Embryonic exposure to environmentally relevant concentrations of PCB126 affects prey capture ability of larvae

Catherine M. Couillard , Benoît Légaré , Andréane Bernier (1) , Zara Dionne

1 UQAR - Université du Québec à Rimouski

Early life stages from a marine fish species, , were exposed to sublethal doses of 3,3',4,4',5-pentachlorobiphenyl (PCB126) to evaluate its effects on ecologically relevant responses: growth and behavior. A few hours after fertilisation, eggs were treated topically with PCB126 (3.1 to 50 pg egg). Four days post-hatching (dph), morphological changes (body length and malformations), spontaneous locomotor activity (active swimming speed, rate of travel, % inactivity), prey capture ability ( nauplii) and whole body EROD activity were evaluated in larvae. Untreated larvae collected at 0.5, 1, 2, 3, 4 dph were also examined. PCB126 did not increase the mortality or malformation rates. Body length and spontaneous locomotor activity were altered only in larvae treated with the highest dose. Treatment with PCB126 caused a dose-responsive reduction in prey capture ability (rate of decline in the number of ) and induction of EROD activity. The lowest observed effective dose for both of these responses was 6.3 pg PCB126 egg or 6.3 TCDD-toxic equivalents pg g egg, using a TCDD toxic equivalent factor of 0.005 and an egg mass of 5 mg. Prey capture efficiency (number of captured per feeding strike) was reduced at ≥ 12.5 pg egg. In untreated developing larvae, prey capture ability and efficiency increased as post-hatching development progressed and EROD activity remained low. The pattern of behavioral responses observed in PCB126-exposed larvae differed from that observed in less developed larvae indicating that other mechanisms than retarded development were involved. Behavioral dysfunction was a more sensitive response to PCB126 than morphological alterations and it occurred at environmentally-relevant concentrations.

Mots clés: PCB126; fish larvae; behavior; EROD

Domaines: Sciences du Vivant [q-bio]

Catherine M. Couillard, Benoît Légaré, Andréane Bernier, Zara Dionne. Embryonic exposure to environmentally relevant concentrations of PCB126 affects prey capture ability of larvae. Marine Environmental Research, 2011, 71 (4), pp.257. ⟨10.1016/j.marenvres.2011.01.010⟩. ⟨hal-00682414⟩