Harmful algal blooms

Outbreaks of the dinoflagellate Alexandrium catenella have caused significant economic losses to the salmon industry in the south of Chile. However, the precise ichthyotoxic mechanism by this paralytic shellfish toxin (PST) – producing dinoflagellate remains poorly understood. The rainbow trout cell line RTgill-W1 assay was used to investigate fish gill damage by multiple A. catenella strains under different environmental conditions, and potency of whole cells, lysed cells and culture medium were compared. Cytotoxic potency was highly variable among strains and strongly correlated to dinoflagellate cell- abundance. Lysed cells produced more gill damage than intact cells and supernatant, reducing gill cell viability down to 20% of controls at 4000 cells mL􏰀1. However, gill cells exposed to pure PST fractions (C1&C2, STX, GTX 1&4) exhibited only very limited loss of viability (<30%), even at cell concentrations equivalent to exceeding those detected in southern Chilean fjords. A. catenella lytic compounds rapidly (1–4 days) degraded in the light, but were pH (7–9) and temperature stable (17–85 8C), thus arguing against the involvement of proteinaceous compounds. Superoxide production by Chilean dinoflagellate strains was as high as by the raphidophyte Chattonella marina (max. 8.67 􏰂 0.14 pmol O2􏰀 cell􏰀1 h􏰀1), variable among strains and enhanced by cell disruption and environmental stress (low nutrients, low salinity, low or high pH). Fatty acid profiles included high concentrations of the long-chain (􏰃C20) polyunsaturated fatty acids (PUFA) – docosahexaenoic acid (DHA, 22:6v3; 16–20% of total fatty acids) in addition to several other PUFA, which were highly cytotoxic against gill cells as a purified fraction (LC50 1.30 mg mL􏰀1). In addition, potency was enhanced 9-fold in combination with superoxide anion (LC50 0.15 mg mL􏰀1). In conclusion, the present study demonstrates that fish gill damage during A. catenella fish-kill events in Chilean fjords cannot be explained by PST toxins, but can to a large extent be accounted for by the synergistic interaction between ROS (superoxide anion) and DHA, and potentially other PUFA, notably under conditions that promote cell lysis.

Macroalgal blooms may lead to dramatic changes in physicochemical variables and biogeochemical cycling in affected waters. However, little is known about the effects of macroalgal blooms on marine bacteria, especially those functioning in nutrient cycles. We measured environmental factors and investigated bacterial diazotrophs in two niches, surface waters that were covered (CC) and non-covered (CF) with massive macroalgal canopies of Ulva prolifera, in the Yellow Sea in the summer of 2011 using real-time PCR and clone library analysis of nifH genes. We found that heterotrophic diazotrophs (Gammaproteobacteria) dominated the communities and were mostly represented by Vibrio-related phylotypes in both CC and CF. Desulfovibrio-related phylotypes were only detected in CC. There were significant differences in community composition in these two environments (p < 0.001) and a much higher abundance of nifH in CC (4.55 x106 copies l-1) than in CF (2.49 x106 copies l-1). The nifH copy number was inversely related to concentrations of ammonium and dissolved inorganic nitrogen and to the stoichiometric ratios of N:P and N:Si. This indicates that macroalgal blooms significantly affect diazotrophic abundance and community composition and that vibrios and Desulfovibrio-related heterotrophic diazotrophs adapt well to the (N-rich but P-limited) environment during blooming. Potential ecological and microbiological mechanisms behind this scenario are discussed.

50-day's free access https://authors.elsevier.com/a/1dnnLB8ccr0ST ........................................................................................................................................... Cyanobacteria are notorious for producing harmful algal blooms that present an ever-increasing serious threat to aquatic ecosystems worldwide, impacting the quality of drinking water and disrupting the recreational use of many water bodies. Remote sensing techniques for the detection and quantification of cyanobacterial blooms are required to monitor their initiation and spatiotemporal variability. In this study, we developed a novel semi-analytical approach to estimate the concentration of cyanobacteria-specific pigment phycocyanin (PC) and common phytoplankton pigment chlorophyll a (Chl a) from hyperspectral remote sensing data. The PC algorithm was derived from absorbance-concentration relationship, and the Chl a algorithm was devised based on a conceptual three-band structure model. The developed algorithms were applied to satellite imageries obtained by the Hyperspectral Imager for the Coastal Ocean (HICO™) sensor and tested in Lake Kinneret (Israel) during strong cyanobacterium Microcystis sp. bloom and out-of-bloom times. The sensitivity of the algorithms to errors was evaluated. The Chl a and PC concentrations were estimated with a mean absolute percentage difference (MAPD) of 16% and 28%, respectively. Sensitivity analysis shows that the influences of backscattering and other water constituents do not affect the estimation accuracy of PC (~2% MAPD). The reliable PC/Chl a ratios can be obtained at PC concentrations above 10 mg m−3. The computed PC/Chl a ratio depicts the contribution of cyanobacteria to the total phytoplankton biomass and permits investigating the role of ambient factors in the formation of a complex planktonic community. The novel algorithms have extensive practical applicability and should be suitable for the quantification of PC and Chl a in aquatic ecosystems using hyperspectral remote sensing data as well as data from future multispectral remote sensing satellites, if the respective bands are featured in the sensor.

