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The presence of harmful algal blooms (HAB) is a growing concern in aquatic environments. Among HAB organisms, cyanobacteria are of special concern because they have been reported worldwide to cause environmental and human health problem through contamination of drinking water. Although several analytical approaches have been applied to monitoring cyanobacteria toxins, conventional methods are costly and time-consuming so that analyses take weeks for field sampling and subsequent lab analysis. Capillary electrophoresis (CE) becomes a particularly suitable analytical separation method that can couple very small samples and rapid separations to a wide range of selective and sensitive detection techniques. This paper demonstrates a method for rapid separation and identification of four microcystin variants commonly found in aquatic environments. CE coupled to UV and electrospray ionization time-of-flight mass spectrometry (ESI-TOF) procedures were developed. All four analytes were separated within 6 minutes. The ESI-TOF experiment provides accurate molecular information, which further identifies analytes.

Eutrophication of freshwater lakes has led to an increase in the occurrence of harmful cyanobacterial blooms, and it is expected that a warming climate will further exacerbate the frequency and duration of such blooms. Microcystin is a cyanobacterial hepatotoxin that is found worldwide, and poses a serious threat to the ecological communities in which it is found as well as to those who use these waters for drinking, recreation, or as a food source. Although microcystin is known to accumulate in fish and other aquatic biota, the prevalence of microcystin in fish tissue and the human health risks posed by microcystin exposure through fish consumption remain poorly resolved. Very few studies have quantified microcystin (a broadly present cyanotoxin) in water from East African lakes, despite the large human and animal populations that rely on these lakes for both water and food, and to date there is very little information available on the accumulation of microcystin in fish from these lakes. A comprehensive set of water and fish samples was collected on a monthly basis between September 2008 and February 2009 from several lakes in Uganda. The study sites included two embayments in northern Lake Victoria (Murchison Bay and Napoleon Gulf), Lake Edward, Lake George, Lake Mburo, and the crater lakes Saka and Nkuruba. The large lakes sampled all support substantial commercially important fisheries, while the smaller lakes support subsistence fisheries that provide a critically important source of protein and income for riparian communities. Microcystin concentrations in water were determined in addition to chlorophyll and nutrient concentrations, phytoplankton community composition, mixing dynamics and light conditions. At all study sites except Lake Nkuruba, microcystin concentrations in water regularly exceeded the WHO guideline for microcystin in drinking water of 1.0 µg/L. Microcystis spp. emerged as the cyanobacterial taxa that is primarily responsible for microcystin production in these lakes, and as such, microcystin concentrations were closely linked to environmental factors that favour the development of high Microcystis biomass, including high nutrient concentrations, as well as shallow mixing depth which acts to increase mean mixed layer light intensity. Because of the importance of understanding the underlying food web when considering the accumulation and trophic transfer of a compound, stable carbon and nitrogen isotope analysis was used to characterize the food webs at the previously mentioned Ugandan study sites as well as in the East African great lake Albert. Omnivory was found to be common at all study sites, and based on δ13C values, the food webs in these lakes were strongly based on pelagic primary production, with no strong evidence of substantial benthic contribution to these food webs, likely as a result of reduced benthic primary productivity in these generally low-transparency eutrophic lakes. The distribution and trophic transfer of mercury was also characterized in the Ugandan study lakes (including Lake Albert) in order to provide a contrast for the trophic transfer of microcystin in the same lakes. Furthermore, relatively little is known about the behaviour of mercury in tropical hypereutrophic lakes, and the study sites included in the current study provided an opportunity for the exploration of this topic. Consistent biomagnification of mercury was