Interspecific differences in mercury and organochlorine pesticides concentrations in Arctic and subarctic fishes.

The diversity and complexity of Arctic fish communities will increase as subarctic species expand their range poleward. In turn, borealization of fish communities will modify the species composition of Arctic food webs, trophic interactions, and distribution of contaminants. Comparing how contaminants in marine fish vary as a function of feeding ecology and location in Arctic and subarctic regions provides insight into how biomagnification and contaminant loads will be altered by shifts in species composition. Here we assess the drivers of total mercury (THg) and organochlorine pesticides (OCPs) concentrations in subarctic capelin (Mallotus villosus), glacier lanternfish (Benthosema glaciale), Greenland halibut (Reinhardtius hippoglossoides), blue hake (Antimora rostrata), and abyssal grenadier (Coryphaenoides armatus). We also examine regional differences in THg concentrations in Arctic cod (Boreogadus saida) across the Canadian Arctic. Glacier lanternfish were sampled using an Isaac Kidd Mid-Water Trawl (IKMT) and Arctic cod were sampled using a benthic beam trawl on the CCGS Amundsen. Capelin were hand-picked from beaches in coastal Labrador, while demersal fish were sampled using longlines on the FV Clears Cove Pride. Muscle tissue plugs were extracted and analyzed for methyl mercury (MeHg), total mercury (THg), OCP analytes, total lipid, and stable isotopes (δ14N, δ13C, and δ34S). Trophic position and species were the most important determinants of THg concentrations in all fishes, with habitat (δ13C and δ34S) also playing a role. While most OCPs varied by species, only three varied by trophic position, and one varied by location. Generally, demersal fishes had higher Hg and OCP concentrations than pelagic fishes. Mercury concentrations were lower in subarctic fish species than Arctic cod and higher in the western than the eastern Canadian Arctic, likely due to increased atmospheric inputs. Future Arctic contaminant seascapes will depend in part on the prevalence of boreal species and their anticipated altered predatory-prey interactions. We predict that future THg concentrations in Arctic marine fishes will decrease, while OCP concentrations levels will remain similar in a borealized Arctic.

随着亚北极鱼类物种向极地扩张其分布范围，北极鱼类群落的多样性与复杂性将随之提升。进而，鱼类群落的北方化将改变北极食物网的物种组成、营养级互作以及污染物的分布格局。通过对比北极与亚北极海域海洋鱼类污染物含量随摄食生态与分布区位的变化规律，可揭示物种组成变化将如何影响污染物的生物放大效应与负载水平。本研究针对亚北极毛鳞鱼（Mallotus villosus）、冰川灯笼鱼（Benthosema glaciale）、格陵兰大比目鱼（Reinhardtius hippoglossoides）、蓝无须鳕（Antimora rostrata）以及深渊胶鼬鳚（Coryphaenoides armatus）体内总汞（total mercury, THg）与有机氯农药（organochlorine pesticides, OCPs）的浓度影响因子展开评估，同时调查了加拿大北极海域内北极鳕（Boreogadus saida）体内THg浓度的区域差异。本研究使用艾萨克·基德中层拖网（Isaac Kidd Mid-Water Trawl, IKMT）采集冰川灯笼鱼样本，并在加拿大海岸警卫队“阿蒙森”号（CCGS Amundsen）科考船上使用底栖桁拖网采集北极鳕样本；毛鳞鱼样本采自拉布拉多沿海滩涂的手捡个体，而底栖鱼类样本则通过延绳钓在“Clears Cove Pride”号渔业船舶（FV Clears Cove Pride）上采集获得。研究人员提取肌肉组织栓样，随后分析其中的甲基汞（methyl mercury, MeHg）、总汞（THg）、有机氯农药检测物、总脂质以及稳定同位素（δ¹⁴N、δ¹³C与δ³⁴S）含量。分析结果显示，营养级与物种类型是所有鱼类体内THg浓度的最主要影响因子，生境特征（δ¹³C与δ³⁴S）同样发挥一定作用；尽管多数有机氯农药的含量因物种而异，但仅有3种有机氯农药的含量随营养级变化，另有1种随采样区位变化。总体而言，底栖鱼类体内汞与有机氯农药的浓度高于中上层鱼类。亚北极鱼类体内的汞浓度低于北极鳕，而加拿大北极西部海域的鱼类汞浓度高于东部海域，这一现象可能与大气输入量增加有关。未来北极海域的污染物海洋景观将在一定程度上取决于北方物种的分布占比，以及其预期发生改变的捕食-被捕食互作关系。我们预测，在发生北方化的北极海域，海洋鱼类体内的THg浓度将呈下降趋势，而有机氯农药浓度则将保持相对稳定。