In addition to answering Hutchinson's question ''Why are there so many species?'', we need to understand why certain species are found only under certain environmental conditions and not others. Trait-based approaches are being increasingly used in ecology to do just that: explain and predict species distributions along environmental gradients. These approaches can be successful in understanding the diversity and community structure of phytoplankton. Among major traits shaping phytoplankton distributions are resource utilization traits, morphological traits (with size being probably the most influential), grazer resistance traits, and temperature responses. We review these trait-based approaches and give examples of how trait data can explain species distributions in both freshwater and marine systems. We also outline new directions in trait-based approaches applied to phytoplankton such as looking simultaneously at trait and phylogenetic structure of phytoplankton communities and using adaptive dynamics models to predict trait evolution.

Dinoflagellates of the genus Alexandrium are photosynthetic microalgae that have an extreme importance due to the impact of some toxic species on shellfish aquaculture industry. Alexandrium catenella is the species responsible for the production of paralytic shellfish poisoning in Chile and other geographical areas. We have constructed a cDNA library from midexponential cells of A. catenella grown in culture free of associated bacteria and sequenced 10,850 expressed sequence tags (ESTs) that were assembled into 1,021 contigs and 5,475 singletons for a total of 6,496 unigenes. Approximately 41.6% of the unigenes showed similarity to genes with predicted function. A significant number of unigenes showed similarity with genes from other dinoflagellates, plants, and other protists. Among the identified genes, the most expressed correspond to those coding for proteins of luminescence, carbohydrate metabolism, and photosynthesis. The sequences of 9,847 ESTs have been deposited in Gene Bank (accession numbers EX 454357–464203).

The Raphidophycean Fibrocapsa japonica Toriumi & Takano was detected for the first time offshore in the Eastern Alboran Sea (Western Mediterranean) in October 2006. Its distribution appeared very localised and atypical, as it was abundant in the open waters of a cyclonic eddy. Microscope counts of the natural phytoplankton assemblages revealed that F. japonica was dominant in the microplankton, together with Dinophyceae, within and below the cyclonic nutrient-rich dome (25 -30 m). Bacillariophyceae were the primary microplanktonic fraction in only a few samples on the edges of the eddy. Moderately high abundances of F. japonica (maximum of 60 cells ml -1 ), with preliminary cysts and many cells aggregated in mucous nets, indicated a senescent phase. Despite the Atlantic origin of the cyclonic water masses, the molecular identification and the water temperature of 15 °C, which could have favoured pre-cyst formation, would suggest a Mediterranean source for F. japonica cells. Finally, we hypothesise that F. japonica, which is generally a coastal species, could have a coastal origin. In fact, F. japonica was mainly detected at a depth of 40-60 m at the coastal sites and at 25-30 m at the cyclonic dome. F. japonica generally being a coastal species, it can be hypothesised that it was entrapped by the cyclonic eddy, which typically detaches from the coastal waters, and thus carried offshore to the cyclonic waters.

This report of A. catenella is important due to the following issues;
· it shows a northward expansion of
the species range
· it is the first record of the species in
SE Pacific coastal oceanic waters, off Chiloé Island.
This new distribution of A. catenella suggests cell transport to inland waters through the Chacao Channel. Cells can reach Chiloé waters and further north, not only from the fjords and channels south of 43o S, but also from water masses of coastal oceanic origin.

