Growth Of Filamentous Green Algae Research Articles

Fertilizer-induced manganese oxide formation enhances cadmium removal by paddy crusts from irrigation water

Fertilization is a crucial agrological measure for agricultural production that can significantly impact the removal of Cd from irrigation water by paddy crusts (PC). In this study, laboratory and field experiments were conducted to investigate the impact of fertilization at low, medium, and high concentrations on the accumulation of Cadmium (Cd) in PC and the underlying mechanisms involved. The results showed that only low fertilizer concentration could promote the removal of Cd by PC, which reduced the Cd concentration in irrigation water from 19.52 μg/L to 5.35 μg/L. Conversely, medium and high fertilizer concentrations reduced the accumulation of Cd by PC. After fertilizer addition, the proportion of Fe-Mn oxidizable-Cd in PC reached 55 % (with low concentration of fertilizer treatment). The application of low concentration of fertilizer was found to stimulate the growth of filamentous green algae, leading to a significant increase in the relative abundance of sphingomonadaceae (by 1.39 %) and comamonadaceae (by 1.29 %). The XRD, SEM and correlation analysis show that a large amount of manganese oxide is formed on the surface of PC, which increases the fixation of Cd. These findings provide a new perspective for the remediation of heavy metal contamination in paddy fields.

Freshwater snail and shrimp differentially affect water turbidity and benthic primary producers

Benthic macroinvertebrates play key roles in shallow aquatic ecosystems and can contribute substantially to aquatic food webs. However, how macroinvertebrates with different behaviors (for example, pertaining to locomotion, foraging and burrowing) impact water quality and primary producers has not been fully explored. Here, we performed two consecutive microcosm experiments to test the effects of (1) macroinvertebrates with different behaviors (a low mobility scraper aquatic snail Bellamya aeruginosa and a high mobility shredder freshwater shrimp Macrobrachium nipponense) and (2) different shrimp biomasses on water clarity and the composition of benthic primary producers. The results showed that presence of snails significantly increased the biomass of filamentous green algae and decreased the biomass of periphyton. In contrast, presence of shrimp significantly decreased the biomass of filamentous green algae and increased the biomass of periphyton, and these effects were biomass dependent. Filamentous green algae disappeared when shrimp biomass reached 9.8 ​g ​m−2. No interactive effects of snail and shrimp presence were found. This could be attributed to different food preferences by the two consumers, with snails preferring periphyton (mainly diatoms) and shrimp preferring filamentous green algae. The presence of snails decreased water turbidity, while shrimp increased water turbidity, which showed a hump-shaped response to shrimp biomass with a peak at 24.2 ​g ​m−2. These results are likely because the snail is a low mobility grazer and can filter suspended particles, while the shrimp is a high mobility shredder with burrows, which can strongly disturb sediment. The decrease in water disturbance at high shrimp biomass might be due to food limitation, thus reducing burrowing and foraging activities. Neither snail nor shrimp affected the biomass of H. verticillata, while the biomass of V. spinulosa increased with shrimp biomass. The reason for this could be that shrimp increased nutrient availability and decreased the growth of filamentous green algae that compete with macrophytes. Our study demonstrated that different macroinvertebrates have complementary functions in benthic habitats; thus, maintaining macroinvertebrate diversity is important for shallow aquatic ecosystems. Furthermore, the freshwater shrimp M. nipponense could be a potential consumer to control filamentous green algal blooms in its native range, but their biomass should be taken into consideration.

Filamentous green algae Spirogyra regulates methane emissions from eutrophic rivers.

Excessive growth of filamentous green algae in rivers has attracted much attention due to their functional importance to primary production and carbon cycling. However, comprehensive knowledge of how filamentous green algae affect carbon cycling, especially the CH4 emissions from river ecosystems, remains limited. In this study, incubation experiments were conducted to examine the factors regulating CH4 emissions from a eutrophic river with dense growth of filamentous green algae Spirogyra through combinations of biogeochemical, molecular biological, and stable carbon isotope analyses. Results showed that although water dissolved oxygen (DO) in the algae+sediment (A+S) incubation groups increased up to 19 mg L-1, average CH4 flux of the groups was 13.09 μmol m-2 day-1, nearly up to two times higher than that from sediments without algae (S groups). The significant increase of sediment CH4 oxidation potential and methanotroph abundances identified the enhancing sediment CH4 oxidation during Spirogyra bloom. However, the increased water CH4 concentration was consistent with depleted water [Formula: see text] and decreased apparent fractionation factor (αapp), suggesting the important contribution of Spirogyra to the oxic water CH4 production. It can thus be concluded that high DO concentration during the algal bloom promoted the CH4 consumption by enhancing sediment CH4 oxidation, while algal-linked oxic water CH4 production as a major component of water CH4 promoted the CH4 emissions from the river. Our study highlights the regulation of Spirogyra in aquatic CH4 fluxes and will help to estimate accurately CH4 emissions from eutrophic rivers with dense blooms of filamentous green algae. Graphical abstract.

