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Toxins produced by cyanoprokaryotes are a key issue in aquatic management because of their potential to exert adverse effects on humans and aquatic biota. The information gap regarding bioaccumulation and biomagnification processes associated with cyanotoxins, however, has resulted in inadequacies in the management and maintenance of biological diversity in lakes and reservoirs affected by toxic cyanoprokaryote blooms. This paper examines the potential for, and effects of, bioaccumulation of two common cyanotoxins, microcystin and cylindrospermopsin, in aquatic organisms. The factors influencing cyanotoxin bioavailability are discussed in the context of the challenges associated with understanding and managing toxin accumulation. Based on the characteristics of cyanotoxin bioavailability, exposure and uptake routes, a theoretical, predictive model for cyanotoxin bioaccumulation is proposed. Key concepts include monitoring changes in toxin availability throughout the progression of a toxic bloom and the prediction of ecological effects based on internal tissue concentrations. The model explores the minimum requirements that managers must undertake in order to properly assess bioaccumulation risk in terms of frequency of toxin testing, toxin fraction determination and assessment of aquatic organisms.

Lake Elphinstone is a tropical inland water body in the far north of the Fitzroy Catchment in Central Queensland, Australia, and has experienced recurrent toxic cyanoprokaryote blooms since 1997. This article reports on an examination of the environmental conditions of the lake and the concurrent cyanoprokaryote species together with their toxicity. The lake was sampled three times during periods of high cyanoprokaryote cell concentrations. Successive changes in the dominant Microcystis species were accompanied by variation in the concentration of the hepatotoxin microcystin. Environmental parameters recorded during dominance by both the highly toxic species Microcystis panniformis and the nontoxic M. botrys are provided. Nutrient status, temperature, and light conditions were associated with species change within the blooms. Variation of microcystin concentrations coincided with speciation change (i.e., morphological variation) within the blooms. Also discussed is the environmental impact of toxin production by M. panniformis with respect to influence on cell division, energy states, and toxin photodegradation. Lake Elphinstone is the first Australian location reported to have M. panniformis.

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