Academic literature on the topic 'Marine algal toxins'

SUMMARYFive major human toxic syndromes caused by the consumption of shellfish contaminated by algal toxins are presented. The increased risks to humans of shellfish toxicity from the prevalence of harmful algal blooms (HABs) may be a consequence of large-scale ecological changes from anthropogenic activities, especially increased eutrophication, marine transport and aquaculture, and global climate change. Improvements in toxin detection methods and increased toxin surveillance programmes are positive developments in limiting human exposure to shellfish toxins.

Toxic blooms of several strains of blue-green algae are found in both natural and man-made freshwater lakes. Furthermore, mussels may accumulate toxic marine dinoflagellates, rendering them toxic to humans. Traditionally, the presence of algal toxins is tested by intraperitoneal injections of extracts in mice. However, toxic waterblooms and mussels can both be detected by means of freshly prepared rat hepatocytes in suspension.

Phytoplankton produce a diversity of secondary metabolites that have deleterious effects on other organisms. Some of the most potent of these toxins affect neuronal function in animals. These algal neurotoxins bind selectively to specific receptors on ion transporters in neuronal cell membranes, altering their function and kinetic behaviour. The outcome of such toxin–transporter interactions is the disruption of cell signalling, leading to neurotoxicity through either excitatory or inhibitory mechanisms. Algal neurotoxins may affect non-neuronal cell types as well, but toxic effects are most pronounced in neuronal cells.

Abstract Algal toxins produced by marine and freshwater microalgae present a significant analytical challenge because of their complex structures and frequent occurrence as mixtures of structural congeners, which differ in toxic potencies and are present at varying proportions in contaminated samples. Rapid, sensitive in vitro detection methods specific for each class of algal toxins have been developed over the past decade, including immunoassays, enzyme inhibition assays, receptor assays, and cell assays. This review discusses the conceptual approaches to assay development and provides a detailed assessment of the use of in vitro detection methods for marine and freshwater algal toxins.

Harmful algal blooms (HABs) are increasing worldwide as a result of climate change and global marine traffic. HABs contain high concentrations of algal toxins. Toxin contaminated shellfish cannot be detected by taste, sight, or smell; the toxins are heat-stable and therefore are not destroyed by cooking. Human consumption of toxin-contaminated shellfish leads to illness. Treatment of shellfish poisoning is limited to symptom management. The burden of shellfish poisoning in humans is often underestimated, and the effects of chronic exposure are unknown. Currently there are regulatory practices for shellfish monitoring in Canada and the United States. Yet there is poor communication of HAB risks to the public.

Fear of predation may influence food webs more than actual predation. However, the mechanisms and magnitude of nonconsumptive predator effects are largely unknown in unicellular-dominated food webs such as marine plankton. We report a general mechanism of chemically induced predator effects in marine plankton. Copepods, the most abundant zooplankton in the oceans, imprint seawater with unique polar lipids—copepodamides—which trigger toxin production and bioluminescence in harmful dinoflagellates. We show that copepodamides also elicit defensive traits in other phytoplankton, inducing the harmful algal bloom-forming diatom Pseudo-nitzschia seriata to produce 10 times more toxins, and colony-forming diatoms to decrease colony size by half. A 1-year study in the northeast Atlantic revealed that natural copepodamide concentrations are high enough to induce harmful algal toxins and size reduction in dominant primary producers when copepods are abundant. We conclude that copepodamides will structure marine plankton toward smaller, more defended life forms on basin-wide scales.

