: This study documents effects of macronutrient (nitrogen and phosphorus) concentrations, pH, and salinity on giant salvinia growth.

: Aquatic plants are a vital, but often missing, component of shallow, freshwater systems. Manmade systems, such as multipurpose reservoirs, of course do not come equipped with aquatic plant communities. Even natural systems, such as streams, ponds, and lakes, have often been so disturbed that they, too, lack aquatic plants. An absence of plants often results in relatively poor aquatic habitat; shoreline erosion; water quality problems; development of noxious algal blooms; and, often, susceptibility to invasion by harmful, nonnative, aquatic weeds. If resource managers wish to avoid these problems and to realize sustainable environmental benefits, they must take action to restore a diverse plant community dominated by native species. To date, the best method to ensure successful establishment of a diverse, native plant community is to plant robust propagules of desirable species in selected, favorable environments and to provide them with protection from grazing. This report provides general information on production of aquatic plant propagules and on methods of planting and protection that should facilitate the development of diverse native plant communities in aquatic systems. We document the successful application of these techniques in a number of aquatic ecosystems.

hydrilla is an invasive, nonindigenous submersed aquatic plant first discovered in the United States in the 1960s (Blackburn et al. 1969, Pieterse 1981). a native of asia, the Pacific islands, and new Zealand (Pieterse 1981, Cook and luond 1982, Madiera et al. 2004), hydrilla exhibits aggressive growth, rapidly expanding to the surface (especially dioecious biotype) and forming a dense canopy. limited light availability beneath the dense canopy results in competitive reduction of native vegetation and lower diversity (Sutton 1990, Barko et al. 1991). additionally, excessive growth of hydrilla may degrade water quality and habitat for fish and other wildlife (Madsen 1997). two distinct biotypes, monoecious and dioecious, exist in the United States (Spencer and anderson 1986); monoecious hydrilla has both male and female flowers on the same plant, while the dioecious biotype produces male and female flowers on separate plants. distribution of both biotypes includes the northern states of Maine, wisconsin, and washington; the Gulf and atlantic coastal states; the western states of arizona, idaho, and California; the midwestern states of tennessee, arkansas (USGS 2010), Oklahoma (Gene Gilliland, Oklahoma department of wildlife Commission, pers. comm.), indiana (lembi 2006), kentucky (http://www.apms.org/apn/oct2008.pdf), kansas (http://www.apms.org/apn/oct2009.pdf), and recently the Ohio River from west Virginia to indiana. Monoecious hydrilla tends to be located in the northern states but has been found in recent years in many tennessee Valley authority (tVa) reservoirs, including lake Guntersville in alabama and nickojack Reservoir in tennessee. dioecious hydrilla has always been considered an invasive plant of the south; however, this perception is changing because it has now been found in idaho and kentucky (Figure 1), suggesting it can endure more northern locations. to better understand differences in the tuber dynamics between monoecious and dioecious hydrilla, an outdoor mesocosm study was conducted in texas to compare differences between two biotypes under similar conditions. By understanding the tuber/turion dynamics of different hydrilla biotypes, implementation of management options may be better applied with more consistent control efficacy (Madsen and Owens 1998). this study examines differences in tuber/ turion dynamics between monoecious and dioecious hydrilla. METHODS

The objective of this study was to investigate the impact of invertebrates on three native macrophytes: American pondweed ( Potamogeton nodosus Poir.), Illinois pondweed ( P. illinoensis Morong), and Mexican water lily ( Nymphaea mexicana Zucc.). Biomass production of the three plant species was measured and compared under two conditions: one with an uncontrolled population of herbivorous invertebrates and one in which most herbivorous invertebrates were removed by an insecticide treatment. The insecticide effectively removed most plant-feeding insects, including those in orders Coleoptera, Diptera, Trichoptera, and Lepidoptera, but did not remove one invertebrate group likely to impact plants, Hemiptera (aphids). Differences in plant biomass due to feeding and nonconsumptive damage by remaining invertebrates were variable and dependent upon plant species. Nontreated samples of Mexican water lily exhibited high levels of insect damage (primarily herbivory), as well as case making and egg deposition, but biomass differences between treatments were not detected. The impacts of invertebrate herbivory and nonconsumptive damage were more pronounced in both pondweed species as nontreated biomass was significantly less than biomass of insecticide-treated pondweeds. Biomass of American and Illinois pondweed was reduced by 40 and 63%, respectively, due to invertebrate herbivory. Invertebrate herbivory, once thought to be insignificant to aquatic macrophytes, was shown to cause substantial biomass reductions in two of the three plant species studied.

