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

Abstract

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 total 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. The experimental fish were exposed to 4 different natural populations of cyanobacterial water blooms. In 1996, the populations of filamentous cyanobacteria (WB I) formed by Anabaena flos-aquae (90%) and Aphanizomenon flos-aquae (10%) at a concentration of 5.6 × 104-3.2 × 105 cells·ml-1 without the presence of microcystins and colonial cyanobacteria Microcystis ichthyoblabe (80%) with subdominant Microcystis aeruginosa (20%) (WB II) at a concentration of 2.6 × 105 -3.6 × 106 cells·ml-1 with detected Microcystin LR (17.2 μg·g-1 of dry mass) were used. Exposure time was 168 h for filamentous species and 96 h for colonial species. In 1997 the monospecies population of filamentous cyanobacteria Anabaena flos-aquae (WB III) at a concentration of 5.3 × 104 - 7.9 × 104 cells·ml-1 containing two different microcystins (total concentration 56.06 μg·g-1 of dry mass) and water bloom (WB IV) formed by colonial species Microcystis ichthyoblabe (40%) and Microcystis aeruginosa (30%) with filamentous Anabaena flos-aquae (30%) at a concentration of 1.8 × 106 - 1.4 × 107 cells·ml-1 which contained three microcystins (total concentration 289.3 μg·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 leukocrit (BC) of fish exposed to the cyanobacterial population WB I, and in haematocrit (PCV) values, total protein concentration (TP), ALT and AST activities in fish exposed to the population WB II as compared to control fish. LDH activity in blood plasma of carp exposed to cyanobacterial population WB II was increased (p < 0.01) as compared to control fish. TP values from cyanobacterial populations WB 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 cyanobacterial water bloom WB III. The observations confirmed adverse effects of cyanobacterial biomass on juvenile carp. The effect of toxic water bloom populations was manifested by changes of blood plasma indices. Toxins supply here water the role of catalyzers enhancing the negative influence of toxic high ammonia values.