Microalgae in marine and brackish waters of Europe regularly cause harmful effects, considered from the human perspective, in that they cause economic damage to fisheries and tourism. Cyanobacteria cause similar problems in freshwaters. These episodes encompass a broad range of phenomena collectively referred to as harmful algal blooms (HABs). For adequate management of these phenomena, monitoring of microalgae is required. However, present day monitoring is time consuming and based on morphology as determined by light microscopy, which may be insufficient to give definitive species and toxin attribution. In the European Union (EU) FP7 project MIDTAL (microarrays for the detection of toxic algae), we will first target rapid species identification using rRNA genes. The variable regions of the rRNA genes can be used for probe design to recognize species or even strains. Second, a toxin based microarray will be developed that includes antibody reactions to specific toxins produced by these microalgae because even when cell numbers are low, toxins can be present and can accumulate in the shellfish. Microarrays are the state of the art technology in molecular biology for the processing of bulk samples for detection of target RNA/DNA sequence. Existing rRNA probes and antibodies for toxic algal species/strains and their toxins will be adapted and optimized for microarray use. The purpose of MIDTAL is to support the common fisheries policy and to aid the national monitoring agencies by providing new rapid tools for the identification of toxic algae and their toxins so they can comply with EU directive 91/1491/CEE to monitor for toxic algae, and reduce the need for the mouse bioassay.

Natural high proliferations of toxin-producing microorganisms in marine and freshwater environments result in dreadful consequences at the socioeconomically and environmental level due to water and seafood contamination. Monitoring programs and scientific evidence point to harmful algal blooms (HABs) increasing in frequency and intensity as a result of global climate alterations. Among marine toxins, the okadaic acid (OA) and the related dinophysistoxins (DTX) are the most frequently reported in EU waters, mainly in shellfish species. These toxins are responsible for human syndrome diarrhetic shellfish poisoning (DSP). Fish, like other marine species, are also exposed to HABs and their toxins. However, reduced attention has been given to exposure, accumulation, and effects on fish of DSP toxins, such as OA. The present review intends to summarize the current knowledge of the impact of DSP toxins and to identify the main issues needing further research. From data reviewed in this work, it is clear that exposure of fish to DSP toxins causes a range of negative effects, from behavioral and morphological alterations to death. However, there is still much to be investigated about the ecological and food safety risks related to contamination of fish with DSP toxins.

Algal toxins can have a significant impact on human and ecological health as the toxins accumulate in the food chain and are consumed by both humans and marine organisms. This study focussed on the following marine algal toxins that were present at the study sites: okadaic acid (OA), domoic acid (DA), gymnodimine (GD), pectenotoxin-e (PTX-2) and PTX-2 seco acid (PTX-2SA). The study sites investigated for potential algal toxin exposure were selected from the waters around North Stradbroke Island, Queensland, Australia, where shellfish are harvested by the local population, and where dugongs are known to feed on seagrass. Samples were collected monthly for two consecutive years. The species of toxinproducing algae present at the sites studied were Pseudo-nizschia sp., Dinophysis caudata, D. acuminata and Prorocentrum lima. The occurrence of Dinophysis species was observed to be dependent on the season while Pseudo-nitzschia sp was present both in colder and warmer months. Data on the dose-response analysis were extracted from published literature. This data was categorised into whole organisms, human and animal cell lines, and compared to one another. For further toxicodynamic studies, human cell lines were dosed with known concentrations of the toxins: OA, DA and GD. These cytotoxicity and microarray analyses were performed to observe the effects of toxins on gene regulation. A more extensive analysis was performed using GD alone. Expression of numerous genes was affected, and real time polymerase chain reaction reactions were performed to confirm the regulation of those genes. Gymnodimine was demonstrated to affect genes within pathways relating to oxidative phosphorylation, apoptosis, MAPK and Wnt signalling pathways. The cytotoxicity and microarray data and the data accumulated from the published literature were combined to form a comprehensive database of both chronic and acute effects. The database was then referred to for the dose-response analysis for the risk assessment. The exposure data attained from field sampling in the current study was analysed against the doses for any shown effects. Total daily intake for humans and dugongs sourcing food from around the island were calculated and health risks were estimated by incorporating tolerable daily intake, guideline values and total daily intake. The risk characteristics of algal toxins on the health of humans (consuming shellfish) and dugongs (consuming seagrass) indicated that acute health risks were unlikely, unless an outbreak of toxic algae (algal bloom) were to occur. Since there were no occurrences of algal blooms during the study period, high levels of toxins were not detected in any of the collected shellfish, phytoplankton or seagrass samples. However, if such blooms were to occur around the island, the phytoplankton could potentially produce algal toxins at high enough concentrations to cause acute toxic effects in the consumers. The current study has also demonstrated that there is a potential for chronic, long term health effects from consuming shellfish and seagrass around the island. The presence of low-level concentrations of algal toxins in the food sources can lead to chronic effects. Toxins such as OA are known tumour promoters. For dugongs, which feed on seagrass on daily basis, the potential for chronic effects is high. It was demonstrated that GD also possesses toxicological characteristics that may enhance the possibility of tumour promotion because of its effect of down-regulating parts of the apoptosis pathway, which may prevent cell death and as a consequence, lead to uncontrolled cell growth.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Faculty of Science, Environment, Engineering and Technology
Full Text

