Otolith chemistry indicates recent worsened Baltic cod condition is linked to hypoxia exposure
Otolith chemistry indicates recent worsened Baltic cod condition is linked to hypoxia exposure
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DOI：
10.1098/rsbl.2019.0352
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发表时间：
2019-12-24
期刊：
影响因子：
3.3
通讯作者：
Casini, Michele
中科院分区：
文献类型：
--
作者：
Limburg, Karin E.;Casini, Michele
在世界范围内，水生系统的脱氧正在增加，对生物生物学、群落和生态系统产生影响。过去20年来，东波罗的海鳕鱼的平均身体状况（即特定长度的体重）急剧下降，对依赖这种资源的渔业产生了影响。在文献中，鳕鱼状况的减少已初步与可能影响栖息地范围的缺氧地区的增加联系起来，但也与底栖动物猎物和/或鳕鱼的生理直接相关。到目前为止，还没有进行任何研究来测试这些机制。利用耳石微量元素微化学和基于锰（Mn）和镁（Mg）的缺氧响应指标，研究了捕获时鱼类身体状况与缺氧暴露的关系。2000年以后捕获的低体质鳕鱼在生命最后一年的Mn/Mg水平较高，表明其暴露于缺氧水域的程度高于高体质鳕鱼。此外，终生缺氧暴露与身体状况的相关性更强，表明身体状况可能反映了长期缺氧状态。这些结果与鱼的年龄或性别无关。这意味着，当波罗的海鳕鱼造访低氧水域时，可能是在寻找底栖生物食物，它们会损害自己的表现。这项研究特别揭示了导致鳕鱼低状态的机制，并普遍指出了脱氧对生态系统和渔业的影响。
Deoxygenation worldwide is increasing in aquatic systems with implications for organisms' biology, communities and ecosystems. Eastern Baltic cod has experienced a strong decline in mean body condition (i.e. weight at a specific length) over the past 20 years with effects on the fishery relying on this resource. The decrease in cod condition has been tentatively linked in the literature to increased hypoxic areas potentially affecting habitat range, but also to benthic prey and/or cod physiology directly. To date, no studies have been performed to test these mechanisms. Using otolith trace element microchemistry and hypoxia-responding metrics based on manganese (Mn) and magnesium (Mg), we investigated the relationship between fish body condition at capture and exposure to hypoxia. Cod individuals collected after 2000 with low body condition had a higher level of Mn/Mg in the last year of life, indicating higher exposure to hypoxic waters than cod with high body condition. Moreover, lifetime exposure to hypoxia was even more strongly correlated to body condition, suggesting that condition may reflect long-term hypoxia status. These results were irrespective of fish age or sex. This implies that as Baltic cod visit poor-oxygen waters, perhaps searching for benthic food, they compromise their own performance. This study specifically sheds light on the mechanisms leading to the low condition of cod and generally points to the impact of deoxygenation on ecosystems and fisheries.