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1
Fong, Yin-shan. "Harmful Algal Blooms (HABs) in coastal waters and their management /". Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25436247.
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Yang, Zhenbo. "Harmful algal blooms in selected Hong Kong coastal waters". Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22534374.
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Wang, Jing. "Detection and characterization of harmful algae by bioluminescent stress fingerprinting". College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1978.
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Thesis (M.S.) -- University of Maryland, College Park, 2004.Thesis research directed by: Dept. of Nutrition and Food Science. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
4
Al-Kandari, Manal A. "Molecular studies of Karenia mikimotoi (Dinophyceae) from the Celtic Sea region". Thesis, University of Plymouth, 2012. http://hdl.handle.net/10026.1/1088.
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K. mikimotoi has been classified under many names and has been mis-assigned to different species and genera in the North Atlantic and Pacific because of its morphological similarities to other Gymnodinoid species. It is now known to be widely distributed, but there remain unresolved questions about whether K. mikimotoi was introduced into the North Sea from Japanese waters, or whether it has always inhabited this region and been erroneously classified as Gymnodinium spp. or has been a part of the hidden flora prior to be recognised in a bloom off the Norwegian coast in 1966. To address questions about geographical genetic variation within K. mikimotoi and broader issues about its biogeography it was deemed important to develop a suitable diagnostic molecular marker that could then be used to monitor the presence/absence of different K. mikimotoi ecotypes over long time scales in European waters. This study showed that the partial rDNA LSU (D1-D2) was too conserved to separate the different strains of K. mikimotoi, while, the ITS region was better able to discriminate between the different strains. However, the rbcL gene was the most informative gene and contained sufficient substitutions to separate the different strains of K. mikimotoi. Specific PCR-primers were designed to amplify a variable region of the rbcL gene able to distinguish differences between K. mikimotoi isolates from the different regions. The innovative high resolution melting temperature (HRM) technique based on specific primer set allowed rapid discrimination of K. mikimotoi from distinct geographic localities (= sequence variants) that differed by only a single nucleotide. Moreover, this study used archival environmental samples collected from the Celtic Sea shelf-break region. The high resolution melting temperature assay successfully detected the European K. mikimotoi isolate within the south-western English Channel in a 1963 sample, which is prior to thefirst report of a K. mikimotoi bloom in Norwegian waters in 1966 and in the south-western English Channel in 1975 and in western Japan in 1965. HRM observations were further validated using clone libraries and sequencing. In summary, this data provided more information about the genotypes present over the analysed timescales, revealing that K. mikimotoi sub-species 2 (European and New Zealand strains) was present in south-western English Channel and south-west Ireland for over 47 years, with sub-species 1 (the Japanese isolate) being absent from all examined samples. This finding supports the hypothesis that K. mikimotoi isolates within Europe are not of Japanese origin and suggests that they are native species to the region.
5
Graham, Sylvia Lynne. "Growth and grazing of microzooplankton in response to the harmful alga Heterosigma akashiwo in prey mixtures /". Online version, 2008. http://content.wwu.edu/cdm4/item_viewer.php?CISOROOT=/theses&CISOPTR=305&CISOBOX=1&REC=8.
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Hardman, Ron C. "Harmful algal blooms in the Gulf of Mexico : brevetoxin degradation and derivation formation via photochemical processes /". Electronic version (PDF), 2003. http://dl.uncw.edu/etd/2002/hardmanr/ronhardman.pdf.
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Yang, Zhenbo, i 揚振波. "Harmful algal blooms in selected Hong Kong coastal waters". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31242583.
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Cohen, Margaret A. "Estimating the growth rate of harmful algal blooms using a model averaged method". View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-1/rp/cohenm/margaretcohen.pdf.
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Kamikawa, Ryoma. "Development of a highly sensitive, molecular-based method for monitoring harmful algae". Kyoto University, 2009. http://hdl.handle.net/2433/123971.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第14659号
農博第1741号
新制||農||967(附属図書館)
学位論文||H21||N4432(農学部図書室)
UT51-2009-D371
京都大学大学院農学研究科応用生物科学専攻
(主査)教授 左子 芳彦, 教授 平田 孝, 准教授 吉田 天士
学位規則第4条第1項該当
10
方燕珊 i Yin-shan Fong. "Harmful Algal Blooms (HABs) in coastal waters and their management". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B3125519X.
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Hinder, Stephanie Louise. "The effects of climate change on harmful algal blooms and plankton communities in the NE Atlantic". Thesis, Swansea University, 2012. https://cronfa.swan.ac.uk/Record/cronfa42990.
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Climate change has a profound impact on the phenology and abundance of plankton in the NE Atlantic and North Sea. There is concern that harmful algal bloom (HAB) species may increase, accompanied by negative socio-economic impacts, including threats to human health and marine harvesting. We reviewed historical major UK outbreaks of poisoning and attempted to examine the epidemiology on a finer scale by linkage of hospital admissions, GP and pathology records. As expected the incidence of shellfish poisonings was very low but accurate identification of poisoning was generally unreliable. The current UK shellfish monitoring programme is the key indicator for monitoring trends in the risk of human exposure. Using the Continuous Plankton Recorder (CPR) survey, we mapped spatial and temporal trends of various phytoplankton, including HAB species, and zooplankton (Tintinnids and Calanus). We found fundamental shifts in the relative abundance of diatoms versus dinoflagellates, with a dramatic dinoflagellate decline in recent years. Northward shifts in abundance were found for some Tintinnid and Calanus taxa. Using criteria of statistical causality, these changes were linked to climate, in particular sea surface temperature and increasingly windy conditions in the summer, with a notable non-linear interaction between these factors. Focusing on Calanus, we showed the strength of statistical links between abundance and climate variables can wax and wane as the time series lengthens. We found tentative evidence for adaptation of Calanus to climate change, but not at a level that could reverse overall long-term patterns. Links with climate are often argued to be proxies for unobserved mechanisms that determine species abundance, such as stratification. We developed a new stratification index, covering the whole NE Atlantic from 1970 to 2009. We propose that this has wide applicability in marine climate change studies. Throughout, our work demonstrates the importance of consistent long-term ecological survey data.
12
Zhang, Fangzhu. "Harmful algae from container ship ballast water taken from the open ocean and from Oakland, California (May, 1996 to April, 1997) /". Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19589049.
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Poulson, Kelsey L. "Sublethal interactions between the harmful alga karenia brevis and its competitors". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49096.
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I investigated how competitor species respond to chemical cues released from the red tide dinoflagellate Karenia brevis. K. brevis produces a mix of unstable, relatively polar, allelopathic organic molecules that are produced and released at low concentrations. The production of these compounds also varies greatly within and among strains of K. brevis. The majority of these compounds caused sublethal reductions in competitor growth. In laboratory experiments, these compounds inhibited the growth of competitors Asterionellopsis glacialis, Skeletonema grethae, Prorocentrum minimum, and Akashiwo sanguinea, although each species was susceptible to a different sub-set of K. brevis compounds. Cell physiological state and population densities were important in dictating the susceptibility of competitors to allelopathy: phytoplankton were most susceptible to K. brevis allelopathy when in earlier growth stages (rather than later stages) and in lower cell concentrations. However, these compounds have limited negative effects on natural, mixed populations of competitors from both near and offshore environments, and competitors from inshore and offshore environments appear to respond similarly to K. brevis allelopathy. In the sensitive competitor, Thalassiosira pseudonana, allelopathic compounds ultimately caused a reshuffling of cellular nitrogen pools, altered carbon storage and impaired osmotic regulation as determined using a nuclear magnetic resonance (NMR) based metabolomics approach. By characterizing the pool of primary metabolites present in the cell after exposure to K. brevis cues, we inferred which metabolic pathways may be affected by allelopathy. For instance, concentrations of betaine and the aromatic metabolite homarine were suppressed, indicating that K. brevis allelopathy may disrupt this competitor’s ability to osmoregulate. Exposure to K. brevis cues enhanced the concentrations of glutamate and the fatty acid caprylate/caprate in T. pseudonana, suggesting that protein degradation was enhanced and that energy metabolism was altered. This contrasts with the response to K. brevis allelopathy of the diatom Asterionellopsis glacialis, which was much more resistant to chemical cues produced by K. brevis, likely through as yet unidentified detoxification pathways. Overall, my dissertation research provides insight into how species-specific, antagonistic interactions among phytoplankton competitors can affect community structure through direct or indirect mechanisms, highlights the potential role of allelopathy in the maintenance of K. brevis blooms, and uses a novel tool set (i.e., metabolomics) to determine the molecular targets of K. brevis allelopathy. It further demonstrates that planktonic communities are complex and dynamic ecological systems and that interspecific interactions between phytoplankton can have unexpected, cascading impacts in marine systems.
