BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

VI. SYSTEM OF THE PLANT WORLD

LOWER SPORE PLANTS

GENERAL CHARACTERISTICS AND FEATURES

Water "Blooming"

Recently, in many continental Water bodies (with slow flow), as well as in seas and oceans, cases of water "blooming" have become more frequent. This phenomenon occurs when a significant accumulation of Algae causes the environment or substrate to acquire a green, red, blue, or yellow hue due to the mass development of one or more algal species best adapted to these conditions.

Water "blooming" caused by the mass development of microscopic plants is an extremely widespread phenomenon on our planet. As a result of "blooming," water can take on various colors ranging from blue-green, bright red, brick-red, to reddish-brown and brown (depending on the pigmentation of the organisms causing the bloom). It is observed in all types of water bodies: natural and artificial, marine or continental, hyper-, eu-, meso-, and oligohaline, poly-, meso-, and oligosaprobic. This is facilitated by increased eutrophication of water bodies, which occurs under METABOLISM/18.html">The Influence of natural factors (over thousands and tens of thousands of years) and, to a much greater extent, anthropogenic factors (over years or decades).

Water "blooming" is observed in continental water bodies as well as in seas and oceans (primarily in coastal areas). In seas and oceans, water "blooming" is mainly caused by diatoms (Centrophyceae) and dinoflagellates (Dinophyta), as well as blue-green algae.

In Arctic seas, a spring-summer water "blooming" has been noted, driven by the intensive development of diatoms from the genera Fragilaria Lyngb., Amphiprora Ehr., Achnanthes Bory, Bacterosira Gran., and Chaetoceros Ehr. In the seas of the Northern Hemisphere (Baltic, Black, and Azov seas), water "blooming" in summer is caused by blue-green algae, and in spring and autumn by diatoms. For example, in the Baltic Sea, summer brings the mass development of Aphanizomenon flos-aqae (L.) Ralf ex Born. et Flah., Nodularia spumigena Mert., and species of the genus Anabaena Bory.

The seas of tropical and subtropical latitudes are most characterized by so-called red tides, caused by the intensive development of dinoflagellates, which is frequently observed along the coasts of South America and Africa, as well as near the shores of India and Japan. The Red Sea got its name due to the excessive proliferation within it of the blue-green alga Oscillatoria erythraea Kütz.

In temperate seas, cases of red "blooming" caused by the intensive development of diatoms have been described: Sceletonema costatum (Grev.) Cl., Eutreptiella pascheri, Aulacodius kitttonii Arn. var. africana (Cottan) Rattr., and Pyramimonas cruciata. Water "blooming" caused by toxic species of pyrophytic algae (species of the genera Gonyaulax Diesing and Gymnodinium Stein) is extremely dangerous.

More than 200 species of marine water "blooming" agents have been recorded worldwide, of which 20% form toxic "red tides" (Ryabushko, 2003).

Red "blooming" is also observed in continental water bodies. For instance, in Japan, the freshwater golden alga Prymnesium parvum Cart. often develops excessively, causing "blooming" in lakes, mountain basins, and estuaries of Western Europe and the Middle East. Puddle-like freshwater bodies in Central Europe are frequently colored red by Haematococcus pluvialis Flotow, while saline water bodies in the south acquire a brick-red color from the green alga Dunaliella salina Teod.

The reddish coloration of the waters off the coast of Fukuyama (Japan) in 1966 was found to be caused by the mass Development of the dinoflagellate Entomosigma sp. The water "blooming" was preceded by rainfall. Studying the effects of salinity (within the 40% range), concentrations of phosphates, nitrates, organic matter, Trace Elements, and changes in medium pH, Japanese scientists achieved maximum growth of this alga at pH 7.5 and 16% salinity. Cell growth is significantly enhanced by adding trace elements, weak chelates, Vitamin B12, or its analogues to the medium.

Among freshwater bodies subject to "blooming," large lowland rivers and reservoirs built on them should be noted first, along with various ponds for different purposes (biological, technical, fish-rearing, diverse sedimentation tanks), lakes, and cooling ponds.

In freshwater bodies during the summer, water "blooming" is most commonly caused by blue-green and dinoflagellate algae, and in spring and autumn by diatoms. Less frequently, water "blooming" is triggered by green and yellow-green algae. Among the blue-green algae causing blooms in the Dnieper reservoirs are Microcystis aeruginosa Kütz. em. Elenk., M. wesenbergii Koarek, Woronichinia naegeliana (Ung.) Elenk., Anabaena flos-aquae Breb., A. lemmermannii P. Richt., A. circinalis (Kütz.) Hansg., A. spiroides Klebs., A. affinis Lemm., A. scheremetievi Elenk., and Aphanizomenon flos-aquae (L.) Ralfs ex Born. et Flah. (Kondratyeva, 1972).

During the period of freshwater "blooming," algal biomass reaches 1.5–2.0 kg/m³, and in accumulation zones—5–7 kg/m³. In calm weather, algae gather in the surface layers of water in so-called "bloom patches," where their biomass reaches 40–50 kg/m³ (calculated in terms of dry matter represented by seston). For comparison, during water blooms in Arctic seas, phytoplankton biomass reaches 14 g/m³, in the Caspian Sea 1–3 g/m³, and in the Azov Sea 270 g/m³.