Harmful algal blooms (HABs) have been documented along the coasts of India and the ill effects felt by society at large. Most of these reports are from the Arabian Sea, west coast of India, whereas its counterpart, the Bay of Bengal (BOB), has remained unexplored in this context. The unique characteristic features of the BOB, such as large amount of riverine fresh water discharges, monsoonal clouds, rainfall, and weak surface winds make the area strongly stratified. In this study, 19 potentially harmful species which accounted for approximately 14% of the total identified species (134) of dinoflagellates were encountered in surface waters of the BOB during November 2003 to September 2006. The variations in species abundance could be attributed to the seasonal variations in the stratification observed in the BOB. The presence of frequently occurring HAB species in low abundance (≤40 cell L −1 ) in stratified waters of the BOB may not be a growth issue. However, they may play a significant role in the development of pelagic seed banks, which can serve as inocula for blooms if coupled with local physical processes like eddies and cyclones. The predominance of Ceratium furca and Noctiluca scintillans, frequently occurring HAB species during cyclone-prone seasons, point out their candidature for HABs.

The report presents a review of the studies on cyanoprokaryotes from Bulgarian coastal wetlands carried out in the period 1890-2017. The biodiversity of cyanoprokaryotes in coastal water basins (their phytoplankton and phytobenthos) was evaluated and analyzed by wetlands types with emphasis on the new and peculiar taxa described. The conservation status of the recorded species follows the Red List of Bulgarian microalgae. Special attention is paid to the occurrence of cyanoblooms, cyanotoxins and toxic species, as well as to the invasive and alien species.

''Red tide'' has become a familiar shorthand for unusual changes in the color of ocean waters. It is intimately related both to blooms of creatures like dinoflagellates and to the devastating effects they pose to coastal fisheries. This essay tracks the early twentieth century emergence of discolored water as an aquacultural problem, known in Japan as akashio, and its trans-oceanic transformation into the terms and practices of ''red tide'' in the post-World War II United States. For Japan's ''Pearl King'' Mikimoto Kokichi and his contacts in diverse marine scientific communities, the years-long cycle of guarding and cultivating a pearl oyster went together with the ascription of moral qualities to tiny creatures that posed a threat to farmed bayscapes of pearl monoculture. As akashio, discolored water went from curiosity to marine livestock pest, one that at times left dead pearl oysters in its wake. Red tide arose from the sustained study of the mechanisms by which changes in the biological and chemical composition of seawater might become deadly to exclusively-claimed shellfish along Japanese coastlines, but came to be seen as a way to understand aquatic manifestations of harm in other parts of the littoral world.

This paper examines normative and political aspects of the peer review, scientific consensus and public policy processes related to harmful algal blooms of Pfiesteria in estuarine waters of North Carolina and Maryland in the 1990s. After laying out a brief science and policy case history, the tension between the scientific consensus and public policy processes in this case is analyzed in terms of conflicts between scientific norms, public values and political expediency. The relationship between scientific consensus and public policy in general is then questioned in light of this case.

The called Harmful Algal bloom (HAB) is a natural phenomenon produced by an input of nutrients to the water that is being very extended in many water bodies worldwide. In this project, we focus on the HAB that the Mar Menor lagoon, located in Region of Murcia’s coastline, suffered in 2015-2016, which led to its environmental collapse.
As several pieces of research have proved, HABs imply important socioeconomic costs to the surrounding areas of the water bodies affected. Thus, we aim to analyse the economic impact that the Mar Menor’s HAB could have had on their surrounding municipalities. For doing so, after making a brief descriptive analysis of some socioeconomic variables, we apply two different methodologies.
First, we conduct a survey within four Mar Menor’s municipalities to analyse the population knowledge about this event, the impact on the frequency of going to Mar Menor’s beaches, economic gains, consumption, and welfare. Second, we apply the difference in differences (DiD) method by running a linear regression through Stata to assess the impact that it had on Social Security affiliations for three municipalities.
As a result, we get from the survey a generalized high knowledge about the Mar Menor’s HAB of 2015-2016, and a lower frequency of going to Mar Menor’s beaches. However, these figures are different for impact on economic gains and consumption: More than a half affirm that it affected a bit or nothing to their economic gains and almost a half declare that they consumed the same or more after the Mar Menor’s HAB. Considering the DiD estimates, we get that the effect on Social Security affiliations was negative (around 900 and 1000 affiliations less in general) for three different samples, but these results are only significant for two of our three samples used. Moreover, our estimates are very imprecise due to high standard errors, which shows a need for larger samples.

