Algae and Protozoa Communities on Solid Matters in Jingyuetan

Algae and Protozoa Communities on Solid Matters in Jingyuetan Lake, Chuangchun, China

Deming Dong*1, Liang Liu1, Xiuyi Hua1, Fan Yang1, and Shuofei Dong2 1College of Environment and Resources, Jilin University, 2699 Qianjin Street, Changchun 130012, P. R.

China 2College of Environment, Beijing University, Beijing 100871, P. R. China

In aquatic environment, microorganisms and their extracellular substances on solid matters as surface coatings (SC), suspended particulate matters (SPM), and deposited sediments (DS) play important roles in controlling the transportation and circulation of trace metals in natural waters. In this paper, the microbial composition of solid matters in Jingyuetan Lake was studied, including identification of algae, protozoa and metazoa species, and determination of their numbers and preponderant species. In addition, water qualitiy of Jingyuetan Lake was evaluated based on the microorganisms indication. The results showed that SC contains abundant algae, protozoa, and metazoa, while both Species and quantity of algae and protoza on DS were less than SC greatly. As far as SPM, species and quantity of algae and protoza were in the midist. Evaluation of water quality based on the indication of algae suggested that Jingyuetan Lake was contaminated with organic pollutants.

Keywords algae; protozoa; SC; SPM; DS

1. Introduction

Solid matters as surface coatings (SC), suspended particulate (SPM) and deposited sediment (DS) were located in different positions of the same aquatic environment. These solid matters, together with water phases, constitute the multi-phases system deciding the activities of heavy metals in the aquatic environment. In aquatic environment, adsorption of heavy metals onto solid matters is very important in controlling the transportation and circulation of them [1-4]. Owing to the different forming conditions like temperature, sunlight and hydrodynamic conditions etc, they possessed respective microbial composition. Microorganisms in the solid matters not only adsorb heavy metals and organic pollutants directly in aquatic environment, but also influence their behaviors through affecting the forming and properties of reactive components like Mn oxides, Fe oxides etc in solid matters [5,6]. In addition, species and quantity of microorganisms, especially algae and protozoa, could reflect the water pollution well, accordingly they were often used as indicator to study the status of natural water quality. In this paper, algae and protozoa on the SC, SPM and DS collected from the same water were analyzed qualitatively and quantitatively.

2. Solid matters in aquatic environment

The SC (biofilms and mineral associated) existed widely on the surface of all kinds of medium in natural waters. It was generally dominated by vital organic matters like algae and protozoa. It also contains abiotic organic matters like humus and minerals like Mn oxides and Fe oxides. The oxidation of Mn(II) on SC is generally kinetically inhibited under circumneutral conditions and requires biological catalysis. This biological formation mechanism has been shown to strongly influence the resultant adsorption properties of the Mn oxides [7-9]. The SPM generally suspended in natural waters and 0.45µm micropore membrane is usually employed to separate SPM in rivers, lakes and oceans [10]. SPM mainly include most minerals, debris of animals and plants decomposition, bacteria and algae. * Corresponding author: e-mail: [email protected], Phone: 86-431- 85166401, fax: 86-431- 85166401

Communicating Current Research and Educational Topics and Trends in Applied Microbiology A. Méndez-Vilas (Ed.)

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The DS was located at the bottom of natural waters. It generally contained a great deal of minerals and abiotic organic matters like humus, while content of vital organic matters were relatively less.

3. Identification of algae and protozoa species on solid matters in Jingyuetan Lake

Here Jingyuetan Lake was chosen as natural waters for collecting SC, SPM and DS in the summer of 2006 to investigate the characteristics of algae and protozoa on solid matters in nature waters. It was located in the national forest park in the suburb of Changchun City with an area of 4.3 km2.

3.1 Collection of SC, SPM and DS samples

Collection of SC: Precleaned glass microscope slides (5.0×7.5×0.1 cm) were fixed on polypropylene racks (Chinese patent ZL 01 2 02517.8) and submerged in the water at a depth of approximately 30 cm for a period of 2 weeks. After retrieval from the lake, SC on the glass slides were scraped off and transferred into the beaker filled with MMS (Minimal Mineral Salts) solution [11], and then stirred homogeneously for use. Collection of SPM: Filter (0.45µm) was used to separate SPM from water, which had been kept still for a period prior to filtration. MMS solution was used to dilute obtained SPM samples. The DS samples were collected at a depth from 0 to 2cm, and MMS solution was still used to dilute obtained DS samples.

