Impacts of Microbial Biofilms Associated with Marine Microplastics on Intertidal Benthic Communities

Abstract

Intertidal benthic organisms are a core force maintaining the structural stability and functional operation of marine ecosystems. They not only serve as a key link in the material cycling and energy flow of ecosystems but also include core economic species in coastal aquaculture, playing a vital role in marine ecological security and fishery economy. However, due to their proximity to terrestrial sources such as cities and rivers, intertidal zones receive terrestrial microplastics transported by rivers to coastal areas and the intertidal zones themselves. This leads to higher microplastic concentrations in intertidal zones compared to adjacent offshore waters, rendering them one of the most severely microplastic-polluted regions. Additionally, areas like beaches exhibit a concentrated distribution of microplastics, exposing the benthic organisms inhabiting these habitats to greater risks. After entering the ocean, MPs, due to their characteristics such as organic nature and long-term stability, become a substrate for microbial colonization and form the "plastisphere" (microbial biofilms on MPs). This poses a serious threat to intertidal benthic communities and may further damage the ecological functions and aquaculture value of the intertidal zone. This article reviews the existing research on microbial biofilms in the marine plastisphere and further focuses on intertidal zones—regions with particularly severe pollution. It also summarizes the harmful effects of microplastics themselves as well as microplastics colonized by microorganisms on benthic organisms. Studies have shown that the microbial community in the plastisphere undergoes phased succession, and the community contains pathogenic bacteria such as Vibrio and Escherichia coli, which increase the risk of antibiotic resistance transmission. Meanwhile, biofilms can enhance the adsorption capacity of MPs for heavy metals, significantly increase the uptake of MPs by benthic organisms, and affect the physiological health of some benthic organisms. Although the community characteristics of the plastisphere and the pathways of harm to benthic organisms have been clarified, there are still weaknesses: insufficient attention to the interaction between biofilms and benthic organisms in the intertidal zone (a heavily polluted area), lack of systematic exploration of the transformation potential of plastic-degrading microorganisms in the plastisphere, and absence of quantitative analysis of the loss of aquaculture economic value. In this regard, the following future research directions are proposed: (1) Focus on the impact of microplastic biofilms in heavily polluted intertidal zones on benthic organisms in those areas; (2)Investigating the Laboratory Cultivation Techniques of Microplastic-Degrading Microorganisms in Plastisphere Biofilms; (3) Conduct research on the impact of microbial biofilms in the intertidal plastisphere on benthic organisms and the quantitative assessment of the loss of aquaculture economic value.