FILAMENTOUS GREEN ALGAE 



Filamentous green algae present serious problems in irrigation 

 canals by attaching to concrete canal linings, thus reducing the 

 carrying capacity. A typical habitat sketch of attached filamentous 

 green algae is shown in the upper portion of the illustration. 



A close visual examination of these attached organisms (insert) 

 reveals that these plant colonies are composed of masses of threadlike 

 structures. Some species of green algae produce filaments that are 

 coated with a gelatinous sheath, giving them a slimelike texture. 

 Certain other species are covered with calcareous deposits that impart 

 a rough, coarse texture. The individual plant body, or thallus, consists 

 of a single row of cells that divide longitudinally to produce fine, green 

 filaments. Some species develop solitary filaments, while the more 

 complex ones are diversely branched. The filaments of certain species 

 attach to a solid substrate, such as a canal lining, by a special cell called 

 a holdfast. 



Filamentous green algae multiply vegetatively by cell division and 

 fragmentation of the threadlike thallus. Thick-walled microscopic 

 spores, or resting bodies, provide a means for the plant's survival during 

 unfavorable growing conditions and for dissemination of the species. 



Identification of the individual genera of algae is often difficult and 

 requires detailed microscopic examination. Single species of algae are 

 seldom found growing alone in a field situation, but a number of 

 species usually grow in association with one another. Some of the more 

 common genera found in irrigation systems are Stigeoclonium , 

 Oedogonium , Ulothnx, and Cladophora . Magnifications of the 

 growth characteristics of these few genera are illustrated in the lower 

 portion of the plate to give some concept of the cellular makeup of 

 these microscopic plants. 



Many of the filamentous green algae also will develop colonies of 

 filaments that are free floating. These develop so extensively as to 

 produce dense mats at or near the water surface. Usually, in these 

 growth states, the algae become a nuisance by fouling pump inlets, 

 irrigation siphon tubes, trashracks, and sprinkler heads. 



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