GEOMETRIC MORPHOMETRIC ANALYSIS OF SILVER CARP LARVAE AFTER EXPOSURE TO TDCIPP

Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP), widely used as a kind of organophosphorus flame retardant, has been detected in the Yangtze River water environments. Many toxicological assessments have shown that TDCIPP could change morphology of fish. Silver carp (Hypophthalmichthys molitrix) lives in the Yangtze River for its entire life story, however, the effects of TDCIPP on silver carp is unclear. In order to clarify the main morphological characters of growth inhibition of silver carp larvae caused by TDCIPP, the present study analyzed the morphological traits between four environmentally relevant concentrations (0.05, 0.5, 5 and 50 μg/L) and the control group by geometric morphometric analysis. After the image information of larvae simple was obtained, the body length and body weight were measured. Then, digitization of landmarks was carried out with the TPS series software. Finally, principal component analysis (PCA), canonical variates analysis (CVA) and results visualization were carried out with Morpho J software. The body length and body weight of silver carp larvae decreased significantly under exposure to 0.5, 5 and 50 μg/L of TDCIPP compared with the control group, but no effects were observed in 0.05 μg/L. This indicated that environmentally relevant concentrations of TDCIPP induced growth inhibition in silver carp larvae. The results of PCA and CVA indicated that the first principal component (PC1) and the second principal component (PC2) together accounted for 62.15% of the overall variables (47.36% and 14.51%, respectively). The first canonical variates (CV1) and the second canonical variates (CV2) together accounted for 79.48% (54.55% and 24.93%, respectively), which satisfied the requirement of morphological analysis of silver carp larvae. The results of grid profile analysis indicated that the average morphology of silver carp larvae in different concentrations was significantly different with the control group (P＜0.05), which identified by the growth retardation of the head, longitudinal axis of body and tail. As a conclusion, TDCIPP could induce the growth retardation of head, longitudinal axis of body and tail in silver carp larvae. Therefore, attentions should be paid to the environmental concentrations of TDCIPP in the Yangtze River Basin, and the ecological risk of TDCIPP to the replenishment of silver carp population resources should be assessed.