Are Ealry Development Satges of Frogs in Danger due to Environmental Pollutants? An Investigation with Low Concentrations of Chlorpyrifos

Abstract

Modern pollutants in the env:rorunent have been blauaed for adverse effeots on varisus orga&isms at cellular and sub-ceilular level. Pestieides luve bee,n given special atrention because of their extensive usage in agrio'ulture throughout the w'orld and their *ffects on non-target speoies. Amphibian fauna represents a$ important non-target speaies. In this reslleet it is thought that early devalopmental stages of frogs are at a risk. due to environmenta! pollutants. The present study was aimed to iavestigate how chlorpyrifos, a widely used pestieide in Sri Lanim, afiflects early developmental stages of RaNa spp. A.ll experiments wete done with 5 replioates each. Completely different eight expedmeats were carried out usrng eoileeted egg masses itotal cormbinaiions 5x8x4:200). Stocking destiny of tadpoles llr the experirnenta! chanrbers vsas maintained Z0-tadpoles/ liter. Ttrey were exposed to 0.01, 0.03 and 0.05 ppm ohlorp5aifes. Observations lvere made every 6 hour tiil 24 hours and &on in every 24 hor.lr. N*rnber paralised, dead and hatching percentsges were inveetigated, LB50 vatrues {24 anC 48 hcurs) of Ctrlorpyrifos to early stages of tadpoles were 2.4-2.6 ppm (24 hours) and 2.0-2.-q ppm (48 horus). Our findings showed expost:rs to very low levels of Chlorppifos delayed hatchreg rate (8.59'o in S.05 ppna and 909ro ln contro!], increased mortality of tadpales sipificantly €<0"05). Tadpole iuetannorphosis also delayed. Fresent investigation ccnfirms eariier work on Rana sylvatica, R. pipierus amd Esrra cldrnrtara" Histologicai evatruetioas confirmed extensive dannage to gitt striJetures during the internal giil stage of tndpoles. Neverihcless, this sfirdy shows that early tadpoie stages are in danger frona rnodern pctriutaats" The present shrdy also explores investigation of pollutants on non-target speoies alld questions rvhether tadpoles can be considered as an indiaator specias in toxicologr. 16r