Landrau-Giovannetti Nelmarie, Murray Ryanne, Reichley Stephen, Moore Debra, Madrigal Theresa, Brown Ashli, Meredith Ashley, Childers Christina, Sparks Darrell, Solangi Moby, Linhoss Anna, Peterman Beth, Lawrence Mark, Kaplan Barbara L F
Global Center for Aquatic Health and Food Security, Mississippi State University, Mississippi State, MS 39762, USA.
Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA.
Toxics. 2025 Jun 18;13(6):511. doi: 10.3390/toxics13060511.
In 2019, an unusual mortality event (UME) affected bottlenose dolphins () in the Mississippi Sound (MSS) following an extended dual opening of the Bonnet Carré Spillway (BCS), which prevents flooding in New Orleans. This resulted in low salinity, skin lesions, and electrolyte imbalances in dolphins. Additionally, the influx likely altered the MSS's environmental chemical composition, including levels of heavy metals and metalloids; thus, we quantified heavy metals, metalloids, and essential elements in the tissues of dolphins that stranded in the MSS before and after the 2019 UME. We hypothesized that levels of heavy metals and metalloids (such as mercury (Hg), arsenic (As), lead (Pb), and cadmium (Cd)) would not show significant changes post-UME. Indeed, we found no major changes associated with the UME in most metals; sodium (Na) and magnesium (Mg) levels were lower in several tissues after 2019, which correlated with the average yearly salinity measured from the MSS. Toxic metals and metalloids were detectable with some changes over time; however, the selenium (Se):Hg molar ratio increased in some tissues post-2019. Additionally, we confirmed that Hg can bioaccumulate, with positive correlations between Hg levels and dolphin size as assessed by straight length. Overall, our findings indicate that freshwater incursions into the MSS can alter dolphin exposure to essential and toxic elements.
2019年，在邦尼特卡雷泄洪道（BCS）长期双孔开放后，一场异常死亡事件（UME）影响了密西西比海峡（MSS）的宽吻海豚。BCS可防止新奥尔良发生洪水。这导致海豚出现低盐度、皮肤损伤和电解质失衡。此外，淡水涌入可能改变了MSS的环境化学成分，包括重金属和类金属的含量；因此，我们对2019年UME前后搁浅在MSS的海豚组织中的重金属、类金属和必需元素进行了量化。我们假设重金属和类金属（如汞（Hg）、砷（As）、铅（Pb）和镉（Cd））的含量在UME后不会出现显著变化。事实上，我们发现大多数金属与UME没有重大关联；2019年后，几个组织中的钠（Na）和镁（Mg）含量较低，这与从MSS测量的年平均盐度相关。随着时间的推移，可检测到有毒金属和类金属有一些变化；然而，2019年后，一些组织中的硒（Se）：汞摩尔比有所增加。此外，我们证实汞可以生物累积，汞含量与海豚体长之间存在正相关。总体而言，我们的研究结果表明，淡水涌入MSS会改变海豚对必需元素和有毒元素的接触情况。