The growth and toxin production of a Philippine  Pyrodinium bahamense isolate in nutrient replete batch cultures were investigated at various stages of the life cycle  and under conditions affected by varying salinity, temperature and combined effects of salinity and temperature. The organism was routinely maintained in sterile seawater enriched with F/2 medium at 24±2°C, 150 uEm-2s-1  under a 12: 12 h  light : dark (L:D) cycle.  Early exponential growth stage was reached after 7 days with a cell division rate of 0.26 div day-1. The toxin content reached a peak of 298 fmol cell-1 at mid exponential phase (14 days) and  rapidly declined to 54 fmol cell-1 as the organism approached  the death phase. Only three sets of toxins composed of STX, dcSTX and B1 were detected. NeoSTX, GTX1-6 and C toxins were not produced during the entire growth cycle. The organism was able to grow  from 26 to 36 0/00 with an optimum growth at 36 0/00. Growth rate was highest at 36 0/00  (0.4 div d-1 ) while the toxin content was highest at 30 0/00 (260 fmol cell-1 ). A decline in STX composition (from 80 to 65 mole %) was observed with increased salinity while dcSTX composition increased from 15 to 32 mole %. B1 toxins remained constant in all the salinity variations conducted. P. bahamense was able to grow from 23 to 36°C and the optimum temperature for growth  was at 25°C. Lowest growth rate (0.22 div day-1 ) was observed at  25°C, while highest growth rate was  achieved  at 0.4 div day-1 at 35°C. Toxin content  reached a peak of 376 fmol cell-1 at 25°C and was lower ( 80 to 116 fmol cell-1 ) at  higher temperatures (32 to 35°C). STX made up to 85 to 98 mole % toxin cell-1. However, a 50% decrease in mole % toxin cell-1 STX was observed at 36°C with increased proportion of dcSTX and B1. No dcSTX was produced at temperatures from 25 to 34°C.  Combined effects  of salinity and temperature showed that P. bahamense was not able to grow at low salinity and temperature (26 0/00 – 28°C). Optimum growth was observed in  higher salinities at all temperature conditions.  Highest specific growth rate was 0.4 div day-1 at 30 0/00  - 32°C, while toxin content peaked at 30°-25 0/00  amounting to 665 fmol cell-1. STX comprised about 80 to 99 mole % toxin cell-1 .

A system of ultrasonic buoys was installed in the Canoe Brook Reservoir #1 in Short Hills, NJ to assess the impact of the system for controlling algae and cyanobacteria in the reservoir. The four buoys operated for five months in the spring/summer 2014. The results of the study indicated that the ultrasonic system was effective for controlling the algae when the correct ultrasonic program was used. During the testing period, geosmin and methyl isoborneol concentrations were well controlled. Additionally, the average alum dose used by the plant was reduced by 22% over the same period in 2013 with improvements in dissolved air flotation effluent turbidity, combined filter effluent turbidity, and an 83% increase in unit filter run volumes. An economic assessment showed the buoys saved approximately $87,800 in operational costs with a projected simple payback for the system of 1.8 years.

Wireless sensor systems have been used in several innovative applications during past few years. However, the key constraints like system design, energy, cost are significantly application dependant. In this paper, we design a wireless sensor system towards an important environmental issue of water quality. Among the various dimensions of water quality, Cyanobacterial Harmful Algal Blooms (CyanoHABs) has emerged as one of the newer challenges. During the past couple of years, researchers from multiple domains including ecologist, neuroscientists, economist and government agencies are actively studying the extent of its impact on their particular are of study. CyanoHABs are ubiquitous and can be found globally during warmer seasons. However, the monitoring systems presently available are expensive. In this paper we present a low-cost, low-energy and low-footprint wireless sensor system which can be deployed remotely. We believe that ours is very first system developed in the domain of monitoring CyanoHABs that is completely based on solar energy and utilizes mobile network to transfer the collected data to our cloud sever in near real-time. Our system is currently deployed at four locations. We also present techniques and experimental results of semi-participatory data transfer when the deployment zone does not have a mobile network.

In this study, data mining using box plots and multivariate statistical analysis using factor analysis are employed for a spatio-temporal analysis of coastal water quality data from Tolo Harbour, Hong Kong. The analysis of box plots reveals pronounced spatial heterogeneity of the parameters studied. The spatial analysis clearly shows monitoring station TM2 in the Harbour Subzone to be most susceptible to eutrophication with the highest nutrient and algal biomass concentrations. The factor analysis brings to light dominant parameters to the ecological system under the coastal marine environment. The temporal analysis confirms the considerable decline in nutrient levels in recent years. In spite of this decline, the factor analysis indicates that nutrient processes play an important role even in recent years, suggesting an adequate supply of nutrients. It seems that they are being released from sources other than known point sources, possibly from nutrients accumulated in the sediment...

