Many proteins depend on metals for proper functioning, yet there is little information on the distribution of low metal concentrations in freshwaters nor what constitutes ‘low’. Eight dissolved metals were surveyed in 2017 in 39 lakes and reservoirs across Canada. RDA analysis revealed Co, Cu, Ni and V in one group with higher concentrations on the Prairies and Fe and Mn in a second group with higher concentrations on the Prairies and the Boreal Shield in Ontario. Zn and Mo lacked geographic patterns. Concentrations ranged several fold. Monod growth kinetic parameters were explored for their potential to infer growth limitation. Metal concentrations at or below growth thresholds (Tm, < 1 nmol L-1) should severely limit growth while concentrations between Tm and twice the half-saturation constant (2Km) will limit growth when other nutrients are in excess. Published and inferred Tm suggest that Co, Mo and Ni could have been low enough to occasionally limit growth in several Canadian oligotrophic lakes. There are too few published Km values to infer limitation above Tm.

Ice and water microbial communities from Lake Winnipeg were explored through V4 region 16S rRNA gene sequencing during a pronounced period of cold temperatures over North America's Great Plains and Great Lakes regions. Diatoms, cyanobacteria, and Xanthomonadales (Gammaproteobacteria) displayed patterns of partitioning into ice fractions.

Lake Erie is subject to recurring events of cyanobacterial harmful algal blooms (cHABs), but measures of nutrients and total phytoplankton biomass seem to be poor predictors of cHABs when taken individually. A more integrated approach at the watershed scale may improve our understanding of the conditions that lead to bloom formation, such as assessing the physico-chemical and biological factors that influence the lake microbial community, as well as identifying the linkages between Lake Erie and the surrounding watershed. Within the scope of the Government of Canada’s Genomics Research and Development Initiative (GRDI) Ecobiomics project, we used high-throughput sequencing of the 16S rRNA gene to characterize the spatio-temporal variability of the aquatic microbiome in the Thames River–Lake St. Clair-Detroit River–Lake Erie aquatic corridor. We found that the aquatic microbiome was structured along the flow path and influenced mainly by higher nutrient concentrations in the Thames River, and higher temperature and pH downstream in Lake St. Clair and Lake Erie. The same dominant bacterial phyla were detected along the water continuum, changing only in relative abundance. At finer taxonomical level, however, there was a clear shift in the cyanobacterial community, with Planktothrix dominating in the Thames River and Microcystis and Synechococcus in Lake St. Clair and Lake Erie. Mantel correlations highlighted the importance of geographic distance in shaping the microbial community structure. The fact that a high proportion of microbial sequences found in the Western Basin of Lake Erie were also identified in the Thames River, indicated a high degree of connectivity and dispersal within the system, where mass effect induced by passive transport play an important role in microbial community assembly. Nevertheless, some cyanobacterial amplicon sequence variants (ASVs) related to Microcystis, representing less than 0.1% of relative abundance in the upstream Thames River, became dominant in Lake St. Clair and Erie, suggesting selection of those ASVs based on the lake conditions. Their extremely low relative abundances in the Thames suggest additional sources are likely to contribute to the rapid development of summer and fall blooms in the Western Basin of Lake Erie. Collectively, these results, which can be applied to other watersheds, improve our understanding of the factors influencing aquatic microbial community assembly and provide new perspectives on how to better understand the occurrence of cHABs in Lake Erie and elsewhere.

