A primary goal of many aquatic ecosystem restoration (AER) projects is to alter and improve plant communities by increasing relative abundance of native species while reducing invasive species abundance, establishment, and spread. Biological control or the use of host-specific pathogens, predators, or herbivores from the native range of a target invader, has been used for invasive plant control, but underutilized as part of integrated pest management (IPM) in government-sponsored AER programs. Weed biological control should be vetted and integrated where possible in all project phases—planning, design, implementation, and maintenance. Using a publicly-funded AER framework—U.S. Army Corps of Engineers or USACE—we define and describe biological control, how it can be seamlessly incorporated at various project stages, a list of common invasive plants that have approved biological controls, and regulatory issues surrounding implementation. Our aim is to illustrate to project managers, planners, environmental personnel, and economists how regulatory agency-approved biological control agents can be a valuable component of AER projects to assist in meeting vegetation community restoration trajectory goals.

Maintaining beneficial, native plant structure and diversity while reducing invasive, nuisance species dominance is an important management domain for natural resource managers.One such vegetation component in North American lakes and reservoirs is submerged aquatic vegetation-a valuable aquatic resource which serves as productive habitat for fish, aquatic macroinvertebrates, and other wildlife.Reservoirs in the southern parts of the United States have experienced varying aquatic plant dominance dynamics due to historical water resource management actions, including drawdowns and introduction of herbivorous fish for the purpose of controlling invasive aquatic vegetation.Some of these management options have also been detrimental to native submerged aquatic vegetation.This paper explores an adaptive management research effort by installing herbivore-protected, fenced-pen submerged aquatic vegetation sites in a high-herbivore reservoir to determine effectiveness of protecting habitat and serving as founder colony sources for propagule spread.Four experimental sites with three management treatments each were planted with American eelgrass.Each site utilized one un-fenced treatment and two treatments with varying mesh sizes for protective fencing-pens.Site integrity, species survival and spread, and grazing were documented.One additional site was installed and planted with other native submerged aquatic vegetation species for nominal species performance descriptions.No plants survived unprotected in the high-herbivore system and plants, in general, performed consistently better within the smaller mesh size.These test planting results were ultimately used to inform adaptive management decision making for plant installation and expansion designs for managing reservoirs invested with Hydrilla, considered one of the most serious

Waterbirds were observed at 13 suburban wetlands in the Blackland Prairie of eastern Denton County, Texas, on 45 dates over a year. Five wetlands were built to improve ecosystem services in areas impacted by Lewisville Lake flood control operations; these habitat restoration wetlands were planted with diverse native flora to enhance the recovery of vegetation communities from natural seedbanks. Eight other wetlands, built to manage stormwater in residential developments, are surrounded by mixed monocultures of groomed turf grasses, with sparse shoreline plants and submerged vegetation in the littoral zone. Thirty-one species of 5,724 birds were observed, including one to nine species in each of six guilds: dabblers, divers, open water waders, dense vegetation waders, moist soil foragers and aerial piscivores. Dabblers were most abundant in count and number of species present, followed by divers and open water waders. Highly represented species were mallards, gadwalls and American coots among dabblers; lesser scaup and ringed-neck duck among divers; and great blue heron and great white egret among open water waders. Abundance averaged 539 individuals at habitat restoration wetlands and 379 individuals at stormwater management wetlands.

Macroinvertebrate community structure and assemblages associated with the planted, native submerged aquatic vegetation (SAV) species Heteranthera dubia (Jacq.) MacMillan and Potamogeton nodosus Poiret were examined in a series of constructed urban floodway wetlands, the Dallas Floodway Extension Lower Chain of Wetlands, Dallas, TX, USA. Macroinvertebrate community metrics, including abundance, richness, diversity, and evenness associated with SAV and three different wetlands of varying construction completion dates, water sources (direct or wetland-channeled wastewater effluent), and ecosystem management stage (established/reference or developing) were compared and analyzed. Assemblages at sampling sites were also classified and related to vegetation and wetland physicochemical parameters. Plant species affected only macroinvertebrate abundance, with the less-dissected P. nodosus supporting higher counts than H. dubia. Wetland age and water-effluent type had the most substantial effect on macroinvertebrate communities. The older, longer-managed wetland and wetland-channeled effluent habitat consistently demonstrated higher quality metrics and biodiversity than newly constructed, direct effluent wetland habitat. Increased vegetation cover and wetland age, coupled with moderate water temperature, pH, and DO levels were characteristics of more rich and diverse macroinvertebrate communities, including pollutant-sensitive taxa, such as Ephemeroptera and Trichoptera.