14
Gerlach, Kyle T. "Assessment of Ferrate for Pre-Oxidation Treatment of Harmful Algal Blooms in Drinking Water Treatment". Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-theses/1332.
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Harmful algal blooms in surface water supply systems pose a threat to public health and are increasing in both frequency and geographical distribution. Cyanobacteria can contribute to taste and odor issues and potentially release harmful cyanotoxins into the water. Several treatment methods are currently employed to control these blooms, including physical separation and chemical pre-oxidation. However, existing oxidation options can be costly; increase the release of intracellular material causing the formation of disinfection byproducts; or disrupt coagulation and filtration processes. This study investigated ferrate (Fe(VI)) as an alternative to other oxidants by measuring its effect on algae cells. Fe(VI) has several advantages as an oxidant, including a high oxidation potential, a low potential for harmful disinfection byproduct production, and formation of Fe(III) - which can potentially be beneficial for downstream treatment processes. Bench scale studies were conducted with laboratory prepared waters containing the common cyanobacteria Microcystis aeruginosa to examine the interactions between Fe(VI) and algae. The effects of ferrate oxidation on algae were characterized by particle counts, UV254 absorbance, total organic carbon (TOC) and dissolved organic carbon (DOC), and total nitrogen. Ferrate decomposition was also monitored. Results showed that Fe(VI) lysed algal cells under some conditions, but further oxidation of released organic matter is possible at some doses. Additionally, some coagulation benefits were observed through an overall decrease in total particle counts and an increase in particle sizes. In general, the results indicate that Fe(VI) could be a possible alternative to other oxidants for water utilities during harmful algal blooms; however, the final fate of resulting organic matter and the potential for disinfection byproduct formation should be further studied.
15
Handy, Sara Marie. "Investigations of the ecology of Delaware Inland Bay harmful algae utilizing quantitative real-time PCR". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 152 p, 2007. http://proquest.umi.com/pqdweb?did=1362527691&sid=13&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Sarkar, Supria. "USING MACHINE LEARNING TO UNDERSTAND THE SPATIOTEMPORAL VARIABILITY OF HARMFUL ALGAE BLOOMS IN ILLINOIS WATERS". OpenSIUC, 2021. https://opensiuc.lib.siu.edu/theses/2873.
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Harmful Algae Blooms (HABs) in inland waterbodies (e.g., lakes and ponds) pose serious threat to human health and natural ecosystem. Thus, it is imperative to assess HABs and their potential triggering factors over broader spatiotemporal scales. This study utilizes Chlorophyll-a (Chl-a) concentration in water samples collected from lakes in Illinois as an indirect measurement of HABs. The major objectives were to assess the spatiotemporal pattern of HABs over Illinois regions in recent decades, and to examine different machine learning models for predicting the Chl-a concentration based on publicly available water quality datasets. The Chl-a dataset was compiled from two different sources, the regular monitoring program by Illinois Environmental Protection Agency (IEPA) and the Voluntary Lake Monitoring Program (VLMP), the latter of which was primarily collected by citizen participants. Seven environmental and water quality zones were selected for spatial analyses. Additionally, the temporal patterns were assessed using time-series decomposition of monthly Chl-a concentration datasets. The machine learning pipeline includes two tasks: a regression modeling task for predicting Chl-a concentration, and a classification task for estimating lake trophic status. Different meteorological, land use and land cover, and lake morphometry variables were used as independent variables. Four regression models, i.e., Partial Least Squares Regression (PLSR), Support Vector Machine Regression (SVR), Artificial Neural Network Regression (ANNR), and Random Forest Regression (RFR) were used for the first task of the modeling pipeline, and four classification models, i.e., Logistic Regression Classification (LRC), Support Vector Machine Classification (SVC), Artificial Neural Network Classification (ANNC), and Random Forest Classification (RFC), were used for the second task. Results indicate that: a) the Collinsville region in southwestern part of Illinois exhibited higher mean concentration of Chl-a in its lakes than any other regions from 1998 to 2018; b) the lakes that showed increasing trends in their monthly mean Chl-a concentrations were also clustered in the southwestern region; c) Random Forest outperformed all other models in both classification (Accuracy=60.06%) and regression (R2=38.88%); and d) the land use and land cover variables were found as the most important set of variables in Random Forest models.
17
Pezzolesi, Laura <1982>. "Harmful algae and their potential impacts on the coastal ecosystem: growth and toxin production dynamics". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3652/1/Pezzolesi_Laura_Tesi.pdf.
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The main goal of the present thesis was to study some harmful algal species which cause blooms in Italian coastal waters, leading to consequences for human health, coastal ecosystem, fishery and tourism.
In particular, in the first part of this thesis the toxicity of Adriatic strains of the raphidophyte Fibrocapsa japonica was investigated. Despite several hypotheses have been proposed for the toxic mechanism of the raphidophytes, especially for the species Chattonella antiqua and C. marina, which have been studied more extensively, just a few studies on the toxic effects of these species for different organisms were reported. Moreover, a careful reading of the literature evidenced as any ichthyotoxic events reported worldwide can be linked to F. japonica blooms. Although recently several studies were performed on F. japonica strains from the USA, Japan, Australia, New Zealand, the Netherlands, Germany, and France in order to characterize their growth and toxicity features, the work reported in this thesis results one of the first investigation on the toxic effects of F. japonica for different organisms, such as bacteria, crustaceans and fish. Mortality effects, together with haemolysis of fish erythrocytes, probably due to the relatively high amount of PUFAs produced by this species, were observed. Mortality for fish, however, was reported only at a high cell density and after a long exposition period (9-10 days); moreover a significant increase of H2O2 obtained in the tanks where sea basses were exposed to F. japonica was also relevant. This result may justify the absence of ichthyotoxic events in the Italian coasts, despite F. japonica blooms detected in these areas were characterized by high cell densities. This work reports also a first complete characterization of the fatty acids produced and extracellularly released by the Adriatic F. japonica, and results were also compared with the fatty acid profile of other strains. The absence of known brevetoxins in F. japonica algal extracts was also highlighted, leading to the hypothesis that the toxicity of F. japonica may be due to a synergic effect of PUFAs and ROS.
Another microalgae that was studied in this thesis is the benthic dinoflagellate Ostreopsis cf. ovata. This species was investigated with the aim to investigate the effect of environmental parameters on its growth and toxicity. O. cf. ovata, in fact, shows different blooming periods along the Italian coasts and even the reported toxic effects are variable. The results of this work confirmed the high variability in the growth dynamic and toxin content of several Italian strains which were isolated in recent years along the Adriatic and Tyrrhenian Seas. Moreover, the effects of temperature and salinity on the behaviour of the different isolates are in good agreement with the results obtained from field surveys, which evidence as the environmental parameters are important factors modulating O. cf. ovata proliferation. Another relevant result that was highlighted is the anomaly in the production of palytoxin-like compounds reported by one of the studied isolate, in particular the one isolated in 2008 in Ancona (Adriatic Sea). Only this strain reported the absence of two (ovatoxin-b and –c) of the five ovatoxins so far known in the toxin profile and a different relative abundance of the other toxins.
