Effects of environmental factors on host-microbiota interactions in the guts of aquatic organisms: A review

Aquatic environments are dynamic systems where multiple factors influence the intricate interactions between hosts and their gut microbiomes. This review explores how various stressors alter the gut microbiota of fish and aquatic invertebrates, by examining factors that include water characteristics, photoperiod, external pollutants such as heavy metals and microplastics, food availability, and practical aquaculture feed additives, for example, ethoxyquin. Across these diverse factors, common patterns emerge, including disruptions to microbial diversity, compromised gut barrier integrity, and the induction of oxidative stress. Conversely, beneficial additives like probiotics and astaxanthin are shown to mitigate these negative effects by reinforcing gut structure and modulating the microbial community. Collectively, these findings underscore the critical role of the gut microbiota in mediating host responses to environmental changes. Future research should therefore focus on elucidating specific toxicological pathways like the gut-organ axis, investigating the transgenerational effects of pollutants, and developing probiotic-based strategies to enhance the resilience and sustainability of aquaculture.