Proliferation of filamentous green algae along with submerged macrophytes planting, and the role of microbe

Excessive proliferation of filamentous green algae (FGA) is a problem that commonly occurs following the remediation of submerged macrophytes during lake restoration. Cultivation of submerged macrophytes changes the physical and chemical environment and micro-habitats for survival and growth of FGA. However, effects of submerged macrophytes on FGA and the mechanisms are largely unknown. In this study, artificial grass (controls) and two submerged macrophytes (Potamogeton maackianus and Vallisneria natans) with different leaf complexity were cultivated at densities of 3, 6, and 9 in aquaria for a month. The proliferation of FGA, photosynthetic performance of macrophytes, and possible roles of bacteria in the interaction of macrophytes and FGA were studied. Compared with controls, planting of P. maackianus promoted the proliferation of epiphytic FGA, and the effects were density-dependent. Also, density-dependent decrease of photosynthetic performance of P. maackianus were observed. However, in the groups of V. natans, proliferation of epiphytic FGA showed density-dependent inhibition, but photosynthesis of V. natans showed density-dependent promotion. Furthermore, photosynthesis of macrophytes was negatively correlated with growth of epiphytic FGA (Chl a contents). Abundances of epiphytic bacteria taxa such as members of orders Rhodobacterales, Nitrosomonadales and Gemmatimonadales on P. maackianus were greater than those on V. natans. The abundances of these bacteria were positively related to Chl a contents of epiphytic algae (FGA). Thus, proliferation of FGA might be partly attributed to accumulation of certain bacteria taxa on the submerged macrophytes planted during lake restoration. To avoid excess proliferation of FGA, careful selection of submerged aquatic macrophytes is needed.

Evaluating Nutrient Reduction, Grazing and Barley Straw as Measures Against Algal Growth

The aim of our study was to experimentally investigate whether it is possible to reduce nuisance growth of filamentous algae in freshwater ecosystems. We used an experimental set-up mimicking a shallow pond system and performed a field investigation in the eutrophic moat of Krapperup castle (Southern Sweden), which exemplifies an extremely impaired ecosystem with ample growth of filamentous green algae. The indoor experiment tested three treatments: I) reduced nutrient concentrations, II) invertebrate grazers and III) addition of barley straw, which may constitute measures against filamentous algal growth and thereby improve the quality of the ecosystem services provided by water bodies. Our results show a decrease in cyanobacteria and diatom abundances in all mesocosms as filamentous algae biomass increased, suggesting that the microalgae suffered from nutrient and light competition with filamentous algae. A tendency for lower filamentous algae final biomass, as well as coverage, was observed in the treatment where the concentration of nutrients was reduced. Grazers treatment showed a tendency to inhibit filamentous algae growth on artificial macrophytes towards the end of the experiment, suggesting that snails initially fed on their preferred food source (diatoms), until it was almost depleted and then started to feed on filamentous algae. Interestingly, the barley straw treatment was the only treatment promoting macrophytes growth and enhancing diatom biomass, but this did not affect filamentous algae biomass. However, the ratio between filamentous algae and macrophyte final biomasses was significantly lower in the straw treatment. In a broader context, it is likely that in a long-term perspective the positive effect of barley straw on macrophyte growth will promote a shift from dominance by filamentous algae to macrophytes as main primary producer. Moreover, our experiment shows that barley straw may be effective in reducing cyanobacterial growth, which may lead to improved water quality and thereby ecosystem services, such as supporting and cultural ecosystem services, since cyanobacteria may produce potent toxins and pose a serious risk to human and animal health. Altogether, our experimental results have important implications for the challenge of reversing nuisance filamentous algal blooms in highly eutrophic systems.

