Research

20 pages, 2633 KiB

Open AccessArticle

Changes in Algal Plankton Composition and Physico-Chemical Variables in a Shallow Oxbow Lake

by Majd Muwafaq Yaqoob, Csaba Berta, László József Szabó, György Dévai, Szilárd Szabó, Sándor Alex Nagy, István Bácsi, Alexandra Simon, János Nagy, Imre Somlyai, Éva Ács and István Grigorszky

Water 2021, 13(17), 2339; https://doi.org/10.3390/w13172339 - 26 Aug 2021

Cited by 5 | Viewed by 2892

Abstract

In our work, we sought to answer whether we find differences among the various zones of an oxbow lake with different land uses based on physico-chemical variables and dominant algal plankton species. The two ends of the oxbow lake are bordered by settlements, [...] Read more.

In our work, we sought to answer whether we find differences among the various zones of an oxbow lake with different land uses based on physico-chemical variables and dominant algal plankton species. The two ends of the oxbow lake are bordered by settlements, and near them there are open water areas where fishing is the major utilization form. Between the two open water areas we find a protected area with a large aquatic plant coverage and two transition zones towards the open water areas. The oxbow lake receives periodic water replenishment only at one end from one of the open water areas. During summer—due to the lack of rain—the water of the oxbow lake is used for irrigation in the surrounding arable land, so the water level fluctuation can be significant in the riverbed. Our study was performed within a vegetation period of spring, early summer, mid-summer, and fall. In connection with the ecological classification of a smaller water body, studies on the physical and chemical properties of the water and the composition of the algal plankton are usually carried out in few places and relatively infrequently. The characteristics of a water body are also influenced by seasonal changes, which can be the changes in the extent of vegetation coverage, the way land is used and the possibility of water replenishment, to which the algal community usually responds with changes. Based on our study, it can be said that even in a relatively small water body, we found a large differences based on the chemical and physical properties of the water and the characteristic algal species. Open water zones, areas with large macrovegetation coverage, and the transition zones were separated from each other. Full article

(This article belongs to the Special Issue Algae: Indices of Water and Ecological Quality)

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10 pages, 948 KiB

Open AccessArticle

Temperature Dependence of Freshwater Phytoplankton Growth Rates and Zooplankton Grazing Rates

by Jennifer Pulsifer and Edward Laws

Water 2021, 13(11), 1591; https://doi.org/10.3390/w13111591 - 04 Jun 2021

Cited by 9 | Viewed by 3440

Abstract

Phytoplankton growth rates and zooplankton grazing rates were estimated on 16 occasions over a period of 17 months in University Lake, a highly eutrophic lake on the campus of Louisiana State University. Phytoplankton growth rates and chlorophyll a concentrations averaged 1.0 ± 0.2 [...] Read more.

Phytoplankton growth rates and zooplankton grazing rates were estimated on 16 occasions over a period of 17 months in University Lake, a highly eutrophic lake on the campus of Louisiana State University. Phytoplankton growth rates and chlorophyll a concentrations averaged 1.0 ± 0.2 d⁻¹ and 240 ± 120 mg m⁻³, respectively. Chlorophyll a concentrations were at or above the inflection point of the Holling type I curve that described the relationship between zooplankton grazing rates and chlorophyll a concentrations. In most cases, it was necessary to dilute lake water by more than a factor of 4 before zooplankton grazing rates became sensitive to chlorophyll a concentrations. Chlorophyll a concentrations were positively correlated with temperature and were roughly fourfold higher at 30 °C than at 15 °C. An analysis of the temperature dependence of the growth rates and grazing rates in this study and 87 other paired estimates of limnetic phytoplankton growth rates and zooplankton grazing rates revealed virtually identical temperature dependences of growth rates and grazing rates that were very similar to the temperature dependence predicted by the metabolic theory of ecology. Phytoplankton growth rates exceeded zooplankton grazing rates by 0.13 ± 0.05 d⁻¹ at all temperatures over a temperature range of 8.5–31.5 °C. The Q₁₀ for both phytoplankton growth rates and zooplankton grazing rates was 1.5 over that temperature range. Full article

(This article belongs to the Special Issue Algae: Indices of Water and Ecological Quality)

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8 pages, 1675 KiB

Open AccessFeature PaperArticle

Ubiquity of Euglena mutabilis Population in Three Ecologically Distinct Acidic Habitats in Southwestern Japan

by Katsunori Yanagawa, Akira Haraguchi, Kai Yoshitake, Katsuhiro Asamatsu, Masanari Harano, Kei Yamashita and Jun-ichiro Ishibashi

Water 2021, 13(11), 1570; https://doi.org/10.3390/w13111570 - 01 Jun 2021

Cited by 7 | Viewed by 2543

Abstract

Three strains of Euglena mutabilis were isolated from sediments in acidic inland water systems (pH = 3.4–4.7), in Southwestern Japan—acid mine drainage in Sensui (Fukuoka), cold sulfidic spring in Bougatsuru (Oita), and a temporal pool in the Ebinokogen volcanic area (Miyazaki). All strains [...] Read more.

