Wendy Scholl Invasion Ecology

Swollen Bladderwort

Scientific name: Order/Family/Genus/Species Scrophulariales/ Lentibulariaceae/ Utricularia L./ Ultricularia inflatalU. infiata waiter

Common Names: Swollen Bladderwort, Floating Bladderwort, Large Floating Bladderwort, Inflated Biadderwort.

1 Overview: Swollen Bladderwort is a known invasive species in the state of Washington. Introduced to Western Washington in the early 1980’sthe plant is now found in at least 5 counties. At this time it’s method of introduction is unknown. Utricularia inflata’sclose resemblance to other native bladderworts is problematic in that it presents the possibility that we may have a larger invasive population than we currently realize. A beautiful and fascinating species, it is known to be endangered in some of its home ranges. That, however, does not prevent it from posing a significant threat to some of our own native populations of flora and fauna in addition to possibly serious financial costs should its local range increase. While U. infiata is, as far as we know, limited to a handful of locations in Western Washington at this time, there is a disturbing lack of any effort to eradicate the population while it remains small.

Key features: Basic features for Utriculariainflata are:

A. Lacy underwater foliage with seed-like bladders B. Yellow snapdragon-like flowers C. Spoke-like structure supporting the flower stalk

Utricularia inflata is differentiated from other bladderworts, especially Utricularia radiata, based on these key features; The lateral foliar units (leaves), floats, vernation (the arrangement of young leaves in a bud) of the branch tips, the inflorescence bracts, flowers, peduncle lengths, orientation of the fruiting pedicel, character correlation (obtained by plotting flower number against peduncle length), and distribution (Reinert et al. 1962). (FIG 1.)

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FIG. 1; Key describing distinguishing features of Utricularia inflata; Courtesy of The American Journal of Botany.

3 Life History and basic ecology: Swollen Bladderwort is a free-floating perennial herb; rootless, carnivorous, and aquatic, it uses “seeds” or bladders to capture prey. The stem and flowers are supported by a wheel or spoke-like structure with lacy, finely divided and haired underwater foliage. The stem can vary from six inches to two meters long and while usually emergent, can be either partly supported by exposed sediment, submersed or 16floating. The emergent flowers are yellow and snap-dragon-like in appearance with a lower, banner-shaped petal. They occur in groups of 3 to 14 on the upright stems. 14 In swollen Bladderwort the seed stalk can be up to 35 mm 4long.’ The plant has no true leaves. Although often referred to as leaves, that functional purpose is served by the bladder-bearing, chiorophyllous laterals. As shoots terminating in tubers do originate from these structures under certain conditions Reinert (1962) felt that they are more likely stem structures (Remert et al. 21962; Farooq Ct al. 1966). The float can appear dense and bushy underwater and has anywhere, from 4 to 10 5spokes The spokes themselves vary from 4 to 9 4cm.’ and are slender at the base, widening. in the middle and then tapering again at the terminal end. U. injiata reproduces from seeds, fragments, tubers, and small coiled winter buds, also called 2turions Turions are tightly packed, ball-shaped groups of concave leaves covered in protective mucus. These are heavy with starches and sink to the bottom of the water column where they remain dormant in the sediment for the 0winter’ The tubers of U inflata are produced when the plant becomes stranded on .sediments due to low water. The plant sends out thin, thread-like shoots that terminate in tiny, starch-filled tubers. While the thin shoots can be produced during periods when the water levels drop and the water becomes stagnant, the tubers themselves are only produced when the plant actually becomes embedded in the benthic deposits (Reinert et al. 1962). Reinert also states in his 1962 paper that while they never saw these tubers result in germination in the field they did so easily when submersed in water in the laboratory. Related to it’s ability to reproduce from fragments, it has also been observed that at the end of the fruiting season the older lnternet Publication/Online Document; www.aquariumarticles.com 26Internet Publication/Online Document; Washington State Department of Ecology lnternet‘ Publication/Online Document; Massachusetts Department Conservation and of 5Recreation. lnternet Publication/Online Document; Washington State Department of Ecology ‘°4 Internet Publication/Online Document; Botanical Society of America. ‘ 4 parts of the plant appear to decay and the branch tips separate, remaining dormant until the next growing season. Swollen Bladderwort is, as stated earlier, carnivorous and obtains nutrients via photosynthesis, absorbing nutrients from the water column and by consuming tiny invertebrates and minute fish that it captures in its 5bladders. The bladders are, in fact, traps and use a vacuum4ike suction to pull prey inside after the prey has triggered the bladders “trap 2door”. The animals are attracted to the bladders by way of a sweet 5“scent” or mucus and open the trap doors by coming into contact with trigger hairs. Enzymes and bacteria digest the animal once it has died inside the bladder. The bladders of carnivorous Utricularia species are 10% - 50% of the total biomass of the plant (Adamec, 2006). When mature the bladders are approximately 3 mm. long (Reinert et al. 1962).

