Microplastisphere as a crowded and inclusive micro-ecosystem in seagrass meadow: Cross-kingdom connections and microbial food web

It is well established regarding microplastic (MPs) prevalence in seagrass meadow as one of blue carbon ecosystems. However, there is limited understanding of how seagrass-associated microbes construct microplastisphere, and even less is known about how such residents intercommunicate with each other and which kingdom is more central to maintaining microbial food web on microplastisphere. To address these points, microplastisphere obtained from in-situ exposure experiment of MPs in seagrass meadow was examined from phenotypic and genotypic perspectives. The obtained results showed that microplastisphere was a crowded, inclusive and self-sufficient microbial world, consisting of bacteria, protist, fungi, micrometazoa and microalgae. The cross-kingdom connections within bacteria and microeukaryotes, especially protist, maintained the complexity and stability of microplastisphere, whereas the contribution of the former was larger than that of the latter. Both stochasticity and determinism assembled microplastisphere communities, and their relative importance was linked with bacterial and microeukaryotic assemblages on MPs, respectively. A complete microbial food web was formed on microplastisphere, referring to photographs (diatom and microalgae), predators (cillate, nematode, rotifera, bryozoa and arthropoda), decomposers (Ascomycota of fungi) and symbionts. Heterotrophic bacteria, protist and nematode occupy central positions of microplastisphere microbial food web. Altogether, the current results shed light on the relative importance of both prokaryotes and microeukaryotes in assembling microplastisphere, and encourage further investigation into ecological effects due to the succession of microbial food web on microrplastisphere.