Environmental and Health Effects Associated With Harmful Algal Bloom and Marine Algal Toxins in China

The frequency and scale of Harmful Algal Bloom (HAB) and marine algal toxin incidents have been increasing and spreading in the past two decades, causing damages to the marine environment and threatening human life through contaminated seafood. To better understand the effect of HAB and marine algal toxins on marine environment and human health in China, this paper overviews HAB occurrence and marine algal toxin incidents, as well as their environmental and health effects in this country. HAB has been increasing rapidly along the Chinese coast since the 1970s, and at least 512 documented HAB events have occurred from 1952 to 2002 in the Chinese mainland. It has been found that PSP and DSP toxins are distributed widely along both the northern and southern Chinese coasts. The HAB and marine algal toxin events during the 1990s in China were summarized, showing that the HAB and algal toxins resulted in great damages to local fisheries, marine culture, quality of marine environment, and human health. Therefore, to protect the coastal environment and human health, attention to HAB and marine algal toxins is urgently needed from the environmental and epidemiologicalview.

The“harmful algae and algal toxins in coastal waters of China:investigation and database”project

The“harmful algae and algal toxins in coastal waters of China:investigation and database”project(HAATC)is funded(US$2.3 million)by the Ministry of Science and Technology of China for 60 months starting on the 1st Jan 2019.Since the 1990s,national projects and other related work have greatly improved harmful algal bloom(HAB)research in China.However,the existing research on HABs is often limited to specific sea areas or specific algal bloom disasters,which is insufficient for understanding the long-term evolution of HAB occurrence under the influence of intensified human activity and global change.The HAATC project intends to determine the overall distribution of marine harmful microalgae and macroalgae,and marine algal toxins(in phytoplankton and shellfish)through a large-scale investigation in the coastal waters of China and continuous investigation in key sea areas.It also aims to observe biotic and abiotic processes during harmful red tides and green tides,and establish an open database and query platform of HABs in China.The research consortium,led by chief scientist Prof.Tian YAN,includes approximately 100 scientists and students.More than 2 years of work have shown the increased distribution of HAB species(including cysts)and algal toxins in China’s coastal waters,the increased occurrence of macroalgae blooms(mainly by Ulva prolifera and Sargassum horneri)in the Southern Yellow Sea,increased amount of causative species being identified due to the use of molecular technologies in taxonomy,and new records of algal toxins such as azaspiracid,cycloimines and neurotoxinsβ-N-methylamino-l-alanine have been detected,which complicates the research in algal toxins and toxicology.Eventually,the project will provide systematic basic data and techniques for the rapid and accurate identification of harmful algae species to support the research,monitoring,and control of harmful algal blooms,as well as seafood safety management in China.

Spatial variation of lipophilic marine algal toxins and its relationship with physicochemical parameters in spring in Laizhou Bay,China

Lipophilic marine algal toxins(LMATs)are produced by some toxigenic microalgae,which pose a serious threat to marine ecosystem and even human health.The occurrence and environmental control factors of LMATs in the surface seawater and phytoplankton in spring in Laizhou Bay in which Huanghe(Yellow)River estuary is included,in Shandong,East China were investigated.Okadaic acid(OA),pectenotoxin-2(PTX2),dinophysistoxin-1(DTX1),pectenotoxin-2 seco acid(PTX2 SA),DTX2,7-epi-PTX2 SA,PTX11,and 13-desmethyl spirolide C(SPX1)were detected from the surface seawater samples,and PTX2,7-epi-PTX2 SA,OA,DTX2,DTX1,PTX2 SA,and PTX11 were discovered in the phytoplankton samples showed a decreasing trend.The concentrations of∑LMATs in the seawater and phytoplankton ranged 2.03-74.38 ng/L on average of 13.72 ng/L and 0.98-479.27 pg/L on average of 50.20 pg/L,respectively.The joint influence of terrigenous input and internal circulation could promote the growth,toxin production,and toxin release of toxin-producing algae,leading to a higher content of LMATs in the bay nearby the Huanghe River estuary in both seawater and phytoplankton.The concentration of LMATs in spring was higher than that in summer,showing obvious seasonal variation.In addition,no significant correlation between most of the physiochemical parameters and LMAT contents in seawater was revealed by correlation analysis except for the positive correlation between DTX2 and chlorophyll a,OA and NH4-N.However,the increase of dissolved inorganic nitrogen content in seawater could enhance the production of OA,DTX1,and DTX2 in phytoplankton due probably to that the inorganic N input could benefit the growth and stimulate toxin production of toxin-producing algae.The result also proved that some PTX2 may be originated from Procentrum spp.and OA,DTXs and part of PTX2 may be originated from Dinophysis spp.

