Algal growth control by a barley straw extract

In recent years, there has been an apparent increase in the occurrence of harmful algal blooms occurring in potable waters. The potential of a simple barley straw extract to inhibit algal growth was assessed. Algal growth in lakewater was inhibited by the addition of barley straw (1% w/v), with the chlorophyll a concentration remaining below the original level (40 micrograms l-1) throughout the experiment. In contrast, in the presence of wheat straw, algal biomass increased, reaching a final chlorophyll a concentration of 1160 micrograms l-1 after 28 days. Analysis of the remaining particulate straw at the end of the experiment showed that the lignin content of barley straw had increased significantly from 10-33% (w/w). Further, a preparation of a simple aqueous extract from the decomposed-barley straw was found to inhibit the cyanobacteria Microcystis sp. and the algal species Scenedesmus, with chlorophyll a levels some 10-fold lower than in untreated flasks. This study shows that a decomposed-barley extract, even in a very dilute concentration (0.005%) was capable of inhibiting the growth of Microcystis sp., a commonly occurring cyanobacterium which produces the toxin microcystin and has been responsible for some of the most serious pernicious algal blooms in the UK.     

Barley straw as an inhibitor of algal growth II: laboratory studies

The presence of rotting barley straw in water inhibited the growth of several planktonic and filamentous algae in laboratory culture. The inhibitory effect was produced progressively during decomposition of the straw at 20 °C and reached a maximum after six months. When the straw was autoclaved, all inhibitory activity was lost. Algae recovered and continued to grow normally when transferred from cultures containing rotting straw to sterile culture medium. Addition of liquor from rotting straw also inhibited algal growth. The capacity to inhibit growth remained in the liquor after passage through a 0.2 ,m filter but was removed by activated carbon. The inhibitory effect of straw shows promise as a practical means of limiting the growth of a range of algae which can cause problems in aquatic systems.author for correspondence     

鲢对藻类摄食效应的室内模拟研究

为研究鲢(Hypophthalmichthys molitrix)对藻类的摄食作用, 采用小环藻(Cyclotella)、小球藻(Chlorella)、微囊藻(Microcystis)和东湖原水开展了小规格鱼种的养殖试验, 对鲢摄食和排泄物进行了研究。结果显示: 在3 种纯培养藻种投喂下鲢存活率从高到低依次是小环藻组 小球藻组 微囊藻组;相应地, 鲢对藻的平均摄食率排序也是小环藻组 小球藻组 微囊藻组。在显微镜下观察粪便发现大部分小环藻为空壳, 一部分小球藻外部形态结构不完整, 外部形态完整的小球藻则色泽暗淡、内部结构紊乱, 微囊藻没有明显变化;3 种藻类细胞的受损率分别为20.04%、7.13%和1.97%。叶绿素荧光活性显示, 粪便中小环藻基本失去光合活性, 小球藻活性极显著降低(P0.01), 微囊藻活性明显降低(P0.05), 东湖原水处理组光合活性较对照极显著降低(P0.01)。对东湖水饲喂试验组排泄物的检测发现, 浮鞘丝藻Planktolyngya、鱼腥藻Anabeana(有破损)、假鱼腥藻Pseudoanabaena 和颤藻Oscillatoria 细胞受损严重;空星藻Coelastrum 和盘星藻Pediastrum 细胞部分破损;针杆藻Synedra、小环藻、桥弯藻Cymbella 和舟形藻Navicula 多为空壳。鱼粪中平裂藻Merismopedia、微囊藻、浮鞘丝藻、鱼腥藻、颤藻、卵囊藻Oocystis、栅藻Scenedesmus 和衣藻Chlamydomonas 在重新培养后恢复了生长。本研究显示硅藻尤其是小环藻、针杆藻和舟形藻对鲢摄食最敏感;栅藻、卵囊藻和平裂藻对摄食压力不敏感。研究表明鲢捕食对藻类群落结构有明显的改变效应, 利用鲢的滤食进行藻类群落调节和水华防控具有可行性。       

Barley straw as an inhibitor of algal growth I: studies in the Chesterfield Canal

The presence of rotting barley straw in a dis used canal reduced the amount of filamentous algae. No effect on algae was observed during the first season after the introduction of straw but algae were decreased in three subsequent years. Algal growth on microscope slides suspended in the water downstream of the straw was reduced by 90%, compared with slides upstream of the straw. A similar result was obtained forCladophora glomerata grown in chambers in the canal. Phosphate, nitrate and ammonium concentrations were not altered significantly by the presence of straw, but nitrite concentrations were increased during summer months. Neither the nitrite increase, nor the possibility of pesticides being washed off the straw were considered likely causes of algal growth inhibition. Growth ofC. glomerata was inhibited in cages from which macro-invertebrate grazers were excluded. No obvious deleterious environmental effects were noted and the technique shows promise as a long-term method of controlling algae.     

Barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis>)-induced growth inhibition of algae: a review

Many field and laboratory studies have attempted to explain the inhibitory effect of rotting barley on algae. Early field studies lacked controls and replication and results depended on visual observations. Such studies offer information on barley bale field construction and application rates. In the laboratory, discrepancies in the barley variety used, algal species tested, barley liquor preparation and phenol extraction methodologies existed. Inconsistencies have led to different growth responses for the same species of algae tested, i.e. with some studies finding an inhibitory response and other studies reporting an accelerated growth response of algae. Two successful forms of investigation have been identified: (a) using commercially available compounds, i.e. with known shikimate-pathway-producing phenols and acids, which can then be combined with algal assays of different algal species and (b) using commercially available algal species from which batch cultures are grown, which are then added to barley liquor of different ages. Algal growth may then be investigated using in vivo fluorescence and the filtrate can be analysed via HPLC/MS. The identification of allelochemicals, which range from phenolics to quinones within the Poaceae family of which barley is a member, has received a lot of attention in recent years.     

Summer algal communities and primary productivity in fish ponds

The paper presents data on primary productivity and phytoplankton communities in new experimental ponds which received the following treatments; ammonium nitrate and triplesuperphosphate, triplesuperphosphate, cracked corn (10% crude protein) and Auburn No. 3 fish feed (36% crude protein). Comparative data on algal communities were also obtained from production ponds which received feeds or fertilizers. Basic ecological data on macro-algae are also presented.

1. All nutrient additions to experimental ponds resulted in higher levels of gross photosynthesis and greater concentrations of chlorophyll a than were found in the control treatments. Fertilization with both nitrogen and phosphorus gave the highest values. Chlorophyll a and gross photosynthesis were higher in ponds receiving high protein content feed (Auburn No. 3) than in ponds to which low protein content feed (corn) was applied.
2. Persistent blooms of blue-green algae occurred in ponds receiving nitrogen and phosphorus fertilization. Phosphorus only fertilization produced blooms of blue-greens, but these blooms did not persist as in the ponds to which nitrogen was also added. Control ponds were dominated by green algae. Blue-green algae were seldom abundant in feed treatments.
3. Production ponds had high level of gross photosynthesis and large concentrations of chlorophyll a.
4. Many of the production ponds which received feed applications developed heavy blooms of blue-green algae.
5. The major species of blue-green algae observed in the present study were Oscillatoria sp., Raphidiopsis curvata, Anacystis nidulans, A. aeruginosa, Spirulina sp., and Anabaena circinalis. Heterocyst bearing forms, which can presumably fix nitrogen, were seldom noted in ponds that received continuous additions of nitrogen from fish feeds.
6. Macro-algae are abundant in many fish ponds. Data illustrating the competition of macro-algae with phytoplankton are presented.

     

Effects of barley straw (Hordeum vulgare) on freshwater and brackish phytoplankton and cyanobacteria