FIG.2 Close-up of Utricularia inflata bladder showing trigger hairs. Courtesy of The Nature Conservancy.

2 Internet Publication/Online Document; Washington State Department of Ecology Internet Publication/Online Document. MassachusettsDepartment of Conservation and Recreation 5 Due to their ability to capture live prey, they are able to flourish in both oligotrophic as well as eutrophic 5lakes This, combined with their tolerance for a wide range of water chemistry conditions,. gives them a competitive edge over many native plants. Optimal conditions for aquatic bladderwort species are warm, shallow, www.BestC

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FIG.3 Utricularia inflata stems and bladders oligotrophic waters that are oxygen 5deficient. Acidity tolerances can vary with some species doing well in more acidic waters and others requiring a high pH. (Dite et al. 2006). It prefers slow moving and still waters and can create dense mats that shade out native vegetation. It’s wide range of tolerances and ability to utilize resources gives it advantages in the unlikeliest of locations. In at least one documented instance it was located in an unnamed drainage pond beside a highway in Thurston

Internet Publication/Online Document; MassachusettsDepartment of Conservation and Recreation. 6 County, Washington, not a site likely visited by recreational boaters or aquaria enthusiasts. Bladderworts in their native ranges provide important food, habitat, and protection for fish and aquatic invertebrates. Waterfowl and another highly invasive species, the muskrat, also consume them. Although it flowers during the winter in its native range it flowers much later, from June to July, in Washington. When not in flower it is difficult to distinguish from our native bladderworts2 but when in flower, is distinguished by its spoke-like float. According to the Washington State Department of Ecology, swollen bladderwort, when not in flower, may be easily confused for other, smaller native blaclderworts as well as water milfoils (Myriophyllumspp.) and White water buttercup (Ranunculusaquatiis).

Origin and Distribution: There seems to be some confusion over the total number of bladderwort species, with Reinert (1962) listing 300 and the American Botanical Society listing 220. Published information indicates that approximately 30 are aquatic. In addition there is little consensus on the native distribution with the general observation being the eastern coastal plains of the United States. Bladderworts have dispersed across the globe and are native to nearly all ecosystems from Australia to Alaska (Reinert et al. 1962). Approximately 20 species are endemic to the United States and U infiata is now known to be present in Alabama, Arkansas, Delaware, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, New Jersey, North Carolina, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Virginia and Washington. Native distribution is reported as occurring on the outer coastal plain from Texas and Alabama to Delaware (Reinert et al. 1962; Urban et al. 2006). It has been reported that U inflata had spread as far north as New York and Massachusetts by the early 1990’s(Urban et al. 2006; Mitchell et al. 1994).Although the plant is native to warmer southern waters it has been shown to be capable of survival in colder climates and is able to survive the winter in frozen lakes.

2 Internet Publication/Online Document; Washington State Department of Ecology Internet Publication/Online Document; Massachusetts Department of Conservation and Recreation. 7 %PLANTS

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I I\rin Islands FIG.4 Map showing current United States distribution of Utricularia inflata. Courtesy of the USDA.

FIG.5 Map showing known occurrences of Utricularia inflata in the state of Washington. Courtesy of Kathy Hamel, Washington State Department of Ecology.

