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Planktonic algae in the water refer to groups of organisms with small individuals, large varieties, large numbers and beautiful shapes. Most algae need to be observed with a microscope, but they are important indicators of the state of the aquatic environment, and they can instruct us to understand the quality status and composition of farmed water bodies.
(Planktonic algae under the microscope)
1. Planktonic algae and water body indication
Algae in the water are primary producers and are the basis for the material cycle and energy flow of the entire aquatic ecosystem. Small they are sensitive to changes in the habitat and their sensitivity, if a certain algae is more sensitive to a certain pollutant, when the water body is polluted by this substance, the more sensitive algae species are the first to be affected, the number is reduced or disappeared; some algae species have a certain tolerance to certain pollutants or "affinity", when pollution occurs, other algae are greatly reduced or disappeared, tolerant or "affinity" species can still survive normally or be less affected, thus becoming a dominant population; in addition, Some algae also have a certain absorption and enrichment effect on pollutants in water bodies, and monitoring the composition changes in algae can help indicate water quality. Therefore, it is precisely because of this property that algae can be used to analyze and evaluate the water quality status by using their species, quantity and community structure.
For example, in freshwater water bodies, cyanobacteria, especially microcystics, are the main indicator species of eutrophication in water bodies. Its outbreak indicates that the nutrient-richness of water is quite serious (excessive fertilizer water).
(Microcysticles and microcysticos blooms)
The following article describes four types of algae as water quality indicator organisms:
2. Diatom phylum
(1) Diatom structure
There are patterns and siliceous matter on the cell wall, of which the outer layer is siliceous and the inner layer is pectin. The cell wall is hard and consists of two half-shells, upper and lower. Benthic species are thicker and planktonic species are thinner.
Diatoms contain a large amount of carotene and lutein, which mask chlorophyll and are yellow-brown. The shape of each cell is circular, linear, oval, columnar, disc-shaped, triangular and so on. Its main feature is that the cell wall consists of two shells chimeric with each other. The shell contains a large number of silicon and fine pores, with different front shapes and complex and regular patterns. However, the sides are rectangular, so it is difficult to distinguish their species from the side. There are two methods of reproduction, namely split reproduction and compound spore reproduction.
(2) The relationship between diatoms and the environment
There are many types of diatoms, and the habits vary depending on the species. According to this habit of diatoms, it can indicate the cleanliness of the water quality. The water quality is divided into three levels: Os - poor saprophyticity, biological oxygen consumption BOD<1mg/L; βm - medium humus, BOD < 1mg/L, but the content of inorganic salts is higher; αm - humus, BOD > 10mg/L, but not in the state of hypoxia.
Diatom water quality analysis table
Water quality indicator species of diatoms
Ecological distribution of diatoms
3. Phylum Chlorella
Green algae are single-celled eukaryotes and also have linear or banded or cluster populations where most cells are integrated. Most have cell walls, the inner layer of the cell wall is cellulose, and the outer layer is pectin. Motor cells usually have two apical hairs of equal length. There are usually 2 telescopic bubbles at the base of the flagellar. 1 eye spot, orange-red, located on the anterior side of the cell.
Wherever there is water, traces of green algae can be found. The survey found that in nutrient-poor waters, oocystis predominates, often accompanied by ---。 In the middle vegetative waters, the genus Dipteroptera and Tympanobacter are dominant. In nutrient-rich waters, disco and gravis are dominant. And in the genus Dipteroptera (S. chaetoceras) Slender Horned Star Tympanobacteria (S. Chaetoceras) gracile）、（S. planetonicum), and drum algae appear in moderately nutritious waters.
Algae are divided into three water quality levels, α grade - poor trophic water quality, β level - moderate trophic water quality, and γ level - eutrophic water quality. These three levels are difficult to give clear water quality boundaries, so the long-term water quality status can be analyzed in conjunction with WQOs to produce a more reliable water quality survey result.
Green algae water quality level analysis table
Poorly nutritious waters indicate species
Indicator species in poor middle vegetative waters
Medium nutrient water indicator species
Indicator species in moderately nutritious waters
Species indicated in nutrient-rich waters
4. Cyanobacteria phylum
Cyanobacteria are the most primitive and oldest algae and are prokaryotes. There are abundant algal cholexins in the pigment, and the plant body is often blue-green, also known as blue-green algae.
(1) Main structural characteristics
The cell structure of cyanobacterial cells is clearly divided into two parts, the inner and outer parts, namely the cell wall and the appendages and protoplasts on it.
