Spatial variability of sediment geochemistry and meiofaunal communities in hydrothermal vent fields along the Central Indian ridge

Abstract

This study investigates the geochemical composition and meiofaunal communities in deep-sea hydrothermal vent sediments along the Central Indian Ridge (CIR). Our analysis focused on five vent fields: Onnuri, Onnare, Onbada, Invent E, and Kairei. Sediment analysis revealed spatial variation in heavy metal concentrations, with Onnare and Onbada exhibiting particularly high levels of As, Cd, Pb, Hg, Cu, and Zn. Meiofaunal abundance was highest at Invent E and was dominated by nematodes, whereas lower abundance was associated with sites exhibiting elevated metal concentrations. Principal component analysis and hierarchical cluster analysis identified Fe, Zn, As, Cd, Hg, and Co as key factors affecting the meiofaunal distribution and grouped stations based on their geochemical profiles. These findings demonstrate that sediment geochemistry plays a critical role in structuring benthic communities in deep-sea vent systems. They provide a crucial foundation for understanding ecological responses to natural geochemical gradients along the CIR and offer insights to guide future monitoring of hydrothermal ecosystems under environmental change.

Keywords: Central Indian ridge; Heavy metals; Hydrothermal vents; Meiofaunal communities; Multivariate analysis.