Jeremy enters the bowels of Lighthouse Cave, San Salvador, Bahamas.
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Introduction
My paper is about marine algae. In the first paragraph as an introduction I am going to talk about that main characteristics, uses, habitats, etc. of algae as a whole. Then I was breaking algae into the four main phyla that algae fall in to: blue-green, green, golden/brown, and red. I gave each phylum a paragraph and described each type more in depth including pigments, reproduction, food sources, symbiotic relationships, and human uses. Finally, I was going to explain the main types of algae found in tropical marine environments such as coral reefs. I was going to describe what kind of algae live there, why they live there, and why they are important to that specific ecosystem.
According to the Biology-Online Dictionary, the definition of Algae is, ÒA group of aquatic, photosynthetic, eukaryotic organisms ranging from unicellular to multicellular forms, and generally possess chlorophyll but lack true roots, stems and leaves characteristic of terrestrial plantsÓ. The number of algal species is estimated to be between one to ten million and most are microalgae (Baranti & Gualtieri, 2006). Most algal groups are considered photoautotrophs, meaning that they get their food and nutrients from the sun through photosynthesis. All algae contain chloroplasts, which depending on the algal type, the method of reproduction can be vegetative, asexual, or sexual. Many forms of algae also form blooms which have serious economic costs (Duddington, 1966). Algae are dependent on solar radiation into the water therefore algae can only grow near/on the surface of the water (Round, 1981). Algae are autotrophic therefore habitats that are not exposed to solar radiation are unlikely to support algal growth. However, some are heterotrophic but very rarely.
Blue-Green Algae:
The phylum called Cyanophyta are more commonly known as blue-green algae has gotten its name from the most prominent member of this phyla, Cyanobacteria. Cyanobacteria is a photosynthetic bacteria that can aid in nitrogen fixation of many plants, also a member of a different phyla. More recently, scientists have established a different view of the relationships between these photosynthetic species. Blue-green algae and the bacteria can now be seen in the same group, prokaryotes (Lewin, 1976). They are the most widely distributed of any other group of algae. The most prominent member of this group is Cyanobacteria which is a photosynthetic bacterium. Bacteria and bluegreen algae have recently been seen as the came group.
Characteristics of blue-green algae are those of the most primitive life forms on Earth, cyanobacteria (Humm & Wicks, 1980). Blue0green algae contain chlorophyll a and three biliprotein pigments: C-phycoerythrin, C-phycocyanin, and allophycocyanin (Humm & Wicks, 1980). Blue-green algae are obligate autotrophs, they depend on light for energy and carbon dioxide as a carbon source.
Blue-green algae can form plankton blooms called red tides (Dawes, 1974).
Cell walls contain pectin and cellulose (Boney, 1966). May also be other colors such as red, bright yellow, pale violet, purple, and black due to proportion of pigments. Asexual reproduction.
Pigments not contained in chloroplasts but dispersed throughout the cytoplasm of the cells (Duddington, 1966). On the Earth more than 500 million years ago and many species have remained the same to this day. Found in the intertidal zone, some are free-living but most grow on or in other algae.
Green Algae:
Phylum Chlorophyta consists of green algae, the most diverse of all algae phyla. Green algae are the ancestors of land plants; they have cellulose as their cell walls, green pigments, and store their food as starch. This phylum is distinguished by its photosynthetic pigments, chloroplast structure, and flagella (Sze, 1998). The principle pigments are chlorophyll A and B with trace carotenoids. The chloroplast has an envelope of two membranes indicating endosymbiosis of cyanobacteria. Green algae usually have two or four flagella. There are four subgroups of green algae, two from a marine habitat (Prasinophyceae and Ulvophyceae) and two from a freshwater habitat (Chlorophyceae and Charophyceae) (Sze, 1998).
There are over 5000 species of green algae, only 20% living in marine environments (Dawes, 1974). Found primarily in shallow water.
