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Monitoring drinking water quality is an important public health issue and pathogenic organisms present a particularly serious health hazard in freshwater bodies. However, many pathogenic bacteria, including cyanobacteria, and pathogenic protozoa can be swept into coastal lagoons and into near-shore marine environments where they continue to grow and pose a health threat to marine mammals and invertebrates. In this study, we tested the suitability of a phylochip (microarray for species detection) developed for freshwater pathogenic organisms to be applied to samples taken across a marine/freshwater interface at monthly intervals for two years. Toxic cyanobacteria and pathogenic protozoa were more numerous in a coastal lagoon than at the freshwater or marine site, indicating that this microarray can be used to detect the presence of these pathogens across a marine/freshwater interface and thus the potential for toxicity to occur within the entire watershed., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019. Published by Elsevier B.V.)

The study region in Sagres, SW Portugal, is subject to natural eutrophication of coastal waters by wind-driven upwelling, which stimulates high primary productivity facilitating the recent economic expansion of bivalve aquaculture in the region. However, this economic activity is threatened by harmful algal blooms (HAB) caused by the diatoms Pseudo-nitzschia spp., Dinophysis spp. and other HAB dinoflagellates, all of which can produce toxins, that can induce Amnesic Shellfish Poisoning (ASP), Diarrhetic Shellfish Poisoning (DSP) and Paralytic Shellfish Poisoning (PSP). This study couples traditional microscopy with 18S/28S rRNA microarray to improve the detection of HAB species and investigates the relation between HAB and the specific oceanographic conditions in the region. Good agreement was obtained between microscopy and microarray data for diatoms of genus Pseudo-nitzschia and dinoflagellates Dinophysis spp., Gymnodinium catenatum and raphidophyte Heterosigma akashiwo, with less effective results for Prorocentrum. Microarray provided detection of flagellates Prymnesium spp., Pseudochattonella spp., Chloromorum toxicum and the important HAB dinoflagellates of the genera Alexandrium and Azadinium, with the latter being one of the first records from the study region. Seasonality and upwelling induced by northerly winds were found to be the driving forces of HAB development, with Pseudo-nitzschia spp. causing the risk of ASP during spring and summer upwelling season, and dinoflagellates causing the risk of DSP and PSP during upwelling relaxation, mainly in summer and autumn. The findings were in agreement with the results from toxicity monitoring of shellfish by the Portuguese Institute for Sea and Atmosphere and confirm the suitability of the RNA microarray method for HABs detection and aquaculture management applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Harmful cyanobacterial blooms are a major threat to water quality and human health. Adequate risk assessment is thus required, which relies strongly on comprehensive monitoring. Here, we tested novel multi-probe RNA chips developed in the European project, μAqua, to determine the abundance of harmful cyanobacterial species and expression of selected toxin genes in six Dutch lakes. All of the targeted cyanobacterial genera, except for Planktothrix, were detected using the microarray, with predominance of Dolichospermum and Microcystis signals, of which the former was found across all sites and detected by the probes for Anabaena where it was formerly placed. These were confirmed by microscopic cell counts at three sites, whereas at the other sites, microscopic cell counts were lower. Probe signals of Microcystis showed larger variation across sites but also matched microscopic counts for three sites. At the other sites, microscopic counts were distinctly higher. We detected anatoxin-a in the water at all sites, but unfortunately no genes for this toxin were on this generation of the toxin array. For microcystins, we found none or low concentrations in the water, despite high population densities of putative microcystin producers (i.e. Microcystis, Dolichospermum). The described method requires further testing with a wider range of cyanobacterial communities and toxin concentrations before implementation into routine cyanobacterial risk assessment. Yet, our results demonstrate a great potential for applying multi-probe RNA chips for species as well as toxins to eutrophic waters with high cyanobacterial densities as a routine monitoring tool and as a predictive tool for toxin potential., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Over the past few decades, there has been an increased frequency and duration of cyanobacterial Harmful Algal Blooms (HABs) in freshwater systems globally. These can produce secondary metabolites called cyanotoxins, many of which are hepatotoxins, raising concerns about repeated exposure through ingestion of contaminated drinking water or food or through recreational activities such as bathing/swimming. An ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) multi-toxin method has been developed and validated for freshwater cyanotoxins; microcystins-LR, -YR, -RR, -LA, -LY and -LF, nodularin, cylindrospermopsin, anatoxin-a and the marine diatom toxin domoic acid. Separation was achieved in around 9min and dual SPE was incorporated providing detection limits of between 0.3 and 5.6ng/L of original sample. Intra- and inter-day precision analysis showed relative standard deviations (RSD) of 1.2-9.6% and 1.3-12.0% respectively. The method was applied to the analysis of aquatic samples (n=206) from six European countries. The main class detected were the hepatotoxins; microcystin-YR (n=22), cylindrospermopsin (n=25), microcystin-RR (n=17), microcystin-LR (n=12), microcystin-LY (n=1), microcystin-LF (n=1) and nodularin (n=5). For microcystins, the levels detected ranged from 0.001 to 1.51μg/L, with two samples showing combined levels above the guideline set by the WHO of 1μg/L for microcystin-LR. Several samples presented with multiple toxins indicating the potential for synergistic effects and possibly enhanced toxicity. This is the first published pan European survey of freshwater bodies for multiple biotoxins, including two identified for the first time; cylindrospermopsin in Ireland and nodularin in Germany, presenting further incentives for improved monitoring and development of strategies to mitigate human exposure., (Copyright © 2016 Elsevier B.V. All rights reserved.)