The influence of daylength,light intensity and temperature on the growth rates of planktonic blue-green algae

The in vitro growth rates under continuous light of the four dominant blue-green algae in Lough Neagh, Anabaena flos-aquae Bréb., Aphanizomenon flos-aquae Ralfs fa. gracile Lemm., Oscillatoria agardhii Gom. and Oscillatoria redekei van Goor were slower than in situ rates from Lough Neagh that had been corrected for hours of light received by the algae. However, by culturing on a 6: 18 light-dark cycle in vitro growth rates were obtained that were similar to the in situ rates. Under continuous light small species showed the fastest growth with Oscillatoria redekei the dominant species. However, this pattern was almost completely reversed under the light-dark cycle with Oscillatoria redekei only exhibiting the fastest growth rate under low light conditions. This observation showed agreement with Lough Neagh field data which showed that Oscillatoria redekei reached its maximum crop in April while the other three species were dominant during the summer months. Compared to the generally assumed high thermal tendency of blue-green algae the temperature maxima of the four species were low. No growth was observed at 35°C for any species while Anabaena flos-aquae was severely inhibited at 25°C.     

Density gradient centrifugation (DGC) in Percoll for isolation and characterization of Oscillatoria spp. from Tjeukemeer

SUMMARY.

• 1 A high degree of separation was achieved in isolating Oscillatoria redekei and O. agardhii separately from Tjeukemeer seston by density gradient centrifugation (DGC) in Percoll. When diatoms were abundant, however, a pre-incubation in settling cyhnders was applied to obtain an optimal separation of O. redekei from diatoms.
• 2 One major band dominated by O. redekei was formed in the gradients. O. agardhii showed a varying distribution over three different bands and its banding pattern seemed to be related to the centrifugation resistance of its gas vacuoles and the turgor pressure.
• 3 Pigment ratios of O. agardhii were not affected by DGC in Percoll.

     

Cyclomorphosis in natural populations of Oscillatoria redekei Van Goor

Evidence is presented of a regular seasonal variation in the filament length of Oscillatoria redekei Van Goor in Lough Neagh. This cycle is not in phase with the seasonal changes of the biomass of the species, but seems to occur in step with the nutrient concentrations. Some possible mechanisms of filament replication are discussed and evidence is presented that mechanical forces are not effective in breaking filaments. The ecological significance of cyclomorphosis in this species is difficult to establish.     

The Nitrogen Cycle in Lough Neagh,N. Ireland 1975 to 1987

Results from thirteen years of weekly observations are presented on the nitrogen cycle in Lough Neagh. The data comprised catchment and atmospheric inputs, output via the outflow and calculated losses by sedimentation and denitrification. Nitrate-nitrogen in the rivers is the dominant input fraction and the nitrate loading has increased over the period observed. 52 % of the input N sediments to the lake bottom, but 65 % of this is lost by denitrification. In spite of increasing nitrogen inputs, the summer soluble nitrate concentrations have decreased due to uptake by a perpetual crop of the cyanobacterium Oscillatoria agardhii GOMONT .     

Population dynamics of Limnothrix redekei,Oscillatoria lanceaeformis,Planktothrix agardhii and Pseudanabaena limnetica (cyanobacteria) in a shallow hypertrophic lake (Spain)

Populations of Limnothrix redekei, Oscillatoria lanceaeformis, Planktothrix agardhii and Pseudanabaena limnetica were found in a hypertrophic, gravel-pit lake near Madrid (Spain), throughout a one year sampling at weekly intervals. Physico-chemical factors, phytoplankton biomass and net growth rates were measured. Oscillatoria lanceaeformis was only observed a few weeks, probably being related to phosphorus limitation. Planktothrix agardhii biomass was related to PhAR irradiances, light attenuation coefficient in the water, Brunt-Väisäla frequency and decrease of soluble reactive phosphorus. Limnothrix redekei and Pseudanabaena limnetica biomass values were related to a decrease of inorganic nitrogen and temperature. A different lag response of populations was observed in relation to the environmental features.     