Recent oxygen depletion and benthic faunal change in shallow areas of Sannäs Fjord, Swedish west coast

Sannäs Fjord is a shallow fjord (<32m w.d.) with a sill depth of 8m, located at the Swedish west coast of the Skagerrak (North Sea). The anthropogenic impact on the fjord represents combination of sewage from the local village of Sannäs and land run-off from agricultural areas. Sewage impact has been reduced since 1991 and today the fjord is included into several nature conservation programs administrated by the European Union. Yet, observations during the summers of 2008–2011 show that the shallow inner fjord inlet experiences severe oxygen depletion at 5–12m water depth. To explore if the oxygen depletion is only a recent phenomenon and to evaluate the potential of fjord sediments to archive such environmental changes, in 2008 and 2009 seven sediment cores were taken along a transect oriented lengthwise in the fjord. The cores were analysed for organic carbon, C/N, benthic foraminifera and lead pollution records (as relative age marker). Carbon content increases in most of the cores since the ~1970–80s, while C/N ratio decreases from the core base upward since ~1995. Foraminiferal assemblages in most core stratigraphies are dominated by agglutinated species. Calcareous species (mainly elphidiids) have become dominant in the upper part of the records since the ~late 1990s or 2000 (the inner fjord and the deepest basin) and since the ~1950–70s (the outer fjord). In the inner Sannäs Fjord, an increase of agglutinated foraminiferal species (e.g. Eggerelloides scaber) and organic inner linings occurred since the ~1970s, suggesting an intensification of taphonomic processes affecting postmortem calcareous shell preservation. A study of living vs. dead foraminiferal assemblages undertaken during June–August 2013 demonstrates that in the shallow inner fjord, strong carbonate dissolution occurs within 1–3months following the foraminiferal growth. The dissolution is linked to corrosive conditions present within the sediment - bottom water interface, and is likely caused by the organic matter decay, resulting in severe hypoxia to anoxia. Oxygen depletion at <10m w.d. develops fast due to the small water volume and limited bottom water exchange caused by a close proximity of pycnocline to the fjord bottom. Sediment cores from the deep fjord basin and the outer fjord are, on the contrary, characterized by good to excellent preservation of foraminiferal shells, higher sediment accumulation rates, and the greatest potential for high-resolution paleoenvironmental studies. Increased frequencies of low-oxygen tolerant species (e.g. Stainforthia fusiformis) in the outer fjord after ~ the 1970s suggests that increased primary productivity and seasonal oxygen deficiency have existed in the area over the last century.Recent milder winters, absent sediment reworking by freezing and grounding of sea-ice, increased nutrient load due to higher precipitation and land run-off, and the luxuriant growth of filamentous green algae followed by the organic matter decay are discussed among the mechanisms driving formation of recent oxygen deficiency in the shallow fjord inlets.

Effects of increased vegetation cover on nesting behavior of sticklebacks (Gasterosteus aculeatus)

To maximize reproductive success, reproductive behaviors have to be adjusted to environmental conditions. The breeding habitats of the threespine stickleback Gasterosteus aculeatus are presently changing in the Baltic Sea due to eutrophication and enhanced growth of filamentous green algae. Earlier studies show that high algae density reduces mate encounter rate and the intensity of selection on a few sexually selected traits, but the willingness of males to nest under the new conditions, and their investment into reproduction, have not been investigated. Here, we investigated the effect that increased algae growth has on nesting behavior of sticklebacks. We allowed males to build nests in aquaria with either a sparse or a dense vegetation structure and recorded male nest building behavior and nest characters. Males that nested in dense vegetation showed a longer latency before commencing nest building and also completed nest building later since there was no difference in time spent building. There was no effect of vegetation cover on nest characters. These results suggest that males prefer to nest in sparser vegetation, but that they eventually nest in dense vegetation if more open habitats are not available. This may arise from a negative effect of vegetation on visibility and mate encounter rate and thus on expected reproductive success. This implies that human-induced changes in the environment may force sticklebacks to breed in non-preferred habitats. Since the intensity of sexual selection is reduced in these areas, this could influence the further evolution of the population.

