School of Marine Sciences, Zhuhai Key Laboratory of Marine Bioresources and Environment, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, Pearl River Estuary Marine Ecosystem Research Station, Ministry of Education, Sun Yat-Sen University, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519082, China.
Department of Biology, Center for Environment, Biodiversity and Conservation, The University of Texas at Tyler, Tyler, TX, USA.
Environ Pollut. 2021 Oct 1;286:117544. doi: 10.1016/j.envpol.2021.117544. Epub 2021 Jun 7.
While polychlorinated biphenyl (PCB)-related risks have been reported at the cellular, organ, and individual levels in some marine mammals, studies quantifying the PCB-associated population-level effects are limited. Here, we combined chemical analysis and individual-based model simulation to investigate the impact of PCBs on the Indo-Pacific humpback dolphin (sub)population from the Pearl River Estuary (PRE). An annual PCB accumulation rate of 0.29 ± 0.07 mg/kg lipid per year was estimated based on the measured age-specific male data as males continue to accumulate PCBs throughout their lifetime, without depurating contaminant loads. Using the Taiwan Strait dolphin population with low PCBs as a baseline, we compare our model simulations in PRE population to estimate relative population impacts of PCBs and other stressors. When using the current vital rates of the PRE dolphins which have been affected by PCBs and other stressors (e.g., underwater noise, prey limitation, etc.), our simulations revealed a substantial decline (8.1%) in the annual population growth rate (λ) of PRE metapopulation compared to baseline over the next 100 years. At the estimated PCB accumulation rate, the PCB-mediated effects on calf survival and immunity would cause a slight decline (0.9%) in λ relative to baseline. Our findings suggest a relatively limited impact of PCBs on the long-term survival of PRE dolphins among all stressors. However, it should be noted that even under model simulations where dietary PCBs were eliminated, humpback dolphins would still need a long time to reduce their PCB burdens to a relatively "safe" level through biological cycling. Considering that the baseline vital rates might also have been affected by PCBs and other stressors, our results are considered relative rather than absolute. This study provides a starting point for quantifying population-level consequences of contaminant exposure on humpback dolphins, although more efforts are needed to perfect this type of analysis.
虽然多氯联苯 (PCB) 相关风险已在一些海洋哺乳动物的细胞、器官和个体水平上得到报告，但量化 PCB 相关种群水平效应的研究有限。在这里，我们结合化学分析和个体基础模型模拟来研究 PCB 对来自珠江口 (PRE) 的印度洋-太平洋驼背豚（亚）种群的影响。根据测量的雄性年龄特异性数据，估计每年 PCB 积累率为 0.29±0.07mg/kg 脂质/年，因为雄性在其整个生命周期中会继续积累 PCB，而不会清除污染物负荷。我们使用 PCB 含量低的台湾海峡海豚种群作为基线，将我们在 PRE 种群中的模型模拟进行比较，以估计 PCB 和其他压力源对相对种群的影响。当使用受 PCB 和其他压力源（例如水下噪音、猎物限制等）影响的 PRE 海豚的当前关键比率时，我们的模拟结果显示，在未来 100 年内，与基线相比，PRE 复合种群的年种群增长率 (λ) 将大幅下降（8.1%）。在估计的 PCB 积累率下，PCB 对幼豚存活率和免疫力的影响将导致 λ 相对于基线略有下降（0.9%）。我们的研究结果表明，与所有压力源相比，PCB 对 PRE 海豚的长期生存的影响相对有限。然而，应该注意的是，即使在消除饮食 PCB 的模型模拟中，驼背海豚仍需要很长时间才能通过生物循环将其 PCB 负荷降低到相对“安全”的水平。考虑到基线关键比率也可能受到 PCB 和其他压力源的影响，我们的结果被认为是相对的，而不是绝对的。本研究为量化污染物暴露对驼背海豚种群水平后果提供了一个起点，尽管需要做更多的工作来完善这种类型的分析。
