Diatom are one of the most prolific phototrophic orfound at http://www.dnr.state.md.us/bay/cblife/algae/diatom/cyclotella_large.jpgganisms on the plant. One of the primary reasons that they are able to do this is because the fact that they can live virtually everywhere and they do so in substantial numbers.
    It’s impressive to think that they are one of the few organisms that can live in open ocean, polar waters, tropical waters, all fresh water areas, soil, snow and even glacial ice. The different species of diatoms though have to develop different adaptations to survive within each environment.
Open Ocean: The species that live in Open Ocean diatoms have a lesser pressure from predation then in some other environments, but they have a greater pressure from the lack of some key element that they need for growth. The largest is often iron and diatoms develop special mechanism to obtain and retain iron. But it still causes a large limitation to their growth. Another key element that diatoms also will experience a lack of is nitrogen in a usable from. Although, this isn’t always a large problem especially in areas of Open Ocean where there is also populations of cyanobateria that will produce nitrate the diatoms will be able to use. Then the last major element that they need that may end up being a restricting agent is silicon concentration in the water. Although, silicon concentrations are almost in sufficient supply if it is in short supply then diatoms will be unable to reproduce at a sufficient rate because they will be unable to produce their famous frustules. Also, since there isn’t a complete dissociation of all the dead and discarded diatom frustules there is a mild decrease in the concentration of silicon in the environment. Although, they are the most dominate primary producers of these ecosystems.
 found at http://earthobservatory.nasa.gov/Features/SeaIce/images/sea_ice_polar_bear.jpg
Polar Water: The species that live in polar waters are going to often have ample nutrients due to ocean currents and the abundance of life adding iron and nitrogen to the water though various means. But they have to adapt to have a good portion of the year being enveloped in darkness and not being able to photosynthesis. They either develop into vegetative cells or they resort to heterotrophic methods. This allows them to be the primary production in polar ecosystems.
Tropical Waters: The species that live in tropical waters have a large amount of competition and probably the greatest pressure from predation than any other habitat. They typically have slightly thick frustules and have protecting adaptations within their frustules to prevent predation. They don’t have to worry aboufound at http://soundwaves.usgs.gov/2004/08/good_reefLG.jpgt any nutrients though since tropical waters have typically high concentrations of just about all the element that organisms need to live. The dominance of diatoms will vary in tropical waters. The dominant primary producers in these will often be some form of algae, or if it’s a reef system it will often be the dinoflagellates that are in association with the coral. Even so diatoms typically have a strong foot hold in these waters and are able to be very prevalent and end up still producing a large degree of the net primary production.
Fresh Water: The fresh water habitats of diatoms’ include lakes, rivers, streams, marshes, swamps, est. they grow in all fresh water habitats. There are almost never special adaptations for obtaining the scarce elements that they need for growth. Although, iffound at http://vulcan.wr.usgs.gov/Imgs/Jpg/CraterLake/Images/CraterLake82_crater_lake_and_wizard_island_09-82_med.jpg they are in rivers or streams they often have to develop mechanisms to allow them to stay relatively steady and prevent them all form getting washed down the river. These often come in forms of the diatoms attaching themselves to various surfaces that will allow them to be steady or they will grow in the upper part of the sediment which allows light to still permeate down to them but prevents them from washing away. Then in lakes, marshes and swamps they don’t typically have any issues with growth because there is relatively little flow to the water so their basic buoyancy is enough to allow them to stay in the areas with relatively no problem. In these habitats though do have a fair competition, which comes from various fresh water plants such as water lilies, cat tails, duck weed andfound at http://www.house.gov/frank/images/taunton-river/taunton-river-480-4.jpg others. The competition isn’t extremely intense though so because light is still able to move past the plants and still reach them, as well as, the fact that diatoms are able to use some wave lengths of light that plants aren’t able to use very well. Also, diatoms are able to photosynthesis year around if the light is available. This allows diatoms to be very effect in these habitats.
Soil: Some species of diatoms are able to grow in moist soils. They have to develop new mechanisms that allow them to withstand a more dynamic temperature are as well as mechanisms that allow them to maintain water more effectively. They are often growing in field soils rather than wooded soils because of the light and they also usually are pennale species that are able to move, (more about movement in facts), usually by a slimy substance that they excrete. Well there are very few of these species, it is impressive that they are able to establish themselves in such a large amount of soil.
 found at http://www.nps.gov/climatefriendlyparks/images/melting_glacier.jpg
Glacial Ice: There have been diatoms found in glacial ice. This is impressive. They have to live in extremely limited environment. Having little silica, iron, nitrogen and sometimes even gasses they are inherently smaller and extremely slow growing. They also have to be able to form a vegetative cyst whenever there isn’t enough light present which would allow them to produce energy and all their organic molecules. Simply an example of how far they can go and how many places that they are able to grow.

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