Golden Brown/Brown Algae:
Phylum Chromophyta is a group of algae that consists of all algae with chlorophyll c. This includes brown algae Phaeophyceae (Sze, 1998). Chromophyta algae contain chlorophylls a and c, and heterokontous flagellated stages. The chromophytes are divided into seven classes distinguished by sell coverings, pigments, and complex multicellular contruction in the phaeophyceae (Sze, 1998). The carotenoid fucoxanthin is an important photosynthetic pigment that gives cells their brown color. Phaeophyceae also contain polyphenolics, compounds that protect brown algae from herbivores and parasites. This algae group is commonly found in coastal marine environments especially in colder oceans. The life cycle of brown algae is alternation of generations meaning that they have a separate haploid and diploid generation. Brown algae are used in many commercial products and are cultivated for food in Asia.
There are approximately 1500 species of brown algae. The majority being found in cold temperatures to arctic marine waters (Dawes, 1974).
Colors range from dark or golden brown to olive green (Boney, 1966). Largest and most complex plant bodies observed in the algae- not unicellular or colonial.
The most familiar and largest algae phyla (Duddington, 1966). Obvious alternation of generations (sexual and asexual generations). Haploid=sexual and Diploid=asexual (Smith, 1969).
Red Algae:
Red Algae are found in the phylum Rhodophyta. This phylum mostly consists of seaweeds but also included free-living unicellular microalgae. Rhodophyta mostly pertain to coastal marine ecosystems but can also be found in freshwater and terrestrial environments. The only chlorophyll found in this phylum is chlorophyll A and phycobiliproteins, which give algae their red color. Red algae are unique because they do not have a flagellated stage of development like all other algal phyla. The most abundant and important storage product is floridean starch which (Baranti & Gualtieri, 2006)ÉMost Rhodophytes are photoautotrophics and have an asexual reproduction system. Red algae are divided into two subclasses: Bangiophycidae and Florideophycidae. Some red algae is grown for food or harvested as phycocolloids which are used in a variety of commercial products (Sze, 1998).
Red algae are the most exclusively marine with less than 2% living in freshwater (Dawes, 1974). They are also the most abundant in tropic and subtropical regions of the ocean. Harvested for extracts. Red algae store their food as carbohydrate called Òfloridean starchÓ.
Under field conditions red algae appear to be brown or green (Boney, 1966). Red color appears due to R. phycoerythrin and R. phycocyanin that mask other pigments. Triphasic alternation of generations: two sporophyte generations (Boney, 1966). Fossils show a lack of affinity with any other algae and shows that they have evolved along their own specialized line.
Deep-water seaweeds, growing at the greatest depth possible for plant life (Duddington, 1966).
Pigments localized in one or more plastids and masked by red pigments (Smith, 1969).
Most popular around Florida/Bahamas (Coral Reefs):
(Sze, 1998) Brown: In Florida, brown algae flora is best developed in the winter months in shallower, cooler waters (Dawes, 1974). Red algae grows deepest, about 300 ft., around Florida due to the high light intensity and clear waters (Duddington, 1966).
Free living algal flora on the coral reefs (Round, 1981).
(The Enchanted Braid) Corals are filled with millions of microscopic algae called Zooxs. Corals are a link between animals and plants. Corals are animals and eat their own food but found to only obtain 20% of food on their own, most nutrients come from algae that live inside each tiny coral. They have a mutualistic relationship because algae supply food for corals and corals provide protection to algae. Coral bleaching is when the algae moves out of their coral homes and the coral is not able to survive on their own so they die and turn white without the photosynthetic pigments of algae.
Algal Plains and Ridges (Round, 1981)
Literature Cited
Baranti, L., & Gualtieri, P. (2006). Algae: Anatomy, Biochemistry, and Biotechnology. Boca Raton: Tylor and Francis Group, CRC Press.
Boney, A. (1966). A Biology of Marine Algae. London: Hutchinson Educational LTD.
Dawes, C. J. (1974). Marine Algae of the West Coast of Florida. Miami : University of Miami Press.
Duddington, C. (1966). Flora of the Sea. New York: Thomas Y. Cromwell Company.
Humm, H. J., & Wicks, S. R. (1980). Introduction and Guide to the Marine Bluegreen Algae. New York: John Wiley and Sons, Inc.
Lewin, R. A. (1976). The Genetics of Algae. Oxford: Blackwell Scientific Publications.
Round, E. (1981). The Ecology of Algae. New York: Cambridge University Press.
Smith, G. M. (1969). Marine Algae of the Monterey Peninsula. Stanford: Stanford University Press.
Sze, P. (1998). A Biology of the Algae. The McGraw Hill Companies Inc.
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