Physiological determinants of individual variation in sensitivity to an organophosphate pesticide in Nile tilapia Oreochromis niloticus
|Author(s)||McKenzie David1, 5, Blasco Felipe R.1, 2, Belao Thiago C.1, 2, Killen Shaun S.3, Martins Nathan D.1, 2, Taylor Edwin W.1, 4, Tadeu Rantin F.1|
|Affiliation(s)||1 : Univ Fed Sao Carlos, Dept Physiol Sci, Sao Carlos, SP, Brazil.
2 : Univ Fed Sao Carlos, Joint Grad Program Physiol Sci, UFSCar Sao Paulo State Univ, UNESP Campus Araraquara, Araraquara, SP, Brazil.
3 : Univ Glasgow, Inst Biodivers Anim Hlth & Comparat Med, Coll Med Vet & Life Sci, Glasgow G12 8QQ, Lanark, Scotland.
4 : Univ Birmingham, Sch Biosci, Birmingham BH5 4LU, W Midlands, England.
5 : Univ Montpellier, UMR9190, Ctr Marine Biodivers Exploitat & Conservat, Pl Eugene Bataillon, F-34095 Montpellier 5, France.
|Source||Aquatic Toxicology (0166-445X) (Elsevier Science Bv), 2017-08 , Vol. 189 , P. 108-114|
|WOS© Times Cited||6|
|Keyword(s)||Trichlorfon, Critical swimming speed, Metabolic rate, Respirometry, Nile tilapia, Individual variation|
Individual variation in sub-lethal sensitivity to the organophosphate pesticide trichlorfon was investigated in Nile tilapia, using critical swimming speed (U-crit) as an indicator. Tilapia exposed for 96 h to 500 mu g l-1 trichlorfon at 26 degrees C (Tcfn group, n = 27) showed a significant decline in mean U-crit, compared to their own control (pre-exposure) performance in clean water (-14.5 +/- 2.3%, mean +/- SEM), but also compared to a Sham group (n = 10) maintained for 96 h in clean water. Individuals varied in their relative sensitivity to the pesticide, with the decline in U-crit after exposure varying from 1 to 41%. The U-crit of the Tcfn group did not recover completely after 96 h in clean water, remaining 9.4 +/- 3.2% below their own control performance. The decline in performance was associated with a significant increase in net cost of aerobic swimming, of +28.4 +/- 6.5% at a sustained speed of 2 bodylengths s(-1), which translated into a significant decline in swimming efficiency (E-swim) of -17.6 +/- 4.0% at that speed. Within the T-cfn group, individual E-swim was a strong positive determinant of individual U-crit across all trials, and a strong negative determinant of individual% decline in U-crit after pesticide exposure (P < 0.001, linear mixed effect models). Trichlorfon had no effects on standard metabolic rate or active metabolic rate (AMR) but, nonetheless, individual U-crit in all trials, and% decline in U-crit after exposure, were strongly associated with individual AMR (positively and negatively, respectively, P < 0.001). Individual U-crit under control conditions was also a strong positive determinant of Ucrit after trichlorfon exposure (P < 0.001), but not of the% decline in U-crit performance. In conclusion, the OP pesticide impaired U-crit performance by reducing E-swim but individual tilapia varied widely in their relative sensitivity. Intrinsic individual physiology determined effects of the pesticide on performance and, in particular, good swimmers remained better swimmers after exposure.