Dr. Colin Brauner
Department of Zoology
University of British Columbia firstname.lastname@example.org
The Salton Sea is the largest lake in California (1000 km^2). It is below sea level, has no outflow, and high evaporative water loss. The salinity is currently 43 g/L, and increasing at a rate of 0.3 g/L per year. This hypersaline lake supports a recreational fishery, consisting of several marine fish species and the California Mozambique tilapia (Oreochromis mossambicus x O. urolepsis hornorum ), which is the most abundant fish species. Lake Qinghai is the largest lake in China (4000 km^2) and resides on the Tibetan plateau at 3200 m. This lake also has no outflow and high evaporative water loss, and significant inflow is diverted away from the lake for agricultural purposes. The lake salinity is presently 9 g/L, but increasing as the lake water levels continue to fall. Lake Qinghai is home to the lake Qinghai scale-less carp (Gymnocypris przewalskii), a Tibetan cultural icon and the species that historically supported a commercial fishery that has since collapsed. In both systems, lake salinity is progressively increasing, largely due to anthropogenic factors, and will eventually surpass salinity tolerance of resident fish species. We are conducting experiments to investigate the physiological mechanism(s) and threshold(s) of salinity tolerance (based upon changes in gill Na+,K+ ATPase activity, gill morphology, drinking rate, plasma ion levels and osmolality, metabolic rate, and growth, among other parameters) of these fish to gain insight into their ability to acclimate to increasing salinity. In each system, tilapia and carp appear to be on the edge of their salinity tolerance, necessitating large changes to water use and water management strategies, if these species are to persist.