Ballast water is a leading vector for the introduction of aquatic invasive species worldwide and, once a novel species is established, regional ballast water exchange between ports can accelerate secondary spread. The importance of shipping induced invasions in the Laurentian Great Lakes has resulted in policies that require more stringent ballast water treatment standards for transoceanic shipping than is required of ships operating regionally within the Great Lakes. As a result, ballast water discharges within the Great Lakes are not well regulated, primarily because of the challenge of treating the high volumes of water carried by vessels that are confined to the waters of the Great Lakes. We used a discrete-time Markov chain model on a network with annual time-steps to simulate ballast water management scenarios at high-priority ports in the Great Lakes shipping network for two potential invaders, golden mussel (Limnoperna fortunei) and monkey goby (Neogobius fluviatilis). We chose high-priority ports by using graph-theoretic network analysis techniques to calculate six network centrality metrics for 151 ports in the network. Ports scoring high in network centrality scores have more ties with other ports or are positioned within the network such that they potentially have greater influence over the secondary spread of aquatic invasive species than other ports. We simulated secondary spread scenarios where hypothetical ballast water treatment was implemented at the top twenty ranked ports in each network centrality metric, as well as the top twenty busiest ports by ship arrivals. The results of each scenario were compared to a scenario where no management action was taken. Simulated secondary spread for both golden mussel and monkey goby resulted in significantly reduced infestation probabilities (p < 0.001) under all management scenarios when compared to unmanaged spread scenarios. Management at ports with inwardly directed ties to other ports reduced infestations by the greatest amount compared to other management scenarios; 65.4% for golden mussel and 74.6% for monkey goby. The indegree centrality of ports in the Great Lakes was found to be an important factor in governing secondary spread. Here we show that prioritized management, like high volume shore based treatment systems based on network centrality, is a potentially effective strategy for impeding the secondary spread of new or localized invasive species in the Great Lakes.
Purpose: In recreational water bodies, herbicides are widely used for controlling unwanted weeds, and impacts of herbicide residues on health risks to aquatic ecosystem is a serious concern. This study was aimed to improve the existing understanding of the deposition of herbicides from water column to bed sediment and leachate of herbicides from bed sediment to water column. We investigated the attachment of two herbicides with sediment and release from sediment: (1) Glyphosate; and (2) Fluridone. The goal of this study was to determine the deposition and release of Glyphosate and Fluridone in bed sediment of the Sacramento-San Joaquin River Delta.Materials and Methods: Field sampling was performed to collect water and sediment samples from Sacramento-San Joaquin River Delta. Bottom dredge sampler was used for collecting sediment samples and horizontal water bottle sampler was used for collecting water samples. A series of experiments were conducted to determine the attachment and release of Fluridone and Glyphosate from sediment at a different level of initial concentrations. For analyzing Fluridone and Glyphosate in sediment leachate and water, samples were processed using enzyme-linked immunosorbent assay (ELISA) based method.Results and Discussion: Observations showed that proportions of Glyphosate concentrations in water were higher than Fluridone concentrations in water, when both herbicides were inoculated in water in same quantity. On the contrary, the concentrations of Fluridone in sediment-bound leachate were higher than Glyphosate concentrations in sediment-bound leachate, regardless of the initial concentrations. Fluridone and Glyphosate concentrations in water column samples differed significantly (p < 0.05) over the time even initial concentrations of these herbicides were kept similar, which indicates that Fluridone interaction with water column was considerably different than the interaction of Glyphosate with the water column. Pandey et al. Herbicide Concentration in Water and Sediment LeachateConclusions: Bed sediment can be an important sink and source for release of Fluridone and Glyphosate from bed sediment to the water column of an ambient water body. Significant concentrations of herbicides were deposited in bed sediment of Sacramento-San Joaquin Delta, and eventually the high concentrations of herbicides were observed in sediment leachate. Improved understanding of this important release pathway can provide much needed information to adequately address the impacts of particle attached herbicides on aquatic and ecological environment of a water body.Keywords: fluridone and glyphosate in ambient water, particle attached herbicides, herbicides leachate from sediment, sediment and water column interaction, deposition and resuspension
Fluridone is widely used as a herbicide for controlling invasive aquatic plants such as hydrilla in surface water bodies. When applied on surface waters fluridone can attach to bed sediment, requiring rigorous extraction methods prior to analysis. Currently, very limited information exists in terms of fluridone residue detection in delta sediment. In this study, we researched fluridone detection in both water and sediment. To extract fluridone from sediment, here we have tested two extraction methods: (1) a rotavapor method (RM); and (2) a quick, easy, cheap, effective, rugged and safe (QuEChERS) method (QM). The extraction results of RM were compared with those of QM. To quantify fluridone concentrations in extracts, a high-performance liquid chromatography (HPLC)-UV detector was used. HPLC separation was achieved using an Allure C18 5 µm 150 × 4.6 mm column with a mobile phase composed of acetonitrile and water (60:40, v/v). The UV detector was operated at 237 nm. The method was tested and validated using a series of water and sediment samples taken from Sacramento–San Joaquin Delta in California. The average recovery of fluridone was 73% and 78% using RM and QM respectively. The proposed method can be used for testing fluridone in water and sediment samples.
Estuaries are ecologically and economically important ecosystems but are threatened by non-native invasive species, including many species of submersed aquatic vegetation (SAV). Herbicides are the primary tool used to control SAV, but most field evaluations of herbicides have been conducted in lentic systems. Therefore, managers working in estuaries must base their SAV control programs largely on findings from systems fundamentally different from their own. We conducted a study in the Sacramento-San Joaquin Delta to determine efficacy of the widely used herbicide fluridone in an estuarine ecosystem. The primary goal of SAV removal was restoration of open water habitat for endangered Hypomesus transpacificus (Delta Smelt). Over 18 months and multiple sets of multi-week fluridone applications, we monitored concentrations of fluridone and responses by SAV across pairs of treated and reference sites. Fluridone concentrations in the water were generally below the 2–5 parts per billion required for SAV control. Monitoring demonstrated that these low water concentrations were likely due to dissipation by tides, despite use of pelleted fluridone formulations marketed for flowing water environments. Fluridone did, however, accumulate in sediment at concentrations hundreds of times higher than those measured in the water. Nonetheless, we did not observe lasting reductions in SAV abundance or changes in SAV community composition. By demonstrating lack of efficacy of one of the few herbicides permitted for use in this estuary, this study highlights the need for development of SAV management tools tailored to the challenges of hydrologically complex environments like estuaries.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.