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

VI. PLANT SYSTEMATICS

LOWER SPORE PLANTS

GENERAL CHARACTERISTICS AND FEATURES

Order Chroococcales

This order unites unicellular and colonial blue-green Algae whose Cells are free, not connected by plasmodesmata, embedded in a mucous matrix, and devoid of polarity (Fig. 11). Reproduction occurs through binary fission of cells in half and exospore budding. Cell shape and colony type, characteristics of mucilage formation, and Cell Division serve as diagnostic features. Representative genera of the order include Cyanobium, Chroococcus, Microcystis, Merismopedia, Gloeocapsa, Chamaesiphon, etc. (Fig. 11).

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Fig. 11 General appearance of selected Representatives of the order Chroococcales: a – Synechocystis minuscula, b – Rhabdonema lineare, c – Microcrocis geminata, d – Microcrocis bella, e – Merismopedia tenuissima, f – Microcystis aeruginosa, g – Gloeocapsopsis magma, h – Coelosphaeridium kuetzingianum, i – Gomphosphaeria aponina, j – Woronichia naegeliana

The genus Microcystis comprises colonial gelatinous freshwater algae that are the most widespread in various types of water bodies in Ukraine, frequently causing water "blooms" in slow-flowing water bodies during the summer, particularly in reservoirs. The colonies are amorphous and microscopic, occasionally reaching several millimeters or even centimeters in size, and unite A large number of individual cells randomly distributed within a mucous matrix. The colonial mucilage is colorless, soft, and diffuse (making it indistinct) or quite dense and clearly visible. The cells are spherical, with or without gas vacuoles. Reproduction proceeds via colony fragmentation and cell division in three mutually perpendicular planes. Species of this genus are among the most important primary producers of organic matter in lakes and ponds, serving as a food source for microfauna.

One of the most well-known agents responsible for water "blooms" is Microcystis aeruginosa. It is distinguished by an exceptionally diverse colony shape and Structure—ranging from spherical and solid to amorphous and reticulate—as well as the presence of numerous gas vacuoles within the cells, giving them an almost blackish hue. This species produces toxins belonging to the hepatotoxin and dermotoxin groups (specifically microcystin).