A short-term laboratory study was conductedto investigate the effect of barley strawin controlling several common phytoplanktonand cyanobacterial species. Following aone-month incubation of barley straw incoarsely filtered fresh Potomac River andbrackish Patuxent River waters, the growthof six autotrophic taxa was followed inculture. Barley straw slurry reduced theyield of three taxa (Ankistrodesmusfalcatus, Chlorella capsulata, Isochrysis sp.) in comparison withcultures not receiving the slurry. Although no significant changes in growthwere detected with three other taxa (Cyclotella sp., Prorocentrumminimum, freshwater Pseudanabaenasp.), some patterns indicated potentialimpacts of the barley straw. First, ahigher addition of straw to Cyclotella sp. resulted in a lower biomassaccumulation than in cultures receivinglower levels. Second, the bloom-formingdinoflagellate Prorcentrum minimumwas apparently stimulated at low barleystraw levels, perhaps suggesting conditionsassociated with the straw(metals-chelation, bacterial-producednutrients) might stimulate dinoflagellategrowth. Third, species shifts wereobserved in two of the cultures, withbarley straw favoring shifts from Isochrysis to a Cyclotella sp. –Thalassiosira sp. mixture and shiftsfrom Pseudanabaena to a Pseudanabaena – Scenedesmus mixture. These results provide new records for thesusceptibility of freshwater and brackishphytoplankton taxa to barley strawexposure, including species-specificresponses and shifts in species dominancein mixed assemblages.     

Contrasting responses of phytoplankton and benthic algae to recent nutrient enrichment in Arctic tundra ponds

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The relative sensitivity of algae to decomposing barley straw

Decomposing barley straw has previously been shown to inhibit the growth of a limited number of algae under both laboratory and field conditions. Bioassays were conducted on a range of algae to evaluate their relative sensitivities to straw-derived inhibitor(s). A range of sensitivities was found, including some species that were resistant to the straw-derived inhibitor(s). A microcystin-producing strain of Microcystis aeruginosa was very susceptible to decomposing barley straw. Bioassays using Euglena gracilis suggest that the inhibitory compounds are not derived from the phototransformation of straw decomposition products and do not act primarily by inhibiting photosynthesis. Susceptibility to barley straw appears not to be related to general taxonomic or structural features. Possible implications for algal populations in natural freshwaters are briefly discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Influence of changes in salinity and light intensity on growth of phytoplankton communities from the Schelde river and estuary (Belgium/The Netherlands)

In the Schelde continuum, a succession in the phytoplankton community is observed along the transition from the river to the freshwater tidal reaches of the estuary and from the freshwater to brackish reaches of the estuary. The goal of this study was to experimentally evaluate the contribution of changes in salinity and light climate to this succession. In summer 2000 and in spring 2001, phytoplankton communities from the river, the freshwater tidal reaches and the brackish reaches of the estuary were incubated under high or low light intensities and exposed to a change in salinity. HPLC analysis was used to evaluate the response of different algal groups to changes in light intensity and salinity. When incubated at a light intensity corresponding to the mean underwater light intensity of the freshwater tidal reaches, growth of phytoplankton from the river as well as from freshwater tidal reaches was significantly lower than when incubated at a light intensity corresponding to the mean underwater light intensity of the river. The phytoplankton community from the freshwater tidal reaches did not appear to be better adapted to low light intensities than the phytoplankton community from the river. Although diatoms were expected to be less sensitive to a reduction in light intensity than green algae, the opposite response was observed. Freshwater and brackish water phytoplankton were negatively affected by respectively an increase or decrease in salinity. However, the effect of salinity was not strong enough to explain the disappearance of freshwater and brackish water phytoplankton between a salinity of 0.5 and 10 psu, suggesting that other factors also play a role. In the freshwater phytoplankton communities from the river and the freshwater tidal reaches, green algae and diatoms responded in a similar way to an increase in salinity. In the brackish water phytoplankton community, fucoxanthin displayed a different response to salinity than lutein and chlorophyll a.     

Towards understanding the nature of algal inhibitors from barley straw

The algal inhibitors released from barley straw decomposing in water and providing the basis for its use in algal control could be either of microbial origin or derived from straw components. We report here that unrotted straw releases algal inhibitors if finely chopped or autoclaved, providing further support for the view that straw, and not microbial colonists, is the primary source of inhibitors. Further support is also provided for the suggestion that inhibitors are or derive from oxidised lignin. Comparisons of lignin-enriched wood (brown-rotted) with lign-indepleted wood (white-rotted) from various deciduous trees show high antialgal activity of the former and little or no activity of the latter. Preliminary studies have shown that solubilised lignin is present in the liquor from rotted barley straw and brown-rotted wood. Since, however, the antialgal effects of deciduous leaf litter appear to depend initially on release of tannins and given that alkaline, oxidising conditions are usually essential for antialgal activity, it is proposed that oxidised polyphenolics, derived from lignin or tannins, are a source of algal inhibitors from plant litter.     