In situ hyperspectral reflectance data were studied at 50 bands (10 nm bandwidth) over the 400-900 nm spectral range to determine their potential for distinguishing among nine aquatic plant species: American lotus [Nelumbo lutea (Willd.) Pers.], American pondweed (Potamogeton nodusus Poir.), giant duckweed [Spirodela polyrrhiza (L.) Schleid.], Mexican waterlily (Nymphaea mexicana Zucc.), white waterlily (Nymphaea odorata Aiton), spatterdock [Nuphar lutea (L.) Sm.], giant salvinia (Salvinia molesta Mitchell), waterhyacinth [Eichhornia crassipes (Mart.) Solms] and waterlettuce (Pistia stratiotes L.). The species were studied on three dates: 30 May, 1 July and 3 August 2009. All nine species were studied in July and August, while only eight species were studied in May; giant duckweed was not studied in May due to insufficient availability. Two procedures were used to determine the optimum bands for discriminating among species: multiple comparison range tests and stepwise discriminant analysis. Multiple comparison range tests results for May showed that most separations among species occurred at bands 795-865 nm in the near-infrared (NIR) spectral region where up to six species could be distinguished. For July, few species could be distinguished among the 50 bands; most separations occurred at the 715 nm red-NIR edge band where four species could be differentiated. The optimum bands in August occurred in the green (525-595 nm), red (605-635 nm) and red-NIR edge (695-705 nm) spectral regions where up to six species could be distinguished. Stepwise discriminant analysis identified 11 bands in the blue, green, red-NIR edge and NIR spectral regions to be significant to discriminate among the eight species in May. For July and August, stepwise discriminant analysis identified 15 bands and 13 bands, respectively, from the blue to NIR regions to be significant for discriminating among the nine species.

Abstract : Quantifying biomass to measure aquatic plant abundance can be costly and labor intensive. This technical note compares several alternate, less exhaustive techniques for biomass sampling in the field.

Abstract : This technical note describes development of a decision support tool that uses multiattribute utility analysis to aid resource managers in selection of suitable sites for establishing native aquatic vegetation in large, multi-purpose reservoirs.

INTRODUCTION: Plant biomass data are critical to many aquatic plant assessment efforts, particu- larly those involving adaptive management of aquatic plant problems, integrated plant management approaches, or ecosystem restoration. Unfortunately, current methods for aquatic plant biomass sam- pling have depended upon expensive, labor-intensive SCUBA techniques or utilization of large, heavy dredging equipment. While these methods are accepted by the scientific community and resource managers, their high costs preclude their use on many projects. As a result, quantitative data are often lacking or inadequate. Research is currently being conducted to explore and develop new sampling methods that could be employed to provide scientifically acceptable plant community assessment data in a cost-effective manner. One area where this research is being conducted is Lake Gaston, NC/VA. Monoecious hydrilla (Hydrilla verticillata (L.f.) Royle) was first discovered in Lake Gaston, NC by North Carolina State University scientists near Eaton Ferry Bridge in 1985 (North Carolina Division of Water Resources (NCDWR) 1997, Figure 1).

Hydrilla ( Hydrilla verticillata [L.f.] Royle) is an invasive, nonindigenous aquatic plant first discovered in the United States in the late 1960s (Blackburn et al. 1969). Current distribution includes the northern states of Maine and Washington, the Gulf and Atlantic coastal states, California, Tennessee, and recently Arkansas (USGS 2007), Oklahoma (Smart pers. comm.), Indiana (Lembi 2006) and Wisconsin (Netherland 2007). Once hydrilla invades an aquatic system, the plant can rapidly spread locally through rhizome expansion or over longer distances through generation of fragments (Sculthorpe 1985, McFarland and Barko 1996) and/ or turions. For example, in the San Marcos River, Texas, Owens et al. (2001) found that healthy, undamaged hydrilla fragments generated by recreational usage, harvesting, and environmental factors eventually led to creation of new colonies downriver (some several miles) as fragments settled. Two host-specific leaf-mining flies, introduced beginning in 1987 (Grodowitz et al. 2007), have shown success in longterm management of hydrilla in controlled experimentation and field sites (Doyle et al. 2002, Grodowitz et al. 2003). The two introduced agents, the Australian leaf-mining fly ( Hydrellia balciunasi Bock) and the Asian leaf-mining fly ( H. pakistanae Deonier), have larval life stages (three-instars) that damage the plant by penetrating, mining, and destroying hydrilla leaves (Balciunas et al. 2002, Buckingham and Grodowitz 2004). Past research has shown that moderate-to-high levels of herbivory can impact hydrilla biomass production and reduce tuber numbers and size (Doyle et al. 2002, 2007, Grodowitz et al. 2003). Doyle et al. (2002) reported that when 10 to 30% of leaves were damaged, the maximum rate of photosynthesis was reduced by almost 40%. When leaf damage reached 70%, photosynthetic rates were reduced by up to 60%. Based on field observations, fragmentation appears to be higher in hydrilla stems damaged by fly mining (Grodowitz, unpubl. data); however, only limited information is available concerning fragment establishment following varying levels of fly leaf-mining. In an earlier study, when fragments were physically planted in container sediment, Owens et al. (2006) determined that high levels of leaf damage (70 to 100%) were associated with significantly reduced above and belowground biomass, stem length and number, rhizome number, and tuber production in comparison to fragments with low levels of herbivory. This study examines establishment success of hydrilla fragments exposed to four different levels of herbivory as measured by percent leaf damage by quantifying fragment settling, rooting, change in length, branching, and aboveground biomass accumulation.

