Elasmobranchs are exposed to mercury (Hg) through a variety of pathways in the environment. This study assessed maternal offloading and diet-based Hg exposure for neonatal and juvenile blacktip sharks (Carcharhinus limbatus) from Charlotte Harbor located along southwest Florida’s coast, a recognized Hg hotspot. Neonates (n = 57) had highest total Hg (THg) concentrations in the kidney (0.56 ± 0.26 mg kg⁻¹; n = 38) and muscle (0.53 ± 0.17 mg kg⁻¹; n = 57), followed by liver (0.31 ± 0.11 mg kg⁻¹; n = 38), and blood (0.05 ± 0.033 mg kg⁻¹; n = 57). Juveniles (n = 13) exhibited a different distribution with highest THg in the liver (0.868 ± 0.54 mg kg⁻¹; n = 6), followed by the muscle (0.84 ± 0.28 mg kg⁻¹; n = 13), kidney (0.55 ± 0.22 mg kg⁻¹; n = 6), and blood (0.11 ± 0.04 mg kg⁻¹; n = 11). The distribution of THg among tissues and liver-to-muscle ratios indicated that Hg originated primarily from maternal offloading in neonates, whereas juveniles continued to accumulate Hg through dietary exposure post-parturition. Additionally, comparisons between results of the present study and previous Florida blacktip shark surveys suggested that Hg levels have not declined in southwest Florida estuaries for over two decades.

弹性分支通过环境中的各种途径暴露于汞（Hg）。这项研究评估了佛罗里达西南沿海夏洛特港的新生儿和少年黑鳍鲨（Carcharhinus limbatus）的母体卸载和饮食中基于汞的汞暴露，这是公认的汞热点。新生儿（n  = 57）在肾脏（0.56±0.26 mg kg ^-1 ; n  = 38）和肌肉（0.53±0.17 mg kg ^-1 ; n  = 57）中的总Hg（THg）浓度最高，其次是肝脏（ 0.31±0.11 mg kg ^-1；n  = 38）和血液（0.05±0.033 mg kg ^-1；n  = 57）。少年（n = 13）表现出不同的分布，肝脏中的THg最高（0.868±0.54 mg kg ^-1 ; n  = 6），其次是肌肉（0.84±0.28 mg kg ^-1 ; n  = 13），肾脏（0.55±0.22） mg kg ^-1 ; n  = 6）和血液（0.11±0.04 mg kg ^-1 ; n = 11）。THg在组织中的分布和肝肌比表明，Hg主要来自新生儿的母体负担，而未成年人在分娩后通过饮食接触继续积累Hg。此外，本研究结果与佛罗里达以前的黑鳍鲨调查结果之间的比较表明，佛罗里达州西南河口的汞含量在过去的20年中并未下降。