Microcystis species not only produce toxic cyanobacterial blooms, but can be a significant source of taste and odour. Previous studies have associated foul-smelling volatile organic sulfur compounds (VOSCs) with Microcystis blooms, but have largely attributed these compounds to bacterial bloom decomposition. However, earlier reports of the production of isopropylthio compounds by several Microcystis strains suggests that these cyanobacteria may themselves be a source of these VOSCs. Sulphur compounds have been shown to play important semiochemical roles in algal cell protection and grazer interactions in marine systems, but little is known about the production and chemical ecology of freshwater cyanobacterial VOSCs. To address this knowledge gap, we undertook the first detailed investigation of the biochemistry, ecophysiology and semiochemistry of these compounds and their production by Microcystis, and tested the hypothesis that they act as multifunctional semiochemicals in processes related to cell protection and grazer defence. Using short-term incubations and an adapted headspace-GC-MS technique, we investigated VOSC production by axenic and non-axenic strains, and verified that isopropylthio compounds are in fact produced by these cyanobacteria, identifying 5 isopropyl moiety-containing VOSCs (isopropylthiol (ISH), isopropylmethyl sulfide, isopropyl methyl disulfide, diisopropyl disulfide (ISSI) and diisopropyl trisulfide) as well as methanethiol in three strains. Further studies with the axenic strain Microcystis PCC 7806 using different light regimes, metabolic inhibitors (sodium azide, DCMU), the antioxidant enzyme catalase and stable labelled precursors (hydrogencarbonate, acetates and sulfate) demonstrated that ISH is a true exo-metabolite, synthesized via the acetate pathway. It is actively produced and continuously excreted by the cyanobacteria during growth, with minimal internal storage or post-lysis catalytic generation. The molar ratios of the redox pair ISH/ISSI are not directly involved in the photosynthetic and respiratory electron transport chains, but dependant on the redox state of the cell - likely mediated by reactive oxygen species (ROS), as shown by a marked effect of catalase. These results, along with toxicological and behavioural assays using the two aquatic invertebrates Thamnocephalus platyurus and Daphnia magna indicate that ISH plays multiple important physiological and ecological roles. It acts as an effective antioxidant against high ROS levels, as often experienced in surface blooms, it elicits avoidance-related behavioural responses in grazer communities and at high levels, it can be toxic to some invertebrates.

1. Impacts of three cobalt (Co) concentrations were examined on heterocyst frequency and growth rate in four diazotrophic cyanobacteria species in nitrogen (N)-depleted culture and growth rate in one non-diazotrophic species in N-replete culture.After 11 days in batch culture, heterocyst frequency (HF, % of all cells that are heterocysts) increased from 4.1-5.7% to 5.4-7.4% to 5.9-9.3% at 0.17, 17 and 170 nmol L -1 Co, implicating Co in heterocyst differentiation.Growth rate was not significantly affected by Co in any of the species suggesting that the impact of low Co on other metabolic pathways was minimized.2. Stoichiometric extrapolation of culture results to N-limited natural systems with lower nutrient concentrations infers that HF could be limited by sub-nanomolar Co concentrations.3. In experimentally fertilized N-limited Lake 227, mean summer HF in 2000-2020 was 3.4% (epilimnion) and 4.0% (metalimnion).However, in 2017 (the only year for which Co data are available) dissolved Co increased from 0.7 to 2.0 nmol L -1 during the bloom simultaneously with increasing HF and cyanobacteria biomass, hence, Co probably did not limit HF and biomass.HF was significantly higher after 2015 following a shift in dominant bloom species from Aphanizomenon schindlerii to smaller A. skujae.The smaller cell size may have required a higher HF in order to maintain a relatively constant supply rate of fixed N per unit biomass.4. Surveys of ambient Co in over 280 aquatic systems across Canada and elsewhere indicate that Co is sometimes low enough to theoretically limit HF in N-limited waters.However, numerous variables influence HF so a clear understanding of relationships between Co and HF in natural systems remains elusive.

