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Show this area to minimize impacts to bird populations, which are substantial. Bear River Bay lies north of the causeway ( Bagley Fill), on the east side of Promontory Point. Water salinity in this bay can also fluctuate substantially, but is usually very low (< 2 percent). There is evidence that when the Bear River flows are very low, a layer of dense brine runs northward into the bay, especially during periods of south winds ( Butts, 1998). Salinity values are being studied at the current time by DFFSL, GSLEP, UGS, DEQ and IMC Kalium Ogden Corp ( formerly Great Salt Lake Minerals, Inc.). Commercial harvesting of brine shrimp is also prohibited in this bay to minimize impacts to substantial bird populations, especially fish- eating birds. The north arm of the lake ( Gunnison Bay) lies north of the northern railroad causeway between Promontory Point and Lakeside. Salinities in this portion of the lake have ranged from 14.5- 28.4 percent in recent times. In August 1999 it is approximately 23 percent. There has been very little harvesting of brine shrimp in this portion of the lake. The water of the north arm is too saline to sustain meaningful populations of shrimp. Periodically, some shrimp and cysts wash through the breach and culverts, and there are a few locations in the lake where brine shrimp populations may occur, probably due to springs which dilute brine salinity. As salinities decrease, brine shrimp populations will increase. In fact, meaningful populations have historically existed and been harvested from the Gunnison Bay. Commercial brine shrimp harvesting is allowed in the north arm. Bird use of the north arm of the lake has been essentially eliminated because of the lack of viable brine shrimp populations, although some foraging occurs near the causeway breach and culverts. Gunnison Island is an important White pelican pod. Aquatic Biota Differences Of primary concern to wildlife managers is the current degree of difference in salinities between the north and south arms of GSL and the lack of brine shrimp productivity in the north arm and diminished cyst production in the south arm. Because brine shrimp are currently managed and considered a focus species, most of the research and attention has centered on brine shrimp. However, the same low productivity concerns extend to other aquatic species which are significant in the lake's food chain, such as algae and brine flies. The northern railroad causeway from Promontory Point to Lakeside is inhibiting the exchange of lake brines between the north and south arms of the lake, and has caused a significant difference between the salinities of the north and south arms since its completion in the late 1950s. It is now thought that the differential, which has averaged between 10- 13 percent, is increasing. ( See " Water- Chemistry" section.) Because brine shrimp and brine fly productivity in the north arm has been essentially lost, and south arm production has declined, substantial negative impacts on avian species are suspected. Wildlife managers are concerned about the causeway's impact on the lake's ecology. Brine shrimp populations flourished in the north arm of the lake during the mid- 1980s, due primarily to high lake levels and resulting lower than average salinities in the north arm. It has been suggested that, at some lake levels, a 95 |