Habitat

Giant salvinia grows in slow moving and stagnant waters such as canals and ponds. It is most productive where there is high nutrient availability, and in waters between 20-30C, although it can survive in a wider range. It does not survive ice formation, save for in well-established populations, and cannot survive salinity over 7 parts per thousand. Buds are killed when frozen, or when exposed to temperatures above 43C.

Life Cycle

Giant salvinia is in the fern family, members of which generally reproduce using spores. However, giant salvinia’s spores are sterile, so it is only able to reproduce vegetatively, through fragmentation. Fragments split off from the main stem and sprout new growth from attached nodes or the broken stem end. The process happens quite rapidly, as giant salvinia is able to double its biomass in 4-10 days under optimal growth conditions. In tropical climates this growth can continue year-round, but in temperate regions, giant salvinia dies back in freezing temperatures, and only lower layers of protected biomass survive. When temperatures increase, growth and fragmentation resume.

Ecological Threat

Giant salvinia spreads to create dense, thick mats that limit light penetration underwater. This, combined with giant salvinia’s strong ability to spread vegetatively, can result in the loss of native aquatic vegetation, and the creation of a monoculture. Mats of giant salvinia also result in decreased dissolved oxygen levels, as dying plant matter consumes available reserves. This decreases habitat suitability for aquatic animals and plants. Giant salvinia mats also clog waterways, impeding agricultural, recreational, and transportational activities. This is a large risk in rural regions where waterways are relied on as a primary source of transportation and income.