Despite the significant role that dissolved organic phosphorus (DOP) plays in ecosystem productivity, efforts to characterize inputs of phosphorus (P) into lakes have largely ignored P fractions complexed to dissolved organic matter (DOM). To address this gap, we characterized DOP and DOM along a transect of a Lake Erie tributary (Kettle Creek) from the headwaters to the rivermouth and into the nearshore and offshore central basin. DOM and DOP characteristics impart a chemical fingerprint that is useful for determining source and production in aquatic ecosystems. We analyzed DOM composition and concentration (DOC; organic carbon) in addition to DOP as phosphomonoesters (MP; predominantly terrestrial in origin) and phosphodiesters (DP; microbially‐produced), along with other water quality parameters. DOM and DOC within the river were relatively invariant. While there were no consistent trends in riverine MP and DP, an impoundment on the river appeared to act as a sink for some soluble P forms and a potential source of DP. At the rivermouth, we observed a rapid decrease in DOC, DOP, and total P and a shift to more autochthonous‐like DOM, though the decrease in DP was weaker. Relative to in‐flowing river water, P pools in nearshore and offshore Lake Erie were enriched in DOP, especially DP. DOP accounted for up to 42% of total P in Kettle Creek and up to 92% in Lake Erie's central basin. Our work shows the importance of considering DOP in P management efforts as its dynamics differ from those of other, more commonly measured P forms.

Several studies have shown that large, experimental additions of nitrate (NO3) to eutrophic systems can mitigate large populations of nuisance cyanobacteria and that high NO3 concentrations can oxidize anoxic sediments. These studies are consistent with observations from numerous aquatic systems across a broad trophic range showing development of reduced surficial sediments precedes the formation of large cyanobacteria populations. We use 50+ years of data to explore whether high NO3 concentrations may have been instrumental both in the absence of large populations of cyanobacteria in eutrophic Hamilton Harbour, Lake Ontario in the 1970s when total phosphorus (TP) and total nitrogen (TN) concen-trations were high, and in delaying large populations until August and September in recent decades despite much lower TP and TN. Our results indicate that large cyanobacteria population events do not occur at the central station in July-September when epilimnetic NO3 > 2.2 mg N L-1. The results further suggest that remedial improvements to wastewater treatment plant oxidation capacity may have been inadvertently responsible for high NO(3 )concentrations > 2.2 mg N L-1 and thus for mitigating large cyanobacteria populations. This also implies that large cyanobacteria populations may form earlier in the summer if NO(3 )concentrations are lowered. (C) 2022 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.

Harmful algal blooms in inland waters are widely linked to excess phosphorus (P) loading, but increasing evidence shows that their growth and formation can also be influenced by nitrogen (N) and iron (Fe). Deficiency in N, P, and Fe differentially affects cellular photosystems and is manifested as changes in photosynthetic yield (Fv/Fm). While Fv/Fm has been increasingly used as a rapid and convenient in situ gauge of nutrient deficiency, there are few rigorous comparisons of instrument sensitivity and ability to resolve specific nutrient stresses. This study evaluated the application of Fv/Fm to cyanobacteria using controlled experiments on a single isolate and tested three hypotheses: i) single Fv/Fm measurements taken with different PAM fluorometers can distinguish among limitation by different nutrients, ii) measurements of Fv/Fm made by the addition of DCMU are comparable to PAM fluorometers, and iii) dark adaptation is not necessary for reliable Fv/Fm measurements. We compared Fv/Fm taken from the bloom-forming Microcystis aeruginosa (UTEX LB 3037) grown in nutrient-replete treatment (R) and N-, P-, and Fe-limited treatments (LN, LP, LFe, respectively), using three pulse-amplitude modulated (PAM) fluorometers and the chemical photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and evaluated the effects of dark adaptation prior to PAM measurement. There were significant differences in Fv/Fm estimates among PAM fluorometers for light- versus dark-adapted cell suspensions over the whole experiment (21 days), which were all significantly higher than the DCMU-based measurements. However, dark adaptation had no effect on Fv/Fm when comparing PAM-based values across a single nutrient treatment. All Fv/Fm methods could distinguish LN and LP from R and LFe treatments but none were able to resolve LFe from R, or LN from LP cultures. These results indicated that for most PAM applications, dark adaptation is not necessary, and furthermore that single measurements of Fv/Fm do not provide a robust measurement of nutrient limitation in Microcystis aeruginosa UTEX LB 3037, and potentially other, common freshwater cyanobacteria.

