Using osmotic shock to control invasive aquatic species

Coastal estuaries are especially vulnerable to the arrival and establishment of invasive aquatic species (IAS) as they are often the receiving locations of ship-based introductions. Rapid response tools, such as mechanical or chemical treatments to capture, remove, and contain of IAS, are needed to prevent subsequent spread into adjacent marine and freshwater systems. Abrupt salinity change, created when infrastructure in estuaries situated at the proximity of river mouths is operated, offers a novel, low-cost and environmentally friendly method for potentially controlling IAS. We investigated the use of osmotic shock to control the invasive brackish water clam Rangia cuneata that is quickly spreading through Europe. Clams were exposed in the laboratory to eight salinity concentrations ranging from 0.5 to 32.0 parts per thousand and monitored for 60 days. Saline shock, but not freshwater shock, could control R. cuneata. Salinities >26 parts per thousand killed 95% R. cuneata in two weeks. All specimens exposed to full strength seawater (32 parts per thousand) were killed within 30 days. At lower salinities, clams collected from the most freshwater locality (1.2 parts per thousand) showed lower mortality than clams from the most saline site (3.1 parts per thousand). Furthermore, even modest increases in salinity during spawning periods of R. cuneata may prevent recruitment. Given the vulnerability of coastal estuaries to introduction of IAS, saline flushing presents a novel and effective management tool for many species.

Automated summary

The study demonstrates that osmotic shock is effective in controlling the invasive brackish water clam Rangia cuneata, with high salinities being able to rapidly kill the clams and even modest increases in salinity potentially preventing their recruitment.