Fig. 1 Micrograph of SC, SPM and DS (a —SC，b, c—SPM，d—DS)


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3.2 Species of algae and protozoa on solid matters in Jingyuetan Lake

Light microscope (COIC，XSJ-2) was used to observe the algae and protozoa on SC, SPM and DS (16×25), glass slides with SC attached were directly observed under microscope, while for SPM and DS, suspension of SPM and DS was droped onto the slides and then observed. The algae, protozoa and metazoan species on three solid matters were identified to genera [12-14]. The results indicated that species of algae and protozoa included Bacillariophyta division, Chlorophyta division, Cyanophyta division, Ciliated Protozoa division and Sarcodina division etc. Fig.1 (a, b, c, d) was the micrograph of solid matters obtained using microcamera and algae and protozoa identified on the SC, SPM and DS were listed in table1～3. From Fig.1, both appearance and microorganisms species on solid matters were different. SC contains large amounts of vital organic matters such as algae, protozoa, metazoan, which could constitute complex minitype ecosystem. Though abundant algae were observed on SPM as well, the species and quantity of protoza and the metazoan were still less than SC greatly. As far as DS, it was consisted of minerals particles and organic crumb and only less algae had been found on it.

Tab. 1(a) Identification of algae genera on SC

Division Genera Bacillariophyta Stephanodiscus Ehr.

Tabellaria Ehr. Fragilaria Lyngby. Synedra Ehr. Achnanthes Bory.

Stayroneis Ehr. Navicula Bory. Pinnularia Ehr. Cymbella Ag.

Chlorophyta Chlamudomonas Ehr. Chlorella Beij. Scenedesmus Mey. Volvox Linn． Closterium Nitzsch．

Chlorococcum Fries. Ankistrodesmus Cord． Pediastrum Mey. Ulothrix Kütz. Cosmarium Cord．

Cyanophyta Oscillatoria Vauch． Gloeocapsa Kütz. Aphanizomenon Morr.

Microcystis Kütz. Merismopedia Mey.

Tab. 1 (b) Identification of protozoa genera on SC

Division Genera Ciliated Protozoa Spathidium Dujardin

Litonotus Paramecium Hill Zoothamnium Bory Spirostomum Ehrenberg

Leptopharynx Mermod Chilodonella Strand Vorticella Epistylis Ehrenberg

Mastigophora Euglena viridis Peridinium Her.

Oikomonas

Sarcodina Genus Amoeba Genus Raphidiophrys

Tab.1 (c) Identification of metazoan on SC

Division Genera Rotifera Diplois daviesiae

Rotaria citrina Monostyla furcata

Tab.2 (a) Identification of algae genera on SPM


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Division Genera Bacillariophyta Tabellaria Ehr.

Fragilaria Lyngby. Synedra Ehr.

Stayroneis Ehr. Cymbella Ag.

Chlorophyta Chlamudomonas Ehr. Chlorella Beij. Scenedesmus Mey. Closterium Nitzsch． Cosmarium Cord．

Chlorococcum Fries. Ankistrodesmus Cord． Pediastrum Mey. Ulothrix Kütz. Crucigenia Morr.

Cyanophyta Oscillatoria Vauch． Merismopedia Mey.

Eucapsis Clem.

Euglenophyta Euglena Her.

Tab.2 (b) Identification of protozoa genera on SPM

Division Genera Mastigophora Euglena viridis

Bodo Ehrenberg Gymnodinium Stein

Sarcodina GenusRaphidiophrys

Tab. 3 Identification of algae genera on DS

Division Genera Bacillariophyta Tabellaria Ehr.

Fragilaria Lyngby Navicula Bory Synedra Ehr.

Chlorophyta Ulothrix Kütz According to table1～2, both SC and SPM contain abundant algae and majority of species were the same, since the solid matters were collected from the same water. Only several algae were different with each other. For example, Stephanodiscus Ehr., Cymbella Ag., Navicula Bory and Pinnularia Ehr. were identified on SC, but not found on the SPM, while Crucigenia Morr., Eucapsis Clem and Euglena Her identified in the SPM were not found in the SC. Compared with SC and SPM, algae on the DS were only included Bacillariophyta division and Chlorophyta division and the species of algae were less, while protozoa, metazoa was not found on it. Algae were kinds of phototrophy microorganisms and they could not survive without sunlight. SC was generally developed on surface of solid mediums in shallow aquatic environment with enough sunlight and adequate oxygen. However, DS was collected at bottom of waters with deficient oxygen and less sunlight. So sunlight may be head limiting factor and cause great difference in microorganisms’ abundance between SC and DS.