Three strains of Euglena mutabilis were isolated from sediments in acidic inland water systems (pH = 3.4–4.7), in Southwestern Japan—acid mine drainage in Sensui (Fukuoka), cold sulfidic spring in Bougatsuru (Oita), and a temporal pool in the Ebinokogen volcanic area (Miyazaki). All strains grew well in acidic media at pH 3.07. Phylogenetic analysis among these three strains showed high similarities to plastid SSU and nuclear SSU rRNA gene sequences (99.86% and 99.76%, respectively). They were closely related to the cultured isolates from other highly acidic habitats (pH = 2.0–5.9). Concentration of sulfate, aluminum, calcium, and iron had 7–70 fold of differences among the three studied habitats. Our results imply that the rRNA genes of E. mutabilis have compensated for their low genetic diversity by adapting to a wide pH range, as well as various water chemistry of habitats. Full article

(This article belongs to the Special Issue Algae: Indices of Water and Ecological Quality)

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19 pages, 2641 KiB

Open AccessArticle

Cultivation and Molecular Studies to Reveal the Microbial Communities of Groundwaters Discharge Located in Hungary

by Marwene Toumi, Gorkhmaz Abbaszade, Yousra Sbaoui, Rózsa Farkas, Éva Ács, Laura Jurecska and Erika Tóth

Water 2021, 13(11), 1533; https://doi.org/10.3390/w13111533 - 29 May 2021

Cited by 4 | Viewed by 3842

Abstract

In the present study 12 water samples of five sampling sites (Tatabánya, Dandár, Szentendre, Szent Flórián and Ciprián groundwaters) known as nutrient-depleted aquatic environments were studied using amplicon sequencing (NGS) and cultivation techniques. Diversity indices and cell counts were determined to assess the [...] Read more.

In the present study 12 water samples of five sampling sites (Tatabánya, Dandár, Szentendre, Szent Flórián and Ciprián groundwaters) known as nutrient-depleted aquatic environments were studied using amplicon sequencing (NGS) and cultivation techniques. Diversity indices and cell counts were determined to assess the species richness in relation to the cell counts within the samples, and the oligocarbophile growth capability of the isolated bacteria was tested in microtiter plates. Altogether, 55 bacterial phyla were identified from the samples by amplicon sequencing. The microbial communities of the different sampling times of the same sites did not differ significantly. Patescibacteria and Proteobacteria were present in all samples. Ciprián sample was dominated by Bacteroidetes, while in Dandár sample a high ratio of Chloroflexi was detected. Rokubacteria and WOR-1 dominated Szent Flórián sample and Tatabánya had a high number of Epsilonbacteraeota. Nine archaeal phyla were also detected; the samples were characterized by the presence of unclassified archaea and Nanoarchaeota, among them Woesearchaeia, as the most dominant. Crenarchaeota and Altiarchaeota were detected in high ratios in Dandár water samples. Among Thaumarchaeota the family Nitrosopumilaceae, and orders of Nitrosotaleales and Nitrososphaerales appeared in Szent Flórián and Tatabánya samples. Key organisms of the different biogeochemical cycles were discovered in these nutrient-depleted environments: methanogenic archaea, methanotrophic bacteria, ammonia oxidizer, nitrate reducers, diazotrophs, sulfate reducers, and sulfur oxidizer. Diversity indices and cell counts of the samples show negative correlation in case of bacteria and positive in case of archaea in Ciprián sample. The high diversity indices in Szentendre samples are connected to low cell counts, most probably due to the vulnerability of the groundwaters to the external environment factors which lead to the infiltration of soil microbes and contaminants to the water. The isolated bacteria were affiliated into four phyla, most of them belonging to Proteobacteria (59%) followed by Actinobacteria (21%), Firmicutes (17%) and Verrucomicrobia (1%). The members of the facultative chemolithotrophic genera of Sphingobium, Sphingomonas, Sphingopyxis were characterizing only Szentendre, Szent Flórián and Tatabánya samples. Only 10% of the isolated species showed an obligate oligocarbophile character. From the samples, a high number of novel bacterial taxa were cultivated. As a conclusion, our results confirmed the predominance of unclassified and unknown taxa in subsurface water, pointing to the importance and necessity of further studies to characterize these microbial populations. Full article