: This technical note quantifies the impact that invertebrate herbivores have on native aquatic plants by comparing dry biomass of five macrophyte species between two treatments; an insecticide treatment to remove invertebrate herbivores, and a control where the herbivore complex was left to develop naturally. There is little information available that quantifies the impact of invertebrate herbivores on native macrophyte biomass in the United States. Early research indicated that while macrophytes were useful as substrates for invertebrates and epiphytic growth, they provided little if any nutritive value (Shelford 1918). However, additional studies have shown the importance of macrophytes as a nutritive source for invertebrates. Soszka (1975) found that Potamogetoit species can lose 50 to 90 percent oftheir leaf area through insect herbivory and non-consumptive destruction mostly from lepidopterans, trichopterans, and dipterans. Sand-Jensen and Madsen (1989) found leaf area damage to be between 2 and 56 percent for Potamogeton species, depending on locality. This damage was primarily attributed to trichopterans and dipterans. Lodge (1991) stated that macrophytes are engaged in aquatic food webs, sometimes to the extent that biomass, productivity, and relative species abundance are dramatically changed by grazers. Finally, Cronin et al. (1998) found that freshwater macrophytes exhibited herbivory similar to that reported for terrestrial plants. These findings countered the conventional idea that aquatic plants offered only surface substrates (Shelford 1918). However, due to the paucity of published accounts of invertebrate herbivory, more research is warranted.

INTRODUCTION: Shawano Lake, Wisconsin has a history of invasive aquatic plant problems, specifically curly-leaf pondweed (Potamogeton crispus L.) and Eurasian watermilfoil (Myriophyllum spicatum L.). In addition to problems associated with invasive plant species, Shawano Lake has been experiencing declining water quality associated with phosphorus (P) loading potentially due to summer senescence of curly-leaf pondweed (James and Owens 2006). Located in east-central Wisconsin, this 6,063-acre lake has been infested with Eurasian watermilfoil, the dominant invasive aquatic plant, since 1991 (www.dnr.state.wi), and more recently curly-leaf pondweed. Both exotic plants are problematic in the northern tier states, and are proven to nega- tively impact water quality, recreational usage, fisheries, native plant populations, and waterfowl usage. In an effort to document P loading associated with curly-leaf pondweed senescence (James and Owens 2006), an aquatic plant survey was conducted in June 2005 to determine the frequency of occurrence for Eurasian watermilfoil and curly-leaf pondweed populations in the lake. In June 2006, plant biomass was collected to document abundance of Eurasian watermilfoil and curly leaf pondweed as well as native plants in Shawano Lake. Additionally, Eurasian watermilfoil and curly- leaf pondweed biomass samples were ground and analyzed for nitrogen, phosphorus, and potassium within plant tissue. METHODS: During the week of June 13-16, 2005, a lake-wide survey of Shawano Lake, WI was undertaken to determine frequency of occurrence of all aquatic plant species observed in the lake, including Eurasian watermilfoil and curly-leaf pondweed (Figures 1 and 2). This survey was conducted using the point-intercept method (Madsen 1999). Using MapInfo mapping software (Troy, NY), coordinates were determined for each intersecting point on a 200- by 200-m grid (Figure 3). A Garmin GPS map 76CS GPS unit (Olathe, KS) was used to navigate to each point. All plant species were identified at 694 points and water depths were recorded. Plant species were identified by visual inspection and by deploying a sampling rake to the bottom. Additionally, voucher specimens were collected for all plant species and stored at the Lewisville Aquatic Ecosystem Research Facility (LAERF) in Lewisville, TX for future reference. During the week of June 1-6, 2006, plant aboveground biomass and curly leaf pondweed turions were collected using a box-core sampler (Figure 4). The box-core sampler had a sampling area of 0.1m2. The boat containing the sampler was driven to predetermined points where curly-leaf pondweed (the primary plant of interest), had been found during the 2005 point-intercept survey. The box-core sampler was raised using a battery-powered winch, deployed into the lake where the sampler snapped closed, cutting the plants. The retrieved sample was dropped into a container, washed, and all plant biomass and turions were collected and bagged. Observational data on sediment type were recorded. Fifty randomly selected sites were sampled for determination of