Inhibition of dinoflagellate growth by extracts of barley straw (Hordeum vulgare)

Growth of dinoflagellates representing three orders, the Gymnodiniales,Peridiniales, and the Prorocentrales was examined following treatment withbarley straw extract. Selected dinoflagellate taxa showed growth responsessimilar to those reported for freshwater algae including: inhibition(Gyrodinium galatheanum, Gymnodiniumsanguineum, Heterocapsa triquetra andH. pygmaea); stimulation (Gyrodinium instriatum,Prorocentrum minimum and P. micans); and no effect(Gyrodinium estuariale, G. uncatenum,Ceratium furca, Peridinium sp.).Although barley straw extracts do not appear to have value as a universalmanagement tool for dinoflagellates, they may have potential in management ofspecific taxa and possibly taxonomic groups.     

MERCURY AND TEMPERATURE INTERACTIONS ON THE GROWTH RATES OF THREE SPECIES OF FRESHWATER PHYTOPLANKTON1,2

Cultures of freshwater algae, representing three algal divisions, Synura petersenii Korshikov; Chlamydomonas sp.: and Nitzschia sp., were subjected to four different mercury-temperature shock interactions to demonstrate synergistic effects between mercury and temperature. Algal growth, measured by temporal changes in vivo fluorescence of chlorophyll was used to ascertain the effects. Mercury addition and temperature shock had various inhibitory effects on algal growth. Prior environmental conditions influence the effect of subsequent treatments. Growth of S. petersenii was severely inhibited by mercury in all experiments. Control cultures would not grow at 30 C and died when shacked at this temperature. Chlamydomonas sp. cultures initially inhibited by mercury were able to recover under most conditions after a period of reduced growth. Nitzschia sp. was resistant to mercury except when simultaneously shocked with temperature. Mercury analyses showed that Nitzschia cells at 25 C and 30 C contained a high percentage of the mercury initially added to the cultures. There was a significant loss of mercury at the end of each experiment from all cultures, probably due to volatilization.     

Factors Influencing Algae–Clay Aggregation

The dumping of bauxite tailings on a clear-water Amazonian lake caused a significant decrease in phytoplankton densities. The influence of these suspended clay particles on algal sinking, through algae–clay aggregation, was investigated under laboratory conditions, by measuring fluctuations in algal population densities over time, with different suspended clay concentrations. The population densities of the four algal species tested, Phormidium amoenum, Mougeotia sp., Staurodesmus convergens and Chlorella sp., were decreased by the algae–clay aggregation. The extent of this process was dependent on algal morphological characteristics such as size and shape, as well as on the concentration of suspended clay particles.     

Macrophytes moderate the taxonomic and functional composition of phytoplankton assemblages during a nutrient loading experiment

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Effects of Nano-Titanium Dioxide on Freshwater Algal Population Dynamics

To make predictions about the possible effects of nanomaterials across environments and taxa, toxicity testing must incorporate not only a variety of organisms and endpoints, but also an understanding of the mechanisms that underlie nanoparticle toxicity. Here, we report the results of a laboratory experiment in which we examined how titanium dioxide nanoparticles impact the population dynamics and production of biomass across a range of freshwater algae. We exposed 10 of the most common species of North American freshwater pelagic algae (phytoplankton) to five increasing concentrations of n-TiO₂ (ranging from controls to 300 mg n-TiO₂ L⁻¹). We then examined the effects of n-TiO₂ on the population growth rates and biomass production of each algal species over a period of 25 days. On average, increasing concentrations of n-TiO₂ had no significant effects on algal growth rates (p = 0.376), even though there was considerable species-specific variation in responses. In contrast, exposure to n-TiO₂ tended to increase maximum biomass achieved by species in culture (p = 0.06). Results suggest that titanium dioxide nanoparticles could influence certain aspects of population growth of freshwater phytoplankton, though effects are unlikely at environmentally relevant concentrations.     

