Anthropogenic Stressors and Microbial Diversity in Aquatic Ecosystems: A Global Systematic Review

Introduction:

Aquatic microbial communities are fundamental to ecosystem functioning, contributing to nutrient cycling, organic matter decomposition, and water quality maintenance. However, increasing anthropogenic stressors, including chemical pollution, wastewater discharge, agricultural runoff, and climate change are altering microbial diversity and disrupting ecosystem processes. Changes in microbial community composition may reduce ecosystem resilience, impair biogeochemical functions, and promote the spread of antimicrobial resistance. This systematic review synthesized current evidence on the major anthropogenic stressors affecting microbial diversity in aquatic ecosystems and their ecological implications.

Methods:

A systematic review was conducted following PRISMA 2020 guidelines. Scopus, Web of Science, PubMed, and Google Scholar were searched for studies published between 2015 and 2025 using keywords including “microbial diversity,” “aquatic ecosystems,” “anthropogenic stressors,” “pollution,” “wastewater,” and “microbial communities.” A total of 236 records were identified, with 192 remaining after duplicate removal. 61 full-text articles were assessed, and 29 studies met the inclusion criteria for qualitative synthesis.

Results:

Among the 29 included studies, wastewater effluents (21 studies), agricultural runoff (18), heavy metals (17), and climate-related stressors (11) were the most frequently reported drivers of microbial diversity changes. Twenty-two studies documented significant shifts in microbial community composition, while 19 reported reduced microbial richness and diversity under increasing environmental stress. Metagenomic sequencing was the predominant analytical approach (20 studies). Sixteen studies identified enrichment of antimicrobial resistance genes and opportunistic pathogens in impacted aquatic environments, whereas 14 reported declines in key microbial taxa involved in nutrient cycling and ecosystem functioning.

Conclusions:

Anthropogenic stressors are major drivers of microbial diversity loss and community restructuring in aquatic ecosystems, with implications for ecosystem functioning, water quality, and environmental health. Strengthening pollution control, long-term microbial monitoring, and integrated conservation strategies is essential for protecting aquatic microbial biodiversity and sustaining ecosystem resilience.