Concentrations of lipid-phosphorus (LP) in aquatic ecosystems can be influenced by algal biomass and the nutritional state of microbial communities, potentially serving a useful indicator of P-limitation. We examined the effectiveness of LP as a bioindicator by examining concentrations of LP and environmental factors controlling its abundance across Lake Erie and its tributaries. LP concentrations were correlated with chlorophyll a (Chl a ) and total suspended solids, total P, and particulate carbon (PC), nitrogen, and P (PP) in both river and lake waters, while dissolved nutrients were only related to lake LP concentrations. Tributary LP was generally higher than in-lake values, and stoichiometric relationships between PC, PP, and LP indicated that Chl a was correlated with tributary LP. Chl a, bacterial production, and LP concentrations decreased significantly across nutrient gradients going from the west to east across the lake. Consistent relationships between lake particulate C:P ratios and Chl a : LP ratios were found across seasons, and higher values of both in August suggested algal P-limitation during this period. To further explore environmental controls on LP, we compared the relative influence of temperature, phytoplankton taxonomy, and water chemistry on lake LP concentrations. Though LP was correlated with well-known factors associated with cyanobacterial abundance in the lake (temperature and ammonium), particulate biomass and algal P-limitation seemed to be the most important correlates of LP concentration, suggesting that Chl a :LP ratios could provide a metric of P-limitation in aquatic ecosystems.

Multi-wavelength Chl a fluorometers are increasingly applied to assess phytoplankton photosynthetic capacity and composition, but their usefulness is limited by uncertainties in fluorescence excitation spectra (FES). We investigated this issue using the Phyto-PAM fluorometer to evaluate the effects of innate and irradiance-dependent variations in background ( F ) and variable ( F v ) FES on analysis of three pigment groups (cyanobacteria, chlorophytes and chromophytes). The effects on group-specific estimates of minimum fluorescence ( F 0 ), a proxy for biomass, and F v / F m , the quantum yield of photochemistry, presented some challenges to the interpretation of group-specific results. F 0 estimates usually had a 5–15% margin of error, even when measuring highly uneven mixtures, and applying imperfectly matched calibration FES or stressing samples with photosynthetically active and ultraviolet radiation; errors in F v / F m were commonly < 15%. Despite such relatively good accuracy, estimates for F 0 and, especially, F v / F m are unreliable for groups at low relative abundance, and results can sometimes be reported for groups not actually present. We report margins of error for different levels of relative abundance to inform interpretation of measurements from natural communities and show that F and F v spectra for some taxa can differ in ways that produce severe errors in F 0 and F v / F m estimates if used uncritically.

The understanding of deep chlorophyll layers (DCLs) in the Great Lakes-largely reported as a mix of picoplankton and mixotrophic nanoflagellates-is predominantly based on studies of deep (>30 m), offshore locations. Here, we document and characterize nearshore DCLs from two meso-oligotrophic embayments, Twelve Mile Bay (TMB) and South Bay (SB), along eastern Georgian Bay, Lake Huron (Ontario, Canada) in 2014, 2015, and 2018. Both embayments showed the annual formation of DCLs, present as dense, thin, metalimnetic plates dominated by the large, potentially toxic, and bloom-forming cyanobacteria Planktothrix cf. isothrix. The contribution of P. cf. isothrix to the deep-living total biomass (TB) increased as thermal stratification progressed over the ice-free season, reaching 40% in TMB (0.6 mg/L at 9.5 m) and 65% in South Bay (3.5 mg/L at 7.5 m) in 2015. The euphotic zone in each embayment extended down past the mixed layer, into the nutrient-enriched hypoxic hypolimnia, consistent with other studies of similar systems with DCLs. The co-occurrence of the metal-oxidizing bacteria Leptothrix spp. and bactivorous flagellates within the metalimnetic DCLs suggests that the microbial loop plays an important role in recycling nutrients within these layers, particularly phosphate (PO4) and iron (Fe). Samples taken through the water column in both embayments showed measurable concentrations of the cyanobacterial toxins microcystins (max. 0.4 µg/L) and the other bioactive metabolites anabaenopeptins (max. ~7 µg/L) and cyanopeptolins (max. 1 ng/L), along with the corresponding genes (max. in 2018). These oligopeptides are known to act as metabolic inhibitors (e.g., in chemical defence against grazers, parasites) and allow a competitive advantage. In TMB, the 2018 peaks in these oligopeptides and genes coincided with the P. cf. isothrix DCLs, suggesting this species as the main source. Our data indicate that intersecting physicochemical gradients of light and nutrient-enriched hypoxic hypolimnia are key factors in supporting DCLs in TMB and SB. Microbial activity and allelopathy may also influence DCL community structure and function, and require further investigation, particularly related to the dominance of potentially toxigenic species such as P. cf. isothrix.

