Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa 310800, Israel.
Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa 310800, Israel.
Environ Int. 2024 May;187:108661. doi: 10.1016/j.envint.2024.108661. Epub 2024 Apr 15.
Deep-sea habitats are currently recognized as a hot spot for mercury (Hg) accumulation from anthropogenic sources, resulting in elevated concentrations of total mercury (THg) in deep-sea megafauna. Among them, deep-sea sharks (Class Chondrichthyes) are characterized by high trophic position and extended longevity and are, therefore, at high risk for mercury contamination. Despite this, sharks are overexploited by fishing activity in increasingly deeper water, worldwide, imposing health risks to human consumption. While it is imperative to better understand long-term mercury contamination in deep-sea megafauna, few historical data sets exist to capture this process. Here we explore four decades (1985-2022) of THg accumulation in five species of deep-sea sharks (G. melastomus, E. spinax, S. rostratus, C. granulosus, and D. licha) of the ultra-oligotrophic Southeastern Mediterranean Sea (SEMS) sampled during 19 research cruises. We exhibited exceptionally high THg levels (per length/weight), the highest as 16.6 μg g (wet wt.), almost entirely (98.9 %; n = 298 specimens) exceeding the limit for safe consumption (0.3-0.5 μg THg g wet wt.). The maximal THg levels of the long-lived species D. licha and C. granulosus in the SEMS were enriched by a factor of ∼ 7 and >10 compared to counterpart species from other oceanic areas, respectively. We attribute this to the ultra-oligotrophic conditions of the SEMS, which cause slower growth rates and dwarfism in deep-sea sharks, resulting in an extended exposure time to mercury contamination. In the long-lived species, C. granulosus and D. licha, a temporal increase of average THg levels of ∼ 80 % was recorded between 1987-1999 and 2021-2022. This likely reflects the long-term accumulation of historical anthropogenic Hg in deep-sea environments, which is further amplified in marginal seas such as the Mediterranean, impacted by global air pollution crossroads and surrounded by land-based pollution sources. Future consumption of products from deep-sea sharks is potentially high risk to human health.
深海生境目前被认为是人为汞源积累的热点，导致深海巨型动物体内总汞 (THg) 浓度升高。其中，深海鲨鱼（软骨鱼纲）具有较高的营养级和较长的寿命，因此面临较高的汞污染风险。尽管如此，由于全球范围内的捕鱼活动越来越深入，鲨鱼仍被过度捕捞，这对人类食用造成了健康风险。虽然更好地了解深海巨型动物中的长期汞污染至关重要，但目前很少有历史数据集可以捕捉到这一过程。在这里，我们研究了东南地中海（SEMS）的五种深海鲨鱼（G. melastomus、E. spinax、S. rostratus、C. granulosus 和 D. licha）在 19 次研究巡航中积累 THg 的情况，时间跨度为 40 年（1985-2022 年）。我们展示了异常高的 THg 水平（按长度/体重计），最高值为 16.6μg g（湿重），几乎全部（98.9%；n=298 个标本）超过安全食用限值（0.3-0.5μg THg g 湿重）。在 SEMS 中，长寿物种 D. licha 和 C. granulosus 的最大 THg 水平分别比其他海洋地区的对应物种富集了约 7 倍和 10 倍。我们将这归因于 SEMS 的超寡营养条件，这导致深海鲨鱼的生长速度较慢和体型较小，从而延长了暴露于汞污染的时间。在长寿物种 C. granulosus 和 D. licha 中，记录到 1987-1999 年和 2021-2022 年之间平均 THg 水平增加了约 80%。这可能反映了历史人为 Hg 在深海环境中的长期积累，而在像地中海这样受到全球空气污染十字路口影响的边缘海以及周围受到陆地污染源影响的海域中，这种积累进一步放大。未来人类消费深海鲨鱼产品可能对健康构成高风险。