3.3 Microorganisms indicator of water quality

The community frame and abundance will be replaced after being polluted. So Algae and protozoa community and dominant species and genera could act as the indicator microorganisms to the water pollution. Kolkwitz and Marson primarily presented the viewpoint of contaminative ecosystem and enumerate different indicator microorganisms in 1908 [15]. In 1969, Palmer listed the most important 60 algae genera resistant to the organic pollution on the basis of 295 research reports [16]. Compared with the species listed in his research, all algae species determined in this research were included in those most important 60 genera; moreover, species like Euglenophyta, Chlorella Beij. Navicula Bory, Synedra Ehr., Scenedesmus Mey and Ankistrodesmus Cord were in the top ten genera. Then it could be deduced that Jingyuetan Lake was contaminated with organic pollutants.


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In this research, the data of BOD5, COD and surfactants of Jingyuetan Lake were measured in the same period. Compared with Chinese Surface Water Quality Standards (GB3838－2002), Jingyuetan Lake was contaminated with obvious organic pollutants, which was in accordance with the conclusion obtained from indicator microorganisms above.

4 Determination of algae and protozoa numbers and dominant species

Haemocytometer (16 medium pane×25 small pane) was used here to count the algae and protozoa on the solid matters quantitatively. After cover clip was covered on the counting chamber (0.1 mm3) in the middle of haemacytometer, and a spot of suspension of solid matters was dropped along the edge of counting chamber. After standing for a while, the algae and protozoa were watched and accounted under microscope. In this research, algae on solid matters were repeatedly measured for five times and protozoa were repeatedly measured for ten times. The amount of algae and protozoa per unit quantity of solid matters (Ni) was calculated as following equation:

1

0

1000i

A VNV m× ×

=× (1)

In the equation： Ni－amount of microorganisms per unit quality of solid matters (total microorganisms, alga, protozoa or

individual species) (cells/g) A－total amount of microorganisms in the counting chamber (total microorganisms, algae, protozoa or

individual species) (cells) V1－cubage of volumetric flask (30 ml) V0－cubage of counting chamber (0.1 mm3) m －quantity of solid phase sample(g). Amount of algae on the SC, SPM and DS and the preponderant species were listed in the table 4, and the amount of protozoa and preponderant species on SC were listed in table 5. Species and quantity of protozoa on SPM and DS were relatively small and would not be discussed here.

Tab. 4 Amount of algae and dominant species on solid matters

Solid matters

Total amount of algae (cells/g)

Bacillariophytadivision (%)

Chlorophytadivision ( %)

Other divisions(%)

Dominant species and percentage accounted

SC 6.0×108 57.1 24.2 18.6 Fragilaria Lyngby 38.7 %

SPM 8.0×108 35.7 50.9 13.4 Synedra Ehr. 25.7% Ankistrodesmus Cord 32.6%

DS 2.0×106 75 25 0 Fragilaria Lyngby 50% Ulothrix Kütz 25 %

Tab. 5 Amount of of protozoa and dominant species on SC

Solid matters

Total amount of protozoa (cells/g)

Ciliated Protozoa (cells/g)

Dominant species and percentage accounted

SC 3×107 1.9×107 Vorticella 47.6 %

Amount of algae on SC was about 6×108 cells/g with a large percentage belonging to Bacillariophyta division and the preponderant genera on the SC were Fragilaria Lyngby in the Bacillariophyta division. For SPM, amount of algae was a little higher than that on the SC, but percentage of Chlorophyta division was the highest and following with Bacillariophyta division. Preponderant genera on the SPM were Ankistrodesmus Cord in Chlorophyta division (Accounting for 32.6% of total algae on SPM) and


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Synedra Ehr. in Bacillariophyta division (Accounting for 25.7% of total algae on SPM). As far as DS, amount of algae on it was only 2×106cells/g, which was about 2 orders of magnitude lower than the other solid matters. A preponderant genus on the DS was Ulothrix Kütz in Chlorophyta division (25%) and Fragilaria Lyngby in Bacillariophyta division (50%). Amount of protozoa on SC was about 3×107cells/g with a large percentage of Ciliated Protozoa and the preponderant genera on the SC were Vorticella in Ciliated Protozoa division. Above all, Bacillariophyta division was the most dominant population for both SC and DS, While for SPM, Chlorophyta division was the most important population. Hutchinson and Wetzel have summarized the dominant population in different lakes. For eutrophic lake，Bacillariophyta division was the most dominant population perennially，especially Synedra Ehr. and Stephanodiscus Ehr. This community characteristic was very close to the characteristics of algae in Jingyuetan Lake and accordingly it could also be deduced that Jingyuetan Lake was in the eutrophic status.