Phytoplankton aus neu angelegten Streckteichen (Waldviertel,Niederösterreich)

The colonization of newly constructed fish-ponds with phytoplankton is considered to be the result of inoculation by influents, airplankton and piscicultural measures. A considerable number of remarkable or new species have been observed, but bluegreen algae were extremely rare. The lack of a distinct seasonal succession in phytoplankton composition is attributed to the astatic character of the ponds. The following species are characteristic of the phytoplankton communities observed: Chlamydomonas sp., Chlorogonium elongatum v. plurivacuolatum, Cryptomonas sp., Cyclotella meneghiniana, C. pseudostelligera, Melosira varians, Pandorina morum.     

集球藻对盐胁迫的生理适应及细胞结构变化

盐胁迫是影响荒漠区土壤藻类生存的重要环境因子。集球藻是一种广泛分布于生物土壤结皮中的球状绿藻, 能够积累红色素(如虾青素)和油滴, 显示出其独特的生理特性和潜在的应用价值。目前对集球藻的生理、细胞结构以及色素积累的研究非常匮乏。以从荒漠生物结皮中分离的一种集球藻为材料, 在实验室条件下研究盐胁迫对集球藻生物量、光合活性、膜脂过氧化产物丙二醛含量、细胞可溶性蛋白质含量和可溶性糖含量以及细胞结构的影响。研究结果表明, 与对照处理相比, 盐胁迫导致集球藻生物量和光合活性的显著降低, 细胞可溶性蛋白和可溶性糖呈现一定的积累。同时盐处理导致集球藻膜脂丙二醛含量大量增加, SOD和CAT 活性升高。研究还表明, 对照处理下细胞结构完整, 细胞器形态清晰, 生长后期有大量脂肪体积累。在盐处理下藻体细胞形态结构出现阶段性破坏特征和脂肪体以及淀粉粒的积累, 此外细胞器结构模糊和消失, 细胞出现质壁分离和空泡化等。研究为更好地揭示集球藻在盐胁迫环境中的生理适应特性、微结构特征以及色素积累机制具有重要的科学意义, 并为该藻的基础和应用研究提供实验资料。       

The influence of macrophytes on a phytoplankton community in experimental conditions

The impact of submerged macrophytes or their extracts on planktonic algae was studied under experimental conditions. Live Ceratophyllum demersum L., its extract, and extracts of four other plant species induced modifications in the phytoplankton dominance structure. These modifications were: a decline in the number of Oscillatoria limnetica Lemm., which was the most numerous cyanobacterian species, and a decline in biomass and percentage contribution of all cyanobacteria to total algal biomass. This was accompanied by an increase in biomass and percentage contribution of green algae, especially Chlorella sp. and Chlamydomonas sp. Also, there was an increase in biomass and percentage contribution of nanoplankton (under 50 µm) to total phytoplankton biomass.The isolation of planktonic algae from direct influence of C. demersum by means of dialysis membranes caused an increase in number, biomass and percentage contribution of cyanobacteria. Release of organic compounds of over 3000 daltons by macrophytes apparently contributed to a decline of cyanobacteria by changing the phytoplankton dominance structure.     

Algal growth on organic compounds as nitrogen sources

Two experimental series were run to evaluate the potential of algal development on dissolved organic nitrogen (DON) compounds as the sole source of nitrogen (N) nutrition. Monocultures of several common Lake Kinneret algae (Pediastrum duplex, Synechococcus sp., Microcystis aeruginosa, Aphanizomenon ovalisporum and Cyclotella sp.) were incubated for 3 weeks in the laboratory with different inorganic (NH4⁺, NO3^-) or organic (hypoxanthine, urea, guanine, ornithine, glucosamine, lysine) nitrogen sources. Even though the cultures were not axenic, marked differences were observed in algal growth response. Pediastrum, Cyclotella and Aphanizomenon grew well on most N sources, and cyanobacterial growth and yield were consistently greatest when the urea was the only N source. We also followed algal growth and eventual species dominance in batch samples of GF/F-filtered lake water, supplemented with orthophosphate and different inorganic or organic N compounds and inoculated with concentrated lake phytoplankton. Although no clear impact on phytoplankton growth (as chlorophyll concentration) was observed, in seven out of 11 experiments we could discern changes in the algal species that became dominant in flasks with different organic and inorganic N sources. Our results are consistent with the proposition that components of the DON pool are not only an important potential, direct or indirect N source for phytoplankton, but also that different algal species can exploit these sources with varying capabilities so that different N substrates may selectively stimulate the development of dominant algal species.