8 The plant’s history of mvasiveness is equally as difficult to nail down as it’s original distribution. At this time experts seem unsure if the plant is native to New York or whether it may have been introduced as early as the mid-nineteenth century, or as late as the 1990’s.Its resemblance to other Utricularia species again may present a confusing factor in determining its actual native and invaded habitats. Utricidaria radiata is sometimes treated as Utriculariainjiata var. radiata adding even further confusion. Another possible case of purposeful introduction, the Missouri Botanical garden Database shows that a specimen of U inflata was collected on 12/12/1999 in Sucumbios, Ecuador but I was unable to confirm that 8finding.’ Invasion Process: Infestation appears to be in its early stages in Washington State. The first plants collected in Washington State were in Horseshoe Lake in Kitsap County in 1980. Although those specimens were sterile they did display the winter-coiled buds used for reproduction. Specimens have now been found in Cowlitz, Kitsap, Mason, Pierce and Thurston Counties, including both the Puget Sound and Deschutes drainages (FIG5). Information on its introduction is limited. Jenifer parsons, sponsor of U inflata on Washington States noxious weed monitor list and an aquatic botanist with the Washington State Department of Ecology, noted that the infestation could not have happened much earlier than 1980 as Adolph Ceska was extensively studying Utricularia in British Columbia and the Pacific Northwest in the 1970’s.Eventually, Ceska’s research culminated in the publication of a key to the Utricularia species of the PNW that did not include U inftata. Several sources, including the Washington State Department of Ecology, the Western Aquatic Plant Management Society and International Carnivorous Plant Society suggest that a carnivorous plant enthusiast may have introduced the plant to Washington State. It could also have been introduced as either an aquarium plant or water garden plant. In Washington it has been found in small isolated ponds that are unlikely to have seen much, if any, boat traffic and so it is more likely that the plants are now being spread via waterfowl.

18 Internet Publication/OnlineDatabase; Missouri Botanical Garden B Personal correspondence 9 Mitchell postulates that New York’s, Spruce Pond location is equally as unlikely a destination for boaters (1994) and in that case waterfowl is also the likeliest culprit. Given that the plant has not been discovered in any locations between Texas and Washington this does tend to indicate that the initial introduction was more likely caused by humans than waterfowl.

Potential ecological and/or economic impacts: The impact of U inflata can be extensive. It’s ability to form dense cover, utilize both dissolved nutrients and live prey, and it’s tolerance for a wide range of temperatures and water chemistry makes it easy for this invasive species to out compete native plants. In addition, it has been shown that carnivorous plants show an increase in reproductive rates over those that rely solely on photosynthesis, providing another advantage over some native species (Mendez et al. 1999). The use of tubers as a reproductive method gives the plant another asset in that it is able to begin growth earlier in the season (Thiebaut 2007) Fragmentation in it’s aquatic environment is also an extremely efficient method of dispersal. Native fish and aquatic invertebrate species can be lost from die-offs due to anoxic water conditions or by the loss of the native aquatic macrophytes they use for food and shelter. U. injiata is often colonized by rotifers that inhabit the area around the bladders using the flow of water from the suction action to grab small particles of 10food Recent field and laboratory experiments have determined that U inflata alters. nutrient cycling and sediment chemistry through suppression of native macrophytes. An example is the recently discovered suppression of Ericaulon aquaticum in some freshwater lakes in the Adirondacks, a region recently invaded by K inflata (Urban et al. 2006). Native E. aquaticum releases oxygen into lake sediments, lowers pH, reduces dissolved organic carbon and ammonia concentrations via an extensive root system. In her laboratory experiments, Urban (2006) showed that the presence of U injiata reduced the biomass of native E. aquaticum and consequently it’s ability to reduce pH, dissolved solutes and redox potential. E. Aquaticum, like other common isoetids is a light-loving macrophyte and the presence of thick mats of U. inflata would tend to reduce photosynthesis and survivability through excessive shading. (Urban et al. 2006). Field experiments mirrored this result (urban et al. 2006).

10 Internet Publication/Online Document; Botanical Society of America 10 Experiments have also shown evidence of leaf lengthening in E. aquaticum in the presence of U inflata but this was apparently not sufficient to overcome the effects of shading. In some invaded Adirondack lakes, native macrophyte species have been reduced by as much as a third, from 18to 12. In addition, another 9 species were significantly reduced (urban et al. 2006). In addition to its ecological impacts, U inflata can also have significant economic impacts. Floating mats of vegetation also interfere with human activity. Lower water quality and dense mats of vegetation can lead to safety concerns for swimmers and recreational boaters. Fishing may be affected by excess vegetation and potential loss of game fish. Property values can be significantly affected when water quality and aesthetics come into play. Water intakes and irrigation pumps can become clogged or lake outlets can become clogged leading to the potential for local 3flooding’ As stated earlier in the report, residents of Limerick Lake, Washington afready pay significant amounts in order to try and control the population in their lake..

