At Bear Lake, several episodes of lake level change during the last 10,000 years are evident in the diatom records
developed by Katrina Moser. Similar changes in lake level today would have a profound impact on people
living around the lake using the lake for irrigation, home water supply or recreation.
The diatoms found in the long core (98-1) are composed of both planktonic and benthonic species. The change in the ratio of these two types of species may reflect changes in the size of the lake through time. It may also be driven by different sources of input water to the lake, such as sudden influx of Bear River water or increased discharge from underground springs.
Short cores from Bear Lake are also being studied for diatom changes. Preliminary results from one of these cores (98-10) indicate that diatoms deposited in the last 10 years contain a greater abundance of centric diatoms, particularly Cyclotella ocellata and Stephanodiscus minutulus, which may be indicative of increasingly nutrient-rich (eutrophic) conditions. This could be caused by fertilizers entering the lake from shore-side lawns, or from sources upriver. It is less likely that natural causes are leading to nutrient enrichment of the lake water. Prior to 1990, diatom assemblages resembled those from long core 96-1, in having relatively few diatoms, and those that exist are fragmented.
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