The last aspect that was studied in this thesis regards the toxin biosythesis. In fact, toxins produced (palytoxin-like compounds) or supposed to be produced (brevetoxin-like compounds) by O. cf. ovata and F. japonica, respectively, are polyketides, which are highly oxygenated compounds synthesized by complex enzymes known as polyketide synthase (PKS) enzymes. These enzymes are multi-domain complexes that structurally and functionally resemble the fatty acid synthases (FASs). This work reports the first study of PKS proteins in the dinoflagellates O. cf. ovata, C. monotis and in the raphidophyte F. japonica. For the first time some PKSs were identified in these species, confirming the presence of PKS proteins predicted by the in silico translation of the transcripts found in K. brevis also in other species. The identification of O. cf. ovata PKSs and the localization of the palytoxin-like compounds produced by this dinoflagellate in a similar location (chloroplast) as that observed for other dinoflagellate and cyanobacterial toxins provides some indication that these proteins may be involved in polyketide biosynthesis. However, their potential function as fatty acid synthases cannot be ruled out, as plant fatty acid synthesis also occurs within chloroplasts. This last hypothesis is also supported by the fact that in all the investigated species, and in particular in F. japonica, PKS proteins were present. Therefore, these results provide an important contribution to the study of the polyketides and of the involvement of PKS proteins in the toxin biosynthesis.
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Pezzolesi, Laura <1982>. "Harmful algae and their potential impacts on the coastal ecosystem: growth and toxin production dynamics". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3652/.
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The main goal of the present thesis was to study some harmful algal species which cause blooms in Italian coastal waters, leading to consequences for human health, coastal ecosystem, fishery and tourism.
In particular, in the first part of this thesis the toxicity of Adriatic strains of the raphidophyte Fibrocapsa japonica was investigated. Despite several hypotheses have been proposed for the toxic mechanism of the raphidophytes, especially for the species Chattonella antiqua and C. marina, which have been studied more extensively, just a few studies on the toxic effects of these species for different organisms were reported. Moreover, a careful reading of the literature evidenced as any ichthyotoxic events reported worldwide can be linked to F. japonica blooms. Although recently several studies were performed on F. japonica strains from the USA, Japan, Australia, New Zealand, the Netherlands, Germany, and France in order to characterize their growth and toxicity features, the work reported in this thesis results one of the first investigation on the toxic effects of F. japonica for different organisms, such as bacteria, crustaceans and fish. Mortality effects, together with haemolysis of fish erythrocytes, probably due to the relatively high amount of PUFAs produced by this species, were observed. Mortality for fish, however, was reported only at a high cell density and after a long exposition period (9-10 days); moreover a significant increase of H2O2 obtained in the tanks where sea basses were exposed to F. japonica was also relevant. This result may justify the absence of ichthyotoxic events in the Italian coasts, despite F. japonica blooms detected in these areas were characterized by high cell densities. This work reports also a first complete characterization of the fatty acids produced and extracellularly released by the Adriatic F. japonica, and results were also compared with the fatty acid profile of other strains. The absence of known brevetoxins in F. japonica algal extracts was also highlighted, leading to the hypothesis that the toxicity of F. japonica may be due to a synergic effect of PUFAs and ROS.
Another microalgae that was studied in this thesis is the benthic dinoflagellate Ostreopsis cf. ovata. This species was investigated with the aim to investigate the effect of environmental parameters on its growth and toxicity. O. cf. ovata, in fact, shows different blooming periods along the Italian coasts and even the reported toxic effects are variable. The results of this work confirmed the high variability in the growth dynamic and toxin content of several Italian strains which were isolated in recent years along the Adriatic and Tyrrhenian Seas. Moreover, the effects of temperature and salinity on the behaviour of the different isolates are in good agreement with the results obtained from field surveys, which evidence as the environmental parameters are important factors modulating O. cf. ovata proliferation. Another relevant result that was highlighted is the anomaly in the production of palytoxin-like compounds reported by one of the studied isolate, in particular the one isolated in 2008 in Ancona (Adriatic Sea). Only this strain reported the absence of two (ovatoxin-b and –c) of the five ovatoxins so far known in the toxin profile and a different relative abundance of the other toxins.
The last aspect that was studied in this thesis regards the toxin biosythesis. In fact, toxins produced (palytoxin-like compounds) or supposed to be produced (brevetoxin-like compounds) by O. cf. ovata and F. japonica, respectively, are polyketides, which are highly oxygenated compounds synthesized by complex enzymes known as polyketide synthase (PKS) enzymes. These enzymes are multi-domain complexes that structurally and functionally resemble the fatty acid synthases (FASs). This work reports the first study of PKS proteins in the dinoflagellates O. cf. ovata, C. monotis and in the raphidophyte F. japonica. For the first time some PKSs were identified in these species, confirming the presence of PKS proteins predicted by the in silico translation of the transcripts found in K. brevis also in other species. The identification of O. cf. ovata PKSs and the localization of the palytoxin-like compounds produced by this dinoflagellate in a similar location (chloroplast) as that observed for other dinoflagellate and cyanobacterial toxins provides some indication that these proteins may be involved in polyketide biosynthesis. However, their potential function as fatty acid synthases cannot be ruled out, as plant fatty acid synthesis also occurs within chloroplasts. This last hypothesis is also supported by the fact that in all the investigated species, and in particular in F. japonica, PKS proteins were present. Therefore, these results provide an important contribution to the study of the polyketides and of the involvement of PKS proteins in the toxin biosynthesis.
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Neely, Tatum Elizabeth. "Differences in growth and toxicity of Karenia". Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/3979.
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Harmful algal blooms (HABs) in the Gulf of Mexico are primarily caused by dense aggregations of the dinoflagellate species, Karenia brevis. Karenia brevis produces a highly toxic neurotoxin, brevetoxin which has been shown to cause Neurotoxic Shellfish Poisoning (NSP) and respiratory distress in humans in addition to a wide range of negative impacts upon natural ecosystems. Karenia mikimotoi is a co-existing species present during K. brevis blooms. K. mikimotoi has caused major HAB events in other parts of the ocean, but has not been recognized as a major contributor to toxicity of blooms in the Gulf of Mexico. K. brevis and K. mikimotoi have both been associated with the presence of unidentified hemolytic toxins. Production of hemolysins has not previously been investigated for either species to date in the Gulf of Mexico. Presence of hemolysins may affect toxicity and the overall impact of HABs. Therefore, detection of hemolysins is imperative for accurate identification of potential harmful impacts of such blooms. The primary goal of this research is to define whether either species is capable of producing hemolytic activity independent of brevetoxin activity; and to identify if there is significant differentiation between a variety of clonal isolates regarding toxicity and growth rate when subjected to variable experimental conditions.
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Zhang, Fangzhu, i 張芳珠. "Harmful algae from container ship ballast water taken from the open ocean and from Oakland, California (May, 1996 to April, 1997)". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31220277.
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Daghighi, Amin. "Harmful Algae Bloom Prediction Model for Western Lake Erie Using Stepwise Multiple Regression and Genetic Programming". Cleveland State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=csu1502190026473106.
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Jensen, Silje-Kristin. "Are toxins from harmful algae a factor involved in the decline of harbour seal populations in Scotland?" Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7035.