Morphology and taxonomy of Oscillatoria redekei (Cyanophyta)

The polymorphous trichome apices of Oscillatoria redekei are described with respect to their shape and size. Breakage of trichomes may occur either trans- or intercellularly. The development and localization of intercellular trichome breakage were observed. Transmission electron microscopy shows that the fine structure of cell walls resembles that of Pseudanabaena galeata. Longitudinal walls consist of three or four layers and lack a sheath, while the cross walls are composed of three layers with a dominating L₂-layer. In contrast to P. galeata, the centroplasm and most of the thylakoidal region of adjacent cells of O. redekei are connected by the cross walls forming obtuse angles at the site of the longitudinal walls. The main characteristics of O. redekei and of Pseudanabaena species are discussed.     

Light/Dark Cycle and Temperature-Their Impact on Phosphate-Limited Growth of Oscillatoria redekei VAN GOOR in Semicontinuous Culture

Phosphate-limited growth of Oscillatoria redekei in semicontinuous culture has been studied under conditions of continuous illumination at 20 °C as well as in a 12/12 hours light-dark cycle at temperatures between 5 °C and 20 °C. The subsistence quota (q₀) amounted to 0.052 μmol mm⁻³ under all conditions, when the phosphate quota was expressed on the basis of cell volume. The interaction between temperature and phosphate quota and its impact on growth rate are described by the following model: Parameter values are t_opt=24.5 °C, t_min=0.95 °C, μ_max =0.873 d⁻¹. The maximum phosphate quota was found to depend on temperature and to increase along with declining temperature.     

Oscillatoria agardhii var. suspensa nov. var.

Zusammenfassung Oscillatoria agardhii var. suspensa n. var. ist ein Süßwasser-Planktont, der O. agardhii nahe steht, sich aber durch geringere Abmessungen und den Bau der Trichom-Enden unterscheidet. Sie wurde durch Waschen von anderen Organismen befreit, was bisher noch bei keiner Cyanophycee gelungen war.Die Art lebt im Wasser schwebend. Nur in alten Kulturen sammelt sie sich an der Oberfläche an. O. agardhii var. suspensa ist streng photo-autotroph und macht von organischen Nährstoffen keinen Gebrauch. Sie ist sogar sehr empfindlich gegen manche von ihnen, besonders gegen Glucose (aber nicht gegen andere Zucker), die schon in geringen Konzentrationen die Vermehrung unterdrückt.Die weißlich-grüne Farbe der Art wird durch die Pseudovacuolen bewirkt; der Chlorophyllgehalt ist aber nicht geringer als der von anderen Cyanophyceen, die tief blaugrün aussehen.

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Summary Oscillatoria agardhii var. suspensa n. var. is a freshwater planktont allied to O. agardhii but differing in smaller dimensions and the shape of the trichome-ends. It was freed from other organisms by the washing procedure, a technique that had not yet been successful in any member of the Cyanophyceae.The organism lives suspended in the water except in old cultures when it tends to accumulate near the surface. O. agardhii var. suspensa is strictly photo-autotrophic not utilizing any organic nutrients and even to some of them very sensitive, particularly to glucose (though not to other sugars) which prevents growth at minute concentrations.The whitish green hue of the species is due to pseudovacuoles while the content of chlorophyll is not lower than that of Cyanophycean species appearing deep blue-green to the eye.

     

Aspects of nitrogen fixation in Lough Neagh. I. Acetylene reduction and the frequency of Aphanizomenon flos-aquae heterocysts

SUMMARY.

• 1 An investigation was made of the relationships between rates of nitrogen fixation (acetylene reduction), Aphanizomenon flosaquae heterocysts, NO₃-N concentration and other environmental factors which occurred in Lough Neagh between 1969 and 1972.
• 2 The maxima of cells differentiated as heterocysts (approximately 5% (1970), and approximately 7% (1971 and 1972) occurred when NO₃-N concentration was very low or undetectable.
• 3 Acetylene reduction was detectable between 16 May and 8 September 1972 but was not measured in the other years. Rates were greatest in the euphotic zone and it appeared that the nitrogenase activity was closely linked to a light dependent system.
• 4 Areal rates of acetylene reduction were highly correlated with Aphanizomenon heterocyst concentration (r=0.92). There was some indication that a release of phosphorus from the sediments might have stimulated Aphanizomenon nitrogen fixation on one occasion at the end of a calm period. Results show that the most likely conditions for the development of large crops of heterocystous species in Lough Neagh include a scarcity of NO₃-N and a plentiful supply of phosphorus.