2011/2012
SUMMARY Biotoxins produced by harmful algae during their proliferation can be accumulated by filter feeding organisms, such as bivalve shellfish, within their flesh. Furthermore, these toxins gradually are transferred to the higher trophic levels in the food chain, posing a threat to human health, after consumption of contaminated seafood. Filter-feeding invertebrates are organisms in which the toxin accumulation is a well-known phenomenon, especially during harmful algal blooms. Mussels, cockles, oysters, and scallops feed on toxic dinoflagellates, transferring them from the gills to digestive organs where the toxins accumulate. Different algal toxins can simultaneously contaminate edible shellfish, representing a world-wide sanitary and economic problem. Among them, Palytoxin (PLTX) is a highly toxic polyhydroxylated compound associated to human seafood intoxications in tropical and subtropical areas, but recently it has been detected also in microalgae and shellfish from temperate areas, as Mediterranean Sea. In the last years, also Yessotoxin (YTX) was frequently detected in mussels from Mediterranean Sea and a possible co-exposure to both PLTX and YTX can occur through contaminated seafood consumption. Therefore, the research was initially focused on the detection and quantification of PLTX and YTX in mussels collected in the Gulf of Trieste in order to verify the simultaneous shellfish contamination by these toxins and, subsequently, to study their toxic effects after simultaneous oral exposure. Analyses by liquid chromatography coupled mass spectrometry (LC-MS) did not reveal the presence of PLTX in mussels but identified the presence of YTX together with the diarrheic toxins okadaic acid (OA) and its acyl esters. Consequently, the final goal of this part of the research was the determination of these toxins in mussels from the Gulf of Trieste by LC-MS as well as that of OA and its esters by a functional assay, the protein phosphatase 2A (PP2A) inhibition assay (comparing the results obtained from two different protocols for the PP2A assay). These assays were used to analyse both cooked and uncooked mussel samples, to verify the influence of the heating procedure on the toxin content of mussels. Globally, no significant difference in toxins concentration between uncooked and cooked mussels was observed. However, comparing the data of single samples, a slight increase (not statistically significant) of toxin concentrations was detected in the cooked mussels with respect to the uncooked ones. The mussel analysis by LC-MS/MS detected also the presence of significant amounts of yessotoxin. Contrary to OA group toxins, yessotoxin was slightly less concentrated in the cooked mussels, probably because of its higher polarity that allows a dissolution in the water lost during the cooking procedure. In the other hand and as it was mentioned before, the palytoxin produced by Ostreopsis sps. microalgae have become a problem in more occasions for the attendance of the coastal environment, both for recreation and for business, representing a loss, as well as to public health, even for the tourism and the aquaculture industry. World market globalization, climatic changes and increasing overseas traffic are considered the main responsible for the appearance of these toxins. The expand of these toxins to temperate regions may be due in part to ballast water of ships and also to general changes in climate conditions, enough to induce bloom formation. Despite the extent of the contaminated area, few methods are currently available for palytoxins detection and quantitation in seafood. Moreover, among palytoxins, only palytoxin is commercially available, though expensive, and no certified standard material is currently sold. For monitoring purposes, a combination of screening methods followed by a chemical confirmatory analysis, such as LC-MS, is commonly used to detect palytoxins. Other methods for PLTX analysis include mouse bioassay, cytotoxicity assays, haemolysis assays, receptor binding assays, and immunoassays. Even if there were no food poisoning from palytoxin in the Mediterranean countries, the toxin was detected in shellfish, which gave positivity to the official test for the lipophilic toxins of algal origin (okadaic acid and derivatives, azaspiracids, yessotoxins and pectenotoxins). Some different experiments were applied in the evaluation of palytoxin toxicity in this study (Haemolytic assay, sandwich ELISA, LC-MS/MS and cytotoxicity studies were carried out). Haemolytic assay, carried out incubating mouse erythrocytes with palytoxin for 4 h (standard assay) or for 1 h in diluted PBS (abbreviated assay) is able to detect palytoxin at picomolar concentrations. Nevertheless, with the aim to detect the toxin in mussels, a significant matrix effect impairing the toxin quantification was observed already at the mussel extract concentration of 0.048 mg edible tissues equivalents/mL, which was more evident by the abbreviated assay. However, most of the experiments lack specificity or have other limitations. Thus, an indirect sandwich ELISA has been set up. The ELISA assay (indirect sandwich) was