Management Strategies and Control Methods: Some control/management efforts have included hiring school kids to rake and pull each plant from the waterA. This treatment can have adverse effects however, as U inflata is capable of reproducing via fragmentation, and manual harvesting can lead to dispersed fragments that develop into new plants. Herbicides have been shown to be effective and in 1996, sonar treatment (fluridone) was tried in Lake Limerick in Mason County, WA. Initially used for the control of Brazilian elodeaA, it appeared to successfully control the U inflata population for approximately 2 years but there have been objections to that treatment. Fluridone is a slow-acting systemic herbicide that requires a 7—12 week treatment with constant levels of herbicide being maintained. According to the Washington Toxics Coalition, fluridone is non- selective, broad-spectrum herbicide and kills native plants as well as the targeted invasive by disrupting carotenoid synthesis’ It has been shown that grass carp will 2 it this feed on Swollen Bladderwort although. did not show any preference for 13 Internet Publication/Online Document; Washington State aquatic Nuisance Species Management Plan A Personal Correspondence

11 macrophyte in Silver Lake, Cowlitz County and experts have advised that the grass carp does not prefer floating 2plants’ Another control method suggested by Massachusetts state authorities. has been the use of benthic barriers, but these can prove problematic by limiting light and upward growth of native benthic macrophytes and may have negative effects on other benthic organisms. They also require near constant maintenance to retain their usefulness. According to the Massachusetts website there is no known biological control for this species.

Conclusion: U inflata is illegal to buy, sell, or transport in the state of Washington and it is on the state’s noxious weed monitor list. Given this plants ability6 to adapt and utilize resources that native plants cannot access, this may be insufficient to stop its eventual spread. Mitchell noted that when U inflata was discovered in Spruce Pond in New York (1994), it was already well-established and covered perhaps 10 acres. He believes it may have gone undetected for a long period because the plants remained vegetative and only flowered under certain climatic conditions at that latitude. This raises the concern that given the difficulty in distinguishing it from other native bladderworts when not in flower, it may in fact, already have spread further than is readily apparent. In researching online for this report I was able to locate Utricularia inflata for sale on the 8Internet. According to WSDA’s Wetland and Aquatic WAC 16-752-505,

“It is prohibited to transport, buy, sell, offer for sale, or to distribute plants or plant parts of these regulated plants, into or within the state of Washington. It is further prohibited to intentionally transplant wild plants and/or plant parts of these species within the state of Washington.”

It’s availability online serves to illustrate the ease with which local laws and regulations can be bypassed. Kathy Hamel with the Washington State Department of Ecology states that until a few years ago there was nobody collecting aquatic plant information from state waters. A She also confirmed that the ONLY group that has

12 Internet Publication/Online Document; John D. Madsen PhD; aquatics.org 6 Internet Publication/Online Document; Washington State Department of Agriculture 8 Internet Publication/Online Document; www.bestcarnivorousplants.com A Personal correspondence 12 attempted to actively eradicate the plant from any area in Washington State are the residents of Limerick Lake. Given the plants potential impacts this seems a grave oversight.

In a final act of irony, although Swollen Bladderwort is considered invasive in Washington State, it has been declared endangered in at least 3 other areas, Maryland (where it is listed as an Si endangered species by the Maryland Department of Natural Resources)”, Michigan and New York. (USDA website). This is doubly ironic as Utricularia inflata is not native to Michigan. The most likely explanation for this is the sometimes continues listing of Utricularia radiata as a subspecies of U inflata. Clearly, information on U inflata can be fragmentary and contradictory

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FIG.6 Swollen Bladderwort, Utricidaria inflata.

‘ Internet Publication/Online Document; Maryland Department of Natural Resources 13 Currently it is listed as both invasive AND endangered in New 7York. The official website for the USDA’s National Agriculture Library, a site that lists legal delinitions of invasive species, Guidance White papers, concepts, terms, and contexts, does not currently have a listing for Utricularia inflata as an invasive 6plant’ Current research and management efforts, and expert contact information in PNW

With the exception of listing the species on the state’s noxious weed monitor list and its indusion by the Washington State Department of Agriculture on the prohibited plant list, there are no current management efforts in place. U. injiata was found to be present in a wetland adjacent to Silver lake in 2005 and so it is believed that once the introduced grass carp die off the plant will likely return to that lake. There does not appear to be a plan to continue stocking grass Carp in Silver Lake. I have been unable to determine if eradication efforts are still ongoing at Limerick Lake but it seems likely as it is an effort spearheaded by local residents rather than any state or local governing body. The local experts I contacted were not aware of any further efforts at suppression or eradication anywhere in the state.

