Predicting consequences of POP-induced disruption of blubber glucose uptake, mass gain rate and thyroid hormone levels for weaning mass in grey seal pups

Persistent organic pollutants (POPs) are endocrine disruptors that alter adipose tissue development, regulation and function. Top marine predators particularly vulnerable because they possess large fat stores accumulate POPs. However, links between or function disruption whole animal energetics have rarely been investigated. We predicted the impact of alterations to blubber metabolic characteristics circulating thyroid hormone (TH) levels associated with polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs) on suckling mass gain weaning in wild grey seal pups. Glucose uptake by inner was a strong predictor rate, which turn, resulted heavier mass. Weaning increase 3.7 ± 1.59 (sem) %, through increased absence previously reported suppressive effect dioxin-like PCB (DL-PCBs) glucose uptake. PBDEs were, conversely, faster gain. Alleviation this reduce 6.02 1.86% (sem). To better predict POPs effects energy balance, it is crucial determine if how promote negatively related total T3 (TT3) levels. A 20% (range = 9.3-31.7%) reduction TT3 DL-PCBs partially overcame DL-PCB -mediated Overall, were thus 1.86 1.60%. Organohalogen impacts whole-animal balance pups appear offset each other opposing different mechanisms. POP generally minor, but largest POP-induced reductions occur already small. Since positively first-year survival, may disproportionately affect smaller individuals, could continue population-level even when relatively low compared historical values. Our findings show vitro experiments combined measurements vivo can help elucidate mechanisms underpin quantify magnitude disruptive contaminants stressors wildlife.