Oxidative effects of the harmful algal blooms on primary organisms of the food web

Degraded water quality from nutrient pollution,physical,biological,and other chemical factors contributes to the development and persistence of many harmful algal blooms(HAB s).The complex dynamics of the HAB s is a challenge to marine ecosystems for the toxic effects reported.The consequences include fish,bird,and mammal mortality,respiratory or digestive tract problems,memory loss,seizures,lesions and skin irritation in many organisms.This review is intended to briefly summarize the recent reported information on harmful marine toxin deleterious effects over the primary organisms of the food web,namely algae,zooplankton and invertebrates.Special focus is made on oxidative stress status of cells and tissues.Even though in situ field research is less controlled than laboratory studies,in which the organisms are directly exposed to the toxins under consideration,both types of approaches are required to fully understand such a complex scenario.On top of that,the contribution of the increasing water temperatures in the sea,as a consequence of the global climate change,will be addressed as a topic for further studies,to evaluate the effect on regulating algal growth,species composition,trophic structure,metabolic stress and function of aquatic ecosystems.

Increased diversity and environmental threat of harmful algal blooms in the Southern Yellow Sea,China

Harmful algal blooms(HABs)in the Southern Yellow Sea(SYS)have shown a trend of increasing diversity and detrimental ef fects.While the Bohai Sea,East China Sea,and South China Sea have experienced a high incidence of HABs since the 1980s,the Yellow Sea provides a relatively healthy ecological environment in which fewer HABs have been documented before the 21s t century.Yet largescale blooms of the green macroalga Ulva prolifera(so-called“green tides”)have occurred annually since 2007 in the Yellow Sea.Six people were poisoned and one person died in Lianyungang in 2008 due to ingestion of algal toxins.Moreover,the Yellow Sea experienced co-occurrence of harmful red tides,green tides,and golden tides in 2017.This combination of events,rare worldwide,indicates the potential for further deterioration of the marine environment in the Yellow Sea,which may be related to climate change,aquaculture,and other human activities.Using the SYS as an example,we collected data of the frequency and scale of HABs over the years,as well as that of marine algal toxins,and analyzed the trend in the diversity of HABs in the SYS,to explore the causes and impacts of HABs,as well as the interrelationships among dif ferent types of HABs,including harmful red tides,green tides,and golden tides.We also attempted to improve our understanding of HAB evolution under the influence of global climate change and intensified human activities.

Reporter Gene Assay for Detection of Shellfish Toxins

Objective To explore the potential reporter gene assay for the detection of sodium channel-specific toxins in shellfish as an alternative for screening harmful algal bloom (HAB) toxins, considering the fact that the existing methods including HPLC and bioassay are inappropriate for identifying HAB toxins which poses a serious problem on human health and shellfish industry. Methods A reporter plasmid pEGFP-c-fos containing c-fos promoter and EGFP was constructed and transfected into T24 cells using LipofectAMINE 2000. Positive transfcctants were screened by G418 to produce a pEGFP-c-fos-T24 cell line. After addition of increasing neurotoxic shellfish poison (NSP) or GTX2,3, primary components of paralytic shellfish poison (PSP), changes in expression of EGFP in the cell line were observed under a laser scanning confocal microscope and quantified with Image-pro Plus software. Results Dose-dependent changes in the intensity of green fluorescence were observed for NSP in a range from 0 to 10 ng/mL and for GTX2,3 from 0 to 16 ng/mL. Conclusion pEGFP-c-fos-T24 can be applied in detecting HAB toxins, and cell-based assay can be used as an alternative for screening sodium channel-specific HAB toxins.