Eutrophication has been linked to increased greenhouse gas emissions from inland waters. Phytoplankton blooms in Lake Erie have increased since the 1990s, although its greenhouse gas emissions are not well characterized. We measured CH4 and N2O concentrations and diffusive fluxes in four seasons around the entire lake, and CO2 fluxes in one summer season. Lake Erie is a source of CH4 all year across the lake, concentrated in spring and summer in the Western Basin. Methane emissions ranged from 0.03 to 14.87 mg C m(-2) d(-1). Methane is predominantly biogenic, and natural gas leaks are an insignificant source. While Lake Erie is an overall N2O source, it is an N2O sink in winter and occasionally during summer. Emissions of N2O ranged from -0.08 to 1.22 mg N m(-2) d(-1). We also measured CO2 fluxes in summer only, when Lake Erie is a small atmospheric CO2 sink. While areal fluxes of CH4 and N2O are similar to those observed elsewhere, total fluxes from Lake Erie are higher due to its surface area. Lake Erie emits similar to 6300 (+/- 19%) metric tons of CH4-C yr(-1) and similar to 600 (+/- 37%) metric tons N2O-N yr(-1): almost 500,000 metric tons CO2-eq yr(-1) total. This is the first comprehensive dataset of CH4 and N2O concentrations and diffusive emissions in a very large lake. More measurements and monitoring are needed to determine whether increased eutrophication in the Great Lakes is tied to increased emissions of these powerful climate forcers in a possible positive feedback to climate warming. (C) 2020 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.

Cyanobacterial blooms are increasing worldwide and have negative impacts on aquatic ecosystems and the services they provide to human societies. A lack of long-term environmental monitoring data, however, has prevented the development of a baseline perspective against which drivers of the increasing frequency and severity of cyanobacterial blooms can be identified. In this study, we evaluate application of spectroscopy-based models to infer historical trends in cyanobacterial abundance from lake sediment cores. Using an amendment series (n = 15) of a sediment matrix spiked with increasing amounts of mixed cyanobacterial culture from 0 to 50 parts per thousand (‰), taxonomically diagnostic carotenoids were measured using visible near-infrared reflectance spectroscopy (VNIRS) and conventional but more costly and time-consuming high-performance liquid chromatography (HPLC). A partial least squares regression model was developed to correlate amendment series VNIR spectra to ‰ of added cyanobacteria. Despite challenges in differentiating carotenoid pigments because of overlapping absorption peaks, applications of the resulting 2-component model (r2 = 0.93, RMSEP = 0.23‰) to sediment cores from four Ontario lakes yielded temporal trends that were significantly correlated with downcore HPLC measures of cyanobacterial pigments in three out of four cases. Although our method is simplistic and may be improved in the future with more complex algorithms employing derivative analysis, we present our results as a possible stepping-stone towards spectral reconstruction of cyanobacterial production. Our study provides proof-of-concept that refinement of a method applying VNIRS to detect cyanobacterial carotenoids in lake sediments has the potential to be an important, rapid and non-destructive assessment tool for research and management of cyanobacterial blooms.

