Physiological responses in C. decemmaculatus exposed to samples from Reconquista River and cadmium

BAODOU F G; OSSANA, N A; FERRARI, L; FICELLA, M

Buenos Aires

Congreso; SETAC Latin America 11 th Biennial Meeting; 2015

SETAC

The aim was toassess the effects of subchronic exposure to samples from Reconquista riverwater and cadmium on ingestion (I) and assimilation efficiency (%U),as well ason the ability to recover, in adult C.decemmaculatus. A water sample was taken on the spring of 2014 from thesource of the main course; it was physicochemically characterized, filtered andstored at 5ºC until its use. Assay organisms were adult (N: 238; body weight: 31.11-169.1mg;length: 17.79-31.85 mm), both sexes, coming from the laboratory culture. Theexperiment was carried out in quadruplicate/sextuplicate, after a 14-dayacclimation in moderately hard water (MHW),with partial renewal every 96h, foodsupply ad libitum. Environmentalconditions (aeration, T 23±1ºC, photoperiod of 16L:8O and dilution medium) wereconstant from acclimation. 4 acuarium were destined to filtered water fromReconquista river (RR), 5 to 0.5 mg Cd/L MHW (Cd) and 6 were destined to controls(MHW). Exposure was extended throughout 12 days. At baseline, the total biomasswas registered by each replicate. Food (daily 2% of the total/replicatebiomass) was offered after removing feces (H) during 60min, and excess wasremoved through aspiration. Excess food and produced H were dried untilconstant weight and weighed, H, I (expressed in animal mJ/mg) and %U(I-H/I*100) were calculated. Recovery in MHW extended through 24 days and wasassessed in 1 replicate of Cd, 3 RR and 3 MHW. Daily pH, medium hardness andsurvival were registered. I, H was calculated, and nominal Cd concentration wasmeasured. At exposure and recovery end time, the condition factor (FC) wasdetermined for surviving animals from each treatment. Statistical assessment ofthe results was performed using ANOVA or Kruskal Wallis. Mortality in RR wasless than 10%, comparable to MHW throughout the assay and for the Cd group itwas progressive through time and was at 57% at exposure end time, lowering to33% at recovery end time. FC did not register significant differences betweengroups, nor between both stages of the assay. The I of the RR group did notdiffer from MHW throughout the assay; however, it showed a %U significantlyhigher compared to MHW in the exposure stage, which was compensated duringrecovery. Cd group showed a significant reduction in I with respect to MHW andRR, throughout the assay, but showed a significant recovery of %U. Underexperimental conditions, an imbalance of %U during toxic stress can be predicted,as well as its restoration in a control situation.