Acute Toxicity of Salt Cavern Brine on Early Life Stages of Striped Bass ( Morone saxatilis )

A plan to create solution-mined salt caverns for natural gas storage by discharging brine into the Shubenacadie River estuary poses a potential risk to an “endangered” stock of striped bass. Toxicity of brine made from both salt-core and artificial sea-salt “Instant Ocean” was assessed by 1-h acute toxicity tests at both 19 °C and 12 °C, the typical thermal range in June, post-spawning. The short test duration was justified given the rapid dilution of the brine in the macrotidal estuary. The median lethal concentration (LC50 1 h) 95% confidence intervals of salt-core brine at 19 °C for eggs was 51–60 parts per thousand (ppt); yolk-sac larvae 34–55 ppt; first-feeding stage larvae (6–8 mm total length, TL) 37–44 ppt, and 30–46 ppt for large larvae (14–20 mm TL). Among juveniles, the median lethal concentration was significantly higher compared to larvae: 51–58 ppt for early juveniles (4-cm fork length, FL) and 63–67 ppt for juveniles 12-cm FL. The toxicity of brine made from either Instant Ocean or salt-core was similar. At 12 °C, yolk-sac larvae salinity tolerance was 30% lower than at 19 °C, whereas other life stages exhibited a similar response to 12 °C and 19 °C. The threshold observed effect concentration (TOEC) of the salt-core ranged from 24.4 ppt on large larvae to 59.7 ppt on 12-cm juveniles. In conclusion, a very low direct threat to striped bass is estimated for the discharge of brine into the Shubenacadie River estuary.