Transformative advances in metagenomics are providing an unprecedented ability to characterize the enormous diversity of microorganisms and invertebrates sustaining soil health and water quality. These advances are enabling a better recognition of the ecological linkages between soil and water, and the biodiversity exchanges between these two reservoirs. They are also providing new perspectives for understanding microorganisms and invertebrates as part of interacting communities (i.e. microbiomes and zoobiomes), and considering plants, animals, and humans as holobionts comprised of their own cells as well as diverse microorganisms and invertebrates often acquired from soil and water. The Government of Canada's Genomics Research and Development Initiative (GRDI) launched the Ecobiomics Project to coordinate metagenomics capacity building across federal departments, and to apply metagenomics to better characterize microbial and invertebrate biodiversity for advancing environmental assessment, monitoring, and remediation activities. The Project has adopted standard methods for soil, water, and invertebrate sampling, collection and provenance of metadata, and nucleic acid extraction. High-throughput sequencing is located at a centralized sequencing facility. A centralized Bioinformatics Platform was established to enable a novel government-wide approach to harmonize metagenomics data collection, storage and bioinformatics analyses. Sixteen research projects were initiated under Soil Microbiome, Aquatic Microbiome, and Invertebrate Zoobiome Themes. Genomic observatories were established at long-term environmental monitoring sites for providing more comprehensive biodiversity reference points to assess environmental change.

Eutrophication is linked to greenhouse gas emissions from inland waters. Phytoplankton blooms in Lake Erie, one of Earth’s largest lakes, have increased with nutrient runoff linked to climate warming, although greenhouse gas emissions from this or other large eutrophic lakes are not well characterized. We measured greenhouse gases around Lake Erie in all four seasons and found that CH4 and N2O emissions have increased 10 times or more with re-eutrophication, especially during and after phytoplankton blooms. Lake Erie is a positive source of CH4 throughout the entire year and around the entire lake, with the highest emissions in spring and summer near the mouth of the Maumee River. While Lake Erie is an overall N2O source, it is an N2O sink in winter throughout the lake and in some locations during large phytoplankton blooms. We estimate that Lake Erie emits ~6300 metric tons of CH4-C yr−1 (± 19%) and ~600 metric tons N2O-N yr−1 (± 37%): almost 500,000 metric tons CO2-eq yr−1 total. These results highlight the gravity of eutrophication-related increases in large lake GHG emissions: an overlooked, but potentially major feedback to global climate change.

The effects of acute solar radiation stress on photosynthetic efficiency in freshwater unialgal cultures representing three phytoplankton pigment groups were measured by pulse amplitude modulated fluorometry (Walz Phyto-PAM) and compared to previous observations on field populations. Ultraviolet radiation (UVR) (UV-B and UV-A) induced a loss of photochemical quantum efficiency (Fv/Fm) in all 13 taxa examined in culture, while effects of photosynthetically active radiation (PAR) were smaller and often insignificant. Cyanobacteria were the most sensitive to PAR and UVR stress, chlorophytes the least and chromophytes intermediate but variable. The kinetics of maximal (Fm) and minimal (F0) fluorescence responses suggested uncoupling of antenna pigments from reaction centers (decreased Fm) persistent after dark adaptation was a common response, in particular for chromophytes, while the extent of impairment from damaged reaction centers (increased F0) was more variable. Changes in Fv/Fm with irradiance exposure were well described by the Kok model of photoinhibition and indicated that damage, rather than recovery, processes were predictive of acute cumulative inhibition. Field populations of cyanobacteria and chromophytes tended to greater tolerance and lower damage rates than laboratory strains. The results for cultures under standardized conditions supported field results in showing cyanobacteria more sensitive to acute UVR exposure than eukaryotic algae, and thus lacking any innate resistance of photosystem II to sunlight stress that might help explain their success in surface bloom formation.

