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Impacts of Recent Climate Change on Diatom Extirpation from the Great Lakes
Diatoms, along with other taxa of phytoplankton, are photosynthetic primary producers supporting the food web of The Great Lakes. The changes in the size or in the function of the primary producers may have a direct or an indirect impact on the food web. Photosynthesis carried out by diatoms comprises about one fifth of the total photosynthesis. By taking CO2 out of the water, to photosynthesize, diatoms help to stabilize the pH of the water, as otherwise CO2 would react with water making it more acidic. Diatoms acquire inorganic carbon thought passive diffusion of CO2 and HCO3, as well they use Carbonic Anhydrase mediated active transport to speed up this process (1 ). Large diatoms require more carbon uptake than smaller diatoms (8 ). There is a positive correlation between the surface area and the chlorophyll concentration of diatom cells (2 ).

Reproduction
In the past, it has been discovered that diatoms can reproduce both sexually and asexually. There are certain advantages and disadvantages to each type of reproduction. Sexual reproduction allows for more diverse gene pool, however it requires more time. On the contrary, asexual reproduction does not require much time, however, it does not allow for a diverse gene pool. Diatoms that reproduce sexually can retain their size. Diatoms that reproduce asexually become reduced in size (3 ). In 14 years diatoms that have been reproducing asexually, have been reduced in size by more than 50 percent. In addition, diatoms that reproduce asexually for long period can lose the allele that makes them heterozygous (9 ). Thus, they lose the ability to reproduce sexually again.

Environmental Factors
Some environmental factors have been known to affect diatoms drastically, and some not so much. Inhibition of photosynthesis, for instance, has been shown to be an important factor leading to inhibition in growth (4 ). Increasing temperatures are correlated with decrease in cell size, in addition to increasing growth rates of the diatoms (5 ). This correlation could be linked with the fact that as water temperature increases, the number of diatom cell divisions per day also increase (6 ). Environmental conditions that are negligible is the change in salinity up to 5 percent (7 ), which will not affect the phytoplankton growth directly.

Active Uptake
Active uptake of inorganic carbon is proportional to the intercellular carbon demand of the diatom (8 ). Since larger cells have a larger volume to surface area ratio, their intercellular carbon demand might not be more than that of smaller diatom cells. Therefore, further research needs to be conducted to determine if the larger surface area of the diatom cells compensate for the larger volume, thus not requiring the use of more CO2.

The positive correlation between surface area and chlorophyll content has been measured on spherical shaped diatoms. Further research needs to be conducted to test the correlation between surface area and chlorophyll content of non-spherical diatoms, as the volume of such diatoms will influence the growth rate differently.

Carbon Isotopic Fractionation
In the (8 ) study, the correlation of carbon isotopic fractionation (Ep) of a diatom is negative to the growth-rate/CO2 concentration ratio. This slope, however, does not indicate if CO2 is directly responsible for the growth rate, as Ep of the diatom is the result of CO2 in the water. Moreover, the ratio of volume to surface area (V/SA) is positively correlated to the size of the diatom. There has been found a negative correlation between the slope and the V/SA of the diatoms. No correlation can be made between diatom size and growth rate, as CO2 can be acquired by Carbonic Anhydrase active transport.