Physical and chemical processes promoting dominance of the toxic cyanobacterium Cylindrospermopsis raciborskii

The freshwater cyanobacterium, Cylindrospermopsis raciborskii （Woloszyflska） Seenayya and Subba Raju is a common species in lakes and reservoirs globally. In some areas of the world it can produce cytoand hepatotoxins （cylindrospermopsins, saxitoxins）, making blooms of this species a serious health concern for humans. In the last 10 15 years, there has been a considerable body of research conducted on the ecology, physiology and toxin production of this species and this paper reviews these studies with a focus on the cylindrospermopsin （CYN）-producing strains. C. raciborskii has low light requirements, close to neutral buoyancy, and a wide temperature tolerance, giving it the capacity to grow in many lentic waterbodies. It also has a flexible strategy with respect to nitrogen （N） utilisation; being able to switch between utilising fixed and atmospheric N as sources of N fluctuate. Additionally this species has a high phosphate （DIP） affinity and storage capacity. Like many cyanobacteria, it also has the capacity to use dissolved organic phosphorus （DOP）. Changes in nutrient concentrations, light levels and temperature have also been found to affect production of the toxin CYN by this species. However, optimal toxin production does not necessarily occur when growth rates are optimal. Additionally, different strains of C. raciborskii vary in their cell quota of CYN, making it difficult to predict toxin concentrations, based on C. raciborskii cell densities. In summary, the ecological flexibility of this organism means that controlling blooms of C. raciborskii is a difficult undertaking. However, improved understanding of factors promoting the species and toxin production by genetically capable strains will lead to improved predictive models of blooms.

An Analysis of Knowledge, Attitudes and Practices of Communities in Lake Victoria, Kenya on Microcystin Toxicity

Exposure to microcystin poses a potential health hazard to humans and other living organisms. This results from eutrophication and warrants an investigation into the problem of microcystin toxicity in Lake Victoria. This study was conducted in Homa Bay, Kisumu, Siaya and Busia counties to understand the effects of microcystin toxicity among fisherfolk and lake riparian communities. Data collection involved 90 semi-structured questionnaires, 11 key informant interviews and seven focus group discussions. Water samples were also collected and analysed for algal toxins. Data were analysed using Stata version 13 (Stata Corp, College Station, Texas, USA) and SPSS version 18.0. Majority (73.3%) of the fisherfolk were aware of microcystin toxicity in the lake with no significant difference in the awareness of microcystin toxicity between men and women (χ2 = 1.1, df = 1, p = 0.293). Most of the respondents relied on lake (48.9%) and tap water (47.8%) with paltry sourcing water from borehole (16.8%) and rain (7.8%). There was no association between level of education and water source (lake;χ2 = 1.61, df = 3, p = 0.656) and (tap;χ2 = 2.23, df = 3, p = 0.527). Fisherfolk was cognizant of the need to curb microcystin toxicity. There was a significant difference (p < 0.05) in the occurrence of microcystin during the wet season compared to the dry season. Cyanophytes were the most significant (p < 0.001) group of phytoplankton. When ingested, microcystin has a long-term effect and therefore pollution control is crucial.

Application of permanganate in the oxidation of micropollutants:a mini review

As a green oxidant,permanganate has received considerable attention for the removal of micropollutants in drinking water treatment.To provide a better understanding of the oxidation of organic micropollutants with permanganate,the oxidation kinetics of 32 micropollutants were compiled.The pollutants include algal toxins,endocrine disrupting chemicals(EDCs),and pharmaceuticals.The oxidation kinetics of micropollutants by permanganate were found to be first order with respect to both contaminant and permanganate concentrations from which second-order rate constants(k″)were obtained.Permanganate oxidized the heterocyclic aromatics with vinyl moiety(i.e.,microcystins,carbamazepine,and dichlorvos)by the addition of double bonds.For the polycyclic aromatic hydrocarbons(PAHs)with alkyl groups,permanganate attacked the benzylic C-H through abstraction of hydrogen.The mechanism for the oxidation of phenolic EDCs by permanganate was a single electron transfer and aromatic ring cleavage.The presence of background matrices could enhance the oxidation of some phenolic EDCs by permanganate,including phenol,chlorinated phenols,bisphenol A,and trichlosan.The toxicity of dichlorvos solution increased after permanganate oxidation,and the estrogenic activity of bisphnol A/estrone increased significantly at the beginning of permanganate oxidation.Therefore,the toxicity of degradation products or intermediates should be determined in the permanganate oxidation processes to better evaluate the applicability of permanganate.The influence of background ions on the permanganate oxidation process is far from clear and should be elucidated in the future studies to better predict the performance of permanganate oxidation of micropollutants.Moreover,methods should be employed to catalyze the permanganate oxidation process to achieve better removal of micropollutants.