observed at all study sites; however, mercury concentrations in fish were generally low, and would not be expected to pose a risk to consumers. Mercury dynamics were strongly linked to lake trophic status, with biomagnification rates significantly lower at the hypereutrophic study sites than at the mesotrophic and eutrophic study sites. I found evidence that growth and possibly biomass dilution can reduce mercury concentrations at the base of the food web, while growth dilution of mercury at consumer trophic levels might effectively reduce the biomagnification rate of mercury in these hypereutrophic lakes. Microcystin was prevalent in fish muscle tissue from all study sites and at all trophic levels. In contrast to mercury, for which consistent biomagnification was observed, neither biomagnification nor biodilution was observed for microcystin; and concentrations were relatively consistent throughout the fish food web, including in top predators, indicating that efficient trophic transfer of microcystin is occurring in these lakes. Microcystin concentrations in fish from several study sites followed seasonal trends that were similar to those observed for microcystin concentrations in water at these sites, suggesting that fish can rapidly respond to changes in microcystin concentrations in water through accumulation and depuration of this toxin. Microcystin concentrations in water and fish from all Ugandan study sites (including Lake Albert) in addition to data from two temperate eutrophic embayments (Maumee Bay in Lake Erie, and the Bay of Quinte in Lake Ontario) were compiled and used to estimate potential microcystin exposure to human consumers of both water and fish from these study sites. Microcystin was pervasive in water and fish from both the tropical and temperate study sites. Also, these results establish that fish consumption can be an important and even dominant source of microcystin to humans, and can cause consumers to exceed recommended total daily intake guidelines for microcystin. These results highlight the need to consider potential exposure to microcystin through fish consumption in addition to water consumption in order to adequately assess human exposure and risk.

Eutrophication of freshwater lakes has led to an increase in the occurrence of harmful cyanobacterial blooms, and it is expected that a warming climate will further exacerbate the frequency and duration of such blooms. Microcystin is a cyanobacterial hepatotoxin that is found worldwide, and poses a serious threat to the ecological communities in which it is found as well as to those who use these waters for drinking, recreation, or as a food source. Although microcystin is known to accumulate in fish and other aquatic biota, the prevalence of microcystin in fish tissue and the human health risks posed by microcystin exposure through fish consumption remain poorly resolved. Very few studies have quantified microcystin (a broadly present cyanotoxin) in water from East African lakes, despite the large human and animal populations that rely on these lakes for both water and food, and to date there is very little information available on the accumulation of microcystin in fish from these lakes. A comprehensive set of water and fish samples was collected on a monthly basis between September 2008 and February 2009 from several lakes in Uganda. The study sites included two embayments in northern Lake Victoria (Murchison Bay and Napoleon Gulf), Lake Edward, Lake George, Lake Mburo, and the crater lakes Saka and Nkuruba. The large lakes sampled all support substantial commercially important fisheries, while the smaller lakes support subsistence fisheries that provide a critically important source of protein and income for riparian communities. Microcystin concentrations in water were determined in addition to chlorophyll and nutrient concentrations, phytoplankton community composition, mixing dynamics and light conditions. At all study sites except Lake Nkuruba, microcystin concentrations in water regularly exceeded the WHO guideline for microcystin in drinking water of 1.0 µg/L. Microcystis spp. emerged as the cyanobacterial taxa that is primarily responsible for microcystin production in these lakes, and as such, microcystin concentrations were closely linked to environmental factors that favour the development of high Microcystis biomass, including high nutrient concentrations, as well as shallow mixing depth which acts to increase mean mixed layer light intensity. Because of the importance of understanding the underlying food web when considering the