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Firstly this study builds on the investigation initiated by Hall and Frame (2010), which found that Scottish harbour seals were exposed to domoic acid (DA), a potent natural neurotoxin produced by phytoplankton. Using the same sample collection technique to gather urine and faecal material from various populations around Scotland with differing population trajectories (Lonergan et al., 2007), the objective was to investigate not only exposure to DA, but also other groups of toxins such as paralytic shellfish poisoning (PSP) toxins and the lipophilic toxins okadaic acid (OA) and dinophysis toxins (DTXs). Toxins from harmful algae are thought to be potential causative factors in the on- going harbour seal decline in some regions of Scotland (Hall and Frame, 2010). This investigation was initiated because Pseudo-nitzschia (which produces DA) in particular was found to be highly prevalent in the phytoplankton communities in Scotland (Fehling et al., 2004; Stobo et al., 2008) and indeed was first observed at increased concentrations at around the time the harbour seal populations were observed as declining (Lonergan et al., 2007; Stobo et al., 2008). Prior to 2000 harbour seal populations in Scotland were largely stable or increasing. In addition DA exposure has had a devastating effect on the California sea lions (CSL) from the US west coast, where morbidity and mass mortality has occurred as a result of exposure (Goldstein et al., 2008; Gulland et al., 2002; Lefebvre et al., 1999; Scholin et al., 2000). In addition to the toxin analysis in urine and faecal samples, blood samples were collected and health parameters such as white blood cell and differential cell counts were investigated. Plasma cortisol concentrations and parasite faecal egg counts were additionally investigated as parameters indicative of adrenal function and parasite burden. CSL exposed to DA have significantly lower blood cortisol levels and higher eosinophil counts (Gulland et al., 2012) so it was possible that these indicators of effects might also be seen in the harbour seals. High parasite loads are often associated with high eosinophil levels (Klion and Nutman, 2004) so these data were needed to ensure any positive relationships found were linked to DA and were not a consequence of parasite burdens. The work presented in this thesis highlights the effect of exposure to the neurotoxin DA and documents that Scottish harbour seals are exposed to multiple toxins such as PSP toxins, OA and DTX-2 (Chapter 2, Chapter 4). Immunomodulatory effects of DA exposure such as lymphocytopenia and monocytosis are also reported. In general, harbour seals from the east coast and Northern Isles, where the decline in abundance has been greatest, had higher levels of DA in their excreta than animals from the west coast. The concentrations in the faeces and urine samples were generally low but time since exposure was unknown. Uptake of DA, PSP toxins, OA and DTXs in randomly selected fish from the east coast of Scotland in the Firth of Forth was investigated (Chapter 3), where benthic, flat and pelagic fish are shown to be vectors of toxin transfer and emphasis is drawn to flatfish as they seem to accumulate higher levels of toxins than the other species analysed. This indicates that harbour seals foraging off the east coast are likely to regularly encounter toxic prey that could impair their health. In addition to live captured harbour seals, samples from dead stranded marine mammals (including cetaceans and in particular harbour porpoise) found a range of species in Scottish waters were exposed to both DA and PSP toxins (Chapter 4). A monitoring tool to rapidly determine chronic DA exposure in blood samples was published recently for DA exposed CSLs and in Chapter 5 this monitoring technique was attempted in phocid seals, and where it failed to be replicated or validated which questions its function as a DA monitoring tool. Questions regarding how quickly a marine mammal excretes DA from the body have been discussed in the literature and in Chapter 6 an experiment was set up to measure the clearance of DA by using a biomarker (Iohexol). Iohexol was successfully measured in plasma samples from captive harbour seals following oral intake, where concentration and time of the iohexol peak was identified together with the calculation of its half-life. These results indicate the approximate elimination rate of DA (and potentially other hydrophilic toxins) and can be used to better interpret urine levels of DA measured in wild caught harbour seals. Collectively the results of this research will enable the risk posed by the ingestion of various toxins present in the Scottish marine food chain to marine mammals (particularly harbour seals but also harbour porpoise and grey seals) to be assessed.
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Marshall, Lauren Elizabeth. "Manta-inspired Robotic Platform and Filter Design for Mitigating Near-Shore Harmful Algal Blooms". University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1556733016555221.
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Paxinos, Rosemary, i paxinos rosemary@saugov sa gov au. "Dynamics of phytoplankton in relation to tuna fish farms in Boston Bay and near-shore Spencer Gulf, South Australia". Flinders University. Biological Sciences, 2007. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20081022.144704.
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Interest in the effect of fish farming practices on the marine environment has arisen because there is concern that the wastes that fish farms produce may be contributing to eutrophication in coastal areas and the problem of harmful algal blooms. The focus of this thesis is an examination of phytoplankton distribution and abundance in relation to tuna fish farms in Boston Bay and near-shore Spencer Gulf. This is the first study in South Australia to define the short-term biomass fluctuations of chlorophyll and in vivo fluorescence, identify phytoplankton species distribution and abundance, including two potentially toxic dinoflagellates, and describe patch distribution relative to tuna fish farms in Boston Bay and the near-shore waters of Spencer Gulf. An ecological interpretation of phytoplankton distribution and abundance is determined and shows that community composition was different in lower Spencer Gulf compared to Boston Bay and upper Spencer Gulf sites. Pico- and nanophytoplankton were often the most abundant organisms. Diatoms and gymnoids were most common. Season and currents predominantly influenced the distribution of phytoplankton in Boston Bay and Spencer Gulf. Individual species may be influenced by inputs from the fish farms.
Chlorophyll levels were different between the Spencer Gulf and Boston Bay sites and no differences were recorded, using mean levels of chlorophyll, between tuna cages and controls. Chlorophyll levels were higher east of Boston Island in autumn of 1999. Chlorophyll levels appeared to show a slight increase between years. This may have been an anomalous natural variation and future research may investigate this in the long term. In addition, Principal Components Analysis (PCA) was used to investigate differences between treatments and the functional grouping model supported an ecological interpretation of the factors from the PCA. A total of 131 taxa of phytoplankton were identified in this study. The 14 dominant taxa were used in the PCA and of these, 9 were diatoms. Phytoplankton abundance was not different between tuna cages and controls. However, when examining individual species, Karenia mikimotoi was more prevalent at tuna cages, close to shore, east and west of Boston Island than at other sites. PCA showed how different species bloomed together and were seasonal. Karenia brevis and K. mikimotoi featured predominantly in the PCA with K. brevis the dominant organism during summer and autumn along with Gyrodinium spp. and smaller gymnoids. K. brevis blooms were most likely influenced by water temperatures and fixation of nitrogen from a Trichodesmium erythaeum bloom. K. mikimotoi bloomed bimodally and may be influenced by ammonia excreted from fish from the tuna farms but , on the other hand, may be limited by the high salinities of South Australian waters. Currents in the region distribute both organisms.
The final aspect of this study assessed finer temporal and spatial sampling using directional transects around tuna cages and controls using in-vivo fluorescence and size fractionated chlorophyll. The chlorophyll a sampling showed little spatial variability within a site in the 1000 m2 that the sampling area covers but far greater temporal variability (days). In contrast, fluorescence `mapping' expands the window of variability both spatially (within a site) and temporally (along transects and between days). This has given a spatial definition, which is unavailable from a single point sample, and thereby leaves room for much greater interpretation. Small patches are evident from the fluorescence mapping where this is impossible to detect from the single point samples. Therefore, the fluorescence `mapping' and patch definition show that the trend is widespread (spatially) and quite persistent (temporally) around the fish farm area.
Size fractionated chlorophyll samples provided further insight into phytoplankton dynamics in this study where diatoms were favored over dinoflagellates and were responsible for the larger fraction of chlorophyll found at the tuna cage one (TC1) site. We suggest that seasonal fluctuations, high nutrient input from the farm activities and turbulence may be responsible for the different chlorophyll/fluorescent structures found at TC1. Future research may look at the long-term regional impact on phytoplankton size structure, biomass and communities from fish farm activities.
As a good part of this journey involved counting phytoplankton using the Utërmohl technique, a short paper, published in the Journal of Plankton Research, on reducing the settling time of this method, is presented in Appendix.
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Beers, Emily N. "Investigating the Effects of Temperature on the Growth and Toxin Production of Saxitoxin, Anatoxin and Cylindropsermopsin-Producing Cyanobacteria". Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1607677838514276.
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Trowbridge, Peter J. "Forecasting cyanobacteria in Lake Rockwell using historical data". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1510311070018351.
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McKindles, Katelyn M. "Parasites of harmful algal blooms: characterization of cyanophages and chytrids as top-down regulators in Lake Erie". Bowling Green State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1616505469449226.
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Vigilant, Veronica Lynn. "The occurrence of the harmful algae bloom toxin, domoic acid, in nearshore and offshore benthic communities of Monterey Bay, California /". Diss., Digital Dissertations Database. Restricted to UC campuses, 2007. http://uclibs.org/PID/11984.
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Mrdjen, Igor. "Harmful Algal Blooms in Small Lakes: Causes, Health Risks, and Novel Exposure Prevention Strategies". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531135626251706.
