Invasiveness
As early as 1980, specimens of U. inflata were beginning to be collected or recorded outside its traditionally accepted range. Populations have been established in Washington state, New York, and Massachusetts. The colonies in Washington are obvious introductions, but while the populations in New York and Massachusetts are most likely the result of recent introductions, it is more difficult to say with certainty how they were introduced.
In southeastern Massachusetts, several samples of U. inflata have been gathered from Federal Pond beginning in 1990, representing its first collection north of New Jersey on the east coast. Bruce Sorrie has identified a substantial population in this location. Sorrie indicated that human-aided introduction of this species to Massachusetts is likely since Federal Pond has been used for various purposes since the late 18th century, though Sorrie also notes that transfer of propagules by waterfowl or herons from U. inflata's native range may be just as likely.
Three years after the first collection in Massachusetts, a study of the area around Spruce Pond in Orange County, New York yielded the first record for U. inflata in New York State. The authors of the study speculate that, unlike the population found in Massachusetts, it is unlikely that the population in Spruce Pond was the result of human introduction because the pond is in a remote area and rarely used. More recently in 2005, a study in northern New York identified populations of U. inflata in six lakes in the Adirondack Mountains, representing another northern extension of its range. In two of these lakes U. inflata was the most frequently encountered species in 2000, whereas a census of the lakes found no U. inflata whatsoever in 1983. This impressive growth in what is probably a new location for the species is similar to the growth patterns of other invasive aquatic plant species. The authors of this study also noted that at one of these sites, many of the native species declined in frequency or could not be found, possibly due to the presence and proliferation of U. inflata. Lab experiments and observations in the field supported the authors' hypothesis that the presence of U. inflata in Adirondack lake systems damages the natural nutrient cycles that sustain the native flora. U. inflata likely shades out the native flora, specifically Eriocaulon aquaticum, a submersed macrophyte isoetid that releases oxygen into the sediment. In this case, U. inflata could indirectly change the biogeochemical cycle in the Adirondack lakes by hindering the growth of native isoetid macrophytes and subsequently having a negative effect on the proper balance of sediment chemistry. The consequence of this may include enhanced growth of algae and other changes to the ecology of the freshwater ecosystems that it may invade.
Even earlier than the collections in Massachusetts and New York, a population of U. inflata was located in Horseshoe Lake in Kitsap County, Washington in 1980. Since then, further specimens of U. inflata have been recorded from other Puget Sound area lakes in Kitsap, Mason, Pierce, and Thurston counties. One population has even been recorded from the more southern Silver Lake in Cowlitz County. Information on this species in Washington State provided by the state's Department of Ecology includes a statement that U. inflata's presence in Horseshoe Lake was "probably the result of a discarded aquarium." Washington's Department of Ecology also indicates that in the areas where it occurs, U. inflata forms dense floating mats, becoming a nuisance for recreational activities. Residents of Lake Limerick, which has extensive populations of U. inflata, spend thousands of dollars each summer to rid their lake of the dense, weedy mats. A variety of control methods have been used to control the weed, including a sonar treatment, biocontrol utilizing grass carp, and manual extraction. Washington considers this species to be problematic but has not classified it as a noxious weed. Instead, it is on a monitor list of wetland and aquatic species under quarantine, meaning that it is prohibited to sell this species and it may be included on the state's noxious weed list in the future.
Most carnivorous plant species require very specific environmental conditions to thrive. This narrow habitat tolerance means that many carnivorous plants are threatened or endangered in their native ranges. U. inflata's ability to thrive in a variety of locations that it has been introduced to represents an ability to tolerate a much larger range of habitats than most carnivorous plant species.
Read more about this topic: Utricularia Inflata