It is believed that moderate vegetation of blue-green algae, up to 250 g/m³ (in wet weight), does not negatively affect the ecosystem of water bodies and may even have a positive effect. With a significant increase in algal biomass (up to 500 g/m³ and higher), the consequences of biological pollution begin to manifest—water quality deteriorates, specifically its color, pH, and viscosity change, transparency decreases, and the spectral composition of solar radiation penetrating the water Column changes due to the scattering and absorption of light rays by algae. Toxic compounds (metabolic products of algae and associated Bacteria) and large amounts of organic matter appear in the water, serving as a nutrient medium for bacteria, including pathogenic ones. The water acquires a pungent, musty odor (e.g., during heavy development of Anabaena lemmermannii P. Richt.), and a deficit of dissolved oxygen arises, consumed by algal Respiration and the decomposition of dead organic matter. The intensity of "blooming" can be so great that it even creates certain navigation problems. The shoreline becomes unsuitable for recreation due to washed-up algae that, upon decomposing, release an unpleasant hydrogen sulfide odor. Oxygen deficiency leads to summer fish kills and the suffocation of other aquatic organisms, and also inhibits the processes of self-purification and Mineralization of organic matter. All this contributes to the accumulation of increasing amounts of various harmful substances in the water, many of which are dangerous to humans (toxins, carcinogenic compounds, allergens).

During the Fermentation and decomposition of algae, acetone, butyric and acetic acids, butyl alcohol, phenols, cadaverine-like amines, and other substances accumulate in the water. In calm weather, the sea acquires an unattractive aesthetic appearance. It resembles dark green meadows, and in autumn, when active diatom vegetation begins, it looks like swamps with dark brown water and a corresponding odor (Plant Life, 1978).

Naturally, the greatest evil is the deterioration of water quality. In "bloom patches," the content of ammonium nitrogen rises to 3.5 mg/L, phosphorus to 0.55 mg/L, and organic nitrogen to 125 mg/L, which is several times higher than in clean river water. Due to the high amount of impurities in "blooming" water, filtration during purification is complicated, and elevated salt concentrations lead to scale and sediment formation in industrial water supply systems.

The "blooming" process is caused by more than 130 species of algae belonging to 110 genera and 8 phyla (blue-green, green, euglenoid, dinoflagellate, diatom, golden, raphidophyte, and yellow-green algae).

Representatives of blue-green algae (Microcystis, Anabaena, Aphanizomenon) are the primary forms occurring en masse in predominantly standing freshwater bodies and soil accumulations, as well as aerophilic forms causing the "blooming" of building Materials, structures, monuments, and tree bark. Dinoflagellates (Ceratium, Alexandrium) and diatoms (Dinophysis, Chaetoceras) are the agents of water "blooming" in seas, oceans, brackish estuary areas, or saline river deltas. At the same time, certain aerophilic forms are known among diatoms (Diatoma, Nitzschia).

Green algae (Scenedesmus, Coelastrum, Chlamydomonas) are common inhabitants of freshwater bodies and often actively vegetate in ponds (fish and rural ponds) and ephemeral water bodies (puddles)—Topaczevskiella; they are also dominants among aerophytic encrustations (Chlorella, Ulothrix) on various structures and tree bark (buildings, fences, tree trunks, industrial materials) or soil accumulations. Euglenoid algae (Euglena, Trachelomonas) have been found in mass quantities in excessively polluted pond-type water bodies and puddles, municipal wastewater rich in Organic compounds, and nitrogen-containing industrial wastewater. Yellow-green algae (Pedinomonadopsis, Monodus) have been discovered among encrustations on building walls.

Combating "blooming" must be aimed primarily at eliminating the already existing negative consequences of blooms and overcoming the anthropogenic eutrophication of water bodies. To prevent the eutrophication of artificial water bodies, it is recommended to strictly implement a set of water protection measures, which includes clearing the site of the future reservoir bed, safely burying peatlands, and creating a water protection zone around water bodies—that is, planting terrestrial and aquatic vegetation. It is believed that among aquatic plants, cattails and reeds are best suited for this purpose, as they absorb huge amounts of chemical elements from the water and detoxify various poisonous compounds. At the same time, cattails suppress The Development of blue-green algae (Ryabushko, 2003).

Measures to prevent eutrophication in various water bodies also provide for limiting the watershed area of the water body, restricting the development of livestock complexes, changing agricultural practices (using granulated fertilizers, increasing their burial depth, adhering to application schedules in the soil), and implementing soil erosion protection measures.

Notable water-protection measures include halting wastewater discharges or diverting them outside water bodies; constructing buffer ponds and pre-reservoirs to prevent wastewater from entering the main water body; improving wastewater Treatment, as well as binding and precipitating phosphorus within water bodies; utilizing artificial aeration with air or oxygen; releasing nutrient-rich natural water layers from lakes or reservoirs; applying algicides to curb algal blooms; and, finally, removing excess organic matter from water bodies. This biomass represents a valuable natural organic resource that can find diverse Applications in the national economy.

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Fig. 9. Some species of algae causing water "blooms": 1-4 – Microcystis aeruginosa, 5-8 – M. wesenbergii, 9-10 – Woronichinia naegeliana, 11-13 – Aphanizomenon flos-aquae, 14-15 – Anabaena flos-aquae, 16-17 – Prorocentrum cordatum, 18-20 – Skeletonema costatum, 21-22 – Pseudo-nitzschia delicatissima, 23-24 – Cerataulina pelagica.

The positive role of herbivorous fish (such as the silver carp) in purifying blooming water bodies has been noted. At the same time, silver carp are neither poisoned by toxins nor accumulate them in their bodies, provided the water "bloom" does not exceed certain limits; however, when encountering massive accumulations of blue-green algae, especially those in the decaying stage, silver carp—just like other fish—will perish. In some countries, thermophilic tilapia are successfully used for reservoir de-eutrophication. In Lake Chad (Africa), tilapia graze on blue-green algae, showing a distinct preference for them over green and diatom algae.

Nevertheless, to this day, neither in Ukraine nor in other countries—particularly within the Azov-Black Sea basin—are there dedicated services to monitor harmful water blooms.