Colonial Blue-green Algae Research Articles

CONTROLS OF ALGAL ABUNDANCE AND COMMUNITY COMPOSITION DURING ECOSYSTEM STATE CHANGE

Shallow lake ecosystems can shift between clear-water, macrophyte-rich conditions and turbid states with abundant phytoplankton. However, little is known about the controls of algal community composition and primary production before, during, and after ecosystem state change, because long time series that monitor biological change through the transition are scarce. Using proxy data sets derived from sediment cores from two shallow hypertrophic lakes in Denmark, variance-partitioning analysis (VPA) was used to determine the relative importance of changes in total phosphorus (diatom inferred), planktivorous fish density (zooplankton inferred), and submerged macrophyte communities (as macrofossil abundance) as determinants of algal abundance and community composition (as sedimentary pigments) over ecosystem state transitions since 1750 (CE) for Lake Lading and 1900 for Lake Søbygaard. Past variation in densities of planktivorous fish explained 12.3% and 18.2% of historical algal community change in lakes Lading and Søbygaard, respectively, while a further 22.3% and 6% of algal variability was explained by variation in macrophyte abundance. Total phosphorus (TP) alone explained nonsignificant amounts of variance (1.5%, 3.6%) but had a significant effect in combination with macrophytes and fish (27%, 13.4%). State transitions occurred ca. 1940 but were preceded by increases in benthic diatoms and macrophytes, suggesting that transitions were gradual rather than instantaneous. In contrast, green, colonial blue-green, and cryptophyte algae were abundant only during turbid states after ca. 1960 and were correlated to changes in planktivorous fish or fish–TP interactions. Contrary to expectations, the shift from predominantly benthic to pelagic algal production represented only a change in habitat and did not result in an increase in total abundance of primary producers.

Knowledge discovery for prediction and explanation of blue-green algal dynamics in lakes by evolutionary algorithms

This paper applies an evolutionary algorithm to the problem of knowledge discovery on blue-green algae dynamics in a hypertrophic lake. Patterns in chemical and physical parameters of the lake and corresponding presence or absence of highly abundant blue-green algae species such as Microcystis spp, Oscillatoria spp and Phormidium spp are discovered by the machine learning algorithm. Learnt patterns are represented explicitly as classification rules, which allow their underlying hypothesis to be examined. Models are developed for the filamentous blue-green algae Oscillatoria spp and Phormidium spp, and the colonial blue-green algae Microcystis spp. Hypothesized environmental conditions which favour blooms of the three species are contrasted and examined. The models are evaluated on independent test data to demonstrate that models can be evolved which differentiate algae species on the basis of the environmental attributes provided.

GLYCOALKALOIDS AFFECT PIGMENTS CONTENT OF SOME FRESH WATER ALGAE

Chlorophyll a synthesis in unicellular green, unicellular and colonial blue-green algae was simulated by moderate concentrations of both alkaloids used (solasodine and diosgenin). Chlorophyll b as well as carotenoids production was enhanced by lower concentrations of solasodine than diosgenin. Phycobilins (phycocyanin and phycoerythrin) pigment production stimulated by lower solasodine and moderate diosgenin concentrations (0.004 and 0.02 %, respectively). The investigated autotrophic green and blue-green algae are more susceptible to solasodine than to its oxygen isomer diosgenin alkaloid.

Effects of nitrogen fertilizer and pesticide management on floodwater ecology in a wetland ricefield

This paper is the first in a series reporting a study on the effects of N fertilizer, green manure, and pesticide applications on the floodwater ecology of a tropical ricefield. Algal, zooplankton, and mollusc popu- lations were monitored during a crop cycle in plots sub- jected to various methods of N management and differ- ent pesticide regimes. This paper presents the experimen- tal design, general features of the statistical methods for data analysis, and the dynamics of algal growth in the floodwater. Transient green algal blooms and increases in floodwater dissolved O2 concentrations were observed after the broadcast application of N fertilizer 7 days after transplanting. These effects were less pronounced after the second N application 55 days after transplanting. Photosynthetic activity in the floodwater of planted plots decreased as the crop season progressed. Mucilaginous colonial blue-green algae proliferated in the zero-N con- trol and unplanted plots, but were inhibited by the broad- cast N fertilizer and green manure incorporation. Deep placement of urea supergranules reduced the negative im- pact of N fertilizer on blue-green algal populations. There was limited evidence that the application of pesticides promoted the development of blue-green algal popula- tions in the absence of readily available N.

