The University of British Columbia
Our Research
Coho salmon (Oncorhynchus kisutch) and chum salmon (Oncorhynchus keta) spawn in streams which traverse highly urbanized areas of the Vancouver Lower Mainland. Contaminants in road runoff pose a threat to the health of freshwater streams, which are home to juvenile salmon and important spawning habitat for returning adults. At UBC, students and professors are analyzing the data from our network of conductivity loggers and are investigating the impact of road salt on the development of early life stages of salmonids. We have found that in some streams, salt concentrations in winter pulses may exceed the BC acute water quality guideline for chloride (600 mg/L), by more than 10-fold. In pilot experiments with rainbow trout (Oncorhynchus mykiss) we have found that these pulses cause significant mortality and developmental abnormalities. We are now investigating how such pulses in salinity are impacting the survival, development, and physiology of coho and chum salmon at early life stages.
MAIN FINDINGS
During spawning, as well as embryonic and larval development, Pacific salmon are frequently exposed to pulses of road salt. Laboratory-based experiments are being conducted to investigate the effects of road salt contamination on these critical early life stages, focusing on various concentrations and exposure frequencies.
(Carley Winter, UBC)
How much salt, is too
much salt?
Coho salmon eggs were fertilized and then immediately exposed to one 24H road salt pulse at one of five environmentally relevant salt concentrations, ranging from 0 to 4,800 mg/L of chloride. After 24H, embryo continued to develop in freshwater until hatch.
Significant mortality was observed when chloride concentrations reached >1,800 mg/L. (3x the provincial guideline for chloride)
(Carley Winter, UBC)
Accumulated Thermal Units (ATU) is the cumulation of daily temperature used to identify salmonid life stages.
Fish develop faster at warmer temperatures!
Do repeated salt pulses increase mortality?
Freshly fertilized coho eggs were exposed to road salt pulse regimes meant to mimic what they might realistically experience in a Vancouver stream. Eggs were exposed to either 1, 2 or 3 salt pulses, spaced 48 hours apart, at 2,400 mg/L chloride (4x the province’s acute guideline).
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There was an increase in mortality with an increase in pulse frequency!
(Clare Kilgour, UBC)