developed using the monoclonal antibody 73D3, and a rabbit polyclonal antibody produced at the University of Trieste. The assay detects the PLTX in a range of concentrations ranging from 1.25 to 40 ng/ml and is able to quantify with very similar sensitivity also biotinilated PLTX as well as 42-OH-PLTX, this latter isolated and characterized from the chemical point of view during the latter years from the group of prof. E. Fattorusso (University of Naples Federico II), in a sample of palytoxin kindly provided by Dr. M. Poly (Maryland, USA). The incapacity to detect okadaic acid (OA), domoic acid (DA), brevetoxin-3 (PbTx-3), saxitoxin (STX) and yessotoxin (YTX)(toxins that may be present along with PLTX in fish contaminated) indicates the specificity of the assay. The structure of Palytoxins is very complex. In addition to this structural complexity, there is still a lack of knowledge about the different congeners involved in this contamination and therefore there is still a very limited availability of standards and reference materials. These issues made difficult the advances in the development and optimization of analytical methods, particularly in the case of LC-MS/MS. Despite of this, a significant progress has been made over the last few years in the development of analytical techniques, particularly on LC-MS/MS approaches. In this part of the study, a LC-MS/MS method was optimized for the analysis of PLTXs in order to be able to detect, quantify and confirm the presence of this toxins in natural samples. During the PhD period, there was the possibility to get some natural contaminated samples to be evaluated by ELISA developed assay and then compare the results with the analysis by the developed LC-MS/MS method. The study was carried out with samples from 3 distinct sites characterized by having different coastal morphologies and continental hydrodynamic conditions: i) Madeira Islands’ archipelago in the NE Atlantic Ocean, Selvagens island in particular (Long, Lat) during the upwelling of August 2008; ii) Cascais, on the west coast of Portugal mainland, located at the northern side of Lisbon bay during the upwelling occurred during the favourable northerly wind periods (from April to September 2011); and iii) Algarve, Lagos, on the South Portuguese coast, also in 2011.
RIASSUNTO Biotossine prodotte da alghe nocive durante la loro proliferazione possono essere accumulati da organismi di alimentazione per filtrazione, come molluschi bivalvi, nell'ambito della loro carne. Inoltre, queste tossine vengono trasferite gradualmente ai livelli trofici superiori della catena alimentare, che rappresenta una minaccia per la salute umana, dopo il consumo di frutti di mare contaminati. Invertebrati con filtro-alimentazione sono organismi in cui l'accumulo di tossine, è un fenomeno ben noto, soprattutto durante fioriture algali nocive. Cozze, vongole, ostriche e capesante si nutrono di dinoflagellati tossici, trasferendoli dalle branchie agli organi digestivi, dove le tossine si accumulano. Diverse tossine algali possono contemporaneamente contaminare molluschi commestibili, che rappresenta un problema mondiale sanitario ed economico. Tra questi, Palitossina (PLTX) è un composto altamente tossico poliossidrilato associato ad intossicazioni ittici dell'uomo nelle zone tropicali e subtropicali, ma recentemente è stato rilevato anche in microalghe e molluschi dalle zone temperate, come il Mare Mediterraneo. Negli ultimi anni, anche yessotossina (YTX) è stato spesso rilevato nei mitili dal Mare Mediterraneo e una possibile co-esposizione sia PLTX e YTX può avvenire attraverso il consumo di frutti di mare contaminati. Pertanto, la ricerca è stata inizialmente concentrata sul rilevamento e la quantificazione di PLTX e YTX nei mitili raccolti nel Golfo di Trieste, al fine di verificare la contaminazione simultanea nei frutti di mare da queste tossine e, in seguito, per studiare i loro effetti tossici dopo esposizione orale simultanea. Analisi mediante cromatografia liquida accoppiata alla spettrometria di massa (LC-MS) non ha rivelato la presenza di PLTX in mitili ma è stata identificata la presenza di YTX insieme alle tossine diarroiche acido okadaico (AO) e suoi esteri. Di conseguenza, l'obiettivo finale di questa parte della ricerca è stata la determinazione di queste tossine nei mitili del Golfo di Trieste mediante LC-MS così come quella di AO e suoi esteri da un saggio funzionale, il Saggio d’inibizione Proteina Fosfatasi 2A (PP2A)(confrontando i risultati ottenuti da due diversi protocolli per il saggio PP2A). Questi test sono stati utilizzati per l'analisi di campioni di mitili sia crude e cotte, per verificare l'influenza della procedura di riscaldamento sul contenuto di tossina nei mitili. A livello globale, nessuna differenza significativa nella concentrazione di tossine tra cozze crude e cotte è stata osservata. Tuttavia, confrontando i dati dei singoli campioni, un lieve aumento (non statisticamente significativo) delle concentrazioni di tossine è stato rilevato nelle cozze cotte rispetto a quelli crude. L'analisi dei mitili per LC-MS/MS rilevò anche la presenza di quantità significativa di