Action: Asian clams: Use gas-impermeable barriers
- A controlled study in North America found that placing gas-impermeable barriers across the bottom of the lake (several small fabric covers or one large cover) significantly reduced the abundance of Asian clams.
Gas-impermeable barriers can be placed on the river or lake bed as a possible management tool for Asian clams Corbicula spp.. As organisms beneath die, oxygen levels fall and this can result in clam death.
Supporting evidence from individual studies
A controlled, replicated study conducted in 2009-2011 in Lake Tahoe, North America (Wittmann et al. 2012) found that gas-impermeable fabric laid across the lake bottom killed 98-100% of Asian clams Corbicula fluminea after 30-120 days. During one trial all clams were killed after one month, compared to only 3% in control plots without fabric. During the second trial the abundance of Asian clams after 120 days under gas-impermeable fabric was 98% lower than clam abundance in control plots. One year after the barrier was removed from this second trial, clam abundance was still 90% lower compared to control plots. Mortality was caused by a reduction in dissolved oxygen concentrations, which dropped to zero after 72 hours during the first trial and after eight days in the second trial. In 2009, six plastic (ethylene propylene diene monomer) barriers (9m2; 1 mm thick) were placed by scuba divers on the lake bottom at 5 m water depth and left in place for 4-56 days. In 2010-2011 a plastic barrier (1,950m2; 1 mm thick) was placed by scuba divers on the lake bottom at 5m depth and left for 120 days. The survival of clams underneath the fabric test sites and in control plots was monitored.