Determination of Median lethal concentration (LC50 96h) lead (II) nitrate and Behavioral responses of hermit crab, Diogenes avarus (Heller, 1865)

The LC50-96h test paradigm is used to measure the susceptibility and survival potential of organisms exposed to particular toxic substances, such as heavy metals. In this study, the statically acute toxicity of Pb on hermit crab D. avarus was determined according to standard methods O.E.C.D in 96h. 84 individual hermit crab with 0.19±.0.01 g weight average were used in five different treatments (75, 100, 150, 175, 200 microgram per liter of lead) with three replicates and a control treatment (15 hermit crab per in each treatment). The effective physical and chemical parameters of water including pH, total hardness, dissolved oxygen and temperature were controlled throughout the experiment. Finelly, the rate of the acute toxicity (LC50 96h) was determined to be 184.045 µg/l by using the statistic method Probity analysis. Furthermore, the rates of LC10, LC50, LC90 (24, 48, 72 and 96h) were calculated. Results indicate that when the experiment time is extended, lower concentration of Pb is leading to mortality in hermit crab D. avarus. The percentage of mortality increased with increasing duration of exposure of crab to different amounts of lead concentration. The behavioral changes observed in hermit crabs D. avarus in the experiment period included an imbalance in walking, reduced activity and movement, slow motion, no irritability and also color change of the abdomen.