A Kinetic Study of Accumulation and Elimination of Microcystin-LR in Yellow Perch (Perca Flavescens) Tissue and Implications for Human Fish Consumption

Fish consumption is a potential route of human exposure to the hepatotoxic microcystins, especially in lakes and reservoirs that routinely experience significant toxic Microcystis blooms. Understanding the rates of uptake and elimination for microcystins as well as the transfer efficiency into tissues of consumers are important for determining the potential for microcystins to be transferred up the food web and for predicting potential human health impacts. The main objective of this work was to conduct laboratory experiments to investigate the kinetics of toxin accumulation in fish tissue. An oral route of exposure was employed in this study, in which juvenile yellow perch (Perca flavescens) were given a single oral dose of 5 or 20 μg of microcystin-LR (MC-LR) via food and accumulation in the muscle, liver, and tank water were measured over 24 h. Peak concentrations of the water soluble fraction of microcystin were generally observed 8–10 h after dosing in the liver and after 12–16 h in the muscle, with a rapid decline in both tissues by 24 h. Up to 99% of the total recoverable (i.e., unbound) microcystin was measured in the tank water by 16 h after exposure. The relatively rapid uptake and elimination of the unbound fraction of microcystin in the liver and muscle of juvenile yellow perch within 24 h of exposure indicates that fish consumption may not be a major route of human exposure to microcystin, particularly in the Great Lakes

A kinetic study of accumulation and elimination of Microcystin-LR in Yellow Perch (Perca Flavescens) tissue and implications for human fish consumption

Fish consumption is a potential route of human exposure to the hepatotoxic microcystins, especially in lakes and reservoirs that routinely experience significant toxic Microcystis blooms. Understanding the rates of uptake and elimination for microcystins as well as the transfer efficiency into tissues of consumers are important for determining the potential for microcystins to be transferred up the food web and for predicting potential human health impacts. The main objective of this work was to conduct laboratory experiments to investigate the kinetics of toxin accumulation in fish tissue. An oral route of exposure was employed in this study, in which juvenile yellow perch (Perca flavescens) were given a single oral dose of 5 or 20 μg of microcystin-LR (MC-LR) via food and accumulation in the muscle, liver, and tank water were measured over 24 h. Peak concentrations of the water soluble fraction of microcystin were generally observed 8–10 h after dosing in the liver and after 12–16 h in the muscle, with a rapid decline in both tissues by 24 h. Up to 99% of the total recoverable (i.e., unbound) microcystin was measured in the tank water by 16 h after exposure. The relatively rapid uptake and elimination of the unbound fraction of microcystin in the liver and muscle of juvenile yellow perch within 24 h of exposure indicates that fish consumption may not be a major route of human exposure to microcystin, particularly in the Great Lakes

Comparative Efficacy of Potential Chemical Disinfectants for Treating Unballasted Vessels

The release of ballast water from transoceanic vessels is a major vector for the introduction of nonindigenous species into the Laurentian Great Lakes. This study assessed the effectiveness of treating unballasted transoceanic vessels using three different biocides: glutaraldehyde plus a surfactant adjuvant (Disinfekt 1000®), sodium hypochlorite (NaOCl), and SeaKleen™ (menadione and menadione metabisulfite 2:8). Efficacy against several classes of aquatic organisms was evaluated using 24 h acute toxicity experiments and 11 day ballast tank simulation experiments. The results indicate substantial, compound-specific variations in organism sensitivity. For water-only exposures, NaOCl and SeaKleen™ were most effective: NaOCl had the lowest LC90 (90% lethal concentration value) for the oligochaete Lumbriculus variegatus (1.0 mg L−1), while SeaKleen™ had the lowest LC90 for the amphipod Hyalella azteca (2.5 mg L−1). Sediments profoundly affected efficacy, particularly for NaOCl: At a 1:4 sediment-water ratio, the estimated LC90 for L. variegatus was > 2,000 mg L−1. Sediment quality also impacted efficacy: Sediments with higher organic carbon content typically required greater biocide concentrations to achieve comparable toxicity. Efficacy was further evaluated with 11 day bioassays using sediments from unballasted vessels. Results indicated that NaOCl and Disinfekt 1000® were more effective than predicted based on small scale sediment-water exposures. Overall, the data suggest that although NaOCl may be effective under water-only conditions, the higher concentrations required in the presence of sediments may cause corrosion problems for ballast tanks. Because of this, less reactive, non-oxidizing biocides such as SeaKleen™ and Disinfekt 1000® may be better candidates for treating sedimented tanks

