Cladophora fracta

Green Filamentous Algae


This is a medium power photomicrograph of Cladophora fracta from Emigration Creek

 

Index


What is Algae?
Habitats and Distribution of Algae
What is Cladophora?
Biological Significance of Freshwater Algae
Dispersal of Algae
Environmental Factors Affecting the Growth of Algae
Other Websites to Investigate
References



What is Algae?

Algae are plantlike protists found in the Kingdom Protista. Protists are eukaryotic, unicellular or multicellular organisms. Like plants, algae have chloroplasts, and their cells are strengthened by the cell wall. Algae refer to aquatic organisms that carry on photosynthesis. Algae are part of a fresh water's phytoplankton (phyton=plant and planktos=wandering), which produce energy that maintains an entire community of organisms. Not only do algae provide food, but they also play a key role in the stream ecosystem because they produce oxygen.

It has been customary to classify algae according to their color, which come in a variety of color such as green Chlorophyta, brown Phaeaphyta, golden brown Chrysphyta, and red Rhodophyta. All algae do contain at least one type of chlorophyll, but they also contain other types of pigments, which mask the color of the chlorophyll.

Green algae are the most plantlike of the all the algae. Green algae are believed to be closely related to the first plants because they have a cell wall that contains cellulose, they possess chlorophyll a and b, and they store reserve food as starch inside the chloroplast.

Some algae are colonial, which means there is a loose association of independent cells that are specialized for reproduction. Algae that are multicellular have specialized tissues, but are not considered to be plants because they are adapted to water environments and have not evolved to protect their gametes and zygotes from drying out. (Mader, pp. 524-526).


Habitats and Distribution of Algae

Green algae like to grow in wet places like lakes, ponds, ditches, and streams. They can also be found on damp soil and on the shaded sides of damp walls and trees. The chemical nature of water is a major factor that strongly influences the growth, abundance and distribution of algae. Some algae favor acidic conditions, some like neutral conditions and a few prefer alkaline conditions. (Flowers, pg. 6)

We think this picture of Cladophora fracta, shows cell division toward production of isogametes due to low-light conditions in a lab aquarium.



What is Cladophora?

When examined with the microscope, Cladophora filaments are branched, which are often spaced distantly and sparingly. Fronds are the whole system of branched filaments and are attached to rocks on the stream bottom. Fronds of Cladophora are frequently covered with ephiphytic diatoms, in fact, there can be so many diatoms that it is difficult to observe the Cladophora cells. (Flowers, pp. 38-41)

When growth conditions are favorable, Cladophora reproduces asexually. The adult alga divides, forming zoospores or flagellated spores that are smaller than the parent cell. A spore is a haploid body that develops into a mature adult. When growth conditions are unfavorable, Cladophora reproduces sexually. Gametes from two different mating gamates come into contact and join to form a zygote. When a zygospore germinates, it produces four zoospore by meiosis. A heavy wall forms around the zygote and it becomes a resistant zygospore, which is able to survive until conditions are favorable for germination. The zoospores are haploid and are released in the spring to grow into adult algal filaments such as those shown in the above photomicrograph. Isogamy (GK. isos: equal and gamos: marriage, union) is the conditions where gametes are identical. These gametes are known as isogametes. (Mader, pg. 525).

Shown is the branching system of Cladophora fracta from Emigration Creek. The brown clumps found at the fork of the branches are epiphytic diatoms, Rhoicosphenia curvata

 


Biological Significance of Freshwater Algae:

 


Dispersal of Algae

Water assists in the dispersal of algae. Water birds distribute algal spores, which are in the mud that sticks to their feet. The wind disperses algal microscopic spores through the air.


Environmental Factors Affecting the Growth of Algae

Water is essential for the growth of the alga in a new location, but there are factors that may prevent its establishment and growth. Three factors instrumental in growth are light, temperature, the chemical composition and acidity or alkalinity of the water.


Other Websites to Investigate

Images of Cladophora fracta

http://protist.i.hosei.ac.jp/PDB/PCD2044/C/81.jpg
http://protist.i.hosei.ac.jp/PDB/PCD2044/C/83.jpg
http://protist.i.hosei.ac.jp/PDB/PCD2044/C/84.jpg
http://protist.i.hosei.ac.jp/PDB/PCD2044/C/93.jpg
http://biosci.sierra.cc.ca.us/msc/m44


References

Flowers, Seville. (privately published). Algae of Utah. University of Utah, Salt Lake City, Utah.

Mader, Sylvia S. 1998. Biology, Sixth Edition. The McGraw-Hill Companies, Inc., Boston, Massachusetts.

Prescott, G.W. University of Montana.1978. How to Know the Freshwater Algae, Third Edition. Wm. C. Brown Company Publishers, Dubuque, Iowa.

Smith, Gilbert M. Professor of Botany, Stanford University. 1933. The Fresh-Water Algae of the United States, First Edition, Fourth Impression. McGraw-Hill Book company, Inc., New York.




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