{"id":327,"date":"2015-11-19T15:07:11","date_gmt":"2015-11-19T22:07:11","guid":{"rendered":"http:\/\/sites.evergreen.edu\/vms\/?p=327"},"modified":"2015-12-15T15:59:41","modified_gmt":"2015-12-15T22:59:41","slug":"species-name-and-genus-sas","status":"publish","type":"post","link":"https:\/\/sites.evergreen.edu\/vms\/species-name-and-genus-sas\/","title":{"rendered":"Chaetocerotaceae, Chaetoceros"},"content":{"rendered":"
Chaetocerotaceae, Chaetoceros:<\/h5>\n
By: \u00a0Sarah Scott<\/h5>\n
\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0\"Chaetoceros<\/a>\u00a0 \u00a0 \u00a0\u00a0\"Chaetoceros<\/a>\u00a0 \u00a0 \u00a0\u00a0\"Chaetoceros<\/a>\u00a0 \u00a0\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0<\/h5>\n

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Introduction:<\/h3>\n

Chaetoceros is the largest genus of marine plank-tonic diatoms.\u00a0 Their cells form chains that are coiled, curved, or straight.\u00a0 Long setae emerge from corners of the cells. \u00a0It is one of the largest genera of diatoms, roughly 400 species, most of which are marine and there were\u00a0a few solitary species that were found in Monterey Bay.\u00a0Chaetoceros species have a worldwide distribution, and they often dominate marine ecosystems. Some have caused important blooms in both oceanic and coastal habitats and some species form resting spores and\/or aux-spore.\u00a0 It is often very difficult to distinguish between different Chaetoceros species and several attempts have been made to restructure this large genus into subgenera but the work is still in progress.\u00a0 The genus Chaetoceros were first detected by Ehrenberg in 1844 from Antarctic Ocean specimen and the cells are more or less rectangular in girdle view and are usually elliptical in valve view.\u00a0 Opposite setae of adjacent cells touch near their origin and the cells are united into chains, they have very characteristic spores and the base of setae is short.\u00a0 The seta structure is an extended empty processes that begin on the valve surface corners. These setae generally comprise terminal and intercalary setae, the former at the end of a chain and the latter within the chain. Sometimes, a few species have unusual intercalary setae, called special intercalary setae, these are thicker and much more strongly silicified than the common intercalary setae.\u00a0 Diameter is 10-50 \u03bcm, the length is 6 – 30 \u03bcm and the shape is elliptic cylinder.<\/h5>\n
Chaetoceros is a centric diatom with very lightly silicified frustules. Each frustule possesses four long, thin spines, or setae. The setae link the frustules together to form colonies of several cells. Frustules are usually seen in girdle view. Chaetoceros is primarily a marine genus, with only a few representatives in inland waters of the United States. Inland cells reach their greatest abundances in saline or brine contaminated rivers and lakes. Chaetoceros produces heavily silicified resting cells that are often preserved in sediments. Because of high growth rates and contain high concentrations of lipids,Chaetoceros has been used as a potential alga to harvest lipids for bio-fuels (Spaulding, S., and Edlund, M., 2008).<\/h5>\n
In mid-March when the water column is stratified and a thermocline is present, diatoms are generally the more dominant phytoplankton.\u00a0 Chaetoeros debills have tiny bristles that extend from the cell of the body which slow down their sinking.\u00a0 This Chaetoceros is the distinctive phytoplankton of the Gulf of Maine.\u00a0 From corners of each cell, long thin setae or bristles extend outward then fuse with the neighboring cell and this arrangement can create a long spiral, up to 2 mm long.\u00a0 Even though it may seem this organism is long, each cell is actually distinct and separate from the neighboring cell.\u00a0 By joining together they increase their surface area.\u00a0 Joining into this long chain ensures that the cells will remain at the surface for a longer period of time, having more of an opportunity to capture energy from the sun.<\/span><\/h5>\n
Physical properties of phytoplankton such as Chaetoceros can physically damage marine organisms.\u00a0 The siliceous spines from the genus Chaetoceros, can stick into the gill filaments of a fish causing irritation.\u00a0 Mucous is then created by fish to coat the gills in order to relieve the irritation.\u00a0 In promoting greater mucous production, the gills are no longer efficient enough to extract oxygen from the water, thereby causing the fish to die from suffocation.\u00a0 Though this type of bloom is rare, there was an incident in Dabob Bay, Washington in October of 1991 where cell abundance did reach up to 103 cells per liter (Runyan, 2014).<\/h5>\n

Morphology:<\/h3>\n

of the species Chaetoceros is characterized by the presence of two 90\u00b0 rotations of the resting spore during maturation. First a rotation in the apical plane of the mother cell resulting in the valvar plane of the resting spore turning from parallel to perpendicular to that of the mother cell, and a second 90\u00b0 rotation in the valvar plane of the mother cell resulting in the valve faces of the resting spore turning from facing narrow girdle view to broad girdle view of the mother cell. It is the first report of two 90\u00b0 rotations of resting spores during maturation in\u00a0<\/span>Chaetoceros.\u00a0(Yang Li, Suying Zhu, Nina Lundholm, Songhui Lu, 2015). The\u00a0 general\u00a0 morphology\u00a0 of\u00a0 Chaetoceros tenuissimus is\u00a0 very\u00a0 similar\u00a0 to\u00a0 that\u00a0 of\u00a0 most\u00a0 members\u00a0 of\u00a0 the subgenus\u00a0 Hyalochaete. This\u00a0 subgenus\u00a0 was\u00a0 defined\u00a0 by\u00a0 Gran\u00a0 (1897)\u00a0 and\u00a0 revised\u00a0 more\u00a0 recently\u00a0 by Evensen & Hasle\u00a0 (1975).\u00a0 It includes delicate forms either chains or solitary cells with thin appendages and chloroplasts only in the body of the cell (not in the setae). The prevalence of intact diatom resting spores such as the genus\u00a0<\/span>Chaetoceros, in newly up-welled waters demonstrates the ability of spores to utilize the mixing and current patterns in order to seed up-welling systems. Higher sinking rates would appear to be the key advantage to spore formation, rapidly removing the population from an inhospitable environment following nutrient depletion, thus preventing offshore advection and maintaining the population close to the center of up-welling.<\/span><\/h5>\n
Morphology is Centric:<\/h5>\n