Ponto-Caspian gammarids: Add chemicals to the water
Overall effectiveness category Unlikely to be beneficial
Number of studies: 1
Background information and definitions
Adding toxic chemical to the water offers the potential for localised control of invasive gammarid shrimps. Chemical ‘dips’ for fishing and sampling gear can also be an effective biosecurity method for preventing the transport of gammarids between water bodies. Most chemicals will have an impact on non-target organisms, and so their use must be carefully considered before being dosed. In many instances, the use of chemicals may be subject to local or national approval by regulatory authorities.
Supporting evidence from individual studies
A controlled laboratory study in 2011 in England, UK (Stebbing et al. 2011), found that when added to freshwater, iodine solution, acetic acid, Virkon S and sodium hypochlorite killed the killer shrimp Dikerogammarus villosus, but methanol, citric acid, urea, hydrogen peroxide and sucrose did not. For iodine solution (FAM30) there was 100% mortality within 15 minutes when the shrimp were placed in solutions of 4-6 ml per litre. However, FAM30 is an irritant and so was not considered a practical control method. For acetic acid, a 10% solution was required to kill all the shrimp in 15 minutes. At lower concentrations, no shrimps died during the test period. However, fifteen minutes was considered too long for acetic acid to be a practical control method. For Virkon S, all shrimp exposed to a 1% solution died within 15 minutes, with half dying within eight minutes. However, Virkon S has a relatively short shelf life and a capacity to bleach and can damage equipment and so was not considered a practical control method. For sodium hypochlorite, at 50,000 parts/million, half of the shrimp were killed within 4.5 minutes. However, at that concentration it is lethal to humans and so is not practical. Equipment containing shrimp could be soaked in sodium hypochlorite at 200 parts/million for over an hour, but is considered impractical. None of the shrimps died when exposed for 15 minutes to methanol (1 or 10 %), urea (1 or 10 g/litre), citric acid (15 or 150 mg/litre), hydrogen peroxide (100 mg/litre), or sucrose (10 or 100 g/litre. All tests were conducted on 5 captive shrimp. Dead and live shrimp were counted.Study and other actions tested