For further information regarding U inflata or to report a possible sighting, you may contact:

Kathy Hamel, Washington State Department of Ecology; [email protected] or Jenifer Parsons, Washington State Department of Ecology; [email protected]

Literature Cited:

‘ Internet Publication/Online Document; www.gardenguides.com lnternet Publication/Online Document; USDA National Agricultural Library ‘6 14 Adamec L (2006) Respiration and Photosynthesis of Bladders and Leaves of Aquatic Utricularia Species. Plant Biology 8 (6): 765-769

Ceska, A. and M.A.M. Bell. 1973. Utricularia (Lentibulariaceae) in the Pacific Northwest. Madrono 22: 74-84.

Dite D, Navratilova J, Hajek M, Valachovic M and Pukajova D (2006) Habitat variability and dassification of Utricularia communities: Comparison of peat depressions in Slovakia and the Trebon basin. Preslia 78: 331-343

Farooq M and Siddiqui SA (1966) Anatomy of floats of Utricularia inflexa forsk var inflexa taylor. Bulletin of the Torrey Botanical Club 93: 301-&

Mendez M and Karisson PS (1999) Costs and benefits of carnivory in plants: insights from the photosynthetic performance of four carnivorous plants in a subarctic environment. Oikos 86: 105-112

Mitchell RS, Maenzagmelch TE and Barbour JG (1994) Utricularia-inflata wait (lentibulariaceae), New to New-York-State. Bulletin of the Torrey Botanical Qub 121: 295-297

Reinert GW and Godfrey RK (1962) Reappraisal of Utricularia inflata and U. radiata (lentibulariaceae). American Journal of Botany 49: 213-&

Thiebaut G (2007) Invasion success of non-indigenous aquatic and semi-aquatic plants in their native and introduced ranges. A comparison between their invasiveness in North America and in France. Biological Invasions 9: 1-12

Urban RA, Titus JE and Zhu WX (2006) An invasive macrophyte alters sediment chemistry due to suppression of a native isoetid. Oecologia 148: 455-463

Other key sources of infonnation:

A. Kathy Hamel; Washington State Department of Ecology, email correspondence with author, November 29, 2007.

B. Jenifer Parsons, Aquatic Botanist, Washington State Department of Ecology, email correspondence with author, November 29 & 30, 2007.

1.http: / /www.wapms. org/plants/bladderwort.htnil

2 .http: / /www . ecv.wa.gov/programs/WQ/plants/weeds/bladder.html

3.http: //plants.usda.gov/java/proffle?svmbol=UTIN

4.http: / /nas. er.usgs.gov/taxgroup/ylants/default.asp

15 5.http: / /www .mass. gov/dcr/waterSupplv/lakeyond/faaslieet/Swollen%2OBla dderwort.pdf

6.http: / /www.nwcb.wa. gov/documents/weed%2Olists/Prohibited%2OPIant%20 Brochure%202006 .pdf

7.http:/ /www.gardenguides.com/ylants/ylant.asp?svmboFUTST2#details

8,http: / /www.bestcarnivorousplants.com/aldrovanda/aldrovanda for sale.htm

9 .http: / /www .watoxics.org/issues/pesticides-in-lakes/aquatics-problems

1O.http:/ /www.botanv.org/Carnivorous Plants/Utiicularia.php

11.http:/ /dnrweb . dur. state.md.us/download/rteplants.pdf

12.http: / /www. aquaiics.org/pubs/madsen2.htni

13.http: / /wdfw.wa.gov/fish/ans/ansplan.pdf

14.http :1 /www.ecv.wa.gov/progams/wg/plants/plantid2/descriptions/utrinf. html

15.http: / /www . aquariumarticles. com/read/?art233 1&tUtricularia+inflata+ Walt. %2C +swoflen+bladderwpzt

16. http: / /www.invasivespeciesinfo. gov/aquatics/main.shtml

17. http: / /dnrweb.dnr.state.md.us/download/rteplants.pdf

18. http: / /www. discoverllfe.org/mp/201?idM002685472

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