     

Feeding ecology of the diving ducks pochard (Aythya ferina), tufted duck (A. fuligula), scaup (A. mania) and goldeneye (Bucephala clangula) overwintering on Lough Neagh, Northern Ireland

1. The diets of pochard (Aythya ferina), scaup (A. marila) and goldeneye (Bucephala clangula) overwintering on Lough Neagh are dominated by chironomid larvae, while molluscs are more important in that of tufted duck (A. fuligula). 2. Inshore areas of Lough Neagh offer poor feeding conditions for these diving ducks because chironomid larvae and molluscs are of small individual body size or low abundance. These factors lead to all four ducks foraging at least in part at depths greater than those usually exploited. 3. Due to their common consumption of molluscs, the diet of tufted duck shows a higher overlap with that of an introduced roach (Rutilus rutilus) population than with any other duck or fish species. 4. The feeding ecology of tufted duck and roach in Lough Neagh may form an example of distant competition and be at least partly responsible for recent fluctuations in the numbers of tufted duck.     

Toxic Blue-green Algae Water Blooms Found in some Lakes in the German Democratic Republic

From 1977 to 1979 plankton samples were taken from 6 lakes in the German Democratic Republic (GDR) during water blooms and examined for their toxicity to homothermal animals. Microcystis aeruginosa, Aphanizomenon flos-aquae, Anabaena spiroides, and Oscillatoria redekei were dominant in the samples. With the exception of Oscillatoria redekei the algae tested had toxic effects on mice after intraperitoneal injection. The rate of survival of the test animals was particularly low when the algae were disintegrated by ultrasound or freeze-drying prior to injection, this indicating the endogenic character of the toxins. Water blooms of Microcystis aeruginosa taken from Lake Pehlitzsee (Eberswalde District) showed the highest toxicity with an LD₃₀ as high as 45 and 43.7 mg/kg, respectively. Injection of the lyophilized cells of Aphanizomenon flos-aquae brought about the same symptoms in the test animals as in the case of Microcystis, but the LD₃₀ was 200 mg/kg.     

Blue-green algae in the sediment of the Lake Brielse Meer

Summary It was demonstrated that the blue-green algaeAphanizomenon flosaquae, Microcystis aeruginosa, Oscillatoria agardhii andO. tenuis are present throughout the year in the sediment of an eutrophic dutch lake.Anabaena flos-aquae does not have a benthic phase.     

Chromatic Adaptation of the Planktonic Blue-green Alga Oscillatoria redekei VAN GOOR and its Ecological Significance

Natural populations and culture strains of Oscillatoria redekei isolated from the same lakes exhibit a great variety of phycoerythrine/phycocyanine ratios even under the same growth conditions. Cytophotometric and spectrophotometric determinations of the phycoerythrine and phycocyanine contents of different strains after exposure to blue-green and orange-red light, respectively, suggested that chromatic adaptation of O. redekei takes place both at cellular and population level. This wide intraspecific diversity is considered at least one reason for competitiveness in highly eutrophic lakes.     

Viability of dried filaments, survivability and reproduction under water stress, and survivability following heat and UV exposure in Lyngbya martensiana, Oscillatoria agardhii, Nostoc calcicola, Hormidium fluitans, Spirogyra sp. and Vaucheria geminata

Dried vegetative filaments ofSpirogyra sp.,Vaucheria geminata andNostoc calcicola died within 1/2, 1 and 4 h, respectively; those ofHormidium fluitans, Oscillatoria agardhii andLyngbya martensiana retained under similar storage conditions viability for 3, 5 and 10 d, respectively. The viability of dried vegetative filaments ofL. martensiana, O. agardhii andH. fluitans decreased on storage at 20°C in the dark.L. martensiana andO. agardhii tolerated 0.8 mol/L NaCl. The resistance to desiccation inL. martensiana andO. agardhii exhibited similar dependence as that to frost, to heat and UV light.O. agardhii filaments became slightly broader and their cells developed large number of gas vacuoles when grown in 0.8 mol/L NaCl-containing medium. The water stress imposed on growing algae either on high-agar solid media or in NaCl-containing liquid media reduced hormogonium formation inL. martensiana andO. agardhii, heterocyst and akinete formation inN. calcicola and fragmentation inH. fluitans; it did not induce conjugation inSpirogyra sp. and formation of reproductive organs inV. geminata. In all studied algae the stress reduced at various levels the survival of vegetative parts. Generally, algal body form and composition rather than habitats seem to decide primarily the level of resistance against various stress conditions.     

