Giant Salvinia (Salvinia molesta)
What is it?
Growth factors paired with features promoting mobility make giant salvinia an aggressive, competitive species that can impact aquatic environments, local economies and human health. In favorable environments plants may be expected to double within about a week (Mitchell and Tur 1975; Mitchell 1978/9). Live biomass weights approach those recorded for water-hyacinth (Mitchell 1979). Excessive growth results in complete coverage of water surfaces which degrades natural habitats in several ways. Heavy growth of giant salvinia competes with and shades desirable native vegetation. Mats of floating plants prevent atmospheric oxygen from entering the water while decaying salvinia drops to the bottom, greatly consuming dissolved oxygen needed by fish and other aquatic life (Thomas and Room 1986).
What else is affected?
Animal habitat is most noticeably altered by the obliteration of open water. Migrating birds may not recognize or stop at waterbodies covered with giant salvinia. Indeed, the resulting loss of open water in the Swinney Marsh region has prompted local waterfowl guides to question the economic benefits of renewing hunting leases. Local fishermen have found it impossible to cast into smothered lakes and are abandoning spots once fished for bass, crappie and sunfish. Toledo Bend residents have resorted to paddling boats out docks after slipping clutches and stalling engines on packing in plants. Giant salvinia clogs water intakes to interfere with agricultural irrigation and electrical generation.
What are you doing in Arizona to combat Giant Salivinia?
This noxious water weed is present in the lower Colorado River, and efforts are underway by federal and state agencies to control the spread of this invasive plant that threatens municipal and agricultural water supplies derived from the river and recreational activities. Department staff from the Plant Services Division are active participants in the Lower Colorado River Giant Salvinia Task Force organized to monitor, survey and control the spread of giant salvinia on the river. The Plant Services Division is actively working with USDA in Arizona on a promising biocontrol agent that is being studied in field releases on the river conducted over the past two years. In addition, laboratory scientists provide official identification services to PSD regulatory officials.