Taste and Odour in Source and Drinking Water provides an updated evaluation of the characterization and management of taste and odour (T&O) in source and drinking waters. Authored by international experts from the IWA Specialist Group on Off-flavours in the Aquatic Environment, the book represents an important resource that synthesizes current knowledge on the origins, mitigation, and management of aquatic T&O problems. The material provides new knowledge for an increasing widespread degradation of source waters and global demand for high quality potable water. Key topics include: early warningdetection and source-trackingchemical, sensory and molecular diagnosistreatment options for common odorants and mineralssource managementmodelling and risk assessmentfuture research directionsTaste and Odour in Source and Drinking Water is directed towards a wide readership of scientists, engineers, technical operators and managers, and presents both practical and theoretical material, including an updated version of the benchmark Drinking Water Taste and Odour Wheel and a new Biological Wheel to provide a practical and informative tool for the initial diagnosis of the chemical and biological sources of aquatic T&O.ISBN: 9781780406657 (paperback)ISBN: 9781780406664 (eBook)ISBN: 9781789060201 (ePub)

Taste and Odour in Source and Drinking Water provides an updated evaluation of the characterization and management of taste and odour (T&O) in source and drinking waters. Authored by international experts from the IWA Specialist Group on Off-flavours in the Aquatic Environment, the book represents an important resource that synthesizes current knowledge on the origins, mitigation, and management of aquatic T&O problems. The material provides new knowledge for an increasing widespread degradation of source waters and global demand for high quality potable water. Key topics include: early warningdetection and source-trackingchemical, sensory and molecular diagnosistreatment options for common odorants and mineralssource managementmodelling and risk assessmentfuture research directionsTaste and Odour in Source and Drinking Water is directed towards a wide readership of scientists, engineers, technical operators and managers, and presents both practical and theoretical material, including an updated version of the benchmark Drinking Water Taste and Odour Wheel and a new Biological Wheel to provide a practical and informative tool for the initial diagnosis of the chemical and biological sources of aquatic T&O.ISBN: 9781780406657 (paperback)ISBN: 9781780406664 (eBook)ISBN: 9781789060201 (ePub)

Harmful algal blooms have important implications for the health, functioning and services of aquatic ecosystems. Our ability to detect and monitor these events is often challenged by the lack of rapid and cost-effective methods to identify bloom-forming organisms and their potential for toxin production, Here, we developed and applied a combination of DNA barcoding and Next Generation Sequencing (NGS) for the rapid assessment of phytoplankton community composition with focus on two important indicators of ecosystem health: toxigenic bloom-forming cyanobacteria and impaired planktonic biodiversity. To develop this molecular toolset for identification of cyanobacterial and algal species present in HABs (Harmful Algal Blooms), hereafter called HAB-ID, we optimized NGS protocols, applied a newly developed bioinformatics pipeline and constructed a BOLD (Barcode of Life Data System) 16S reference database from cultures of 203 cyanobacterial and algal strains representing 101 species with particular focus on bloom and toxin producing taxa. Using the new reference database of 16S rDNA sequences and constructed mock communities of mixed strains for protocol validation we developed new NGS primer set which can recover 16S from both cyanobacteria and eukaryotic algal chloroplasts. We also developed DNA extraction protocols for cultured algal strains and environmental samples, which match commercial kit performance and offer a cost-efficient solution for large scale ecological assessments of harmful blooms while giving benefits of reproducibility and increased accessibility. Our bioinformatics pipeline was designed to handle low taxonomic resolution for problematic genera of cyanobacteria such as the Anabaena-Aphanizomenon-Dolichospermum species complex, two clusters of Anabaena (I and II), Planktothrix and Microcystis. This newly developed HAB-ID toolset was further validated by applying it to assess cyanobacterial and algal composition in field samples from waterbodies with recurrent HABs events.