Toxicity of cyanobacteria isolated from the Guadiana River

Abstract

The Guadiana River flows through the Southwest area of the Iberian Peninsula crossing from the Spanish provinces of Extremadura and Andalucia to the southern region of Portugal. Preliminary studies on the presence and distribution of toxic cyanobacteria led to the identification of several cyanobacterial species in the Guadiana River itself as well as in the freshwater reservoirs established along its course. The objectives of this paper were the identification and quantification of planktonic cyanobacteria in freshwater reservoirs from the Guadiana River, with different applications (human consumption, agriculture purposes and recreational uses), and determination of their toxicity. After the isolation of cyanobacterial strains, the characterisation of their toxicological profile was carried out using immunoadsorbent assays (ELISA) and chromatographic techniques (HPLC-UV). Monitorization studies revealed that predominant species were Microcystis aeruginosa, Anabaena spp. and Aphanizomenon flos-aquae. Some strains of M. aeruginosa were responsible for microcystins production. The toxicity observed in ISACYA 10B was low. The strain ISACYA 2C produces high amounts of microcystins, and probably these toxins were responsible for the toxicity of the cyanobacterial bloom detected in these waters.