Temporal changes in biomass specific photosynthesis during the summer: regulation by environmental factors and the importance of phytoplankton succession

Measurements of phytoplankton photosynthesis vs. irradiance relationships have been made at 3–7 day intervals in Lake Erken (central Sweden) for three years during summer stratification. Both the rate of light-limited (αB) and light-saturated (PB max) photosynthesis per unit chlorophyll a showed distinct and similar temporal trends in each year. Seasonal trends were especially evident for PB max, which increased in value for several weeks following the onset of thermal stratification, and then declined in the presence of the large colonial blue-green alga, Gloeotrichia echinulata. By late summer, when the biomass of G. echinulata had decreased, PB max again rose to its early summer value. The covariation of biomass-specific photosynthesis with the blooming of G. echinulata was the one clear seasonal (week-month) pattern which emerged in each of 3 years. Over short (day-week) time scales, changes in αB were related to changes in irradiance exposure on the day of sampling. However, the relationship between these two parameters was variable in time, since it was superimposed upon longer term trends controlled by changes in phytoplankton species composition. Increases in G. echinulata biomass corresponded with a deepening of the thermocline, which both increased internal phosphorus loading and the transport of resting G. echinulata colonies into the epilimnion. The timing and magnitude of the yearly G. echinulata bloom was as a result related to the seasonal development of thermal stratification. These results illustrate the importance of seasonal changes in the phytoplankton community as a factor regulating rates of biomass specific photosynthesis, particularly when the successional changes involve species with very different life strategies.

Growth and Food Habits of Cage-Cultured Bighead Carp x Silver Carp Hybrids in Ponds of Varying Trophic Status

Four 20m3 cages stocked with 120 bighead carp x silver carp hybrids per cage were placed in each of four ponds varying in trophic status from mesotrophic to hypereutophic. Fish were cultured, without feeding, from 13 March to 1 Octorber 1987. Fish in the mesotrophic pond survived but lost weight (-0.37 g/fish/d). The mesotrophic pond produced insufficient food to sustain fish growth. Maximum fish growth rate occured in the two eutotrophic ponds (6.61vand 7/04 g/fish/d). Fish growth in the hypereutrophic pond was about one-half (3.64 g/fish/d) that in the two eutrophic ponds. Guy analysis of fish in the hypereutrophic pond revealed consumption of larger quantities (P < 0.05) of colonial blue-green algae that were apparently poorly digested and less (P < 0.05) zooplankton (primarily cladocerans) than was found in fish from the eutrophic ponds.

Responses of a eutrophic pond community to separate and combined effects of N:P supply and planktivorous fish: a mesocosm experiment

We conducted an outdoor mesocosm experiment of factorial design consisting of three levels of nutrient supply (no nutrient addition and additions of nitrogen and phosphorus in ratios of 10:1 and 45:1) cross-classified with two levels of bluegill (Lepomis macrochirus) (presence and absence). Nutrient supply significantly affected total phosphorus (TP), total nitrogen (TN), TN: TP ratio, turbidity, Secchi depth, phytoplankton chlorophyll, filamentous blue-green algae, periphyton chlorophyll, Asplanchna and non-predatory rotifers. The presence of bluegill significantly increased TP, turbidity, diatoms, unicellular green algae, colonial blue-green algae, filamentous blue-green algae, periphyton chlorophyll, Asplanchna and non-predatory rotifers, and decreased Secchi depth, cladocerans, cyclopoid copepodids, copepod nauplii and chironomid tube densities. Nutrient supply and fish effects were not independent of each other as shown by significant nutrient × fish interaction effects for TP, Secchi depth, filamentous blue-green algae, periphyton chlorophyll, Asplanchna and non-predatory rotifers.

Experimental Mesocosm Study of the Separate and Interaction Effects of Phosphorus and Mosquitofish (Gambusia affinis) on Plankton Community Structure

We examined community impacts of phosphorus and mosquitofish (Gambusia affinis) in an experimental mesocosm study of factorial design in which two levels of phosphorus addition were cross-classified with two levels of fish. Total phosphorus (TP), chlorophyll, cryptomonads, unicellular green algae, unicellular blue-green algae, colonial blue-green algae, filamentous blue-green algae, chironomid tube length, cladocerans, fish density, and fish biomass were significantly enhanced in the presence of phosphorus addition. Total nitrogen (TN), TN:TP ratio, Secchi depth, chrysophytes, and periphytic diatoms were suppressed in the presence of phosphorus addition. Diatoms, filamentous blue-green algae, chrysophytes, periphytic unicellular and colonial green algae, periphytic filamentous blue-green algae, and rotifers were enhanced in the presence of mosquitofish. Secchi depth, TN:TP ratio, cyclopoid copepodids, nauplii, cladocerans, and chironomid tubes were suppressed in the presence of mosquitofish. We found significant phosphorus × mosquitofish interaction effects for TN:TP ratio, chrysophytes, dinoflagellates, periphytic colonial green algae, cladocerans, and chironomid tubes. These results show that nutrients and fish do not act as independent regulators of plankton communities but instead have effects which can only be predicted from an understanding of their combined impacts.