Holbrook DL, Schad AN, Dick GO, Dodd LL, Kennedy JH. 2020. Invasive bivalve establishment as a secondary effect of eradication-focused nuisance aquatic plant management. Lake Reserv Manage. XX:XX-XX. We evaluated changes in aquatic vegetation cover and community structure in hydrilla (Hydrilla verticillata)-infested constructed experimental ponds after applying the management tools of triploid grass carp (Ctenopharyngodon idella) stockings, herbicide applications, and native macrophyte planting (emergent, floating-leaved, and submersed species). In ponds where aquatic vegetation was most reduced due to management (herbicide and >72 grass carp per vegetated hectare stockings), a secondary infestation of the invasive bivalve (Asian clam orCorbicula fluminea) was observed. Asian clam abundances were analyzed in relation to grass carp stocking densities (0, 40-42, 72-81, and 110-129 per vegetated hectare), depth, and changes in native and invasive vegetation community structure and cover. Data analyses showed inverse relationships of Asian clam abundances to vegetation cover and to depth, as well as a synergetic relationship with grass carp stocking density. Implications of this research indicate that when a nuisance aquatic plant management strategy is focused on full or near eradication of a target species, inevitable damage to native species that might otherwise preserve beneficial ecological components may result in secondary issues, such as the expansion of additional invasive species due to opening of habitats. Excessive control efforts of a targeted nuisance plant species, and the results here highlight potential unintended consequences of over management of natural resources.

Schad AN, Dick GO. Aquatic vegetation community structure response to hydrilla management with triploid grass carp, herbicide, and native vegetation planting. Lake Reserve Manage. 34:417-425.To aid conservation managers conducting hydrilla (Hydrilla verticillata (L.f.) Royle) management, we evaluated changes in aquatic vegetation community structure and dominance in dioecious hydrilla-infested ponds by applying several management tools and monitoring vegetation changes on an annual basis over a 4yr period. The study was conducted in fully vegetated (dioecious hydrilla and native macrophytes) 0.3ha mesocosm ponds using 4 levels of triploid grass carp (Ctenopharyngodon idella Valenciennes) stocking densities (0-129 per vegetated hectare), a one-time second-year herbicide treatment to reduce standing biomass of hydrilla and other submersed aquatic vegetation (SAV), and native plantings to provide the basis for replacing hydrilla as it was controlled. Grass carp stocking density had an inverse relationship with coverage of total vegetation, hydrilla, volunteer SAV, and volunteer emergents. All vegetation categories recovered from the one-time herbicide application, although this was suppressed by higher densities of grass carp. Grass carp did not significantly affect planted growth forms (SAV, floating-leaved, and emergent), with increases in mean coverage in all treatments through time, although coverage was lowest at the highest grass carp density. Vegetation dominance shifted from hydrilla to native in both control and low grass carp density treatments, with most SAV eliminated from treatments stocked with more than 72 per hectare.

Hydrilla verticillata L.F. Royle (hydrilla; Hydrocharitaceae) is an invasive submersed plant that was introduced into the United States on at least two occasions, from India and South Korea (Madeira et al. 2000). These introductions correspond to genetically and ecologically distinct dioecious and monoecious biotypes (Madeira et al. 2000). The dioecious biotype (pistillate flowers only) is thought to have been first introduced into Florida in the 1950s and has since become highly invasive (Schmitz et al. 1991, Balciunas et al. 2002). The monoecious biotype (pistillate and staminate flowers) is a more recent introduction and was first identified in the Potomac River in 1976 (Steward et al. 1984). The dioecious biotype has been reported principally from East Coast and Gulf Coast states, but also from California and Washington State (Langeland 1996). The monoecious biotype is spreading rapidly and is now found in 22 states, more commonly in the northern United States, though it appears to be increasing in southern states as well (Grodowitz et al. 2010). Historically, the two hydrilla biotypes were geographically separated but their North American ranges have begun to overlap. Ryan et al. (1995) reported both biotypes from Lake Gaston, North Carolina. Both biotypes are also believed to coexist at Guntersville Reservoir, Alabama (D. Webb, pers. comm.) and Lake J. Strom Thurmond, Georgia (U.S. Army Corps of Engineers 2013). The occurrence of both biotypes within the same water body raises concerns about potential hybridization. Hybridization may lead to novel secondary chemistry combinations (Orians 2000, Whitehead and Bowers 2013) or structural changes (Grosholz 2010) that give the hybrid a competitive advantage in the environment and lead to reduced efficacy of chemical and biological control technologies (Roley and Newman 2006, Blair et al. 2008, Schierenbeck and Ellstrand 2009, LaRue et al. 2013). Hybridization can also increase genetic variation, thereby increasing the chance of adaptive evolution in the introduced range. Experimental crosses have revealed that female dioecious hydrilla plants are potentially fertile and can produce viable seed when pollinated by monoecious and dioecious strains from Asia, though crosses between the U.S. biotypes have not been attempted (Steward 1993). In addition, viable seeds have been identified from U.S. monoecious plants at a North Carolina lake and in cultures maintained in Florida, though productivity and viability were reportedly low (Conant et al. 1984, Langeland and Smith 1988). For a variety of ecological and management reasons, it is important to determine whether 1) hybridization between hydrilla biotypes in the United States can occur under controlled conditions, and 2) whether hybridization is occurring in field populations. This note reports the results of two studies designed to address these questions.

