The Combined Effects of Ocean Acidification and Heavy Metals on Marine Organisms: A Meta-Analysis

Peng Jin,Jianrong Xia,Mengcheng Ye,Guang Gao,Jingyuan Zhao,Jiaofeng Wan,Jiale Zhang,Mengting Xiao,Sebastian Overmans,Xiaoying Dai

doi:10.3389/fmars.2021.801889

Abstract

Ocean acidification (OA) may interact with anthropogenic pollutants, such as heavy metals (HM), to represent a threat to marine organisms and ecosystems. Here, we perform a quantitative meta-analysis to examine the combined effects of OA and heavy metals on marine organisms. The results reveal predominantly additive interactions (67%), with a considerable proportion of synergistic interactions (25%) and a few antagonistic interactions (8%). The overall adverse effects of heavy metals on marine organisms were alleviated by OA, leading to a neutral impact of heavy metals in combination with OA. However, different taxonomic groups showed large variabilities in their responses, with microalgae being the most sensitive when exposed to heavy metals and OA, and having the highest proportion of antagonistic interactions. Furthermore, the variations in interaction type frequencies are related to climate regions and heavy metal properties, with antagonistic interactions accounting for the highest proportion in temperate regions (28%) and when exposed to Zn (52%). Our study provides a comprehensive insight into the interactive effects of OA and HM on marine organisms, and highlights the importance of further investigating the responses of different marine taxonomic groups from various geographic locations to the combined stress of OA and HM.

Highlights

Marine organisms in coastal waters are exposed to multiple anthropogenic pressures
Our meta-analysis revealed a prevalence of additive interactions between ocean acidification (OA) and heavy metals, indicating that cumulative effects of OA and heavy metals on marine biota can be reasonably well assessed by summing the single stressor impacts
Our syntheses suggest that the prevalence of additive interactions and a substantial proportion of antagonistic interactions meant that ocean acidification alleviates these negative effects

Summary

Introduction

Marine organisms in coastal waters are exposed to multiple anthropogenic pressures Among these pressures, heavy metals are major stressors that threaten marine organisms (Ivanina and Sokolova, 2015), and they are conservative in nature and can persist in the environment for extended periods (Reichelt-Brushett, 2012). Heavy metal contamination constitutes a consequence of anthropogenic activities and is recognized as a growing environmental concern (Doney, 2010). They enter the marine environment in various ways, including as agricultural and urban stormwater runoff, industrial effluents, sewage treatment discharge, and through fossil fuel combustion (Davis et al, 2001; Flint and Davis, 2007; Pan and Wang, 2012). Toxic heavy metals can be taken up by primary producers, enter the food web and be potentially transferred to higher trophic levels and threaten human beings (Wang, 2002)

Methods

Results

Discussion

Conclusion