yessotossina. Contrariamente alle tossine gruppo OA, yessotossina era leggermente meno concentrata nelle cozze cotte, probabilmente a causa della sua polarità superiore che permette una dissoluzione in acqua persa durante la cottura. Altrimenti e come è stato detto prima, la palitossina prodotta da Ostreopsis sps. microalghe sono diventate un problema in più occasioni per la partecipazione dell'ambiente costiero, sia per la ricreazione e per le imprese, con una perdita, così come per la salute pubblica, anche per il turismo e l'industria dell'acquacoltura. Globalizzazione del mercato mondiale, i cambiamenti climatici e l'aumento del traffico all'estero sono considerati il principale responsabile della comparsa di queste tossine. L'espansione di queste tossine per le regioni temperate può essere dovuto in parte alla acque di zavorra delle navi e anche a cambiamenti delle condizioni climatiche generali, tanto da indurre la formazione di fioritura. Nonostante e dovuto alla estensione dell'area contaminata, alcuni metodi sono disponibili per il rilevamento e la quantificazione di palitossina in frutti di mare. Inoltre, tra palitossine, solo palitossina è disponibile in commercio, anche se costoso, e nessun materiale standard certificato è attualmente venduto. A scopo di monitoraggio, una combinazione di metodi di screening seguita da una analisi chimica di conferma, ad esempio LC-MS, è comunemente utilizzato per rilevare palitossine. Altri metodi di analisi includono PLTX biotest sui topi, saggi di citotossicità, saggi emolici, saggi di legame al recettore e saggi immunologici. Anche se non ci sono stati identificate intossicazione alimentare da palitossina nei paesi del Mediterraneo, la tossina è stata rilevata nei molluschi, che ha dato positività al test ufficiale per le tossine lipofile di origine algale (acido okadaico e derivati, azaspiracidi, yessotossine e pectenotossine). Alcuni esperimenti diversi sono stati applicati nella valutazione della tossicità della palitossina in questo studio (saggio emolitico, ELISA, LC-MS/MS e studi di citotossicità sono state effettuate). Saggio emolitico, effettuato incubando eritrociti di topo con palitossina per 4 h (saggio standard) o per 1 h in PBS diluito (saggio abbreviato) è in grado di rilevare la palitossina a concentrazioni picomolari. Tuttavia, con lo scopo di rilevare la tossina nelle cozze, un significativo effetto matrice ledere la quantificazione di tossina è stata osservata già alla concentrazione di estratto di cozze 0,048 mg equivalenti tessuti commestibili/mL, che è stato più evidente con il saggio abbreviato. Tuttavia, per la maggior parte degli esperimenti mancano specificità o hanno altre limitazioni. Così, un indiretto sandwich ELISA è stato istituito. Il saggio ELISA (sandwich indiretto) è stato sviluppato utilizzando gli 73D3 anticorpi monoclonali, e un anticorpo policlonale di coniglio prodotto nella Università di Trieste. Il saggio rileva la PLTX in un intervallo di concentrazioni variabili 1,25-40 ng / ml ed è in grado di quantificare con sensibilità molto simile anche PLTX biotinilata così come 42-OH-PLTX, quest'ultimo isolata e caratterizzata dal punto di vista chimico durante gli ultimi anni dal gruppo del prof. E. Fattorusso (Università degli Studi di Napoli Federico II), in un campione di palitossina gentilmente fornito dal Dr. M. Poli (Maryland, USA). L'incapacità di individuare acido okadaico (AO), acido domoico (AD), brevetossina-3 (PbTx-3), saxitossina (STX) e yessotossina (YTX) (tossine che possono essere presenti insieme a PLTX nel pesce contaminato) indica la specificità del dosaggio. La struttura della palitossina è molto complessa. In aggiunta a questa complessità strutturale, vi è ancora una mancanza di conoscenza sui diversi congeneri coinvolti in questa contaminazione e quindi c'è ancora molto limitata disponibilità di standard e materiali di riferimento. Questi problemi reso difficili gli progressi nello sviluppo e ottimizzazione di metodi analitici, in particolare nel caso di LC-MS/MS. Nonostante, un progresso significativo è stato compiuto negli ultimi anni allo sviluppo di tecniche analitiche, in particolare su approcci LC-MS/MS. In questa parte dello studio, un metodo LC-MS/MS stato ottimizzato per l'analisi di PLTXs per essere in grado di rilevare, quantificare e confermare la presenza di queste tossine in campioni naturali. Durante il periodo di dottorato di ricerca, c’è stata la possibilità di ottenere alcuni campioni naturali contaminati da valutare tramite il saggio ELISA sviluppato e poi confrontare i risultati con l'analisi con il metodo sviluppato di LC-MS/MS. Lo studio è stato effettuato con campioni da 3 posti diversi caratterizzati d’avere diverse morfologie e condizioni idrodinamiche costiere continentali: i) arcipelago Isole Madeira nel nord-orientale dell'Oceano, Selvagens isola in particolare durante il mese di agosto 2008; ii) Cascais, sulla costa occidentale del Portogallo continentale, che si trova sul lato settentrionale della baia di Lisbona durante i periodi favorevoli di vento dal nord (da aprile a settembre 2011), e iii) Algarve, Lagos, sulla costa sud-portoghesa, anche nel 2011.
XXV Ciclo
1983