(This article belongs to the Special Issue Algae: Indices of Water and Ecological Quality)

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19 pages, 11137 KiB

Open AccessArticle

Food Web Responses to a Cyanobacterial Bloom in a Freshwater Eutrophic Lake

by Mengqi Han, Chenchen Dong, Siqi Ma, Cui Feng, Chengqiang Lei, Zemao Gu and Xiangjiang Liu

Water 2021, 13(9), 1296; https://doi.org/10.3390/w13091296 - 05 May 2021

Cited by 4 | Viewed by 2249

Abstract

The microbial food web is an important part in aquatic ecosystem, but studies on the microbial food web in freshwater ecosystem, especially in freshwater eutrophic lakes, still need further investigation. In the present study, using eutrophic Lake Nanhu as model, the community changes [...] Read more.

The microbial food web is an important part in aquatic ecosystem, but studies on the microbial food web in freshwater ecosystem, especially in freshwater eutrophic lakes, still need further investigation. In the present study, using eutrophic Lake Nanhu as model, the community changes of phytoplankton, zooplankton, and bacteria between the bloom and non-bloom period were analyzed, and microzooplankton grazing experiments were also conducted to measure the grazing pressure and selectivity of microzooplankton on phytoplankton community. Phytoplankton community in Lake Nanhu was mainly dominated by Cyanophyta (49.44%), especially Anabaena circinalis and Microcystis flos-aquae, during bloom period. Rotifers were the main components of zooplankton in Lake Nanhu (44.15%), Brachionus calyciflorus and Moina macrocopa were the most dominant zooplankton in the non-bloom and bloom period, respectively. Bacteroidetes showed significantly higher mean proportion in bloom period than that in non-bloom period (p < 0.001). The growth rates of phytoplankton ranged from −1.00 d⁻¹ to 1.29 d⁻¹, while grazing rates of microzooplankton ranged from −1.15 d⁻¹ to 1.05 d⁻¹. Results indicated that microzooplankton could respond quickly to the increase of phytoplankton during bloom period. Meanwhile, microzooplankton showed grazing preference on Cyanophyta and Cryptophyta during bloom period and non-bloom period, respectively. The microzooplankton grazing selectivity during bloom period might depend on phytoplankton community composition. Full article

(This article belongs to the Special Issue Algae: Indices of Water and Ecological Quality)

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11 pages, 1955 KiB

Open AccessArticle

Experimental Study of the Quantitative Impact of Flow Turbulence on Algal Growth

by Haiping Zhang, Yafei Cui, Yuehong Zhang, Hanling Xu and Feipeng Li

Water 2021, 13(5), 659; https://doi.org/10.3390/w13050659 - 28 Feb 2021

Cited by 7 | Viewed by 2321

Abstract

Flow turbulence has been widely accepted as one of the essential factors affecting phytoplankton growth. In this study, laboratory cultures of Microcystis aeruginosa in beakers were carried out under different turbulent conditions to identify the quantitative relationship between the algal growth rate and [...] Read more.

Flow turbulence has been widely accepted as one of the essential factors affecting phytoplankton growth. In this study, laboratory cultures of Microcystis aeruginosa in beakers were carried out under different turbulent conditions to identify the quantitative relationship between the algal growth rate and the turbulent intensity. The turbulent intensity (represented by energy dissipation rate, ε) was simulated with the software FLUENT. Daily measurement of the two parameters (algal biomass and chlorophyll-a concentration) was carried out during the experimental period to represent the algal growth rate. Meanwhile, the rates of photosynthetic oxygen evolution and chlorophyll fluorescence intensity were calculated to investigate the photosynthetic efficiency. The results indicated that the growth rate of Microcystis aeruginosa became higher in the turbulent environment than in the still water environment under the designed experimental conditions. The peak growth rate of Microcystis aeruginosa occurred when ε was 6.44 × 10⁻² m²/s³, over which the rate declined, probably due to unfavorable impacts of strong turbulence. In comparison, the maximum rate of photosynthetic oxygen evolution occurred when ε was 0.19 m²/s³. Based on the findings of this study, an exponential function was proposed in order to incorporate the effect of flow turbulence into the existing algal growth models, which usually just consider the impacts of nutrient availability, illumination, and temperature. Full article

(This article belongs to the Special Issue Algae: Indices of Water and Ecological Quality)

