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One of the most widespread and common invasive aquatic plant species in North America is Myriophyllum spicatum L. (Eurasian watermilfoil). Given the variety of impacts it has on ecological and recreational values, identifying an effective treatment strategy for Eurasian and hybrid watermilfoil is a priority for invasive aquatic plant management agencies. Unfortunately, traditional control efforts using herbicides have not only been variably effective, but they have also resulted in non-target impacts. The herbicide florpyrauxifen-benzyl (trade name ProcellaCOR®) has recently been approved but understanding of effectiveness is mostly limited to mesocosm studies. Our study reports the outcome of using florpyrauxifen-benzyl to treat a strain of hybrid watermilfoil in an inland lake in the Laurentian Great Lakes region. Mean abundance in treatment areas decreased at all points sampled (or stayed the same where initial cover was zero). Percent cover in the two quadrats declined from 50% to 5% in area 1, and 20% to 0% in area 2. Of the nine native plant species present, frequency of occurrence increased (six species) or stayed the same (three species) after treatment. Mean species richness at each transect increased pre- to post-treatment. The substantial decreases in this strain of hybrid watermilfoil abundance and increases in presence of native aquatic vegetation in this field study provide initial evidence that florpyrauxifen-benzyl is effective in partial-lake treatments of this strain of hybrid watermilfoil at an application rate of 12.68 oz/ac ft, with limited non-target impacts to native species. Our study balances observational studies with logistical management concerns to benefit researchers and lake stakeholders, alike. Study outcomes support recent advances in milfoil management that could lead to improved control, which translates to reduced ecological and recreational impacts of milfoil, as well as reduced non-target impacts and long-term management costs. [ABSTRACT FROM AUTHOR]

The inconsistency in regulated species lists across the shared waters of the Great Lakes undermines the collective prevention efforts of the region, resulting in a "weakest link" problem; some jurisdictions regulate more than 100 species, others fewer than 20. We examine progress over the last twelve years toward more consistent regulated species lists within the 10 Great Lakes jurisdictions. Using a risk assessment framework, we assess a suite of regulated and unregulated organisms that have been identified as having the potential for introduction. Using these species assessments, we determine how sufficient current regulated species lists are in protecting against high-risk species. We also use these species assessments to transparently identify potential high-risk candidates for regional regulatory consideration. A total of 136 aquatic species were regulated by at least one jurisdiction (69 plant species and 67 animal species). The number of species regulated by 5 or more jurisdictions has gone from 10 in 2008 to 44 in 2020. However, the majority (68%) of the currently regulated species are listed in less than half of the Great Lakes jurisdictions. The number of regulated species varies widely across jurisdictions for both taxonomic groups. Wisconsin regulates the largest number of plant and animal species (104 in total), followed by Minnesota (71), New York (59), Illinois/Indiana/Michigan/Ohio (45), Pennsylvania (34), Ontario (23) and Québec (19). We observed only a weak positive correlation between impact score and regulation status. Many of the most-regulated species have impact scores in the low or low-moderate categories, and several species with high impact scores are regulated by less than half of jurisdictions. Twenty-one species (17 plant and 4 animal) are identified as priorities for future regulatory listing. [ABSTRACT FROM AUTHOR]

In an effort to harmonize multi-jurisdictional surveillance and detection of aquatic invasive species, regional stakeholders have called for the development of a Great Lakes Aquatic Invasive Species Surveillance Framework to identify species that pose a risk to the basin, quantify the relative risk of various pathways of introduction, provide guidance on monitoring protocols for surveillance, and identify priority locations for surveillance based on this pathway assessment. Here, we screen 448 species to develop a surveillance list of 144 species that are relevant for Great Lakes surveillance: are not yet widespread throughout the basin, have a pathway through which they can arrive, are able to establish and are predicted to cause impacts. Using the Great Lakes Aquatic Nonindigenous Species Risk Assessment for consistent assessment across taxa, the surveillance species list consisted of 144 species: 64 plants, 4 algae, 40 fish, 5 mollusks, 28 crustaceans, 1 platyhelminthes and 2 bryozoans. While pathway risk varies by taxon, the highest risk pathways across all taxonomic groups are natural dispersal, hitchhiking/fouling, and intentional release. The taxonomic group predicted to have the most severe impacts on a per species basis is algae, followed by mollusks, and plants. However, the large number of plant and fish species on the surveillance species list means that overall predicted impact (from a taxonomic perspective) is greatest from these two groups. We recommend ways that the surveillance list could be applied to improve aquatic invasive species management efforts: engage in community-based surveillance, inform taxonomic and species surveillance priorities, provide guidance on monitoring protocols for surveillance, quantify the relative risk of various pathways of introduction and identify priority locations for surveillance based on this pathway assessment. [ABSTRACT FROM AUTHOR]