed chalk surfaces, Westgate, Kent, England, which is the type locality for C. stipitata (generitype) and C. lamellosa. The nuclear-encoded small subunit and large subunit rRNA were used in a molecular phylogenetic analysis. We also examined the cells using light microscopy. Chrysotila stipitata had two chloroplasts per cell, as originally described, and it was positioned within the Coccolithales (Prymnesiophyceae) in a RAxML tree. Chrysotila stipitata gene sequences formed a clade with Pleurochrysis, and because Chrysotila has priority, Pleurochrysis was placed in synonymy. New nomenclatural combinations were also made. Chrysotila lamellosa was located within the order Isochrysidales, and like other members of the order, C. lamellosa had one chloroplast per cell. We reinstated the generic name Ruttnera to accommodate this species (Ruttnera lamellosa comb. nov.). We also showed that several other taxa described from the chalk cliff type locality were alternate life stages for C. stipitata, and we assigned these as synonyms of C. stipitata. [ABSTRACT FROM AUTHOR]

The taxonomy of Grateloupia sensu lato from South America is still to be fully resolved. Based on the phytogeny of the rbcL and female reproductive structures, we described a new genus, Neorubra, to contain two Peruvian species previously known as Grateloupia denticulata and Prionitis decipiens. Neorubra was characterised by having fivecelled carpogonial branches and four-celled auxiliary-cell branches, fusion of carpogonia and hypogynous cells that formed the basal cell or third cell of the carpogonial branch, a markedly elongated auxiliary-cell fusion cell and pericarps that were well developed on the basal side. Based on the carpogonial and auxiliary-cell ampullae and the formation of secondary connecting filaments, we transferred Grateloupia lancifolia to the genus Phyllymenia. [ABSTRACT FROM AUTHOR]

Photosynthetic algal particles are integral to the ecology and optical quality of lake water. Their absorption properties (photopigments, often >20 per species) are modified in response to drivers that affect the intensity and spectral distribution of incident solar energy, including the plankton itself, water, and chromophoric dissolved and suspended particulate matter. The present study was based on the hypothesis that this complex interaction imparts a distinguishing optical signature in lakes. A multivariate discriminant model was applied to in situ phytoplankton spectra from four temperate lakes of different trophy to test this hypothesis. The analysis identified a small set of wavelengths with significant discriminatory power that permitted near-perfect lake classification solely on the basis of the aggregate spectral features in the absorption coefficient of phytoplankton. Furthermore, weighting the sample spectra by the corresponding standard deviation increased model robustness considerably, as shown in both unsupervised and supervised classification. Also presented are additional multivariate techniques that allow for the visualization of the data structure to help explain contributing factors. The results support the possibility of utilizing the optical properties of the phytoplankton to monitor ecological change in lakes. [ABSTRACT FROM AUTHOR]

Seaweed-associated bacteria play a crucial role in morphogenesis and growth of seaweeds (macroalgae) in direct and/or indirect ways. Bacterial communities belonging to the phyla Proteobacteria and Firmicutes are generally the most abundant on seaweed surfaces. Associated bacterial communities produce plant growth-promoting substances, quorum sensing signalling molecules, bioactive compounds and other effective molecules that are responsible for normal morphology, development and growth of seaweeds. Also, bioactive molecules of associated bacteria determine the presence of other bacterial strains on seaweeds and protect the host from harmful entities present in the pelagic realm. The ecological functions of cross-domain signalling between seaweeds and bacteria have been reported as liberation of carpospores in the red seaweeds and settlement of zoospores in the green seaweeds. In the present review, the role of extracellular polymeric substances in growth and settlement of seaweeds spores is also highlighted. To elucidate the functional roles of associated bacteria and the molecular mechanisms underlying reported ecological phenomena in seaweeds requires a combined ecological, microbiological and biochemical approach. [ABSTRACT FROM AUTHOR]

The article discusses research investigating the attachment capacity of juveniles of the seaweed Chondracanthus chamissoi (Gigartinaceae), generated from spores in a laboratory. Topics include the effect of light intensity on C. chamissoi juveniles, the development of secondary attachment discs when placed upon an artificial substrate, and the effect of calcium addition on early attachment C. chamissoi juveniles, as well as their life-cycle phases and development stages.

Abstract: We report on auxospore wall structure and development in the araphid pennate diatom Tabularia fasciculata. Similar to most other pennates, these auxospores showed a typical bidirectional elongation, but unexpectedly bore no transverse perizonium, and with no detectable silicon during much of their expansion. Energy dispersive X-ray spectroscopy (EDS) analyses segregated auxospores into two types: (1) those containing no detectable silicon and (2) those with measureable amounts. Both types were of similar size. Silica precipitation began throughout the auxospore at or near maximal length, but initially was detectable in isolated regions throughout the structure. Following this initial condition, silicon was consistently detectable throughout auxospores of comparable size and corresponded to deposition of longitudinal perizonium (visible through the thin organic outer layer of the wall in some auxospores), followed by the deposition of the initial valves. Our results raise the question as to how the tubular shape of bidirectionally expanding auxospores up to ∼90μm long is maintained in the absence of transverse siliceous elements restricting isodiametric expansion of the cell, which are present in all other known pennate auxospores and all but one other diatom. Our study is the first to systematically examine mineral elements of the auxospore wall analytically. [Copyright &y& Elsevier]

This paper reports data on a community of Trachelomonas species (Euglenophyta) occurring during Planktothrix agardhii bloom formation in a shallow, highly eutrophic dam reservoir. The results come from a long-term study of Siemianówka Dam Reservoir, located on the upper Narew River (NE Poland). From April to October 2007, 132 alga taxa were identified, including 32 Trachelomonas taxa, 23 of which are new for the reservoir; of those, three are first records for Poland: T. armata (Ehrenberg) Stein var. heterospina Swirenko, T. atomaria Skvortzov var. minor Hortobagi and T. minima Dreżepolski. One variety, T. curta var. pappilata Wołowski, is described as new for science. The ultrastructural details of Trachelomonas species are illustrated. The highest number of Trachelomonas taxa was recorded in August in the shore zone of the reservoir. At the end of summer 2007, the conspicuous development of P. agardhii (Gomont) Anagnostidis et Komarek, caused a rapid decrease of Trachelomonas biomass due to lower water transparency and the oxygen concentration. In addition, a decline in the Trachelomonas taxa and biomass was associated with a decrease of water temperature. The negative impact of extracellular microcystin on the Trachelomonas development requires further study. [ABSTRACT FROM PUBLISHER]