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Kielaszek, Andrew. "Public vs. Private Environmental Jobs: A Comparison of Job Experiences with the Maryland Department of Natural Resources and Ecology and Environment, Inc". Miami University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=miami1239628145.
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Panlilio, Jennifer Martinez. "Impacts of developmental exposures to the harmful algal bloom toxin domoic acid on neural development and behavior". Thesis, Massachusetts Institute of Technology, 2019.
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This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution), 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
Harmful algal blooms (HABs) can produce potent neurotoxins that accumulate in seafood and affect human health. One HAB toxin of concern is domoic acid (DomA), a glutamate analog produced by the marine diatom Pseudo-nitzschia spp. Current regulatory limits are designed to prevent acute neurotoxicity in adult humans. However, research shows that low-level exposure during early life can lead to long-term changes in behavior, neural connectivity, and brain morphology. To determine the underlying mechanisms of developmental toxicity, this dissertation used zebrafish as a tool to: i) Establish the developmental window of susceptibility for DomA toxicity, ii) Characterize the behavioral consequences of exposures, and iii) Identify the cellular targets and processes perturbed by DomA. I found that DomA exposure particularly at 2 days post fertilization (dpf) led to altered startle response behavior, myelination defects, and the downregulation of axonal and myelin structural genes.
Using vital dyes and immunolabeling, I assessed DomA-induced alterations in cells required for the startle response. I found no differences in the number of sensory neuromasts or in the sensory cranial ganglia structures that detect the acoustic stimuli. However, the majority of DomA-treated larvae lacked one or both Mauthner cells - hindbrain neurons critical for fast startle responses. DomA-treated larvae also had oligodendrocytes with fewer and shorter myelin sheaths, and appeared to aberrantly myelinate neuronal cell bodies. The loss of the Mauthner neurons and their axons may lead to a cellular environment where oligodendrocytes myelinate neuronal cell bodies in the absence of adequate axonal targets. Indeed, pharmacological treatment that reduced the oligodendrocyte number also led to the reduction in the number of these aberrant, myelinated cell bodies.
These results indicate that exposure to DomA at a particular period in neural development targets specific cell types, disrupts myelination in the spinal cord, and leads to prolonged behavioral deficits. These mechanistic insights support hazard assessments of DomA exposures in humans during critical periods in early development.
"Funding for my research came from the Ocean Ventures Fund, Hill family foundation, Woods Hole Sea grant NA14OAR4170074, and the Woods Hole Center for Oceans and Human Health (COHH), which is jointly funded by the National Institutes of Health (P01ES02192, P01ES028938), and the National Science Foundation (OCE-1314642, OCE-1840381). My funding came from the National Institutes of Health (NIH) P01ES021923-04S1, the Ocean Ridge Initiative Fellowship, the Von Damm Fellowship, and the MIT/WHOI Joint Program Academic Programs Office"--Page 5
by Jennifer Martinez Panlilio.
Ph. D.
Ph.D. Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution)
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Wood, Joseph. "Causes and Consequences of Algal Blooms in the Tidal Fresh James River". VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3429.
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This dissertation includes 3 chapters which focus on algal bloom of the tidal fresh James River. The first chapter describes nutrient and light limitation assays performed on algal cultures and draw conclusions about long-term patterns in nutrient limitation by comparing results with a previous study . This chapter also describes the influence of riverine discharge upon nutrient limitation in a point-source dominated estuary. This chapter was published in Estuaries and Coasts (Wood and Bukaveckas 2014). The second chapter presents the first comprehensive assessment of the occurrence of the cyanotoxin Microcystin in water and biota of the James River. Data presented in this chapter show that bivalve grazing declines in the presence of Microcystin in the water. The chapter also describes feeding habits in fish as a predictor for inter-specific differences in Microcystin accumulation in their tissues. The work presented in this chapter was published in Environmental Science & Technology (Wood et al. 2014). The third chapter describes the fate of algal carbon in the James River Estuary and the importance of autochthonous and allochthonous sources of organic matter in supporting production of higher trophic levels. Here I draw upon ecosystem metabolism data (NPP and R), abundance and grazing estimates for primary consumers and estimates of advective losses of chlorophyll and external inputs of nitrogen to place ‘top-down’ effects in the broader context of factors influencing chlorophyll and nitrogen fluxes in the James. . This chapter also describes results from mesocosm experiments used to assess the influences of grazers on chlorophyll, nutrients and Microcystis. This work will be submitted in the summer of 2014 to the journal Ecosystems.
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Townhill, Bryony Lindsey. "Marine species and climate change : using modelling techniques to investigate effects on species distributions". Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/25283.
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Anthropogenic climate change is one of the main challenges affecting the globe, with particular implications for the oceans. Marine climate change research has moved forward rapidly in recent years, and a range of physical model outputs are available that can be used by ecologists to help predict how species might be affected into the future. Policy makers require a level of understanding of how certain species and their ranges might change so that they can respond with sustainable management actions. This thesis aims to make use of a number of modelling techniques to explore implications of past and future conditions for marine species, and to appraise those tools that can be used under differing circumstances. Policy questions are answered relating to changes in the abundance and distribution of marine species. The links between historical climatic conditions and Barents Sea cod abundance are explored using Generalised Additive Models using data collected in the middle of the 20th century. This valuable historical data indicated that cod have temperature preferences and expand and shift their distributions based on environmental conditions. A simpler modelling technique is used to examine how oxygen conditions have changed in recent decades in the North Sea, how they might change in the future, and what implications this has for commercial fish species. The models show that oxygen conditions have improved recently and that they will not decrease to levels that result in large negative effects in the coming century. Species distribution modelling using a combination of global and downscaled model outputs shows that the UK will become more suitable for some non-native and harmful algal species in the 21st century, and less suitable for others. The model outputs contribute to the understanding of climate change effects and development of management tools to ensure the resilience of marine ecosystems into the future.
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Killberg-Thoreson, Lynn M. "A Tale of Two Blooms: Dynamics of Nitrogen Uptake by Harmful Algae in the Eastern Gulf of Mexico and York River, Virginia, USA". W&M ScholarWorks, 2011. https://scholarworks.wm.edu/etd/1539616713.
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The goal of this study was to determine the significance of dissolved inorganic nitrogen (DIN) and dissolved organic nitrogen (DON) to harmful phytoplankton. Two regions that experience frequent and persistent harmful algal blooms (HABs) were examined, the Eastern Gulf of Mexico and York River, Virginia. Nitrogen uptake by harmful algae in these regions was examined using a combination of stable isotopic (15N) tracer techniques and nutrient bioassays. In the Eastern Gulf of Mexico, kinetic parameters for uptake of N substrates by K. brevis were determined and indicated the greatest preference for ammonium (NH4+), although all substrates tested were taken up. Investigation of N uptake by K. brevis in the light and dark revealed periodicity of diet uptake rates with the maximum and minimum rates measured early in the light and dark periods, respectively. The highest rates of uptake were observed for NH4+. Ratios of NH4+ regeneration:uptake were ∼1, indicating the importance of regeneration processes to blooms. Three strains of K. brevis exhibited significant differences in N uptake rates. The observed nutritional flexibility of K. brevis likely helps it flourish under a range of conditions spanning bloom initiation in oligotrophic offshore waters to bloom maintenance inshore. In the York River, N uptake was dominated by NH4+ with the highest uptake rates at all stations, for all size fractions and for all seasons, ranging from 34 to 80% of total absolute uptake. Rates of N uptake by A. monilatum are the first reported for this species in the York River, and demonstrate uptake of a diverse suite N substrates. During the A. monilatum bloom NH4+ regeneration rates equaled those of uptake, indicating the importance of regeneration to blooms. Additionally, three anthropogenic N sources were used to assess their role in exacerbation of a HAB during a 7 day bioassay. Urban parking lot run-off (+ Urban), soil from a construction site (+ Soil) and paper mill run-off (+ Industrial) were added to a natural bloom assemblage. Results indicated the anthropogenic sources had unique N compositions; DIN comprised ∼9%, 91% and 20% of + Urban, + Soil, and + Industrial, respectively. All N sources stimulated the growth of phytoplankton with the + Urban and + Soil treatments eliciting the greatest response, a doubling in Chl a and/or cell concentrations along with nutrient drawdown of both DIN and DON within two days. The results of this dissertation emphasize the importance of a flexible metabolism to the success of the HAB species investigated here. All harmful phytoplankton studied were able to utilize the variety of DIN and DON sources supplied. Additionally, a universal preference for NH4+ was observed in all studies despite the distinct regions examined and unique characteristics of each species.