1 cell wall and gel indument
The cell wall is the same as that of bacteria and often consists of two layers. The inner layer contains a certain amount of cellulose; the outer layer is pectin. In addition, it also contains mucine ammonia peptides, which is one of the characteristics that distinguish cyanobacteria from other algae.
2 false cavitations
False vacuoles are generally black, red or purple, and formaldehyde will fade to off-white after fixation. There is often gas in the false vacuole, mostly nitrogen.
2 alien cells
Alien cells are found only in some filamentous cyanobacteria, are brighter, and are metamorphosed from ordinary vegetative cells. Such as eyebrow algae, bead-containing algae, candida algae are produced. The nitrogen fixation capacity of some of these cyanobacteria is related to the alien cells.
(2) Types of cyanobacterial blooms
Microcystis, ichthyrophyllum, cronococcus, spirulina, ichthyosis, colucoccus, cucurbita, fibrillation, etc. Currently, the bloom species found in aquaculture are microcystis, fibrillation, and ichthyrophyllum. Among them, ichthyophyllum blooms are found in water bodies with higher alkalinity.
(3) Cyanobacterial toxins
The common cyanobacterial toxin (MC) in freshwater is a cyclic peptide toxin, and there are more than 75 variants of such toxins that have been identified so far [, the most common and most toxic are MC-LR, MC-RR, and MC-YR (L, R, Y represent leucine, arginine, and tyrosine, respectively). Microcystis, ichthyrophytes, fibrillators, and candidas can all produce toxins.
Microcystin is said to be possibly associated with the development of liver cancer.
(4) The indicative effect of cyanobacteria
Cronococcus, sticky chlorella, and brown tube spores are indicator organisms of clear water, while other cyanobacteria usually occur in warmer, eutrophicating waters. A single advantage is often formed, but cyanobacteria and naked algae and phyllodobarb horned algae are found to form a common advantage in the cultured water body, which may be related to their ecological complementarity.
Indicates cyanobacteria drawings
5. Flagellaria
Flagellar algae, mostly distributed in freshwater, are single-celled eukaryotes with no cell wall, one or two flagellar at one end of the cell, and can move freely in water. In waters of different levels of pollution, the species of flagella are different. Flagella can be divided into three categories as indicator organisms: class A is clean water, B is dirty water, and class C is heavy dirty water.
(1) Class A (Clean Waters)
The indicative species, Cysticza, belongs to the Phylum Golden algae.
Cystis is mostly a tree-like population, and the cells have conical, bell-shaped, and cylindrical cyst shells, which are different from ciliated bellworms (protozoa), with 2 unequal flagella at the front and 1 protruding capsule at the front. 1 eye point. Telescopic bubbles 1 to more. 1-2 pigment bodies, significantly degenerated.
Cystaceae prefers to grow in clean waters that are poor in nutrients, and is an indicator organism with good water quality. Cystis dominance is often seen in nutrient-poor lakes. Sometimes it appears at the same time as the diatoms that are poor in nutrients.
(2) Class B (dirty waters)
Indicative species, algae, belong to the phylum Of green algae.
There is a gelatinous indumentum outside the algae, in which most of the cells have two flagella, which are connected to each other by intertwined filaments. The number of population cells is 500-2000. The propagation method of the algae is gradually expanded by one cell in the population, and then divided into two cells, after the second division of the cells become 4, and then the cells grow geometrically, and the number of cells increases from 512 to 1024, becoming a hollow sphere, and the flagella is outward, developing into a new group.
Algae plants prefer to grow in dirty waters and are indicators of vegetative water quality. When they multiply in large numbers, they often make the water appear green and form a bloom.
(3) Class C (severely polluted waters)
Indicative species, eyeworms, belong to the phylum Nudibranchus.
Eyeworms have chlorophyll and red eye spots, can perform photosynthesis and photosensitivity, and have phototropism. The best time to grow is from April to October. In the water, you can use the flagella and body twisting to exercise. The individual is pear-shaped, with a slightly blunt anterior end and a gradually thinned posterior end.
Eyeworms usually like to grow in dirty and nitrogen-rich organic sewage, multiply quickly in severely polluted water, often make the water surface appear green, and are an indicator organism with serious water pollution.
Flagella indicates a water quality analysis table
Figures
Planktonic algae are widely distributed in the water, and it can be traced almost everywhere there is water. And there are many kinds of ecological habits, some like clean water, some like dirty water. We can use this to understand our aquaculture water bodies according to the above contents, so as to do a good job in water transfer.
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