Global change poses new threats for life in the oceans forcing marine organisms to respond through molecular acclimatory and adaptive strategies. Although bivalve molluscs are particularly tolerant and resilient to environmental stress, they must now face the challenge of more frequent and severe Harmful Algal Blooms (HABs) episodes. These massive outbreaks of microalgae produce toxins that accumulate in the tissues of these filter-feeder organisms, causing changes in their gene expression profiles, which in turn modify their phenotype in order to maintain homeostasis. Such modifications in gene expression are modulated by epigenetic mechanisms elicited by specific environmental stimuli, laying the foundations for long-term adaptations. The present work aims to examine the links between environmental stress in bivalve molluscs (with especial emphasis on Harmful Algal Blooms) and specific epigenetic marks triggering responses through modifications in gene expression patterns. Overall, a better understanding of the molecular strategies underlying the conspicuous stress tolerance observed in bivalve molluscs will provide a framework for developing a new generation of biomonitoring strategies. In addition, this strategy will represent a valuable contribution to our knowledge in acclimatization, adaptation and survival. With that goal in mind, the present work has generated transcriptomic data using RNA-Seq and microarray technologies, facilitating the characterization and investigation of the epigenetic mechanisms used by the Mediterranean mussel Mytilus galloprovincialis during responses to HAB exposure. That information was made publicly available through a specialized online resource (the Chromevaloa Database, chromevaloa.com) assessing the response of chromatin-associated transcripts to Okadaic Acid. Specific epigenetic marks have been assessed under lab-controlled exposure experiments simulating the natural development of the HAB Florida Red Tide (FRT). Results demonstrate a role for the phosphorylation of histone H2A.X and DNA methylation in the response to FRT in the Eastern oyster Crassostrea virginica. Lastly, the study of co-expression networks based on RNA-Seq data series from the Pacific oyster Crassostrea gigas reveals dynamic transcriptomic patterns that vary with time, stressor and tissue. However, consistent functional profiles support the existence of a core response to general conditions of environmental stress. Such response involves metabolic and transport processes, response to oxidative stress and protein repair or disposal, as well as the activation of immune mechanisms supporting a tightly intertwined neuroendocrine-immune regulatory system in bivalves.