accumulation and trophic transfer of a compound, stable carbon and nitrogen isotope analysis was used to characterize the food webs at the previously mentioned Ugandan study sites as well as in the East African great lake Albert. Omnivory was found to be common at all study sites, and based on δ13C values, the food webs in these lakes were strongly based on pelagic primary production, with no strong evidence of substantial benthic contribution to these food webs, likely as a result of reduced benthic primary productivity in these generally low-transparency eutrophic lakes. The distribution and trophic transfer of mercury was also characterized in the Ugandan study lakes (including Lake Albert) in order to provide a contrast for the trophic transfer of microcystin in the same lakes. Furthermore, relatively little is known about the behaviour of mercury in tropical hypereutrophic lakes, and the study sites included in the current study provided an opportunity for the exploration of this topic. Consistent biomagnification of mercury was observed at all study sites; however, mercury concentrations in fish were generally low, and would not be expected to pose a risk to consumers. Mercury dynamics were strongly linked to lake trophic status, with biomagnification rates significantly lower at the hypereutrophic study sites than at the mesotrophic and eutrophic study sites. I found evidence that growth and possibly biomass dilution can reduce mercury concentrations at the base of the food web, while growth dilution of mercury at consumer trophic levels might effectively reduce the biomagnification rate of mercury in these hypereutrophic lakes. Microcystin was prevalent in fish muscle tissue from all study sites and at all trophic levels. In contrast to mercury, for which consistent biomagnification was observed, neither biomagnification nor biodilution was observed for microcystin; and concentrations were relatively consistent throughout the fish food web, including in top predators, indicating that efficient trophic transfer of microcystin is occurring in these lakes. Microcystin concentrations in fish from several study sites followed seasonal trends that were similar to those observed for microcystin concentrations in water at these sites, suggesting that fish can rapidly respond to changes in microcystin concentrations in water through accumulation and depuration of this toxin. Microcystin concentrations in water and fish from all Ugandan study sites (including Lake Albert) in addition to data from two temperate eutrophic embayments (Maumee Bay in Lake Erie, and the Bay of Quinte in Lake Ontario) were compiled and used to estimate potential microcystin exposure to human consumers of both water and fish from these study sites. Microcystin was pervasive in water and fish from both the tropical and temperate study sites. Also, these results establish that fish consumption can be an important and even dominant source of microcystin to humans, and can cause consumers to exceed recommended total daily intake guidelines for microcystin. These results highlight the need to consider potential exposure to microcystin through fish consumption in addition to water consumption in order to adequately assess human exposure and risk.

The role and function of hepatotoxins microcystin and nodularin produced by M.aeruginosa PCC 7806 and N. spumigena NSORlO respectively have yet to be elucidated. The mode of transcriptional regulation of these toxins, incorporating DNA binding proteins, was investigated, as an attempt to further understand the key control mechanisms acting on the toxins. The DNA binding proteins that control nitrogen and iron responsive transcription, NtcA and Fur, were identified from M. aeruginosa PCC7806 and N. spumigena NSOR10. Cloning and over-expression in E. coli was followed by mobility shift assays to determine binding characteristics of NtcA and Fur to the promoters, mcyA/D and ndaA/C, those regions that control the toxin encoding gene clusters in M. aeruginosa PCC 7806 and N. spumigena NSOR10, respectively. The results from these studies suggested a role for iron and nitrogen in the transcriptional control of microcystin and nodularin. biosynthesis. As NtcA and Fur classically act to regulate nitrogen and iron dependent genes, a link may be made to the putative function and control of microcystin and nodularin. By identifying the transcription factors NtcA and Fur in these genera, a greater understanding of the link between nutrient levels in the environment and hepatotoxin production in cyanobacteria may be possible.