The Synecological Approach to the Problem of Eutrophication.
[new solution to the problem, prevention, control and reversal of eutrophication, new way of improving water quality, how to solve the problem, new method to combat eutrophication];
https://www.academia.edu/60179271/ ;
doi: 10.1023/a:1013378505630 ;
__
Research Interests:
Eutrophication, Eutrophication control,
Eutrophication Management,Eutrophication, Harmful Algal Blooms, Water Quality Eutrophication, Toxicity, Water resources, Water quality, Water, Aquatic Toxicology, Aquatic Ecotoxicology,Aquatic Ecosystems, Aquatic Ecology, Filter feeding, Filter-Feeders, Detergents, Laundry Detergents, Innovations,Water Pollution, eutrophication reversal,  prevention,

Cyanobacteria Harmful Algal Blooms (or CyanoHABs) represent one of the most conspicuous waterborne microbial hazards in aquatic environments mostly due to the production of harmful secondary metabolites, known as cyanotoxins. In this paper we assessed cyanobacteria blooms in a shallow, Mediterranean, highly eutrophic lake (Lake Pamvotis, NW Greece) in relation to critical environmental parameters using a multi-approach methodology. Microscopic (identification of cyanobacteria), immunological (ELISA), and molecular techniques (PCR) combined with physico-chemical parameters were used to monitor cyanobacteria blooms and the associated cyanotoxin production for 14 months on a monthly basis. Cyanobacteria were the main phytoplankton component, representing more than 75% of the total phytoplankton abundance throughout the study period; dominant species belonged to Microcystis, Anabaena and Aphanizomenon. Microcystins (MCs) were detected throughout the year in all sampling stations in concentrations ranging from 0.16 to 27 mg L À1 , indicating that toxic Anabaena and Microcystis strains are persistent and dominant. Saxitoxins (STXs) found in two samples (concentrations 1.3 and 2.1 mg L À1 ) in the warm period, are reported here for the first time. The total MC concentration was positively correlated with temperature, nitrate nitrogen, ammonia nitrogen, and soluble reactive phosphorus, suggesting that high-temperatures and eutrophic conditions promote the growth of MCproducing genotypes. We also investigated a Microcystis strain specific growth rate, which reached its maximum at 30 8C. Our data, combined with long-term data comparison of key limnological features, spanning a 25-year period, suggest that water temperature and nutrient loads may act synergistically to promote cyanobacterial dominance and persistence in Lake Pamvotis. ß

A B S T R A C T Current climate trends resulting in rapid declines in sea ice and increasing water temperatures are likely to expand the northern geographic range and duration of favorable conditions for harmful algal blooms (HABs), making algal toxins a growing concern in Alaskan marine food webs. Two of the most common HAB toxins along the west coast of North America are the neurotoxins domoic acid (DA) and saxitoxin (STX). Over the last 20 years, DA toxicosis has caused significant illness and mortality in marine mammals along the west coast of the USA, but has not been reported to impact marine mammals foraging in Alaskan waters. Saxitoxin, the most potent of the paralytic shellfish poisoning toxins, has been well-documented in shellfish in the Aleutians and Gulf of Alaska for decades and associated with human illnesses and deaths due to consumption of toxic clams. There is little information regarding exposure of Alaskan marine mammals. Here, the spatial patterns and prevalence of DA and STX exposure in Alaskan marine mammals are documented in order to assess health risks to northern populations including those species that are important to the nutritional, cultural, and economic well-being of Alaskan coastal communities. In this study, 905 marine mammals from 13 species were sampled including; humpback whales, bowhead whales, beluga whales, harbor porpoises, northern fur seals, Steller sea lions, harbor seals, ringed seals, bearded seals, spotted seals, ribbon seals, Pacific walruses, and northern sea otters. Domoic acid was detected in all 13 species examined and had the greatest prevalence in bowhead whales (68%) and harbor seals (67%). Saxitoxin was detected in 10 of the 13 species, with the highest prevalence in humpback whales (50%) and bowhead whales (32%). Pacific walruses contained the highest concentrations of both STX and DA, with DA concentrations similar to those detected in California sea lions exhibiting clinical signs of DA toxicosis (seizures) off the coast of Central California, USA. Forty-six individual marine mammals contained detectable concentrations of both toxins emphasizing the potential for combined exposure risks. Additionally, fetuses from a beluga whale, a harbor porpoise and a Steller sea lion contained detectable concentrations of DA documenting maternal toxin transfer in these species. These results provide evidence that HAB toxins are present throughout Alaska waters at levels high enough to be detected in marine mammals and have the potential to impact marine mammal health in the Arctic marine environment.

