Ecotoxicity assessment in aquaculture system using the test organism Pseudokirchneriella subcapitata (Chlorophyceae) - doi: 10.4025/actascibiolsci.v34i4.9391

The purpose of this study is to perform toxicity tests with microalgae Pseudokirchneriella subcapitata (Chlorophyceae) using inland water samples to evaluate the impact caused by aquaculture. Six field samples were collected ranged November 2006 to March 2007, at Experimental Station, Pindamonhangaba, State of São Paulo. Abiotic factors pointed out to the mesotrophic and eutrophic characteristics already observed at the fish pond and its effluent. The results of ecotoxicological tests carried out with the microalgae Pseudokirchneriella subcapitata showed that the fish pond effluent was potential enough to stimulate the algal growth, therefore eutrophication, to the extent that it is naturally diluted to at least 12.5% of its initial concentration. This type of test can be a tool to be used by environmental managers in attempts to measure the extents of the impacts of effluent discharges from fish farming and to propose treatments based on qualitative and quantitative information.

Determination of selenium toxicity to Oreochromis niloticus based on hematological parameters - doi: 10.4025/actascibiolsci.v34i2.8755

Selenium (Se) is described as an essential micronutrient and participates in different biological functions, as the antioxidant defense systems maintenance and regulation. However, when in high concentrations, Se may cause toxic effects as well as hematological changes in fish. The aim of the present study was to determine the toxicity of selenium in the form of sodium selenate (Na2Se6+O4) in Oreochromis niloticus based on hematological parameters, after exposure to different concentrations (0.01, 0.14 and 1.4 mg Se6+ L-1). The erythrocytic and leukocytic series were examined over 14 days at intervals of 0, 3, 5, 7,10 and 14 days. The erythrocytic series showed significant alterations in the first 7 days, including the control group. Neutrophils and monocytes showed variations in the first 3 days at a concentration of 1.40 mgSe6+ L-1 characterizing an acute response. The total number of leukocytes was different in relation to time zero on all Se concentrations. The thrombocyte count also differed statistically from time zero and control in the first 3 days at 0.14 mgSe6+ L-1. These results indicate that different concentrations induce an acute response with diminution of total leukocytes, neutrophilia, monocytosis and thrombocytosis.