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Karasiewicz, Stéphane. "The phytoplankton community response(s) to global changes and their effect(s) on ecosystem functioning with a special focus on Phaeocystis spp, a harmful algae". Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10191/document.
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Les écosystèmes côtiers, interface entre terre et mer, sont soumis au changement climatique ainsi qu’à de fortes pressions anthropiques. Par conséquent, les eaux côtières sont sujettes à eutrophisation. Le phytoplancton demande une attention particulière dû à son rôle de producteur primaire des écosystèmes marins. Récemment, l’efflorescence des algues nuisibles est devenue mondialement, une inquiétude croissante. Le but de la thèse a été de décrire et de mesurer les réponses temporelles et les causalités de la structure de communauté phytoplanctonique sous impact des changements globaux, en présence d’une algue nuisible. Pour ce faire, le concept de niche écologique et une méthode statistique, ont été adaptés. Les "Within Outlying Mean Indexes" ont été proposés pour affiner l’analyse "Outlying Mean Index" en combinant ses propriétés avec la décomposition de la marginalité de l’analyse "K-select". Les dynamiques des sous-niches de la communauté d’espèce ont été étudiées dans des conditions environnementales d’ abondances basses (L) ou fortes (H) de Phaeocystis spp. Le sous-ensemble H était caractérisé par une large niche de Phaeocystis spp. ainsi qu’une forte diversité de diatomées. Dans le sous-ensemble L, Phaeocystis spp. a subit une forte contrainte biologique probablement induite par la compétition des diatomées pour les ressources. La relation diversité-productivité du phytoplancton s’est avérée plus forte à l’échelle saisonnière que sur le long-terme. Le déséquilibre des ressources n’a pas eu de lien direct avec la productivité à long terme. Le succès à long terme de l’espèce invasive et de son impact sur la productivité, est favorisé par une suite d’années froides avec des ressources élevées et déséquilibrées, augmentant le nombre de petites espèces de diatomées et donc son efflorescence. Enfin, je discute des améliorations méthodologiques, du potentiel d’utilisation de l’approche par traits, et d’éventuelles montages expérimentaux pour supporter les résultats de la thèseCoastal ecosystems, the interfaces between land and sea, are subject to climate change and high anthropogenic pressure. Consequently, most coastal waters are prone to eutrophication. The phytoplankton require a special attention because of its role of primary producer in marine ecosystems. Recently, Harmful Algae Bloom outbreaks has raised concern worldwide. The thesis aim was to describe and to measure the temporal responses and causalities of the phytoplankton community structure, with the occurrence of a harmful algae, under global changes. To do so, the ecological niche concept and a statistical method were adapted. The Within Outlying Mean Indexes was proposed to refine the Outlying Mean Index analysis by combining its properties with the K-select analysis species marginality decomposition. The subniche dynamics of the species composing the community were studied under environmental conditions hosting low (L) and high (H) Phaeocystis spp. abundance. Subset H was characterized by a large Phaeocystis spp. niche and a high diatom diversity. In subset L, Phaeocystis spp. was subject to great biological constrain suspected to be caused by diatom competition for resources. The phytoplankton diversity productivity was stronger at a seasonal scale than on the long-term. The resource imbalance had no direct link with productivity in the long-term. The long-term invasive species success and its impact on productivity is favored by successive cold years with high resource imbalance which rise the number of small species and its bloom. I finally discussed on the methodological improvements, the potential use of the trait-based approach, and possible experimental set-ups to support the thesis results
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Rieseberg, Ashley. "Holistic approach to the evaluation of the anthropocentric influence on domoic acid production and the corresponding impact on the California Sea Lion (Zalophus californianus) population". Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-179182.
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Domoic acid (DA) is a neurotoxin produced by the harmful algae Pseudo-nitzschia that has been directly linked to mass stranding events of the California Sea Lion (CSL). The purpose of this paper is to review the anthropogenic influence on the production of this neurotoxin and examine how human activities are impacting this marine mammal species. A comprehensive and interdisciplinary literature review was conducted to evaluate the future sustainability of the CSL population. It was found that while Pseudo-nitzschia bloom developments are vulnerable to anthropogenic influences, the incontestable existence of natural contributing factors adds a certain complexity to the determination of causalities and the development of solutions. Strong evidence exists to show that DA can cause major and irreversible neurological damage in CSLs. Rehabilitation of DA-impacted CSLs is a polarizing issue in the U.S. and presents interesting implications for sustainable development. While the CSL population is currently healthy and plenteous, the strong abundance of future uncertainties warrants concern. A balance must be found between the involving social, economic, and environmental factors to ensure a promising future for the CSL species.
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Leverone, James R. "Comparative effects of the toxic dinoflagellate, Karenia brevis, on bivalve molluscs from Florida". [Tampa, Fla] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0001870.
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Delaney, Jennifer A. "Molecular Detection of the Toxic Marine Diatom Pseudo-nitzschia multiseries". Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3558.
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The marine diatom genus Pseudo-nitzschia includes species that produce domoic acid, a neurotoxin responsible for illness and mortality in both humans and marine wildlife. Because of the expertise and time required for the microscopic discrimination of species, molecular methods that monitor environmental concentrations of Pseudo-nitzschia provide a rapid alternative for the early detection of blooms and prediction of toxin accumulation. We have developed a nucleic acid sequence-based amplification with internal control RNA (IC-NASBA) assay and a quantitative reverse transcription PCR (qRT-PCR) assay for the detection of the toxic species P. multiseries targeting the ribulose- 1,5-biphosphate carboxylase/oxygenase small subunit (rbcS) gene. Both methods use RNA amplification and fluorescence-based real-time detection. Due to a limited rbcS sequence database, primers were designed and used to sequence this gene from 14 strains of Pseudo-nitzschia (including four P. multiseries) and 19 other marine diatoms. The IC-NASBA and qRT-PCR assays had a limit of detection of one cultured cell of P. multiseries and were linear over four and five orders of magnitude, respectively (r2 ! 0.98). Neither of the assays detected closely related organisms outside the Pseudo-nitzschia genus, and the qRT-PCR assay was specific to P. multiseries. While cross-reactivity of primers with unknown species prevented reliable detection of P. multiseries in spiked environmental samples using IC-NASBA, the qRT-PCR assay had positive detection from 107 cells/L to 103 cells/L. Nearly a 1:1 relationship was observed between predicted and calculated cell concentrations using qRT-PCR. Based on a diel expression study, the rbcS transcript copy number per cell ranged from 2.16 x 104 to 5.35 x 104, with the highest expression during early to mid photoperiod. The rbcS qRT-PCR assay is useful for the detection and enumeration of low concentrations of P. multiseries in the environment.
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Garrett, Matthew. "Influence of Water Column Stratification and Nutrient Gradients on the Migratory Behavior of the Red Tide Dinoflagellate, Karenia brevis". Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5950.
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Diel vertical migration (DVM) can offer motile phytoplankton a competitive advantage over other phytoplankton species. DVM has been well documented in the harmful dinoflagellate, Karenia brevis; however, the extent to which changes in nutrient regimes and density stratification modify migration patterns has not been thoroughly investigated. A 2 m experimental column was constructed with sensors and sampling ports at four depths to obtain fluorescence and temperature measurements and discrete water samples. The environmental parameters of the experimental column represented temperature and nutrient conditions found on the West Florida Shelf (WFS), where Karenia blooms frequently occur. Results demonstrated a clear DVM pattern for K. brevis where surface aggregations occurred during light periods, and bottom aggregations occurred in dark periods. However, the rate and intensity of migration varied between experimental conditions. Injections of nutrient replete water at the surface and bottom did not appear to modify migratory behavior, in that a portion of the population resided at depth regardless of light or dark periods. Weak density stratification caused a delay in downward migration in dark periods, whereas strong density stratification caused a complete cessation of downward migration. In a weakly stratified environment with a bottom injected replete water mass, DVM patterns most closely replicate the pattern under weakly stratified conditions alone. Modifications in the natural DVM pattern of K. brevis with respect to varying environmental and nutrient conditions that occur on the WFS can have major implications current forecast model predictions, and for monitoring and mitigation strategies.
