Climate change and pollution are some of the greatest anthropogenic threats to wild animals. Transgenerational plasticity—when parental exposure to environmental stress leads to changes in offspring phenotype—has been highlighted as a potential mechanism to respond to various environmental and anthropogenic changes across taxa. Transgenerational effects may be mediated via multiple mechanisms, such as transfer of maternal hormones to eggs/foetus. However, sources of variation in hormone transfer are poorly understood in fish, and thus the first step is to characterise whether environmental challenges alter transfer of maternal hormones to eggs. To this end, we explored the population variation and environmental variation (in response to temperature and endocrine disrupting copper) in maternal thyroid hormone (TH), transfer to offspring in a common fish model species, the three-spined stickleback (Gasterosteus aculeatus) using multiple approaches: (i) We compared ovarian TH levels among six populations across a wide geographical range in the Baltic Sea, including two populations at high water temperature areas (discharge water areas of nuclear power plants) and we experimentally exposed fish to (ii) environmentally relevant heat stress and (iii) copper for 7 days. We found that populations did not differ in intraovarian TH levels, and short-term heat stress did not influence intraovarian TH levels. However, copper exposure increased both T4 and T3 levels in ovaries. The next step would be to evaluate if such alterations would lead to changes in offspring phenotype.

气候变化和污染是对野生动物最大的人为威胁。跨代可塑性（当父母暴露于环境压力导致后代表型发生变化时）已被强调为响应跨类群的各种环境和人为变化的潜在机制。跨代效应可能通过多种机制介导，例如母体激素转移到卵子/胎儿。然而，人们对鱼类激素转移变异的来源知之甚少，因此第一步是确定环境挑战是否会改变母体激素向卵子的转移。为此，我们探索了母体甲状腺激素（TH）的种群变化和环境变化（对温度和内分泌干扰铜的反应），并将其转移到常见鱼类模型物种三刺刺鱼（ Gasterosteus aculeatus ）的后代中。多种方法：（i）我们比较了波罗的海广泛地理范围内的六个种群的卵巢 TH 水平，包括高水温地区（核电站排放水区）的两个种群，并且我们通过实验将鱼暴露于（ii）与环境相关的热应激和 (iii) 铜，持续 7 天。我们发现不同人群的卵巢内 TH 水平没有差异，短期热应激不会影响卵巢内 TH 水平。然而，接触铜会增加卵巢中 T4 和 T3 的水平。下一步将是评估这种改变是否会导致后代表型的变化。