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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT & EVALUATION OF BIOLOGICAL CONTROL AGENTS FOR INVASIVE SPECIES THREATENING THE EVERGLADES & OTHER NATURAL AND MANANGED SYSTEMS

Location: Invasive Plant Research Laboratory

Title: Ecology of common salvinia, Salvinia minima, in southern Florida

Authors
item Tipping, Philip
item Martin, Melissa -
item Bauer, Laurie -
item Pierce, Ryan -
item Center, Ted

Submitted to: Aquatic Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 13, 2012
Publication Date: April 25, 2012
Citation: Tipping, P.W., Martin, M.R., Bauer, L., Pierce, R.M., Center, T.D. 2012. Ecology of common salvinia, Salvinia minima, in southern Florida. Aquatic Botany. 102:23-27.

Interpretive Summary: Populations of common salvinia are regulated by biotic and abiotic factors in South Florida that include herbivory, disturbance, and plant competition. This plant is less weedy in Florida compared to other states primarily because of the presence of the salvinia weevil, Cyrtobagous salviniae, which helps keep it in check. The influence of herbivory by insects was the single most important factor influencing the abundance and density of common salvinia. Although this plant will often colonize areas rapidly, it usually declines over time as the populations of insects, including the salvinia weevil, build up and suppress it. Common salvinia populations persisted over time at field sites in South Florida despite being subjected to a constantly changing array of environmental and biological conditions.

Technical Abstract: The floating macrophyte, Salvinia minima, grows in a variety of freshwater habitats in Florida. We conducted a 39-month study at four sites in southern Florida to elucidate the abiotic and biotic factors that influenced the density, nutritional profile, and size of S. minima. These factors included interspecific plant competition for space or light, disturbance, water quality, and herbivory. Smaller plants with similar morphology like Spirodela polyrhiza competed for space while taller, larger species like Eichhornia crassipes, Pistia stratiotes, and Limnobium spongia competed for light. The nature and intensity of interspecific plant competition (space or shade) varied over time among sites. Disturbance was estimated by the relative change in water depth between sample dates and was negatively correlated with S. minima biomass and herbivory. The water quality parameters of temperature, DO, conductivity, and pH varied among sites as well as seasonally (dry vs. wet), with temperature negatively correlated with S. minima biomass at two sites. Insect herbivores were separated into two categories based on feeding strategy, namely borers (Cyrtobagous salviniae) and defoliators (Samea multiplicalis and Syclita obliteralis). Borers were more common in less disturbed sites while defoliators were distributed more evenly across all sites. It is clear from these data that S. minima undergoes regular, if unpredictable, cycles in southern Florida in response to a shifting array of abiotic and biotic factors. The relative importance of these factors was less clear although the influence of herbivory was consistently apparent. Salvinia minima populations, with their ability to grow quickly, move, and grow in shaded conditions, were resilient across habitats and over time.

Last Modified: 7/31/2014
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