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Payton, Laura. "Chronobiologie moléculaire et comportementale des huîtres Crassostrea gigas diploïdes et triploïdes exposées à l'algue toxique Alexandrium minutum". Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0613/document.
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Les efflorescences de la micro-algue toxique Alexandrium minutum sont en constante augmentation au niveau mondial, accentuées par les apports anthropiques et le réchauffement global, et posent des problèmes écologiques, économiques et sanitaires. Lors d’une exposition à A. minutum, l’accumulation des phycotoxines paralysantes (PSP) dans les tissus semble être différente entre les huîtres diploïdes et triploïdes. Par ailleurs, de nombreuses fonctions physiologiques de l’huître C. gigas sont impactées. L’ensemble des fonctions physiologiques d’un organisme est régulé par des rythmes biologiques. Propriété fondamentale de la vie, les rythmes biologiques permettent aux organismes de se synchroniser et d’anticiper les variations cycliques de l’environnement. Dans mes travaux, je me suis intéressée aux rythmes biologiques des huîtres diploïdes et triploïdes C. gigas et à leurs interactions avec la contamination par les PSP. Une analyse in situ sur un an a mis en évidence une relation jusque-là inconnue entre le comportement valvaire de C. gigas et le cycle d’éclairement de la lune, ainsi qu’une relation fine et subtile des cycles comportementaux nycthéméraux et tidaux avec l’évolution annuelle de la photopériode. Cette relation est modulée par la ploïdie. Par ailleurs, la mise au point d’une approche non-invasive d’interférence par ARN a permis de mettre en évidence l’implication de l’horloge circadienne dans les processus de bioaccumulation des PSP chez C. gigas. Enfin, l’analyse du transcriptome cyclique dans les branchies de C. gigas a mis en évidence qu’au moins 42 % du transcriptome peut être exprimé de façon oscillante. Contre intuitivement, en condition d’alternance jour / nuit, une majorité de transcrits sont ultradiens, trois fois plus nombreux que les transcrits circadiens. Exposées à A. minutum, les huîtres ont montré un remodelage profond de leur transcriptome cyclique, pouvant entraîner la perte de synchronisation de l’huître avec son environnementHarmful algal blooms of Alexandrium minutum are constantly increasing at the global level, accentuated by anthropogenic contributions and global warming, causing ecological, economical and sanitary problems. During exposition to A. minutum, paralytic phycotoxins (PSP) accumulation differs between diploid and triploid oysters. Moreover, many physiological functions of the oyster C. gigas are impacted. All physiological functions of an organism are regulated by biological rhythms. As a fundamental property of life, biological rhythms allow organisms to synchronize and anticipate cyclic variations of the environment. In my work, I was interested in the biological rhythms of diploid and triploid oysters C. gigas, and their interactions with PSP contamination. A one-year in situ analysis revealed a previously unknown relationship between valve behavior of C. gigas and the lunar illumination cycle, as well as a fine and subtle relationship of the nycthemeral and tidal behavioral cycles with the annual evolution of the photoperiod. This relationship was modulated by the ploidy. Moreover, the development of a non-invasive approach of RNA interference revealed the involvement of the circadian clock in bioaccumulation processes of PSPs in C. gigas. Finally, analysis of the cyclic transcriptome in the gills of C. gigas showed that at least 42 % of the transcriptome can oscillate. Surprisingly, in day / night entrainment, most of transcripts were ultradians, three times more abundant than circadian transcripts. Exposed to A. minutum, results showed a profound remodeling of the cyclic transcriptome of C. gigas, which could lead to loss of synchronization of the oyster with its environment
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Howard, Lucas Margiotta. "Nutrient Loading from the Maumee River to Lake Erie". Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1557246987101065.
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Fontana, Isabella. "Propostas para o sistema de vigilância de moluscos bivalves de Santa Catarina". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/10/10134/tde-27092016-145251/.
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Moluscos bivalves são organismos filtradores capazes de concentrar susbtâncias produzidas por microalgas tóxicas. No estado de Santa Catarina, líder na produção nacional, os cultivos têm sido oficialmente monitorados para a detecção de ficotoxinas causadoras dos Envenenamentos Diarreico (DSP), Amnésico (ASP) e Paralisante (PSP) por Consumo de Moluscos nas partes comestíveis. Amostras de água também são coletadas para a quantificação de algas nocivas. O objetivo deste trabalho foi sugerir o uso de áreas amostrais para coletas semanais, bem como calcular o tamanho das amostras agrupadas e analisar os dados de ocorrência. Diferentes cenários foram desenvolvidos para simular a variação dos tamanhos amostrais, utilizando-se o EpiTools®. Considerando-se uma alta prevalência e altas sensibilidades dos testes, é possível sugerir dois pools amostrais para a detecção de Toxinas Lipofíficas (2x30), duas para detectar PSP (2x15) e uma para detectar ASP (1x20) em cada uma das 24 áreas amostrais sugeridas. Se o teste de Cromatografia Líquida com Espectrometria de Massa (LC-MS/MS) for validado para todas as biotoxinas, apenas um pool amostral seria suficiente (1x15). Informações espaçotemporais de ocorrência também foram analisadas e apenas ficotoxinas causadoras de DSP foram encontradas. Utilizando-se os softwares SaTScan® e QGIS 2.12.2- Lyon®, foram desenvolvidos mapas de calor com os dois clusters espaciais encontrados para as detecções de DSP em moluscos e os quatro para Dinophysis acuminata (≥100cels/L) em amostras de água. Os resultados com maiores riscos relativos corresponderam ao cluster temporal do segundo semestre de 2014, os clusters espaciais das áreas 7 a 11 para DSP e áreas de 7 a 9 para D. acuminata. Esses resultados poderão contribuir para o planejamento de estratégias a serem incorporadas num futuro sistema de vigilância de moluscos bivalves do estado.Bivalve molluscs are filtering organisms capable to concentrate substances produced by toxic microalgae. In Santa Catarina state, main Brazilian producer, the crops have been officially monitored for the detection of phycotoxins that cause Diarrheic (DSP), Amnesic (ASP), and Paralyzing (PSP) Shellfish Poisonings in edible parts. Water samples are also collected for harmful algae quantification. The goal of this study was to suggest the use of areas to be weekly sampled, as well as to calculate pooled sample sizes and to analyze the occurrence data. Different scenarios were developed to simulate the variation of sample sizes in EpiTools®. Considering a high prevalence and high tests sensitivities, we can suggest two pools to detect Lipophilic Toxins (2x30), two to detect PSP (2x15), and one to detect ASP (1x20) in each of the 24 suggested sampling areas. If the test of Liquid Chromatography with Mass Spectrometry (LC-MS/MS) becomes validated for all biotoxins, only one pool would be enough (1x15). Space-time occurence information was also analyzed and only phycotoxins causing DSP were found. Using SaTScan® and QGIS 2.12.2-Lyon® softwares, we developed heatmaps with two clusters found for DSP detection in shellfish and the four found for Dinophysis acuminate (≥100cels/L) in water samples. The results with higher relative risk values corresponded to the time cluster of the second semester of 2014, spatial cluster of the areas 7 to 11 for DSP, and areas 7 to 9 for D. acuminate. These results can contribute for the strategic plans to be incorporated in a future bivalve molluscs surveillance system of the state.
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Nauman, Callie A. "The Spatial and Temporal Distribution and Environmental Drivers of Saxitoxin in Northwest Ohio". Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1589644025246293.
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Black, Edward Adam. "Differentiation of morphology and toxicity in harmful algal blooms caused by the raphidophyte alga Heterosigma akashiwo". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0019/NQ52753.pdf.