Ecophysiological Examination of the Lake Erie Microcystis Bloom in 2014: Linkages between Biology and the Water Supply Shutdown of Toledo, OH

Annual cyanobacterial blooms dominated by Microcystis have occurred in western Lake Erie (U.S./Canada) during summer months since 1995. The production of toxins by bloom-forming cyanobacteria can lead to drinking water crises, such as the one experienced by the city of Toledo in August of 2014, when the city was rendered without drinking water for \u3e2 days. It is important to understand the conditions and environmental cues that were driving this specific bloom to provide a scientific framework for management of future bloom events. To this end, samples were collected and metatranscriptomes generated coincident with the collection of environmental metrics for eight sites located in the western basin of Lake Erie, including a station proximal to the water intake for the city of Toledo. These data were used to generate a basin-wide ecophysiological fingerprint of Lake Erie Microcystis populations in August 2014 for comparison to previous bloom communities. Our observations and analyses indicate that, at the time of sample collection, Microcystis populations were under dual nitrogen (N) and phosphorus (P) stress, as genes involved in scavenging of these nutrients were being actively transcribed. Targeted analysis of urea transport and hydrolysis suggests a potentially important role for exogenous urea as a nitrogen source during the 2014 event. Finally, simulation data suggest a wind event caused microcystin-rich water from Maumee Bay to be transported east along the southern shoreline past the Toledo water intake. Coupled with a significant cyanophage infection, these results reveal that a combination of biological and environmental factors led to the disruption of the Toledo water supply. This scenario was not atypical of reoccurring Lake Erie blooms and thus may reoccur in the future

Ecophysiological Examination of the Lake Erie <i>Microcystis</i> Bloom in 2014: Linkages between Biology and the Water Supply Shutdown of Toledo, OH

Annual cyanobacterial blooms dominated by <i>Microcystis</i> have occurred in western Lake Erie (U.S./Canada) during summer months since 1995. The production of toxins by bloom-forming cyanobacteria can lead to drinking water crises, such as the one experienced by the city of Toledo in August of 2014, when the city was rendered without drinking water for >2 days. It is important to understand the conditions and environmental cues that were driving this specific bloom to provide a scientific framework for management of future bloom events. To this end, samples were collected and metatranscriptomes generated coincident with the collection of environmental metrics for eight sites located in the western basin of Lake Erie, including a station proximal to the water intake for the city of Toledo. These data were used to generate a basin-wide ecophysiological fingerprint of Lake Erie <i>Microcystis</i> populations in August 2014 for comparison to previous bloom communities. Our observations and analyses indicate that, at the time of sample collection, <i>Microcystis</i> populations were under dual nitrogen (N) and phosphorus (P) stress, as genes involved in scavenging of these nutrients were being actively transcribed. Targeted analysis of urea transport and hydrolysis suggests a potentially important role for exogenous urea as a nitrogen source during the 2014 event. Finally, simulation data suggest a wind event caused microcystin-rich water from Maumee Bay to be transported east along the southern shoreline past the Toledo water intake. Coupled with a significant cyanophage infection, these results reveal that a combination of biological and environmental factors led to the disruption of the Toledo water supply. This scenario was not atypical of reoccurring Lake Erie blooms and thus may reoccur in the future