TOXICITY OF Ricinus communis (De Geer, 1778) LEAF POWDER TO HETEROCLARIAS JUVENILES

Abstract

The study evaluated the toxicity effects of Ricinus communis leaf powder at 4g/l on Heteroclarias juveniles. Blood profiles, gills, liver and kidney were used as biomarkers for testing the toxicity of leaf powder of R. communis leaves using the standard methods of the American Society for Testing and Materials (ASTM). Two hundred and forty (240) apparently healthy Heteroclarias juveniles with mean weight 24±0.25g were randomly distributed into twelve (12) bioassay tanks of 10L of water with stocking density of ten (10) fish per tank. Fish were exposed to varying concentrations of R. communis (0.0, 2.0, 3.0, 4.0., 5.0 and 6.0g/l). The experiment was setup in triplicate using a static bioassay procedure. The Median Lethal Concentration (LC50) was determined using probit analysis. A range finding test was conducted prior to the setting-up of the experiment. Water quality parameters such as temperature (°C), pH, dissolved oxygen (mg/L) and conductivity (μS/cm) were monitored, measured and recorded. The results showed significant differences (P<0.05) in the physico-chemical parameters: temperature (23.10 ± 0.00 - 25.60±0.00), pH (7.05±0.01 - 7.54±0.01), dissolved oxygen (6.30 ± 0.14 - 3.40±0.14) and conductivity (237.50 ± 0.71 - 295.00±141) across the treatments. There was a reduction in the values of temperature and dissolved oxygen while conductivity and pH increased with increase in concentration of R. communis. The LC50 for Heteroclarias juveniles during the 96 hours exposure was 4.37g/l. Observed behavioural response includes erratic swimming, frequent jumping, gaping, loss of reflex, vertical swimming, mucous discharge, skin discoloration and non-response to stimuli, which deviated from normal and intensified with increasing concentration of R. communis. Mortality observed increased with increase in concentrations, but no mortality or any abnormal behaviour was observed in the control tank. The blood profiles analysis showed that there was decrease in haematological parameters (PCV, Hb, and RBC) with significant difference (p<0.05) between the control (0.0g/l) and fish in the medium with the highest concentration (6.0g/l) of toxicant. The White Blood Cells (WBC) in fish increased with the highest value (8.75±0.21) recorded in 6.0g/l concentration and the least value (5.20±0.14) was recorded in the control tank. The highest PCV (36.50±0.71) was recorded in the control (0.0g/l) while the least (23.00±1.41) was recorded in the medium with the highest concentration (6.0g/l) of toxicant. The highest Hb value (12.20±0.14) was recorded in control (0.0g/l) and the least (7.65±0.49) in (6.0g/l) concentration. The concentration with 6.0g/l has the least RBC value (2.50±0.14) and highest RBC value (3.95±0.60) in control 0.0g/l. There was a decrease in immunological parameters (Mean Cprpuscular Haemoglobin, Mean Cell Haemoglobin Concentration and Mean Corpuscular Volume) but with no significant difference at (p > 0.05). Highest and lowest values were recorded in control (0.0 g/l) and highest concentration (6.0 g/l) in MCV (92.44±3.44) and (91.99 ± 0.45). MCH highest value (30.90±0.91) was recorded in the control concentration while the lowest (30.09±0.13) in 5.0 g/l. MCHC highest value (3.35±0.01) and lowest value of (3.32±0.00) was recorded in the 4.0 g/l and 5.0 g/l concentrations of R. communis respectively. The histology of the organs of the experimental fish (kidney, liver and gills) revealed different alteration in the architecture of the organs such as fragmentation of gill filaments and supporting structures, severe fusion of the primary and secondary lamellae, haemorrhage and sloughing of gill filaments; liver showed congestion of the hepatic artery veins, foci hepatocellular degeneration with monocytic; kidneys showed alterations such as congestion of the renal artery, diffused inflammation of the renal tubules and haematopoietic cells and inflamed nephrons, hyperplasia of the glomerular vessels, pynotic nephrons and degenerated renal corpuscle. This study therefore has shown that the exposure of Heteroclarias juveniles at high concentration is dangerous to the health of fish thus Ricinus communis leaf should therefore be handled with extreme care so as not to pollute or enter the aquatic ecosystem.