5 Comparison of algae and protozoa community on SC between Nanhu Lake and Jingyuetan Lake

In the actual bio-monitoring，natural and artificial substance including rocks, dyke，docks and slides were often chosen to collect algae and other microorganisms for analysis. As inserted algae (periphyton) was often fixed and in the relatively steady status, it could reflect the change of water quality well rather than plankton. So in this study, SC contains most abundant algae and protozoa and more suitable for studying the water quality conditions compared with the other solid matters. In our previous study, characteristics of algae and protozoa community on SC in Nanhu Lake have also been undertaken. In this paper, comparison of two lakes about microbial composition on SC will be made in the following. Nanhu Lake was a eutrophic lake located in the south of Changchun City, P.R. China. The lake area is 0.91 km2 and the largest storage capacity is 3106 m3. The average depth is approximately 3 m. Comparison of microbial composition on SC collected from Nanhu Lake and Jingyuetan Lake showed microorganism community on SC in two lakes were generally the same. In other words, algae were mainly involved in Bacillariophyta and Chlorophyta division and protozoa was mainly involved in Ciliated Protozoa division, which was the same for two lakes. But some genera of algae and protozoa were different. For example, Fragilaria Lyngby, Synedra Ehr., Cymbella Ag. and Navicula Bory. were identified in both lakes, while Asterionella, Cocconeis, Gomphonema, Meridion and Cyclotella determined in Nanhu Lake were not found in Jingyuetan Lake and Stephanodiscus Ehr., Stayroneis Ehr., Tabellaria Ehr. and Pinnularia Ehr. present in Jingyuetan Lake were not found in Nanhu Lake. Similarly, for the Chlorophyta division, Ankistrodesmus Cord, Pediastrum Mey., Chlorella Beij, Ulothrix Kütz, Scenedesmus Mey and Volvox Lin. were identified on SC in both lakes, whereas Dictyosphaerium, Oocystis and Stigeoclonium etc. determined in Nanhu Lake were not found in Jingyuetan Lake and Closterium Nitzsch, Chlorococcum Fries, Cosmarium Cord present in Jingyuetan Lake were not found in Nanhu Lake. As far as protozoa, Chilodonella Strand, Vorticella, Epistylis Ehrenberg, Litonotus, Paramecium Hill and Zoothamnium Bory etc. were present on the SC in both lakes, but Halteria, Cyclidium, Strobilidium, Hemiophrys were determined only in the Nanhu Lake and Spathidium Dujardin, Spirostomum Ehrenberg, Tetramitus Perty, Leptopharynx Mermod etc. were only detected in Jingyuetan Lake. The dominant algae and protozoa species on SC in Nanhu Lake was compared with Jingyuetan Lake and the results suggested that the most dominant algae species were Chlorella and Ulothrix (Accounting for 59.3% of the total cell densities of algae) on SC in Nanhu Lake and Fragilaria Lyngby (accounting for38.7% of the total cell densities of alga) in Jingyuetan Lake. The dominant protoza species were the same for two lakes, viz. Vorticella. Above all, microorganisms communities on SC in Jingyuetan Lakes and Nanhu Lake were similar, which may be resulted from similar climate conditions, environmental background values and trophic state, viz. eutrophic status. However, some microorganisms genera were different for two lakes due to different water quality condictions and hydrodynamic conditions etc.


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Conclusion

Microbial composition of SC, SPM and DS was very different due to the distinct forming conditions like temperature, sunlight and hydrodynamic conditions. Evaluation of water quality based on the indicator microorganisms suggested that Jingyuetan Lake was contaminated with organic pollutant. Microorganisms communities on SC in two lakes were generally the same.

Acknowledgments This research was supported by National Natural Science Foundation (20477014).

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Algae and Protozoa Communities on Solid Matters in Jingyuetan