Factors influencing the return of submerged plants to a clear-water, shallow temperate lake

Lack of submerged vegetation was studied in a small, shallow, alkaline, clear-water lake with high nitrate concentration (mean 9 mg NO 3–N L −1) and profuse filamentous green algae (FGA) (mainly Spirogyra sp.). A laboratory microcosm and two lake enclosure experiments were carried out using Elodea nuttallii (Planchon) St John. E. nuttallii grew about 1.7 times as well in sediment from its place of origin compared with sediment from the lake. Differential water quality had no effect, and neither sediment nor water prevented growth in the lake. Nutrient addition reduced plant growth by more than 55% because of shading from epiphytic filamentous green algae (shoot dry weight versus epiphytic algal dry weight, r = −0.491, P < 0.05). Transplanted Elodea plants grew better in enclosures in the lake than in laboratory conditions with lake water and sediment ( P < 0.001, t-test). Rare Elodea individuals in the lake indicate the presence of plant propagules in the lake sediment, but excessive growth of filamentous green algae (summer mean 3.2 g dry weight m −2) significantly hamperd plant growth (shoot length reduced from 29 ± S.E.M. 1 to 25 ± 1 cm) and bird herbivory significantly reduced survival (from 82 ± 7 to 40 ± 6%) and shoot growth (from 78 ± 6 to 18 ± 5 cm) and thus eliminates establishment of even modest plant beds. Fish disturbance and sediment stability were not important. Restoration of submerged plants may require reduction of nitrate input, control of filamentous green algae and protection from birds.

Biofilms as food for decapods (Atyidae, Palaemonidae) in the River Murray, South Australia

Stable water levels and turbidity associated with flow regulation in the River Murray have promoted the growth of filamentous green algae and Cyanobacteria in biofilms on submerged wood. We investigated the assimilation of biofilm algae by two dominant consumers, the decapod crustaceans Macrobrachium australiense (Palaemonidae) and Paratya australiensis (Atyidae), in two river reaches differing in the extent of floodplain development, hence wetland connectivity. Filamentous Cyanobacteria, a major part of the biofilms assimilated in combination with other foods, were up to 83% of the algal component of the gut content volume of P. australiensis and 44% that of M. australiense. Cyanobacteria have not previously been reported as a major source of nutrition for adult decapods. There was little difference between the stable isotopic signatures (13C/12C, 15N/14N) of the two decapod species, or between decapods in the two reaches. Coarse and fine particulate organic matter from the gorge had similar isotopic signatures to those from upstream and so were likely derived from macrophyte detritus rather than local willows. Red gum leaves and wood were too depleted in both δ13C and δ15N to register in the diets of either decapod in gorge or floodplain reaches. The most likely food sources for the decapods are littoral plants in the gorge reach and fine particulate organic matter material processed upstream. This is consistent with current hypotheses of organic matter flux in large river systems.

The Humic Lake Acidification Experiment (HUMEX): Impacts of acid treatment on periphyton growth and nutrient availability in Lake Skjervatjern, Norway

The aim of the Humic Lake Acidification Experiment (HUMEX) was to study the role of humic substances in the acidification of surface waters, and the impacts of acid deposition on chemical and biological properties of humic water. The dystrophic Lake Skjervatjern, Norway, was separated into two basins by a plastic curtain in 1988, and acid treatment of one basin with sulphuric acid and ammonium nitrate started in 1990. Shortly after the onset of the acid treatment, an extensive growth of filamentous green algae occurred in the acidified basin. Clay flower pots filled with nutrient diffusing agar were used to study periphyton growth. Additions of ammonium, nitrate, and bicarbonate, as well as two parallel releases of phosphate were tested. The control basin (B) proved to be N limited for most of the growth season. Consistently higher accumulation of chlorophyll a per area in the acidified basin (A) than in the control, is suggested to be due to N fertilization by the acid treatment (addition of NH 4NO 3). Both the untreated and acidified basins showed pronounced seasonal and temporal variations in nutrient limitation. The assumption that low bioavailability of DIC limits primary production in acidified water was not confirmed for acid humic water. A large increase in areal chlorophyll a in the acidified basin in 1994 occurred simultaneously with increased nutrient supply, particularly ammonia and TP. This is hypothesized to be caused, at least partly, by changed metabolism in the acidified environment, probably by reduced/disrupted nitrification.

