Hossain Nafis Imtiaj, Rahman S M Mustafizur, Hossain Md Alamgir, Bin Hafiz Kashafad, Sowrav Sheikh Fahim Faysal, Masud-Ul-Alam Md, Choudhury Tasrina Rabia
Department of Oceanography and Hydrography, Bangabandhu Sheikh Mujibur Rahman Maritime University, Pallabi, Mirpur-12, Dhaka 1216, Bangladesh.
Department of Oceanography and Hydrography, Bangabandhu Sheikh Mujibur Rahman Maritime University, Pallabi, Mirpur-12, Dhaka 1216, Bangladesh.
Mar Pollut Bull. 2025 Apr;213:117669. doi: 10.1016/j.marpolbul.2025.117669. Epub 2025 Feb 13.
Phytoplankton, as primary producers and bioindicators, are vital for assessing aquatic ecosystem health. This study developed a Phytoplankton Quality Index (PQI) to evaluate the ecological health of Bangladesh's Sundarbans estuarine zones, using data from 24 stations across the Pashur River and estuaries in Bagerhat, Khulna, and Satkhira regions during the winter of 2021. Thirty-two variables were incorporated into a comprehensive multivariate and index-based framework, including ten heavy metals, eight phytoplankton indices, eight physicochemical, and four nutrient parameters. Diatoms dominated the phytoplankton community (93.38 %), followed by Dinoflagellates, Chlorophyta, and Charophyta together accompanying high abundance, richness and diversity in estuarine regions and high dominance in upstream regions with varying level of evenness throughout the study area. Moderate pollution was indicated by the Heavy Metal Evaluation Index (HEI = 6.24) in Satkhira and Nemerow's Pollution Index (NPI = 1.65) in Bagerhat. Normality (P > 0.05) and multicollinearity tests (Variance Inflation Factor < 10) finalized fifteen variables for Redundancy Analysis (RDA) and Canonical Correspondence Analysis (CCA), which identified temperature (23.85 ± 1.36 °C), pH (8.04 ± 0.08), nitrate (0.612 ± 0.15 ppm), HEI (5.14 ± 1.48), and ORP (285.11 ± 34.86 miliVolts) as key drivers for Diatoms, while ammonia (0.203 ± 0.105 ppm) and phosphate (0.096 ± 0.05 ppm) favored Chlorophytes and Charophytes. Further PQI was calculated using Principal Component Analysis (PCA) integrating the varimax method ensuring Measure of Sampling Adequecy (MSA > 0.5) for all variables. Results revealed significant spatial variability in phytoplankton quality with poor PQI in the upstream (20 %) and downstream (18 %) sections of the Pashur River driven by metal pollution and nutrient imbalances. Estuarine zones showed good quality (76 %) with localized poor-quality areas were linked to pollution and restricted water circulation. The study introduces a novel framework to identify PQI integrating multiple ecological metrics to assess the health of mangrove estuarine ecosystems. This tool is essential for monitoring ecosystem conditions, detecting pollution hotspots, and supporting sustainable management strategies globally.
浮游植物作为初级生产者和生物指示物，对于评估水生生态系统健康至关重要。本研究开发了一种浮游植物质量指数（PQI），以评估孟加拉国孙德尔本斯河口地区的生态健康状况，使用了2021年冬季帕舒尔河以及巴盖尔哈德、库尔纳和萨特希拉地区河口24个站点的数据。三十二个变量被纳入一个综合的多变量和基于指数的框架，包括十种重金属、八个浮游植物指数、八个理化参数和四个营养参数。硅藻在浮游植物群落中占主导地位（93.38%），其次是甲藻、绿藻和轮藻，它们在河口地区丰度、丰富度和多样性较高，在上游地区优势度较高，整个研究区域均匀度水平各异。萨特希拉的重金属评价指数（HEI = 6.24）和巴盖尔哈德的内梅罗污染指数（NPI = 1.65）表明存在中度污染。正态性检验（P > 0.05）和多重共线性检验（方差膨胀因子 < 10）最终确定了十五个变量用于冗余分析（RDA）和典范对应分析（CCA），结果确定温度（23.85 ± 1.36°C）、pH值（8.04 ± 0.08）、硝酸盐（0.612 ± 0.15 ppm）、HEI（5.14 ± 1.48）和氧化还原电位（285.11 ± 34.86毫伏）是硅藻的关键驱动因素，而氨（0.203 ± 0.105 ppm）和磷酸盐（0.096 ± 0.05 ppm）有利于绿藻和轮藻生长。进一步使用主成分分析（PCA）结合方差最大化方法计算PQI，确保所有变量的抽样充足性度量（MSA > 0.5）。结果显示浮游植物质量存在显著的空间变异性，帕舒尔河上游（20%）和下游（18%）部分的PQI较差，这是由金属污染和营养失衡导致的。河口地区质量良好（76%），局部质量较差的区域与污染和水循环受限有关。该研究引入了一个新颖的框架来确定整合多个生态指标的PQI，以评估红树林河口生态系统的健康状况。这个工具对于监测生态系统状况、检测污染热点以及支持全球可持续管理策略至关重要。