Dinoflagellates of the genus Alexandrium are photosynthetic microalgae that have an extreme importance due to the impact of some toxic species on shellfish aquaculture industry. Alexandrium catenella is the species responsible for the production of paralytic shellfish poisoning in Chile and other geographical areas. We have constructed a cDNA library from midexponential cells of A. catenella grown in culture free of associated bacteria and sequenced 10,850 expressed sequence tags (ESTs) that were assembled into 1,021 contigs and 5,475 singletons for a total of 6,496 unigenes. Approximately 41.6% of the unigenes showed similarity to genes with predicted function. A significant number of unigenes showed similarity with genes from other dinoflagellates, plants, and other protists. Among the identified genes, the most expressed correspond to those coding for proteins of luminescence, carbohydrate metabolism, and photosynthesis. The sequences of 9,847 ESTs have been deposited in Gene Bank (accession numbers EX 454357–464203).

Over the last decade, our understanding of the environmental controls on Pseudo-nitzschia blooms and domoic acid (DA) production has matured. Pseudo-nitzschia have been found along most of the world's coastlines, while the impacts of its toxin, DA, are most persistent and detrimental in upwelling systems. However, Pseudo-nitzschia and DA have recently been detected in the open ocean's high-nitrate, lowchlorophyll regions, in addition to fjords, gulfs and bays, showing their presence in diverse environments. The toxin has been measured in zooplankton, shellfish, crustaceans, echinoderms, worms, marine mammals and birds, as well as in sediments, demonstrating its stable transfer through the marine food web and abiotically to the benthos. The linkage of DA production to nitrogenous nutrient physiology, trace metal acquisition, and even salinity, suggests that the control of toxin production is complex and likely influenced by a suite of environmental factors that may be unique to a particular region. Advances in our knowledge of Pseudo-nitzschia sexual reproduction, also in field populations, illustrate its importance in bloom dynamics and toxicity. The combination of careful taxonomy and powerful new molecular methods now allow for the complete characterization of Pseudo-nitzschia populations and how they respond to environmental changes. Here we summarize research that represents our increased knowledge over the last decade of Pseudo-nitzschia and its production of DA, including changes in worldwide range, phylogeny, physiology, ecology, monitoring and public health impacts.

Mass appearances of the toxic dinoflagellate genus Ostreopsis are known to cause dangerous respiratory symptoms in humans exposed to aerosols. The outbreaks can appear in shallow marine waters of temperate regions around the globe. We followed a massive bloom event on a public beach on the northern Adriatic coast near Rovinj, Croatia. We identified the responsible species and the produced toxins as well as the
dynamics of the event with respect to environmental conditions. Ostreopsis cf. ovata appeared in masses from September through October 2010 on a public beach near Rovinj, Croatia but stayed undetected by public health organizations. Respiratory symptoms were observed whenever humans were exposed to substrate samples containing large numbers of Ostreopsis cells. During the mass abundance of O. cf. ovata also exposure to the aerosols on the beach evoked respiratory symptoms in humans. Our measurements showed high cell abundances and high toxin contents with a stable relative contribution of putative Palytoxin and Ovatoxins a-e. Artificial beach structures proved to dramatically reduce settling of the observed Ostreopsis biofilm. Blooms like those reported herein have a high potential to happen undetected with a high potential of affecting the health of coastal human populations. Increased monitoring efforts are therefore required to understand the ecology and toxicology of those bloom events and reduce their negative impact on coastal populations.