Periphyton investigations in HUMEX Lake Skjervatjern in 1992

During the first year of artificial acidification of the dystrophic Lake Skjervatjern with a combination of sulphuric acid and ammonium nitrate, extensive growth of filamentous green algae occurred in the acidified half. Therefore, investigations studying the effect of acidified humic water on periphyton started early 1992. Quantitative measurements in the two lake-halves (acidified-A, control-B) were carried out, using small clay flower pots as growth substrates. The pots were placed in the two lake halves at 0.5 and 2 m depth. During the first three months, accumulated periphyton, measured as dry weight and chlorophyll a, was 50–600% higher in the acidified basin A than in B. Chlorophyll a per unit dry weight was higher in A than B, indicating higher photosynthetic activity in the acidified half. C/N-ratios in freeze-dried material from basin A were 10–11, indicating little or no N-deficiency during the first three months of the experiment at both 0.5 and 2 m depth in the acidified half. In the control basin B, C/N-ratios between 15 and 19 indicated N-deficiency during the first three months of the experiment at 0.5 m depth. At 2 m, there was no growth in basin B for the first 56 d of the experiment. After three months, periphyton accrual at 2 m had approximately the same chlorophyll a per unit dry weight and C/N-ratios as in basin A. This indicated that conditions in basin B at 2 m depth changes from strong growth limitations early in the summer to high photosynthetic activity and little or no N-limitation later in the year. The bluegreen alga Hapalosiphon fontinalis (Ag.)Born. is known to fix elemental nitrogen. It proliferated in the control basin, but was scarce in the acidified half. This supported the assumption of nitrogen limitation in the control basin.

Grazing and nutrient interactions in controlling the activity and composition of the epilithic algal community of an arctic lake1

The effects of grazing by the snail Lymnaea and enrichment with N and P were examined in the epilithic algal community of an arctic lake. Increased nutrients raised chlorophyll a levels and primary production and favored the growth of filamentous green algae and coccoid blue‐greens. Intensive grazing reduced algal concentration and activity. Grazing increased the relative abundance of small green and blue‐green coccoid cells at the expense of larger (&gt;20 µm) diatoms.Photosynthetic activity of snail feces was 77–79% that of ungrazed algae per unit mass. Split chamber experiments and measurements of dissolved phosphorus indicated that nutrients released in grazing may be tightly recycled within snail guts or on the rock surface, rather than transferred into the water.Radioisotope tracing was used to develop a simple energy budget for Lymnaea. Despite viable gut passage of some of the algae, the snail was an efficient grazer, assimilating 68% and incorporating 25% of ingested carbon.

Periphyton in the Volta Lake. II. Seasonal changes on wooden blocks with depth

A seasonal study of the periphyton developed on wooden blocks suspended at five constant depths (0, 0.5, 1, 2, 5 m) in the Pawm-pawm arm of the Volta Lake is reported. The early colonizers at all depths were diatom species, they gradually declined in diversity and numbers and blue-green algae and green algae became more common. After one year the shallower (0–1 m) blocks were covered by a luxuriant growth of filamentous green algae though at lower levels diatoms predominated. Diversity and cell numbers of algae decreased with depth, this was most pronounced below 2 m. It appears that filamentous green algae eventually come to dominate wooden surfaces floating at relatively shallow depths in the Volta Lake.

Decomposition of Four Species of Leaf Litter in Response to Nitrate Manipulation

Input of leaf litter and other allochthonous debris constitute the biological energy base of small watershed streams. The relationship of decomposition rate to nitrate inputs of a 3—4 fold magnitude was tested in three replicate experimental streams. Such a magnitude of nitrate inputs simulated possible input effects of nitrogen fertilization or logging, two common forest practices. At the levels tested, no significant increase in decomposition rate was observed on any of four litter species as a result of nitrate addition. Common parameters measured included weight loss, changes in carbon quality, absolute changes in nitrogen content, and microbial respiration measured as O_2 consumption. Results were partially confounded by growth of filamentous green algae during spring. As a result of chemical O_2 demand or leaf pack envelopment by the decaying algal mat, °° of the total O_2 consumption was not related to litter decomposition. Although not related to increases in nitrate concentration in water, decomposing litter did exhibit a twofold increase in nitrogen content following initial leaching. The mechanism of this increase, whether by biological or chemical means, remains uninvestigated.