Last week’s temperatures dipping into the 20s and hovering in the low 30s may have caused some people to worry about their vegetation, but for the Louisiana Department of Wildlife and Fisheries, it offers a sign of hope in the state’s fight against giant salvinia, an invasive aquatic plant overtaking many of the state’s freshwater systems.
Biologists with LDWF hope the freeze will result in a reduction of salvinia this spring and summer, as it did in 2010 when salvinia coverage was drastically reduced following a winter freeze.
LDWF Secretary Jack Montoucet, who was with state Rep. Gene Reynolds on Saturday at Lake Bistineau, said they saw what appears to be a die back of salvinia on the lake. Lake Bistineau, a popular recreational site in north Louisiana, runs through Webster, Bossier and Bienville parishes.
However, significant visible reduction in coverage will not likely occur for a few months due to the amount of time it takes the plant to decompose. The department also notes that although the freezing temperatures may cause some level of die-off, it will not completely eradicate it.
Unfortunately, the cold weather may have killed the salvinia weevils brought in to attack the plant. The department will continue to monitor the salvinia weevils to determine the impacts of the freezing temperatures to the population. LDWF plans to have at the ready a new supply of weevils to restock once optimal weather conditions allow later this year. The department will also continue its chemical spray efforts on lakes where growth is present.
Giant salvinia, or salvinia molesta, one of the world's most noxious aquatic weeds, is notorious for dominating slow-moving or quiet freshwaters.
Its rapid growth, vegetative reproduction and tolerance to environmental stress make it an aggressive and competitive species. It is known to degrade water quality for fish and other aquatic organisms, and to impede boating and swimming which could affect the economy in some areas.