Toxic blooms

The main genera responsible for freshwater toxic blooms are Microcystis, Anabaena, Aphanizomenon and Oscillatoria. Toxins produced include 1. anatoxins, alkaloids and peptides of Anabaena 2. the peptide microcystin and related peptides of Microcystis 3. aphantoxins, compounds of Aphanizomenon with properties similar to some paralytic shellfish poisons. Properties of Oscillatoria toxin suggest they are peptides similar to those of Microcystis. Microcystis toxins are peptides (M.W. approx. 1200) which contain three invariant D-amino acids, alanine, erythro-3-methyl aspartic and glutamic acids, two variant L-amino acids, N-methyl dehydro alanine and a 3-amino acid. Individual toxic strains have one or more multiples of this peptide toxin. The one anatoxin characterized is a bicylic secondary amine called anatoxin-a (M.W. 165). The aphantoxin isolated in our laboratory contains two main toxic fractions. On TLC and HPLC the fractions have the same characteristics as saxitoxin and neosaxitoxin. 

Isolate NRC-1 and the SS-17 clone of NRC-1 of K, aeruginosa were cultured in BG-11 medium (9) They were kindly provided by Dr. W. W. Carmichael, Wright State University, Dayton, Ohio. A lyophilized sample of a toxic bloom of >1. aeruginosa collected from Kezar Lake, New Hampshire on October 10, 1978 was generously provided by Dr. J. J. Sasner, Jr., University of New Hampshire, Durham, New Hampshire. 

Partially purified extracts of the two isolates and the Kezar Lake toxic bloom sample of >1. aeruginosa were chromatographed. The HPLC elution profiles of these are shown in Figure 1. All components of the elution profiles of isolates NRC-1 and SS-17 are closely similar, and they are each characterized by one major toxin, toxin-LR. The elution profile of the Kezar Lake bloom extract also consists primarily of toxin-LR. Moreover, it does not contain some of the minor components observed in the elution patterns of NRC-1 and SS-17. The toxin-LR content of the Kezar Lake bloom was higher than that of the isolates. 

Figure 1. HPLC elution patterns of extracts of M. aeruginosa isolate NRC—1, clone SS-17 of isolate NRC-1, and a toxic bloom sample from Kezar Lake, New Hampshire. Toxin-LR eluted at about 2.7 minutes. Smaple volumes injected were NRC-1 (17 SS-17...

Cyanobacterial toxins produced and released by cyanobacteria in freshwater around the world are well documented [158,159]. Microcystins are the most common of the cyanobacterial toxins found in water, as well as being the ones most often responsible for poisoning animals and humans who come into contact with toxic blooms and contaminated water [ 160]. Acute exposure results in hepatic injury, which can in extreme cases prove fatal. One such incident occurred that resulted in the death of over 50 dialysis patients due to the use of microcystin-contaminated water in the treatment [161]. Chronic exposure due to the presence of microcystin in drinking water is thought to be a contributing factor in primary fiver cancer (PLC) through the known tumour-promoting activities of these compounds [162],... 

The occurrence of toxic algal blooms has increased in the last decades. Not only the nnmber of toxic blooms has mnltiplied and their geographical distribution has spread all over the world, bnt also new toxins and new toxic algae species have been described. Azaspiracids are the most recently identified class of marine toxins present in shellfish. Only known since 1997, azaspiracid and its analognes have awakened both public health concern and scientific interest. 

Another common featnre with other shellfish toxins is that heat does not destroy azaspiracids either (EU/SANCO 2001 Hess et al. 2005). Therefore, cooking does not ehminate the toxicity of shellfish due to an azaspiracid toxic bloom. Overall, these componnds seem to be quite stable during storage (EU/SANCO 2001), althongh there are some concerns abont their stability in certain organic solvents and alkaline conditions (James et al. 2002b Satake et al. 1998b). 

