Meeting Abstract
In a 2X2 design, we raised tadpoles from embryos at either 22 or 27 oC on a control diet, and then at day 17 post-hatch (approx. Gosner stage (GS) 27) we began feeding them food either with or without a commercial mix of PBDE congeners (DE-71; 100 ng/g wet food). Tadpoles developed (increased in GS) and grew (increased in mass) slower at cooler temperature and in the presence of PBDE. PBDE also changed the relation between mass and GS, which was linear (from GS 30 – 37) with no significant difference of temperature in the control animals but with a significant difference of temperature in tadpoles fed PBDE. We tested whether slower growth in tadpoles fed PBDE might be due to an effect of PBDE on resting metabolic rate (RMR), measured as O2 consumption. Between GS 30-40 (masses approx. 1 to 6.6 g, n=35 tadpoles), whole tadpole ln(RMR) linearly increased with ln(mass) (P<0.001) and with temperature (P=0.001) but there was no significant effect of PBDE exposure on mass-corrected RMR (P>0.7). The slope of ln(RMR) on ln(mass) was significantly steeper for tadpoles raised at 22C (0.50 +/- 0.04) than at 27 C (0.22 +/- 0.07) (P < 0.001). We conclude that slower growth and development in tadpoles exposed to PBDE is not due to proportionally greater allocation of ingested energy to respiration, but more likely to lower feeding or digestion rate. The relatively low scaling of ln(RMR) on ln(mass) (slopes <<3/4) may relate to relatively higher respiratory costs of growth at smaller masses. The data on respiration and production at different temperatures can be used to improve predictions on effects of warming climate on tadpole energetics. Funding provided by Sea Grant College Program, NOAA (Grant no. NA10OAR4170070, Project R/HCE-14).