富栄養湖におけるラン藻と動物プランクトンの相互関係

Studies on interrelations between blue-green algae and zooplankton are reviewed, and the interrelations in eutrophic lakes are discussed. Laboratory experiments have shown that several blue-green algae are toxic to zooplankton and reduce the feeding, assimilation, survival and growth rates of various zooplankters. The algal toxicity differs among algal species and among algal strains. Blue-green algae are considered to be nutritionally inadequate to zooplankton, even if they are non-toxic. In nature, however, the deleterious effects of blue-green algae are recognized only on large bodied cladocerans. In lakes where blue-green algae are blooming, the zooplankton community is usually dominated by small-bodied cladocerans, rotifers and copepods. They seem to have different mechanisms to coexist with the algal blooms ; i.e., inability to consume filamentous or large colonial blue-green algae (small-bodied cladoccerans), resistance to toxic chemicals of the algae (rotifers), avoidance of consumption of the algae by chemosensory feeding (cope-pods). Zooplankters probably promote the dominance of filamentous or colonial blue-green algae by grazing on small edible algae which compete with blue-green algae for nutrients and by releasing nutrients obtained from these algae for use by the blue-green algae. In eutrophic lakes, bloom forming blue-green algae are considered to be hardly ingested by zooplankton. The organic matters produced by the algae are probably utilized by zooplankton through bacteria which had grown in the process of the decomposition of the algae. Thus, the main path way of the organic matters from phytoplankton to zooplankton is detritus food-chain in these lakes.

Inorganic carbon and ammonium uptake by phytoplankton in nitrogen depleted waters in Lake Suwa.

Inorganic carbon and NH4+ uptake by phytoplankton was studied during a period of nitrogen depletion in early fall of 1985 in Lake Suwa to investigate a possible effect of NH4+ supply from the bottom sediments on phytoplankton production. Phytoplankton samples from the experimental enclosures were, after being size-fractionated using 40 μm netting, incubated with the simultaneous addition of 13C inorganic carbon at tracer level (6.515.6% in excess of ambient DIC) and 15NH4+ in substrate saturated concentration (541330% in excess of ambient NH4+) under saturation light intensity for 34 hr. The 40 μm fraction, exclusively composed of large colonial blue-green algae Microcystis spp. There was little difference in specific carbon uptake rates and no difference in photosynthetic activity between the two size fractions. It was suggested that during a period of nitrogen depletion in Lake Suwa a large supply of NH4+ from the bottom sediments could more favorably affect the small-sized phytoplankton than the large colonial Microcystis.

Effects of the blue-green alga Microcystis aeruginosa on zooplankton competitive relations.

Field distribution patterns and laboratory feeding experiments have suggested that blooms of colonial blue-green algae strongly inhibit relatively large-bodied daphnid cladocerans. We conducted laboratory experiments to test the hypothesis that blooms of the colonial blue-green alga Microcystis aeruginosa would shift competitive dominance away from large-bodied daphnid cladocerans toward smaller-bodied cladocerans, copepods, and rotifers. In laboratory competition experiments, increasing the proportion of M. aeruginosa in the algal food supply resulted in a shift from dominance by the relatively largebodied cladoceran Daphnia ambigua to dominace by the copepod Diaptomus reighardi. The small-bodied cladoceran Bosmina longirostris was always numerically heavily dominant over D. ambigua, but its estimated population biomasses were only slightly higher than those of D. ambigua. Daphnia ambigua consistently outcompeted the rotifer Brachionus calyciflorus. Our results demonstrate that blooms of M. aeruginosa can alter zooplankton competitive relations in laboratory experiments, favoring small-bodied cladocerans and copepods at the expense of large-bodied cladocerans. However, contrary to predictions, blooms of M. aeruginosa did not improve the competitive ability of rotifers.

Investigation of a toxic water-bloom of Microcystis aeruginosa (Cyanophyceae) in Lake Akersvatn, Norway

During the summer and fall of 1984 and 1985, the eutrophic Lake Akersvatn in south-eastern Norway, used as reserve drinking water reservoir, was found to produce heavy water-blooms of the colonial blue-green alga Microcystis aeruginosa. Samples of the water-bloom were found to be toxic using the mouse bioassay. No toxin was found free in the water as detected by HPLC and mouse bioassay. The toxic cells (minimum lethal dose 8–15 mg/kg body weight in mice) and purified toxin (minimum lethal dose 50 µg/kg body weight in mice) showed signs of poisoning in laboratory rats and mice identical to that of other hepatotoxin-producing M. aeruginosa blooms and strains reported from other parts of the world. The toxin has chemical properties similar to the cyclic heptapeptide reported for a South African M. aeruginosa toxin. The toxin from Lake Akersvatn bloom material has a molecular weight of 994. The toxic bloom of M. aeruginosa persisted from August to November in 1984 and reappeared in July of 1985. While water from Lake Akersvatn was not used for municipal water supply during this period, the presence of toxic blue-green algae in a drinking water reservoir indicates the need to develop monitoring and detection methods for toxic cells and toxin(s).

