Jordon Bright and Rick Forester are collaborating on the ostracode
work at Bear Lake. The ostracode species abundance's change with depth in the cores, probably in response to changes in environmental
properties of the water, amount of groundwater input or output, size of the lake, and water sources. Over the next few years, we'll
examine the relation between the Bear Lake ostracode species and particular environmental parameters, by analyzing the oxygen and
carbon isotopes contained within the ostracode shells and changes in ostracode species assemblages. Some of this isotope work has
already been done by An Lui.Many of the fossil ostracodes found so far in the Bear Lake sediment cores are new, unnamed species discovered during our investigation and occur only in Bear Lake (as endemics). The ostracodes in streams and springs near Bear Lake are more common types that live in many places throughout North America. We think it likely that the endemic types live around mineral-rich springs coming up along the lake bottom. In August 2000 we plan to sample the sediments and water around some of these springs to see if we can locate the microhabitat that is home to these endemic species.
Most of the ostracode species found in the longest core (96-1) do not live in the lake today. We're finding evidence that when the diversion of Bear River water into Bear Lake began in A.D. 1912, it changed the chemistry of the lake enough to kill many of the endemic types. The ecological consequences resulting from the diversion are virtually unknown, but fish species that usually feed on ostracodes eat Daphnia (water fleas) in Bear Lake now. Sometime in the recent past, a gastropod (snail) die-off occurred, evident from a thick layer of shells in the shallower regions of Bear Lake. Like ostracodes, gastropods are sensitive to water chemistry changes and its possible the Bear River diversion caused the mortality.
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