Herbicide leakage into seawater impacts primary productivity and zooplankton globally

This study investigates the global impact of herbicide runoff into seawater on primary productivity and zooplankton. Analysis of data from 661 bay and gulf stations worldwide (1990-2022) revealed median triazine herbicide concentrations of 0.18 nmol L⁻¹. At current herbicide levels, phytoplankton primary productivity was inhibited by >5% at 25% of sites and >10% at 10% of sites. This is attributed to the inhibition of sensitive species, shifts in community structure (from Bacillariophyta to Dinophyceae), changes in particle size (nano- to micro-phytoplankton), and reduced growth rates. Consequently, micro-zooplankton shifted from larger copepod larvae to smaller ciliates, potentially impacting food chain efficiency. Herbicide application rates on farmlands correlate with residues in adjacent seas, suggesting that increased herbicide use will further destabilize coastal waters.

Liqiang Yang, Xiaotong He, Shaoguo Ru, Yongyu Zhang