Partitioning of CO 2 Fixation in the Colonial Cyanobacterium Microcystis aeruginosa : Mechanism Promoting Formation of Surface Scums

Constraints on inorganic carbon (C(i)) availability stimulated buoyancy in natural, photosynthetically active populations of the colonial blue-green alga (cyanobacterium) Microcystis aeruginosa. In nonmixed eutrophic river water and cultures, O(2) evolution determinations indicated C(i) limitation of photosynthesis, which was overcome either by CO(2) additions to the aqueous phase or by exposure of buoyant colonies to atmospheric CO(2). Microautoradiographs of M. aeruginosa colonies revealed partitioning of CO(2) fixation and photosynthate accumulation between peripheral and internal cells, particularly in large colonies. When illuminated colonies were suspended in the aqueous phase, peripheral cells accounted for at least 90% of the CO(2) assimilation, whereas internal cells remained unlabeled. However, when CO(2) was allowed to diffuse into colonies 15 min before illumination, a more uniform distribution of labeling was observed. Resultant differences in labeling patterns were most likely due to peripheral cells more exclusively utilizing CO(2) when ambient C(i) concentrations were low. Among colonies located at the air-water interface, internal cells showed an increased share of photosynthate production when atmospheric CO(2) was supplied. This indicated that C(i) transport was restricted in large colonies below the water surface, forcing internal cells to maintain a high degree of buoyancy, thus promoting the formation of surface scums. At the surface, C(i) restrictions were alleviated. Accordingly, scum formation appears to have an ecological function, allowing cyanobacteria access to atmospheric CO(2) when the C(i) concentration is growth limiting in the water column.

The composition and ecology of periphyton communities in freshwaters. II. Inter-relationships between water chemistry, phytoplankton populations and periphyton populations in a shallow lake and associated experimental reservoirs (‘Lund tubes’)

Water chemistry, phytoplankton populations and periphyton populations on Potamogeton pectinatus, have been compared in a shallow, brackish lake, Hickling Broad, and in two enclosed, 20 m diameter butyl rubber reservoirs, placed in it. The seasonal changes of periphyton on Hippuris vulgaris and Myriophyllum spicatum in the lake have also been examined. The lake has been made more eutrophic by agricultural land drainage and roosting gull populations, the tubes to a greater extent by gulls perching on their rims. The water in the tubes became persistently dominated by colonial blue-green algae, a spring diatom pulse was absent, and severe nitrogen limitation was found. Periphyton on P. pectinatus in the tubes was scanty. In the lake, however, though phytoplankton chlorophyll a levels were lower, an alternation of spring diatom and summer colonial blue-green algae was recorded. Nitrogen limitation was less severe in the lake and abundant periphyton crops, mainly of diatoms, developed on P. pectinatus and to a...

A simple technique for washing microalgae in preparation for laboratory culture experiments, with particular reference toMicrocystis aeruginosaKutz. emend. Elenkin

A simple method was developed which allows the colonial blue-green alga, Microcystis aeruginosa Kütz. emend. Elenkin, to be washed in order to minimize extracellular nutrient carry-over to a new growth medium. The technique involves the filtration of an algal suspension on to a cellulose ester or polycarbonate membrane filter (pore size 0·22–3·0 µm) to allow in situ washing. The filter is transferred to a small beaker and the alga is resuspended into the desired medium using a magnetic stirring bar. This technique did not affect the growth rate or the mean colony volume of an exponentially growing culture of Microcystis filtered on to a 0·45 µm pore size cellulose ester membrane filter. Stagnant cultures of Microcystis were found to have significantly larger mean colony volumes than swirled cultures.

Use of a Multiple Diffusion Chamber Unit in Culture Studies. Application toGomphosphaeria Aponina

Abstract The application of an apparatus with multiple diffusion chamber (EcoloGen) to studies of the Florida red tide is indicated. The unit consists of four growth chambers mounted radially to a central reservoir and separated from the central chamber by means of membrane filters (pore size 0.5 μ). A mixed culture system using three types of plankton indicated symbiotic-antibiotic effects. Ectocrine interrelationships were further examined using multiple diffusion chambers, and it was found that the metabolic products of a ciliate stimulated growth of colonial blue-green alga, G. aponina.