The results of this study indicate that exposure of rainbow trout to 0.06 portion of the 96-hour
LC50 of Cu+Zn ions mixture induced a six-fold decrease in the abundance of total heterotrophic bacteria in digestive tract of rainbow trout.
The concentration of Cu that kills 50% of larvae (
LC50) and the concentration of Cu that causes 50% inhibition of normal larval development (EC50) were determined by probit analysis (piecewise linear regression analysis) using measured concentrations of dissolved Cu at the beginning of the experiment (t = 0).
Regarding overall sensitivity of three fish species, Labeo rohita showed significantly least sensitivity to metal mixtures with a mean
LC50 and lethal concentrations of 81.73+-12.73 and 128.80+-19.95 mgL-1, respectively.
Taciau veikiant vaivorykstinio upetakio jauniklius 0,16 mg/l Cu (0,25
LC50 suaugusiu zuvu) koncentracija, kvepavimo daznis reiksmingai padidejo nuo 70,0 [+ or -] 2,6 iki 83,0 [+ or -] 3,4 krt./min.
Studies carried out by (21) showed that the
LC50 of Poecilia reticulata when exposed to copper-cyanide and zinc-cyanide was 0.3 mg/L and 0.3 mg/L, respectively at 24 h.
Keywords: Acute toxicity, copper,
LC50, Cryphiops caementarius postlarvae.
The
LC50 value for glyphosate (the active ingredient in Roundup[R]) (Relyea 2005) is relatively high (4,000 [micro]g/L for Daphnia magna), indicating that it poses minimal risk to aquatic invertebrates.
The data were used to derive median lethal concentration (
LC50) using probit method (Finney 1971).
(c).reacts vigorously with water to produce a toxic or very toxic gas (
LC50 not exceeding 2,500 parts per million).
Dead flies were counted after two days, and mortality percentages, plotted against concentrations, allowed a graphic estimate of the lethal concentration killing 50% of the flies (
LC50).
Table I.-
LC50 values for different essential oils against CLM larvae by using two bioassay techniques.
The average mortality of each treatment (three replications pretreatment)at each concentration was calculated, and the
LC50 value which was defined as the concentration causing 50% mortality, was also determined.