Toxic blooms of cyanobacteria with associated animal poisonings have been reported in all continents except Antarctica. There have been frequent reports of thirsty domestic animals and wildlife consuming freshwater contaminated with toxic cyanobacterial... 

New outbreaks were recorded later. Between 1976 and 1984, Kawabata reports that there were 34 outbreaks affecting 1257 people [30]. The Japanese and European shores are the most affected by toxic blooms. 

No temporal trend data for human illness exists. Similar to the case with other marine biotoxins, some authors have argued that toxic blooms are increasing [123],... 

Chang E.H. Gymnodinium brevisulcatum spp. nov. (Gynmodiniales, Dinophyceae), a new species isolated from the 1998 summer toxic bloom in Wellington Harbor, New Zealand, Phycologia, 38, 377-384, 1999. 

In 1947, Davis [13] identified the causative organism of these toxic blooms as the unarmored dinoflagellate Gymnodinium brevis (later Ptychodiscus brevis, now G. breve), and a decade later, Starr [14] suggested that a lethal toxin elucidated by G. breve was the cause of the fish kills. With this knowledge came the need for detection methods to better understand the ecological and public health implications of brevetoxins in the environment. 

Mortalities of channel catfish, Ictalurus punctatus, have been atfributed to ingestion of toxic blooms of Microcystis aeruginosa (Zimba et al., 2001). The mortalities followed sudden temperature drops of 5°C and necropsy of fish revealed congested hver and spleen tissue, which indicated microcystin toxicosis. Other channel catfish farms in southeastern United States using brackish well water have experienced fish kills that have been reported to be associated with thick blooms of a halophytic cyanobacteria, Anacystis marina rather than Microcystis (Snyder et al., 2002). 

In United States toxic blooms of Microcystis aeruginosa and Anabaena spp. were associated with mortalities in shrimp ponds at a hatchery producing Litopenaeus vannamei (Zimba et al.,... 

Smith, P.T. and Kankaanpaa, H. Toxic blooms of Nodularia sp. in prawn farms that culture Penaeus monodon. In Abstracts of Fifth International Conference on Toxic Cyanobacteria, Noosa, Queensland, 2001. 

Carmichael, W.W. and Gorham, P.R., The mosaic nature of toxic blooms of cyanobacteria, in The Water Environment, Algal Toxins and Health, Carmichael, W.W., Ed., Plenum Press, New York, 1981, 161. Boone, D.R. and Castenholz, R.W., Eds. Vol. 1 The Archaea and the deeply branching and phototrophic bacteria, in Bergey s Manual of Systematic Bacteriology, Garrity, G.M., Ed., Springer, New York, 2001, 721 pp. 

Microcystis, Nostoc, and Oscillatoria (Planktothrix). Cyanobacteria toxins (cyanotoxins) include cytotoxins and biotoxins (neurotoxins anatoxin-a, anatoxin-a(s) and saxitoxins, and the hepatotoxins microcystins MCs, and nodularins), with biotoxins being responsible for acute lethal, acute chronic, and subchronic poisonings of wild/domestic animals and humans. In most of the reported cases, afflicted animals consumed water from water bodies where there was an obvious presence of cyano-bacterial scum on the water surface. More recent measurements of cyanobacterial toxins using sensitive modem analytical methods have often revealed high frequencies of toxic blooms even when animal poisonings have not been reported. 

Throughout the world, it appears that hepatotoxic, microcystin-containing freshwater blooms of cyanobacteria are more commonly found than neurotoxic blooms (Table 40.1). Liver toxic blooms have been reported from aU continents where samples were collected for analysis. Nevertheless, mass occurrences of neurotoxic cyanobacteria are common in some countries and these have been reported from North America, Europe, and Australia, where they have caused... 

Section Haptophyta (=Prymnesiophyta), only one class Haptophyceae, e. g. Chrysochromulina polyle-pis, which led to an enormous toxic blooming in the south coastal seas of Norway in 1988 ... 

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