In fresh waters where cyanobacteria (blue-green algae) flourish, dense growths known as blooms occur. Such blooms present a threat to human and animal health as many of these cyanobacteria produce toxins. One such group of toxins are the microcystins which are hepatotoxic resulting in haemoraging and tumour promotion in the liver. There have been several reports of human poisonings resulting from the presence of cyanotoxins in potable waters, some of which have resulted in fatalities. The most frequently cited cyanotoxin in these poisonings has been microcystin-LR, which has prompted the World Health Organisation (WHO) to set a guideline for the recommended safe level of this toxin in drinking water of 1 mgl-1. Removal of microcystin-LR from potable waters has proven to be inefficient using conventional water treatment techniques such as coagualtion, filtration and chemical oxidation using chlorine. While activated carbon adsorption and membrane filtration have been shown to physically remove microcystin-LR from water the toxin is not destroyed. Recently the use of photocatalysis was shown to rapidly degrade microcystin-LR even at high concentrations. The process involves the illumination of a titanium dioxide catalyst with ultraviolet (UV) light to produce highly oxidising hydroxyl radicals in solution. While several researchers have demonstrated the process's effectiveness in degrading the toxin none have determined the fate of the compound, or if the toxicity related to microcystin-LR has been removed. This study was carried out to determine if photocatalytic oxidation of microcystin-LR was suitable as a treatment method for potable water supplies. Analysis of treated toxin samples by high performance liquid chromatography (HPLC) with photo-diode array detection (PDA) and mass spectroscopy established that the toxin was not completely degraded during photocatalysis. A simple toxicity assessment however indicated that by-products were non-toxic. Using the data from this work a proposed pathway for toxin destruction was produced giving the speculative identity of some of the by-products. The use of hydrogen peroxide to enhance UV mediated destruction of microcystin-LR has been previously reported. There have also been reports of the enhancement of photocatalytiC reaction in the presence of this oxidant. The work carried out in this study demonstrated that the destruction of microcystin-LR by photocatalysis was both more rapid and more efficient when hydrogen peroxide was present in the system. The use of a fixed film flow reactor was also investigated for microcystin-LR destruction. While degradation of the toxin occurred it was demonstrated that batch reactors were more efficient as a treatment method. The effectiveness of the photocatalytic process on microcystin-RR, -LW and -LF was also investigated. While destruction of a" the variants occurred during photocatalytic treatment each microcystin demonstrated different rates and efficiencies of photooxidation. It was concluded from this study that photocatalysis is a promising treatment method for the removal of microcystin-LR and other variants from potable waters. Further research however is required to assess if the tumour promoting effects of microcystin-LR are rendered inactive and to determine the behaviour of the toxins degradation in natural water supplies. The study also allowed for speculation as to how the degradation of the toxin occurred during the photocatalytic process.

Black band disease (BBD) is a cyanobacterial dominated pathogenic consortium that affects corals worldwide. Recently two cyanobacteria (Oscillatoria strains 101-1 and 100-1) were isolated into culture from BBD. The aim of this study was to characterize the strains and assess their role in BBD pathogenesis. Light, scanning electron and transmission electron microscopy, coupled with 16S rRNA gene sequencing, were used for taxonomic characterization. Cyanotoxin production was assessed by enzyme-linked immunosorbent assay. Toxin identification was performed by high performance liquid chromatography. The ability of the strains to initiate BBD was tested on host coral fragments of Siderastrea siderea and Diploria strigosa under controlled laboratory conditions. Results showed that both Oscillatoria sp. strains caused infection that resulted in complete lysis of coral tissue. Both strains produced a cyanotoxin, identified as microcystin-LR, with production affected by different environmental factors. This study provides evidence that BBD Oscillatoria is a key component in BBD pathogenicity.

Cyanobacterial blooms, such as those recently reported in Great Slave Lake (GSL, NWT), have sparked concern over the occurrence of toxic blooms in the North. This study investigated past and present incidences of cyanobacteria in lakes above latitude 60° N. The abundance of the toxin (microcystin) gene mcyE, as well as genes common to all cyanobacteria (16S rRNA) and bacteria (glnA) were quantified from lake sediment cores using ddPCR. Individual colony isolates from a surface bloom in Yellowknife Bay (GSL) in August 2015 were amplified and identified as non-toxigenic Dolichospermum lemmermannii. Very low levels of microcystin genes were detected through the sediment archives (over ~100-150 yr) of GSL and other lakes, as well as in the plankton of GSL. While recent increases in mcyE were not observed, an increase in the cyanobacterial 16S rRNA and glnA genes was seen through time. In the high Arctic Meretta Lake, gene abundance profiles reflected the effects of past eutrophication and recovery.