Blooms, occurrence

Various actions can be used to decrease the probability of bloom occurrence, and some effective treatments are available for removal of cyanobacteria or their toxins. 

Phytoplankton abundance and occurrence of blooms are the parameters for which a not necessarily taxonomic determination is required. The abundance can be measured as the total count of cells and/or colonies in a unit volume of water or recalculated further into biovolume or biomass. The WFD allows use of chlorophyll a as a surrogate for phytoplankton biomass, thus it is considered a biological parameter. In fact, chlorophyll a is the most frequently measured phytoplankton metric in lakes. Not all countries have included the bloom occurrence in routine monitoring as in some areas (e.g. countries belonging to the Alpine GIG) they occur too rarely and inegu-larly (if at all). Other non-taxonomy-based metrics, like size composition and primary productivity, are successively less considered in lake monitoring schemes. 

Nutrient enrichment of coastal waters is known as an eutrophication and is manifested in algal blooms. Occurrences of red tide, which is a toxic plankton bloom, is a major environmental problem in coastal waters of the Asian region. The frequency of the appearance of red tide in Tolo Habor, Hong Kong ranged from two in 1977 to nine in 1994 with a maximum in 1988 (Figure 3). 

The detection and analysis, including quantification, of cyanobacterial toxins are essential for monitoring their occurrence in natural and controlled waters used for agricultural purposes, potable supplies, recreation and aquaculture. Risk assessment of the cyanobacterial toxins for the protection of human and animal health, and fundamental research, are also dependent on efficient methods of detection and analysis. In this article we discuss the methods developed and used to detect and analyse cyanobacterial toxins in bloom and scum material, water and animal/clinical specimens, and the progress being made in the risk assessment of the toxins. 

Not all cyanobacterial blooms and scums contain detectable levels of toxins. Indeed, the incidence of toxicity detection by mouse bioassay, and toxin detection by HPLC among environmental samples, ranges from about 40% to However, in view of this high occurrence, it is the policy of regulatory authorities and water supply operators in some countries to assume that blooms of cyanobacteria are toxic until tested and found to be otherwise. In the absence of available analytical facilities or expertise or for logistical reasons, this precautionary principle should be regarded as sensible and prudent. 

The final article, by S. G. Bell and G. A. Codd of the University of Dundee Department of Biological Services, is concerned with detection, analysis, and risk assessment of cyanobacterial toxins. These can be responsible for animal, fish, and bird deaths and for ill-health in humans. The occurrence of toxic cyanobacterial blooms and scums on nutrient-rich waters is a world-wide phenomenon and cases are cited from Australia, the USA, and China, as well as throughout Europe. The causes, indentification and assessment of risk, and establishment of criteria for controlling risk are discussed. 

All known occurrences of ANTX-A production have been from Canada or the United States. More recently, ANTX-A has been detected in A. flos-aquae blooms from Japan (Watanabe, personal communication), Norway (Skulberg, personal communication), and Finland (99). 

The influence of genetics in leukemia is supported by several observations. For example, among identical twins, the occurrence of ALL is associated with a 20% to 25% chance of the disease developing in the other twin within 1 year. In fraternal twins, there is a fourfold increase in the risk of leukemia compared with the normal population. Additionally, leukemia is known to be increased in several chromosomally abnormal populations. Patients with Down s syndrome have a 20 times increased risk of developing leukemia compared with the rest of the population. Patients with Klinefelter s syndrome and Bloom s syndrome also have an increased incidence of leukemias.7... 

The environmental occurrence of the lower A9PEO oligomers in several types of sediments was studied in the Venice lagoon [2]. A distinction was made between sediments covered with a layer of macroalgae (which are blooming massively in spring-summer), and sediments free of macroalgae. 

A continuing problem in water treatment is the occurrence of algal blooms. Algae may be killed relatively easily on exposure to ultrasound and a lightly polluted system... 

Shellfish accumulate dangerous levels of PSP only under certain conditions. Typically, this occurs when the microorganisms undergo periods of very rapid growth, resulting from the simultaneous occurrence of several favorable environmental conditions. This growth, or bloom, frequently imparts a red color to the affected area of the ocean, and is referred to as a red tide. Shellfish growing in a red tide area can accumulate lethal amounts of PSP. 

Hassett IJ, Banwart WL (1989) The sorption of nonpolar organics by soils and sediments In Sawhney BL, Brown K. (eds) Reactions and movement of organic chemicals in soils Soil Science Society of America, Madison, Wl, pp 31 5p Hayes MHB, Malcom RL (2001) Considerations of compositions and aspects of the structure of humic substances. In Clapp CE, Hayes MHB, Senesi N, Bloom PR Jardine PM, Humic substances and chemical contaminants. Soil Science Society of America, Madison, Wl, pp 1-39 Herbillon AJ, Erankart R, Vielvoye L (1981) An occurrence of interstratified kaoUnite-smectite minerals in a red-black soil top sequence. Clay Miner 16 195-201 Horne RA (1969) Marine chemistry. Wiley, New York... 

Freshwater cyanobacteria blooms implicated in human and livestock intoxications have been extensively studied. And they have become a serious health problem in recent years. Blooms of marine cyanobacteria are also becoming an increasingly familiar occurrence within the tropical and subtropical regions of the world. Several systematic surveys within Europe and the USA have concluded that the two most commonly isolated groups of cyanotoxins are the alkaloids-neurotoxins and the cyclic peptide hepato-toxins, both of which are destructive to liver cells. Several genera... 

The toxin content of Bay of Fundy zooplankton has reached high levels in most years since 1977 (Table IV). Yet, curiously, herring kills have not been observed in years other than 1976 and 1979. The occurrence of kills may depend upon the temporal and spatial overlapping of dense Gonyaulax blooms, highly toxic zooplankton, and actively feeding herring. 

The presence of organic chelates of iron in surface waters has been related to the red tide." an explosive "bloom of algae CymnoJium breve) that results m mass mortality of fish. It is possible to correlate the occurrence of these outbreaks with the volume of stream Dow and the concentrations of iron and humic acid.103 At least one of the dinoflagellales in the red tide possesses an iron-binding siderophore (see below). 4... 

Cylindrospermopsin has also been isolated from Umezakia natans and Aphanizomenon ovalisporum. Algal blooms that produce cylindrospermopsin are widespread in tropical waters where occurrences of gastro-... 

Nichols, P.D., Palmisano, A.C., Rayner, M.S., Smith, GA., and White, D.C. (1990) Occurrence of novel C20 sterols in Antarctic sea ice diatom communities during spring bloom. Org. Geochem. 15, 503-508. 

Wasmund, N. (1997) Occurrence of cynaobacterial blooms in the Baltic Sea in relation to environmental conditions. Inti. Rev. Ges. Hydrobiol. 82, 169-184. 

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