This study examined the interaction and main-effect impacts of herbivory by the leaf-mining fly Hydrellia pakistanae and plant competition from Vallisneria americana on the growth, expansion and tuber formation of Hydrilla verticillata in a 2×2 factorial design experiment. The study was conducted in 14,000-L tanks, over two growing seasons. Each tank represented a single experimental unit and contained 32 1-L pots. At the beginning of the experiment half of these were planted with H. verticillata while the other half were either left empty or planted with V. americana (the competitor). H. pakistanae fly larvae (the herbivore) were added to tanks as appropriate. No significant interactions were identified between herbivory and competition on any parameter of H. verticillata growth analyzed (i.e., total tank biomass accumulation, total number of rooting stems, total tuber number, total tuber mass, and tuber size), indicating that the factors were operating independently and neither antagonism nor synergism was occurring. Both competition and herbivory impacted the growth of H. verticillata. H. verticillata plants grown in the presence of V. americana developed less total biomass, had fewer total basal stems, had fewer tubers and less tuber mass per tank, and produced significantly smaller tubers relative to control plants. Herbivory also suppressed H. verticillata biomass accumulation and tended to suppress the number and total mass of tubers produced in each tank. Both factors showed 30–40% reduction of total H. verticillata biomass, although the mechanism of impact was different. Competition suppressed expansion of H. verticillata into adjoining pots but had little impact on its growth in pots where it was originally planted. Herbivory resulted in a general suppression of growth of H. verticillata in all pots. Although herbivory significantly impacted H. verticillata biomass, it did not result in competitive release for V. americana under the current experimental conditions. We conclude that management activities that promote competition or herbivory will impact the growth and expansion of H. verticillata. Furthermore, since these factors operated independently, the combined use of both factors should be beneficial for suppression of H. verticillata dominance.

BACKGROUND: Aquatic system restoration often involves establishment or reestablishment of native aquatic plant communities. The role of plants in aquatic systems is significant: in addition to providing valuable fish and wildlife habitat (Dibble et al. 1996), aquatic plants can improve water clarity and quality (James and Barko 1990), reduce rates of shoreline erosion and sediment resuspension (James and Barko 1995), and help prevent spread of nuisance exotic plant species (Smart and Doyle 1995). Efforts to restore beneficial aquatic plant communities are best concentrated on establishment of small, protected plant colonies at strategic locations within unvegetated reservoirs (Smart and Dick 1999). Once successfully established, these plants serve as founder colonies, which will spread beyond their protective borders to adjacent, unvegetated areas of the reservoir when conditions are favorable. Each restoration project usually requires many individuals of several aquatic plant species. Because acquisition of large numbers of appropriate plant propagules in a timely manner can be difficult, the authors have begun developing methods for producing their own transplants, tailored to each specific project. Although commercial suppliers may provide some of the plant materials needed for a restoration project, propagule production may be preferred for several reasons. Currently, only a limited selection of aquatic plant species (particularly submersed plant species) is readily available from commercial sources. Propagule types offered are also frequently unsuited to the demands of plant establishment in large water bodies. For the most part, stem fragments, seeds, root crowns, or dormant perennating organs (tubers, winterbuds) are sold commercially. These propagules are weak, and require near-ideal conditions for successful establishment. In the harsh environment of artificial reservoirs, most are destined to fail. Additionally, such propagules are often only available at certain times of the year, very possibly at the wrong time of the year for a particular restoration project. As an example, northern suppliers generally must wait until spring thaws occur, which may be beyond the period for optimal establishment in southern reservoirs. Plant origin may be an issue as well. Although a particular species may be found throughout the United States, there may be pertinent genetic variability among plants from different regions. For instance, a northern variety may not do well in southern climates. Finding source plants locally (or as locally as possible) is highly recommended. For the above reasons, the authors recommend finding local plant stocks and cultivating desired species to produce mature transplants (potted plants) for many restoration efforts. These propagules are much more likely to survive harsh environmental conditions faced when transplanted into reservoirs and lakes. Included in this technical note are some general requirements and considerations for the culture of a variety of aquatic plants, including submersed, floating-leaved, and emergent growth forms. A more specific treatment of this information is given in Smart and Dick (1999). FACILITIES FOR OFF-SITE PRODUCTION: Production of aquatic plants requires adequate facilities, but these need not be complicated or expensive. Small ponds, tanks, or raceways may be used to grow aquatic