Blooms of the toxic dinoflagellate Ostreopsis genus are a recurrent phenomenon in tropical and temperate regions worldwide. The most widely distributed species in the Mediterranean Sea, Ostreopsis cf. ovata, produces blooms with increasing intensity, frequency and distribution. These blooms have been associated with respiratory problems and skin irritations in humans, causing health problems along Italian coasts. In addition, palytoxin-like substances produced by this species can be accumulated by various organisms and make the seafood toxic, with further risks to human health. This thesis is based on the analysis of a multiannual dataset gathered at different coastal sites along the Campania region: 1) the area of Posillipo, in the Gulf of Naples, where the most intense blooms of O. cf. ovata for the Campania Region are regularly recorded; 2) the Ischia Island coasts, which are subjected to natural acidification due to the presence of volcanic vents; 3) the sandy littoral of the Gulf of Salerno littoral, where O. cf. ovata has not been found previously, and where structures for the defence from coastal erosion will be built. Results showed that: i) Ostreopsis cf. ovata blooms are a stable phenomenon, occurring at regular frequency over the years in summer months along Posillipo and Ischia Island coasts; ii) the blooms show a marked seasonality, with peaks in the summer months, thus representing a risk for people during the bathing season, either through direct contact and aerosol or following the consumption of contaminated seafood; iii) based on the results from the Ischia island, a lower pH does not affect Ostreopsis blooms, meaning no risk decrease in future scenarios of ocean acidification; iv) Ostreopsis does occur in the Gulf of Salerno, although at low concentrations, probably due to the absence of a suitable substrate; by providing a hard substrate for macroalgae hosting Ostreopsis blooms, artificial structures against coastal erosion might determine an increase of the species in an area where it has not represented a risk so far. The present study highlights the relevance of appropriate strategies for monitoring Ostreopsis blooms. Knowledge and data obtained can be used for a better assessment and interpretation of these phenomena, thus supporting informed management actions to protect the environment, seafood resources and human health.

Monitoring programs for harmful algal blooms (HABs) are currently reactive and provide little or no means for advance warning. Given this, the development of algal forecasting systems would be of great use because they could guide traditional monitoring programs and provide a proactive means for responding to HABs. Forecasting systems will require near real-time observational capabilities and hydrodynamic/biological models designed to run in the forecast mode. These observational networks must detect and forecast over ecologically relevant spatial/ temporal scales. One solution is to incorporate a multiplatform optical approach utilizing remote sensing and in situ moored technologies. Recent advances in instrumentation and data-assimilative modeling may provide the components necessary for building an algal forecasting system. This review will outline the utility and hurdles of optical approaches in HAB detection and monitoring. In all the approaches, the desired HAB information must be isolated and extracted from the measured bulk optical signals. Examples of strengths and weaknesses of the current approaches to deconvolve the bulk optical properties are illustrated. After the phytoplankton signal has been isolated, species-recognition algorithms will be required, and we demonstrate one approach developed for Gymnodinium breve Davis. Pattern-recognition algorithms will be species-specific, reflecting the acclimation state of the HAB species of interest.Field data will provide inputs to optically based ecosystem models, which are fused to the observational networks through data-assimilation methods. Potential model structure and data-assimilation methods are reviewed.

Dinoflagellates of the genus Alexandrium are photosynthetic microalgae that have an extreme importance due to the impact of some toxic species on shellfish aquaculture industry. Alexandrium catenella is the species responsible for the production of paralytic shellfish poisoning in Chile and other geographical areas. We have constructed a cDNA library from midexponential cells of A. catenella grown in culture free of associated bacteria and sequenced 10,850 expressed sequence tags (ESTs) that were assembled into 1,021 contigs and 5,475 singletons for a total of 6,496 unigenes. Approximately 41.6% of the unigenes showed similarity to genes with predicted function. A significant number of unigenes showed similarity with genes from other dinoflagellates, plants, and other protists. Among the identified genes, the most expressed correspond to those coding for proteins of luminescence, carbohydrate metabolism, and photosynthesis. The sequences of 9,847 ESTs have been deposited in Gene Bank (accession numbers EX 454357–464203).

As part of an ongoing monitoring study of phytoplankton in Yemeni coastal waters we report, for the first time, a dense bloom (14.310 6 cell L −1) of the marine dinoflagellate species Protoperidinium quinquecorne (Abé) Balech on June 6, 2012 from the coastal water of Al Hodeidah and Khor Al-Khateeb lagoon, southern Red Sea. Water temperature was 34°C and salinity was 36 during the bloom, indicating its tropical and subtropical nature. This bloom was accompanied by a massive kill of small pelagic fish, which were mostly sardines. Among the phytoplankton species reported during the P. quinquecorne bloom, the red tide-forming species, Trichodesmium erythraeum (cyanobacteria), Gonyaulax verior, and Prorocentrum micans, and the known toxic species, Dinophysis acuminata, were notable.

