National Centre for Coastal Research (NCCR), Ministry of Earth Sciences, NIOT Campus, Pallikaranai, Chennai 600100, India.
National Centre for Coastal Research (NCCR), Ministry of Earth Sciences, NIOT Campus, Pallikaranai, Chennai 600100, India.
J Environ Manage. 2024 May;359:120982. doi: 10.1016/j.jenvman.2024.120982. Epub 2024 Apr 27.
Metals are essential at trace levels to aquatic organisms for the function of many physiological and biological processes. But their elevated levels are toxic to the ecosystem and even brings about shifts in the plankton population. Threshold limits such as Predicted No Effect Concentration (PNEC - 0.6 μg/l of Cd; 2.7 μg/l of Pb), Criterion Continuous Concentration (CCC - 3.0 μg/l of Cd; 4.5 μg/l of Pb) and Criterion Maximum Concentration (CMC - 23 μg/l of Cd; 130 μg/l of Pb) prescribed for Indian coastal waters were used for the study. Short-term mesocosm experiments (96 h) were conducted in coastal waters of Visakhapatnam to evaluate responses of the planktonic community on exposure to threshold concentrations of cadmium and lead for the first time. Four individual experimental bags of 2500 L capacity (Control, PNEC, CCC & CMC) were used for the deployment and ambient water samples were analysed simultaneously to evaluate the impacts of the threshold levels in the natural waters. Chaetoceros sp. were dominant group in the control system whereas, Prorocentrum sp. Ceratium sp. Tintinopsis sp. Chaetoceros sp. and Skeletonema sp. were major groups in the test bags. Throughout the experiment the phytoplankton community did not show any significant differences with increased nutrients and plankton biomass (Chl-a <8.64 mg/m). Positive response of plankton community was observed in the experimental bags. High abundance of diatoms were observed in PNEC, CCC & CMC bags at 48 h and the abundance decreased with shift in the species at 72-96 h. The catalase activity in phytoplankton (5.99 nmol/min/ml) and the zooplankton (4.77 nmol/min/ml) showed induction after exposure to PNEC. The present mesocosm study is confirmed that short-term exposure to threshold metal concentration did not affects the phytoplankton community structure in PNEC, but CCC and CMC affects the community structure beyond 24 h. The insights from this study will serve as a baseline information and help develop environmental management tools. We believe that long-term mesocosm experiments would unravel metal detoxification mechanisms at the cellular level and metal transfer rate at higher trophic levels in real-world environment.
金属对水生生物的许多生理和生物过程的功能来说是必需的微量元素。但它们的含量过高对生态系统是有毒的，甚至会导致浮游生物种群的变化。印度沿海水域规定了预测无影响浓度 (PNEC-0.6μg/l 的 Cd；2.7μg/l 的 Pb)、连续浓度标准 (CCC-3.0μg/l 的 Cd；4.5μg/l 的 Pb) 和最大浓度标准 (CMC-23μg/l 的 Cd；130μg/l 的 Pb) 等阈值限制，用于本研究。首次在维沙卡帕特南的沿海水域进行了短期中宇宙实验 (96 小时)，以评估浮游生物群落在接触镉和铅的阈值浓度时的反应。使用四个 2500 升容量的单独实验袋 (对照、PNEC、CCC 和 CMC) 进行部署，并同时分析环境水样，以评估天然水中阈值水平的影响。在对照系统中，优势种群是角毛藻属，而在试验袋中，主要种群是原甲藻属、菱形藻属、金藻属、角毛藻属和骨条藻属。整个实验过程中，浮游植物群落没有表现出明显的差异，营养物质和浮游生物生物量增加 (Chl-a<8.64mg/m)。浮游生物群落表现出阳性反应。在 48 小时时，PNEC、CCC 和 CMC 袋中观察到大量的硅藻，而在 72-96 小时时，随着物种的转移，丰度下降。暴露于 PNEC 后，浮游植物 (5.99nmol/min/ml) 和浮游动物 (4.77nmol/min/ml) 的过氧化氢酶活性被诱导。本中宇宙研究证实，短期暴露于阈值金属浓度不会影响 PNEC 中的浮游植物群落结构，但 CCC 和 CMC 会在 24 小时后影响群落结构。本研究的结果将作为基线信息，并有助于开发环境管理工具。我们相信，长期中宇宙实验将揭示金属在细胞水平上的解毒机制，以及在真实环境中更高营养级别的金属转移率。