These (Ph.D.)--University of Massachuesetts Lowell, 2008.
Title from PDF title page. Available through UMI ProQuest Digital Dissertations. Includes bibliographical references (leaves 55-66). Also issued in print.

Algae are distributed worldwide in the sea, in freshwater and in wet situations on land. Most are microscopic algae, but some of them are so large, also some marine seaweeds that can exceed 50 m in length. The algae have chlorophyll and can make their own food through the steps of photosynthesis. Recently they are classified in the kingdom of protested, which include a variety of unicellular and some basic multinuclear and multicellular eukaryotic organisms that have cells. Algal poisoning is an intense, often lethal condition caused by high concentrations of toxic blue-green algae (more commonly known as cyanobacteria—literally blue-green bacteria) in drinking water as well as in water used for recreation, agriculture and aquaculture. The study cur in the productive dangerous from the algae toxin that productive from cyanobacteria in aquatic environment. The important contamination for water source identification and non-identification and identify on algae that responsible on productive of toxin in water that represented by Cylindrospermum, Aphanizomenon Anabaena, Microcystis, Lyngbya, Oscillatoria, phormidium, and suitable environment for algae to productive toxin. Such as temperature, pH, nutrient, salinity, density identify on the toxin concentration in water that content organisms that productive toxin between (1–100 mg/l). With the use of different methods of treating algal toxins such as (potassium permanganate, activated carbon, oxidation, chlorine and ozone), and the best treatment was the use of potassium permanganate at a concentration (2 mg/l), which gave the best treatment while preserving the ecosystem.