Limnological Differences in a Two-Basin Lake Help to Explain the Occurrence of Anatoxin-a, Paralytic Shellfish Poisoning Toxins, and Microcystins

Harmful algal blooms in Cayuga lake, NY: From microbiome analysis to eDNA monitoring

The global increase in harmful algal blooms (HABs) has become a growing concern over the years, and New York State (NYS) is no exception. The Finger Lakes region in NYS has been identified as a hotspot for HABs, with Cayuga Lake having the highest number of blooms reported. The Cayuga Lake HABs Monitoring Program has been tracking cHABs (dominant bloom taxa, chlorophyll A, and microcystin levels) since 2018. However, limited research has been conducted on the microbiome of HABs in this region. In this study, the microbiome of HABs in the Cayuga Lake was surveyed and compared with non-HAB baseline samples. Using 16S rDNA community analysis, common bloom-forming cyanobacteria, were identified, with Microcystis being the dominant taxa in high toxin blooms. Further, this study evaluated the ability of Microcystis mcyA qPCR to detect elevated levels of potential toxigenic Microcystis in water samples using both benchtop and handheld qPCR devices. The results showed good performance of the qPCR assay as a screening for high toxin versus low/no toxin blooms. Additionally, the handheld qPCR device holds potential for in-field rapid (<1 h) screenings for high toxin blooms. This study provides insights into the microbiome of HABs in Cayuga Lake and offers a potential tool for rapid screening of high toxin blooms.

Trace determination of multiple hydrophilic cyanotoxins in freshwater by off- and on-line solid phase extraction coupled to liquid chromatography-tandem mass spectrometry

Hydrophilic cyanotoxins (HCTs), such as paralytic shellfish toxins (PSTs), anatoxin-a (ATX-a), and cylindrospermopsin (CYN) are highly toxic and toxin-producing algae are widely distributed worldwide. However, HCTs, especially PSTs, are rarely reported in freshwater due to analytical limitations. This may result in an underestimation of the ecological risks and health risks. This study developed a new method to detect ATX-a, CYN, and thirteen common PSTs in freshwater simultaneously by using off-line solid phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The limits of detection (LODs) of all targets were lower than 0.05 μg/L, which could meet the regulatory requirements for monitoring of HCTs in drinking water in different countries and regions. To improve the detection sensitivities for trace PSTs, a method based on off-line SPE and on-line SPE-LC-MS/MS was established with LOD around 0.001 μg/L. GTX1&4, GTX2&3, and GTX5 were detected in freshwater in China for the first time, highlighting that overall communities are facing potential risks of exposure to various PSTs in China. High concentrations of ATX-a and CYN were also detected in freshwater from Northern China. The proposed method helps to understand the pollution status of HCT in water bodies, especially during the non-algal bloom period.

Rapid Immunochemical Methods for Anatoxin-a Monitoring in Environmental Water Samples

Algal blooms that contaminate freshwater resources with cyanotoxins constitute, nowadays, a global concern. To deal with this problem, a variety of analytical methods, including immunochemical assays, are available for the main algal toxins, for example, microcystins, nodularins, and saxitoxins, with the remarkable exception of anatoxin-a. Now, for the first time, highly sensitive, enantioselective immunoassays for anatoxin-a have been validated using homemade monoclonal antibodies. Two competitive enzyme-linked immunosorbent assays were developed in different formats, with detection limits for (+)-anatoxin-a of 0.1 ng/mL. Excellent recovery values between 82 and 117%, and coefficients of variation below 20%, were observed using environmental water samples fortified between 0.5 and 500 ng/mL. In addition, a lateral-flow immunochromatographic assay was optimized for visual and instrumental reading of results. This test showed a visual detection limit for (+)-anatoxin-a of 4 ng/mL. Performance with a reader was validated in accordance with the European guidelines for semiquantitative rapid methods for small chemical contaminants. Thus, at a screening target concentration of 2 ng/mL, the probability of a blank sample to be classified as “suspect” was as low as 0.2%. Finally, the optimized direct enzyme immunoassay was validated by comparison with high-performance liquid chromatography-tandem mass spectroscopy data and showed a good correlation (r = 0.995) with a slope of 0.94. Moreover, environmental water samples containing more than 2 ng/mL of anatoxin-a were detected by the developed dipstick assay. These results provide supplementary and complementary strategies for monitoring the presence of anatoxin-a in water.

Harmful algal bloom resources for livestock veterinarians

Harmful algal blooms can have deleterious effects on animal and human health as well as the environment and are anticipated to become more frequent and intensified in the future because of climate change. Veterinarians are well positioned to diagnose and treat animals affected by HABs and to educate livestock owners and the public about health risks and environmental issues associated with those toxic events. Pets, livestock, wildlife, and marine life can all be affected by HABs. Information about HABs is becoming increasingly assessable as a result of ongoing research into the structure, properties, toxic mechanisms, and geographic distribution of toxins found in HABs. The AVMA's multi-entity working group on HABs is comprised of members from the Aquatic Veterinary Medicine Committee, Committee on Environmental Issues, and Council on Public Health and is working to make more information and resources regarding HABs available to practicing veterinarians. The present article is the first of those resources and provides a review of HABs, with a focus on livestock. It includes background material about bloom formation, appearance, and persistence as well as descriptions of clinical observations from early field cases and more recent information about the causative organisms and toxins to provide livestock veterinarians a foundation for understanding HABs. Reporting of HABs and prevention and mitigation strategies for livestock owners are also discussed.

Roles of Nutrient Limitation on Western Lake Erie CyanoHAB Toxin Production

Cyanobacterial harmful algal bloom (CyanoHAB) proliferation is a global problem impacting ecosystem and human health. Western Lake Erie (WLE) typically endures two highly toxic CyanoHABs during summer: a Microcystis spp. bloom in Maumee Bay that extends throughout the western basin, and a Planktothrix spp. bloom in Sandusky Bay. Recently, the USA and Canada agreed to a 40% phosphorus (P) load reduction to lessen the severity of the WLE blooms. To investigate phosphorus and nitrogen (N) limitation of biomass and toxin production in WLE CyanoHABs, we conducted in situ nutrient addition and 40% dilution microcosm bioassays in June and August 2019. During the June Sandusky Bay bloom, biomass production as well as hepatotoxic microcystin and neurotoxic anatoxin production were N and P co-limited with microcystin production becoming nutrient deplete under 40% dilution. During August, the Maumee Bay bloom produced microcystin under nutrient repletion with slight induced P limitation under 40% dilution, and the Sandusky Bay bloom produced anatoxin under N limitation in both dilution treatments. The results demonstrate the importance of nutrient limitation effects on microcystin and anatoxin production. To properly combat cyanotoxin and cyanobacterial biomass production in WLE, both N and P reduction efforts should be implemented in its watershed.