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Hogfors, Hedvig. "Summer cyanobacterial blooms in the Baltic Sea - implications for copepod recruitment". Doctoral thesis, Stockholms universitet, Systemekologiska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-81680.
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During summer, the Baltic Sea is subjected to the world’s largest cyanobacterial blooms. These blooms are linked to eutrophication and raise many questions concerning their effects on the ecosystem. To understand their impacts on the food web dynamics, it is essential to assess growth responses of grazers to these cyanobacteria. In the northern Baltic proper, copepods are the most important herbivores providing an essential link between the primary producers and higher trophic levels. In this Thesis, Papers I & II evaluate methods to estimate copepod growth in response to feeding conditions in situ. The most conspicuous diazotrophic filamentous cyanobacterium in the Baltic Sea is Nodularia spumigena, a producer of nodularin which is highly toxic to vertebrates, yet its ecological role is largely unknown. In Paper III, reciprocal interactions between cyanobacteria, sympatric algae and copepods are studied. The results suggest that nodularin is likely involved in allelopathic interactions, but it is not an inducible defense against grazers. Furthermore, the results of Papers IV & V, indicate that natural assemblages of N. spumigena and Anabaena spp. may support copepod reproduction and that total diazotrophic filamentous cyanobacteria appear to provide a beneficial feeding environment for the feeding stages of copepod nauplii, most probably by stimulating the microbial communities that nauplii feed upon. Since cyanobacterial blooms are projected to increase due to global climate change, the combined effects of toxic cyanobacteria, ocean acidification and global warming predicted for year 2100 are further investigated on copepods in Paper IV. Taken together, these studies indicate that filamentous diazotrophic cyanobacteria contribute to sustaining secondary productivity and have potential implications of management practices with respect to combating eutrophication, global climate change and sustaining fish feeding conditions.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.
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Fontana, Isabella. "Propostas para o sistema de vigilância de moluscos bivalves de Santa Catarina". Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3421910.
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Bivalve molluscs are filtering organisms capable to concentrate substances produced by toxic microalgae. In Santa Catarina state, main Brazilian producer, the crops have been officially monitored for the detection of phycotoxins that cause Diarrheic (DSP), Amnesic (ASP), and Paralyzing (PSP) Shellfish Poisonings in edible parts. Water samples are also collected for harmful algae quantification. The goal of this study was to suggest the use of areas to be weekly sampled, as well as to calculate pooled sample sizes and to analyze the occurrence data. Different scenarios were developed to simulate the variation of sample sizes in EpiTools®. Considering a high prevalence and high tests sensitivities, we can suggest two pools to detect Lipophilic Toxins (2x30), two to detect PSP (2x15), and one to detect ASP (1x20) in each of the 24 suggested sampling areas. If the test of Liquid Chromatography with Mass Spectrometry (LC-MS/MS) becomes validated for all biotoxins, only one pool would be enough (1x15). Space-time occurence information was also analyzed and only phycotoxins causing DSP were found. Using SaTScan® and QGIS 2.12.2-Lyon® softwares, we developed heatmaps with two clusters found for DSP detection in shellfish and the four found for Dinophysis acuminata (≥100cels/L) in water samples. The results with higher relative risk values corresponded to the time cluster of the second semester of 2014, spatial cluster of the areas 7 to 11 for DSP, and areas 7 to 9 for D. acuminate. These results can contribute for the strategic plans to be incorporated in a future bivalve molluscs surveillance system of the state.I molluschi bivalvi sono organismi filtratori capaci di concentrare sostanze prodotti da microalghe tossiche. Nello stato di Santa Catarina, il più grande produttore in Brasile, le coltivazioni sono ufficialmente monitorate tramite il rilevamento di ficotossine che causano le Sindromi di avvelenamento Diarroico (DSP), Amnesico (ASP) e Paralitico (PSP) da consumo di bivalvi nelle parti commestibili. Campioni di acqua sono stati anche raccolti per la quantificazione di alghe tossiche. L’obiettivo di questo studio è di suggerire l’uso di aree per campionamenti settimanali oltre che calcolare le dimensioni dei campioni aggregati ed analizzare i dati di occorrenza. Sono stati sviluppati diversi scenari per simulare la variazione delle dimensione campionarie, utilizzando EpiTools®. Con valori elevati di prevalenza e sensibilità dei test diagnostici, è possibile suggerire due campioni aggregati per il rilevamento di tossine lipofiliche (2x30), due per PSP (2x15) e uno per ASP (1x20) in ciascuna delle 24 aree campionarie suggerite. Con la validazione della cromatografia liquida con spettrometria di massa (LC-MS/MS) per tutte le biotossine, solo un campione aggrupato sarà sufficiente (1x15). Solo ficotossine che causano DSP sono state trovate sulla base delle informazione spazio-temporale di occorrenza. Con i software SaTScan® e QGIS 2.12.2-Lyon®, mappe di calore sono state sviluppate con i due cluster spaziali trovati per DSP in molluschi e i quattro cluster trovati per Dinophysis acuminata (≥100 cellule/L) in campioni di acqua. I risultati con valori più elevati di rischio relativo sono corrispondenti al cluster temporale del secondo semestre del 2014, al cluster spaziale delle aree 7 a 11 per DSP e alle aree 7 a 9 per D. acuminata. Questi risultati possono contribuire alla pianificazione di strategie ad essere incorporate in un futuro sistema di sorveglianza di molluschi bivalvi del suddetto Stato.
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Lowry, David S. "In Vitro Trial of Lake Guard Copper-Based Algaecide Efficacy inManaging Algal Blooms Using Field Sampled Organisms". University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619784878084637.
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Li, Shuo. "Interactions of Toxic Metals with Algal Toxins Derived from Harmful Algal Blooms". FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/478.
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The purposes of this study were to characterize the complexation of toxic metals with algal toxins and to determine the effects of arsenic and copper on the growth of Karenia brevis under specific experimental conditions.
Microcystins, pahayokolides, brevetoxins and okadaic acid were used as representatives of algal toxins while arsenic, copper, cadmium, cobalt, iron, manganese and mercury were selected as typical toxic metals (including metalloids here) in the aquatic environment. The stabilities of the toxin-metal complexes were determined using equilibrium dialysis and/or centrifugal ultrafiltration technique. A direct exposure of arsenic and copper to the K. brevis was carried out to determine the effects of these metals to the growth of the algal cell.
The results indicated that Cu2+, Hg2+, Co2+, Cd2+ and Fe2+ were capable of complexing with the algal toxins. Moreover, the exposure experiments demonstrated that the high concentration of arsenic and copper could affect the growth of the K. brevis.
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Bernard, Stewart. "The bio-optical detection of harmful algal blooms". Doctoral thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/6461.
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Includes bibliographical references (p. 176-188).An analytical framework for the simulation and quantitative interpretation of ocean colour data is presented, providing an inverse reflectance algorithm designed for the detection of harmful algal blooms. The adopted framework focuses on establishing quantitative relationships between optically important algal intracellular properties and inherent optical properties (IOPs), such as the absorption and backscattering coefficients, and the resultant effects on remote-sensing reflectance. A principal aim of the study is to establish the determinant variables of the IOPs associated with natural algal assemblages, and provide a means of simulating these IOPs. Algal size is an important determinant of optical properties, and the study demonstrates algal IOP simulation, using equivalent particle size distributions that can be simply parameterised with regard to effective cell diameter. Statistical analyses of causal variability are also conducted on absorption data from a variety of natural algal assemblages, revealing the relative importance of cell size, intracellular Chi a concentration, and accessory pigment complement. An improved understanding of algal angular scattering is regarded as key to the analytical modelling of ocean colour, and the use of two-layered spherical models for the simulation of algal scattering properties is investigated. Preliminary validation of the combined use of the equivalent size and two-layered models indicates that they are capable of adequately simulating the remote-sensing reflectance properties of high biomass bloom waters.
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Schroeder, Adam. "Mitigating Harmful Algal Blooms using a Robot Swarm". University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo154444245336465.
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