Ezhilarasan P, Panda U S, R S Pandiya Rajan, Vijay Akhilesh, Kumaraswami M, Jinoj T P S, Murthy M V Ramana
National Centre for Coastal Research, Ministry of Earth Sciences, Government of India, Chennai, 600100, India.
Environ Monit Assess. 2025 Jun 30;197(7):826. doi: 10.1007/s10661-025-14273-2.
Zooplankton in the mangrove and coastal waters play an important role in higher trophic levels. This study examines the zooplankton abundance and community changes across the Coringa mangrove creeks, Kakinada Bay, and the coastal waters of the Bay of Bengal. It focuses on their interactions with key environmental factors such as temperature, salinity, dissolved oxygen, nutrients, and chlorophyll-a. By analysing three distinct regions: (1) the mangrove ecosystem, including upstream and downstream creeks, (2) the adjacent bay, and (3) the connected coastal waters, providing insights into zooplankton variations in response to environmental changes across interconnected habitats. The results indicate significant variation in environmental variables, with salinity showing a prominent decreasing gradient (p < 0.0001; n = 29), markedly toward the upstream mangrove regions. A total of 67 zooplankton taxa were recorded, with copepods emerging as the dominant group and exhibiting marked spatial variation across the study area. Holoplanktonic organisms such as the freshwater cladoceran Daphnia sp. and euryhaline copepods Acartia clausi and Oithona brevicornis, along with meroplanktonic forms including fish eggs, fish larvae, and molluscan larvae, were particularly prominent in the mangrove creek habitats. Salinity influences zooplankton variation, highlighting its role in shaping the community structure. The diversity index and the meroplankton to holoplankton ratio revealed distinct variation between the coastal and mangrove-influenced environments. Cluster analysis identified distinct assemblages of zooplankton taxa, reflecting habitat-specific environmental conditions. The RDA analysis underscores the relationships between environmental factors and dominant zooplankton taxa, providing valuable insights for zooplankton assemblages in different habitat conditions.
红树林和沿海水域中的浮游动物在较高营养级中发挥着重要作用。本研究调查了科林加红树林小溪、卡基纳达湾以及孟加拉湾沿海水域的浮游动物丰度和群落变化。研究重点关注它们与温度、盐度、溶解氧、营养物质和叶绿素a等关键环境因素的相互作用。通过分析三个不同区域：（1）红树林生态系统，包括上游和下游小溪；（2）相邻海湾；（3）相连的沿海水域，深入了解浮游动物在相互关联栖息地中对环境变化的响应差异。结果表明环境变量存在显著差异，盐度呈现出明显的递减梯度（p < 0.0001；n = 29），尤其朝着红树林上游区域递减。共记录到67种浮游动物分类单元，其中桡足类成为优势类群，且在整个研究区域表现出明显的空间差异。全浮游生物，如淡水枝角类的大型溞属物种，以及广盐性桡足类的克氏纺锤水蚤和短角异肢水蚤，还有包括鱼卵、仔鱼和软体动物幼体在内的阶段性浮游生物，在红树林小溪栖息地尤为突出。盐度影响浮游动物的变化，凸显了其在塑造群落结构中的作用。多样性指数和阶段性浮游生物与全浮游生物的比例显示出沿海和受红树林影响环境之间的明显差异。聚类分析确定了浮游动物分类单元的不同组合，反映了特定栖息地的环境条件。冗余分析强调了环境因素与优势浮游动物分类单元之间的关系，为不同栖息地条件下的浮游动物组合提供了有价值的见解。
