Changes of haematological indices of juvenile carp (Cyprinus carpio L.) under the influence of natural populations of cyanobacterial water blooms

The aim of the presented paper was to evaluate the effect of cyanobacterial water blooms common in eutrophic reservoirs on blood indices of carp. A to tal of 180 individuals of juvenile carp (Cyprinus carpio L.) of the average body mass 36.9 g (1996) and 26.3 g (1997) were used in the experiments. Th e experimental fish were exposed to 4 different natural populations of cyan obacterial water blooms. In 1996, the populations of filamentous cyanobacteria (WS I) formed by Anab aena flos-aquae (90%) and Aphanizomenon flos-aquae (10%) at a concentration of 5.6 x 10(4)-3.2 x 10(5) cells.ml(-1) without the presence of microcysti ns and colonial cyanobacteria Microcystis ichthyoblabe (80%) with subdomina nt Microcystis aeruginosa (20%) (WB II) at a concentration of 2.6 x 10(5)-3 .6 x 10(6) cells.ml(-1) with detected Microcystin LR (17.2 mu g.g(-1) of dr y mass) were used. Exposure time was 168 h for filamentous species and 96 h for colonial species. In 1997 the monospecies population of filamentous cy anobacteria Anabaena flos-aquae (WB III) at a concentration of 5.3 x 10(4)- 7.9 x 10(4) cells.ml(-1) containing two different microcystins (total conce ntration 56.06 mu g.g(-1) of dry mass) and water bloom (WB IV) formed by co lonial species Microcystis ichthyoblabe (40%) and Microcystis aeruginosa (3 0%) with filamentous Anabaena flos-aquae (30%) at a concentration of 1.8 x 10(6)-1.4 x 10(7) cells.ml(-1) which contained three microcystins (total co ncentration 289.3 mu g.g(-1) of dry mass) were used. Both populations were exposed for 48 h. Control fish in both tests were kept in treated drinking water infused 24 h before the start of the experiment. Haematological examination showed significant changes (p < 0.05) in leukocr it (BC) of fish exposed to the cyanobacterial population WB I, and in haema tocrit (PCV) values, total protein concentration (TP), ALT and AST activiti es in fish exposed to the population WE II as compared to control fish. LDH activity in blood plasma of carp exposed to cyanobacterial population WE I I was increased (p < 0.01) as compared to control fish. TP values from cyan obacterial populations WE III a WB IV, were significantly reduced (p < 0.05 ) and values of ALT activities increased (p < 0.01). Moreover, significant increase (p < 0.05) of AST activity was recorded for fish exposed to cyanob acterial water bloom WE III. The observations confirmed adverse effects of cyanobacterial biomass on juv enile carp. The effect of toxic water bloom populations was manifested by c hanges of blood plasma indices. Toxins supply here water the role of cataly zers enhancing the negative influence of toxic high ammonia values.