Chemotaxonomy of planktonic cyanobacteria based on non-polar and 3-hydroxy fatty acid composition

Twenty-eight axenio planktonic cyanobacterial strains (10 Microcystis, three Oscillatoria, one Spirulina, one Aphanizomenon, 13 Anabaena) were investigated for their fatty acid composition by measurement of non-polar and hydroxy fatty acids. No 2-hydroxy fatty acids were detected in any strain, but 3-hydroxy fatty acids were detected in minor quantities in 24 strains. The highest portion of total fatty acids were non-polar fatty acids. Qualitative and quantitative analyses of 3-hydroxy fatty acids showed no taxonomic value in these strains, while the type of non-polar fatty acid composition was shown to be consistent within Microcystis and Anabaena strains, distinguishing them as type 4, characterized by the presence of 18:4, and type 2, characterized by 18:3 (α) of the Kenyon-Murata system. Two Oscillatoria agardhii Gomont strains were also included in the type 2 group due to the presence of 18: 3 (α), but the difference in characteristics of 16:2 and 16:3 between O. agardhii and Anabaena further divided type 2 into two subgroups: type 2A for Anabaena and type 2B for O. agardhii. A simplified unweighted pair group method with arithmetic averages (UPGMA) dendrogram demonstrated that the classification of 28 strains (Microcystis spp., Anabaena spp., Aphanizomenon flos-aquae (Lemmermann) Ralfs f. gracile (Lemmermann) Elenkin, O. agardhii and Spirullnasubsalsa Oersted ex Gomont based on numerical analysis of non-polar fatty acids corresponded to morphological species criteria, suggesting that non-polar fatty acid composition is a valuable chemical marker in the taxonomy of planktonic cyanobacteria. However, the fatty acid composition in Oscillatoria raciborskii is similar to that of Microcystis and very different from that of O. agardhii, suggesting its special position in Oscillatoria and the chemical diversity in the genus Oscillatoria.     

Predicting the spring algal biomass in Lough Neagh using time series analysis

1. Lough Neagh is a large eutrophic lake covering 387 km² with a mean depth of 8.9 m. It is an important natural resource, being the largest single source of potable water for Belfast, Northern Ireland. 2. This report examines the causes of the year-to-year variation in the April–June (spring) algal biomass, measured as chlorophyll a, for the period 1974–92. 3. The spring chlorophyll a declined following the introduction of a phosphorus (P) reduction programme at major sewage treatment works in 1981. However, since 1990 the chlorophyll a concentrations in the spring have increased. 4. Time series methodology was employed to develop a model which explained 76% of the annual variation in spring chlorophyll a concentrations. 5. The independent variables used in the multiple regression model were the previous year’s spring chlorophyll a concentration, soluble reactive P inputs for April–June and the particulate P concentration in the Lough during the previous summer.     

Fatty acids with antibacterial activity from the cyanobacterium Oscillatoria redekei HUB 051

Bioassay-guided fractionation of the n-hexane extract prepared from the biomass of the cyanobacterium Oscillatoria redekei syn. Limnothrix redekei HUB 051 by silica gel and RP-18 column chromatography followed by HPLC resulted in the isolation of a mixture of two unsaturated hydroxy fatty acids. Their further separation using normal phase HPLC resulted in the identification of -dimorphecolic acid, a 9-hydroxy-10E, 12Z-octadecadienoic acid (9-HODE) and of coriolic acid, a 13-hydroxy-9Z, 11E-octadecadienoic acid (13-HODE). In agar plate diffusion test these fatty acids inhibited the growth of the Gram-positive bacteria Bacillus subtilis SBUG 14, Micrococcus flavus SBUG 16 and Staphylococcus aureus SBUG 11 and ATCC 25923, but no activity was observed against multiresistant Staphylococcus aureus strains. This is the first report about antibacterial activity of these hydroxylated unsaturated fatty acids and about the occurrence of coriolic acid in cyanobacteria.     