Seeds from the Texas Northern Blackland Prairie ecotype of western soapberry (Sapindus saponaria L. var. drummondii (Hook. & Arn.) L.D. Benson [Sapindaceae]) were collected, stored, pretreated (with sulfuric acid scarification and stratification), and germinated for the purposes of silviculture projects. Seeds were scarified for 0, 20, 40, and 60 min using 96% sulfuric acid (H2SO4) and half were stratified at 2 to 5.5 °C (35.5–42 °F) for 45 d. Results from the pretreatment methods were significantly different (stratification, P < 0.001; scarification, P = 0.039), with the greatest difference being between mean germination percentage for non-stratified and stratified seeds at 14.67% and 60.33%, respectively. For both stratification methods, the 20-min acid scarification method produced the highest germination percentages; however, germination occurred without acid scarification in both stratified and non-stratified seeds. This outcome could indicate the ecotype lacked physical dormancy or that a less volatile seed scarification pretreatment method, such as peat moss storage, could be a viable germination method.

Balancing techniques used to control nuisance aquatic plants while establishing or preserving beneficial vegetation can be complex. Survival and growth of 10 US native aquatic plant species were examined after transplanting into Hydrilla verticillata infested ponds stocked with 4 triploid grass carp (Ctenopharyngodon idella) densities: control (no fish), low(42 fish per vegetated hectare), medium (77), and high (120). Half of the transplants were protected from grass carp herbivory with exclosures. During the first year establishment phase, individual transplants of most species survived within exclosures, but increased mortality was observed for some species without protection. Unprotected Heteranthera dubia, Potamogeton illinoensis, Eleocharis quadrangulata, and Schoenoplectus pungens did not survive the high density treatment. Two-year post-planting coverages of all species combined outside of protected areas averaged 240 m(2) in controls, 238 m(2) under low density, 179 m(2) under medium density, and 109 m2 under high density treatment. Three categories in terms of species' ability to persist in the presence of grass carp were discerned: (1) highly susceptible to herbivory (Heteranthera dubia and Potamogeton illinoensis); (2) susceptible to herbivory but able to establish and spread up to a maximum grass carp density (Vallisneria americana, Eleocharis quadrangulata, Schoenoplectus pungens, and Schoenoplectus tabernaemontani); and (3) established and spread at all grass carp densities (Nymphaea odorata, Echinodorus cordifolius, Justicia americana, and Pontederia cordata). This study demonstrated that restoring native plant communities may be possible when managing nuisance plant species with grass carp and provided insight into species selection to maximize vegetation establishment efforts.

The objectives of this study were to evaluate the allelopathic effects of Chinese privet ( Ligustrum sinense Lour.) extract on native seeds and cuttings and to assess the survivability of native plants in a flooded riparian corridor. Field sites occupied the Trinity River floodplain in southeast Dallas County, Texas. Eight native species were evaluated. They were soapberry, red mulberry, persimmon, elderberry, beautyberry, coralberry, mustang grape, and heartleaf peppervine. From this study, we concluded that:

Secondary production and seasonal development of the damselfly Enallagma civile Hagen, 1861 were determined as part of an epiphytic macroinvertebrate study in the Dallas Floodway Extension Trinity River Project Lower Chain of Wetlands, Dallas, TX, USA. These wetlands were constructed to mitigate flooding of the Trinity River, but also provided quality wildlife habitat and removal of wastewater effluent contaminants. Variations in life history were observed between two macrophytes and three different wetlands of varying age, effluent source, and vegetation establishment. Mean annual production of E. civile was 1393 mg/m(2)/year, standing stock biomass was 1376 mg/m(2)/year, cohort production/biomass (P/B) ratio was 4.30/year, and annual P/B was 10.18/year. These values are in the upper range of known Odonata production values from a lentic system. Enallagma civile biomass growth rates were observed to be higher from populations on the better established macrophyte (Potamogeton nodosus Poiret, 1816) and in the longest established wetland.

: The purpose of this work was to evaluate the efficacy of mechanical cutting and herbicide applications to control invasive phragmites at Times Beach, a 56-acre nature preserve located in Buffalo, New York. The overall objective of this five-year project is to replace the dense monotypic stands of phragmites with a diverse native plant community that will repair ecosystem function.

: 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

Weighted hydrilla fragments were introduced to containers of wild celery (Vallisneria americana Michx.) grown at four water depths (18, 46, 91, 122 cm) in a research pond at the Lewisville Aquatic Ecosystem Research Facility, Lewisville, Texas. Established wild celery effectively reduced invasion by hydrilla fragments, while hydrilla fragments readily established in control containers filled with sediment alone. Hydrilla biomass harvested from controls, representing the "empty niche," was significantly greater (40 times) than hydrilla biomass harvested from containers planted with wild celery for all water depth treatments. This study addresses the concept that preemptive establishment of wild celery can slow or prevent invasion from hydrilla fragments at different water treatment depths.

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).