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12 pages, 833 KiB

Open AccessArticle

Characteristics of Fluorescence Spectra, UV Spectra, and Specific Growth Rates during the Outbreak of Toxic Microcystis Aeruginosa FACHB-905 and Non-Toxic FACHB-469 under Different Nutrient Conditions in a Eutrophic Microcosmic Simulation Device

by Qi Wang, Wenjing Pang, ShuJie Ge, Hengguo Yu, Chuanjun Dai, Xianfeng Huang, Jun Li and Min Zhao

Water 2020, 12(8), 2305; https://doi.org/10.3390/w12082305 - 17 Aug 2020

Cited by 4 | Viewed by 2416

Abstract

Microcystis aeruginosa is the dominant alga forming cyanobacteria blooms, the growth of which is limited by available nutrients. Thus, it is necessary to study cyanobacteria blooms and explore the growth of Microcystis aeruginosa under different nutrient conditions. In this paper, we take Microcystis [...] Read more.

Microcystis aeruginosa is the dominant alga forming cyanobacteria blooms, the growth of which is limited by available nutrients. Thus, it is necessary to study cyanobacteria blooms and explore the growth of Microcystis aeruginosa under different nutrient conditions. In this paper, we take Microcystis aeruginosa, including toxic Freshwater Algae Culture of Hydrobiology Collection (FACHB)-905 and non-toxic FACHB-469 strains, into account. The strains were cultured using a simulation device under different nutrient conditions. Ultraviolet spectra, three-dimensional fluorescence spectra, and kinetic parameter indicators of the two species are studied. Compared to FACHB-469, the results show that the specific growth rate of FACHB-905 is much higher, in particular, FACHB-905 is the dominant species under low nutrient conditions. Furthermore, the UV spectral characteristics indicate that the molecular weight of dissolved organic matter in the culture tank of toxic FACHB-905 is greater than that of FACHB-469. Additionally, the humification index of toxic FACHB-905 is slightly higher as well, which suggests that it is more stable in the presence of dissolved organic matter during blooms. Therefore, the toxic Microcystis strain is more likely to become the dominant species in water blooms under lower eutrophic conditions and water blooms formed by the toxic Microcystis strain may be more difficult to recover from. Full article

(This article belongs to the Special Issue Algae: Indices of Water and Ecological Quality)

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17 pages, 2054 KiB

Open AccessArticle

Mesozooplankton Selective Feeding on Phytoplankton in a Semi-Enclosed Bay as Revealed by HPLC Pigment Analysis

by Cui Feng, Mengqi Han, Chenchen Dong, Jingyi Jia, Jianwu Chen, Chong Kim Wong and Xiangjiang Liu

Water 2020, 12(7), 2031; https://doi.org/10.3390/w12072031 - 17 Jul 2020

Cited by 3 | Viewed by 2067

Abstract

Mesozooplankton have been known to be important consumers of phytoplankton, and the community plays an important role in removing the primary production in the marine ecosystem. In the present study, mesozooplankton grazing on phytoplankton were studied in situ at two sampling stations (TM4 [...] Read more.

Mesozooplankton have been known to be important consumers of phytoplankton, and the community plays an important role in removing the primary production in the marine ecosystem. In the present study, mesozooplankton grazing on phytoplankton were studied in situ at two sampling stations (TM4 and TM8) in Tolo Harbour. HPLC analysis showed that diatoms were the dominant phytoplankton in the two stations throughout the year, and contributed on average to over 40% of total phytoplankton biomass. Dinoflagellates were the second most abundant group of phytoplankton in the two monitoring stations, while the contribution of haptophytes, green algae, cyanobacteria, and cryptophytes was negligible. Feeding experiments, combined with HPLC pigment analysis, were conducted to measure mesozooplankton selective feeding on phytoplankton. The results demonstrated that mesozooplankton displayed a clear feeding selectivity for phytoplankton in Tolo Harbour. Firstly, mesozooplankton showed strong preference for the phytoplankton with the size of 20–200 μm, which suggested that the grazing selectivity and grazing rates of mesozooplankton were affected by the size of the food particles. On the other hand, mesozooplankton assemblages in Tolo Harbour displayed significant feeding selectivity for diatoms, dinoflagellates, and cryptophytes over other types of phytoplankton. The three algae groups are all the major phototrophic components in marine planktonic communities, and they often cause red tides in the marine environment. These results, taken together, suggested that mesozooplankton should play an important role in the regulation of red tides. Full article

(This article belongs to the Special Issue Algae: Indices of Water and Ecological Quality)

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