Growth and potential photosynthesis of cyanobacteria are stimulated by viable gut passage in crucian carp

Growth and potential photosynthetic activity of phytoplankton passed through intestine of crucian carp (Carassius auratus) from a small Siberian reservoir were compared with those of phytoplankton taken the directly from the reservoir. The dominant phytoplankton species in the reservoir, Microcystis aeruginosa, showed a significant increase of growth after the passage. Subdominant Planktothrix agardhii also showed an increase in growth rate, while subdominants Anabaena flos-aquae and Aphanizomenon flos-aquae were not stimulated by the gut passage.     

Seasonal succession of the phytoplankton in the upper Mississippi River

Species composition and seasonal succession of the phytoplankton were investigated on the upper Mississippi River at Prairie Island, Minnesota, U.S.A. Both the numbers and volume of individual species were enumerated based on cell counts with an inverted microscope. A succession similar to algal succession in the local lakes occurred. The diatoms were dominant during the spring and fall and blue-green algae were dominant during the summer. The algal concentrations have increased up to 40 fold the concentrations of the 1920's, since the installation of locks and dams. The maximum freshweight standing crop was 4 mg · l^–1 in 1928 (Reinhard 1931), 13 mg · l^–1 in 1975 a wet year, and 47 mg · l^–1 in 1976, a relatively dry year with minimal current discharge. The diatoms varied from 36–99%, the blue-green algae from 0–44% and the cryptómonads from 0–50% of the total standing crop. The green algae were always present but never above 21% of the biomass. The dominant diatoms in recent years were centric -Stephanodiscus andCyclotella spp. (maximum 50,000 ml^–1). The dominant blue-green algae wereAphanizomenon flos-aquae (L.) Ralfsex Born.et Flahault andOscillatoria agardhii Gomont (maximum 800 ml^–1). These algal species are also present in local lakes. Shannon diversity values indicated greatest diversity of algae during the summer months.     

Coidingham Loch, S.E. Scotland

SUMMARY. 1. Coidingham Loch (Berwickshire. Scotland) (area. 8.4 ha, mean depth 2.9 m, max. depth 12.3 m) belongs to Hakansson's convex shape category. It lies in a basin of Silurian Greywackes rock within 0.25 km of coastal sea cliffs (c. 133 m a.s.l.). The theoretical hydraulic replacement time is 3.17 years. 2. The loch stratifies intermittently in summer. Fluctuations in oxygen concentration generally correspond to spells of mixing and stratification; low values of 10% saturation occur at the bottom. 3. The sum of the concentrations of major cations (Na+, K+, Ca²⁺, Mg²⁺) is in accordance with measured conductivities ranging between 380 μS cm^?1 and 420 μS cm^?1 (k.₂₅). The ratios (by equivalents) of Na⁺/Cl^? (0.04) are similar to those in sea-water, whilst values for Ca+²⁺/Cl^? (0.85–1.01) and Mg²⁺/Cl^? (0.79–0.88) reflect the bedrock. 4. Nitrate concentrations were lowest (<0.05 mg N1^?1) in summer following losses from the column of 107 mg N m^?2 1^?1, a rate corresponding well with published figures on microbial nitrate reduction. Nitrate increased at a rate of 8μg N I^?1 d^?1 to a winter maximum of 1.55 mg N I^?1. Mass balance calculations show that if this rise is attributed to run-off from surrounding land, a loss rate of 11.1 kg N ha^?1 yr^?1 would be required; this value is also commensurate with published figures. 5. Changes in phosphorus and factors controlling them contrast markedly with those of nitrate. The minimum concentration of 55 μg total P l^?1 (mainly in soluble reactive form) occurs in spring. An increase to the maximum ofc. 300 μg l^?1 in summer is sustained mainly by release from the sediments at a regular rate of 3 μg P l^?1 d^?1 (8.7 mg m^?2 d^?1). Adsorption by the sediments is considered to be the major process accounting for autumnal losses of phosphorus of 2.6 mg P M^?2d^?1. 6. Silica showed a less regular seasonal pattern, but varied some 45-fold with a maximum of 2.25 mg SiO₂, l_?1 in August.