The data produced from Earth Observation (EO) satellites has recently become so abundant that manual processing is sometimes no longer an option for analysis. The main challenges for studying this data are its size, its complex nature, a high barrier to entry, and the availability of datasets used for training data. Because of this, there has been a prominent trend in techniques used to automate this process and host the processing in massive online cloud servers. These processes include data mining (DM) and machine learning (ML). The techniques that will be discussed include: clustering, regression, neural networks, and convolutional neural networks (CNN). This paper will show how some of these techniques are currently being used in the field of earth observation as well as discuss some of the challenges that are currently being faced. Google Earth Engine (GEE) has been chosen as the tool for this study. GEE is currently able to display 40 years of historical satellite imagery, including publicly available datasets such as Landsat, and Sentinel data from Copernicus. Using EO data from Landsat and GEE as a processing tool, it is possible to classify and discover historical algal blooms over the period of ten years in the Baltic Sea surrounding the Swedish island of Gotland. This paper will show how these technical advancements including the use of a cloud platform enable the processing and analysis of this data in minutes.

During the past three decades, harmful algal blooms (HAB) events have been frequently observed in marine waters around many coastal cities in the world including Hong Kong. The increasing occurrence of HAB has caused acute influences and damages on water environment and marine aquaculture with millions of monetary losses. For example, the Tolo Harbour is one of the most affected areas in Hong Kong, where more than 30% HAB occurred. In order to forewarn the potential HAB incidents, the machine learning (ML) methods have been increasingly resorted in modelling and forecasting water quality issues. In this study, two different ML methods-artificial neural networks (ANN) and support vector machine (SVM)-are implemented and improved by introducing different hybrid learning algorithms for the simulations and comparative analysis of more than 30-year measured data, so as to accurately forecast algal growth and eutrophication in Tolo Harbour in Hong Kong. The application results show the good applicability and accuracy of these two ML methods for the predictions of both trend and magnitude of the algal growth. Specifically, the results reveal that ANN is preferable to achieve satisfactory results with quick response, while the SVM is suitable to accurately identify the optimal model but taking longer training time. Moreover, it is demonstrated that the used ML methods could ensure robustness to learn complicated relationship between algal dynamics and different coastal environmental variables and thereby to identify significant variables accurately. The results analysis and discussion of this study also indicate the potentials and advantages of the applied ML models to provide useful information and implications for understanding the mechanism and process of HAB outbreak and evolution that is helpful to improving the water quality prediction for coastal hydro-environment management.

A total number of 40 potentially toxic microalgae and 5 taxa causing discolorations have been identified along the coasts of the Campania region (South Tyrrhenian Sea, Mediterranean Sea). This number is based on results of over 20 years of research at a coastal station in the Gulf of Naples, 4 years of monitoring activity along the Campania coasts and of a series of scattered and sporadic observations. Several species of the recently erected genera Karenia and Takayama are reported for the first time in the area. Information on the period of highest abundances or most probable period of occurrence indicates the late spring and summer as the periods of maximum risk of harmful events. Despite the variety of potentially toxic species, no human health problems nor fish kills have ever been recorded in Campania. The reasons for this apparent paradox are probably to be found in the ecological factors that regulate the abundance, toxicity and spatial distribution of the potentially harmful species and reflect as well the relatively low number of aquaculture plants in the area. #

The Northern Adriatic Sea is the area of the Mediterranean Sea where eutrophication and episodes related to harmful algae have occurred most frequently since the 1970s. In this area, which is highly exploited for mollusk farming, the first occurrence of human intoxication due to shellfish consumption occurred in 1989, nearly 10 years later than other countries in Europe and worldwide that had faced similar problems. Until 1997, Adriatic mollusks had been found to be contaminated mostly by diarrhetic shellfish poisoning toxins (i.e., okadaic acid and dinophysistoxins) that, along with paralytic shellfish poisoning toxins (i.e., saxitoxins), constitute the most common marine biotoxins. Only once, in 1994, a toxic outbreak was related to the occurrence of paralytic shellfish poisoning toxins in the Adriatic coastal waters. Moreover, in the past 15 years, the Adriatic Sea has been characterized by the presence of toxic or potentially toxic algae, not highly widespread outside Europe, su...