Comparably Characterizing the Gut Microbial Communities of Amphipods from Littoral to Hadal Zones

Amphipods are an important group of invertebrates in marine ecosystems due to their high abundance and diversity. As an essential part of the marine food web, amphipods play a vital role in nutrient recycling and provide large amounts of detritus-derived fine-particulate organic matter for other invertebrates. Although the importance of gut microbiota and the necessity to consider them has been increasingly recognized, the gut microbial community and diversity of amphipods have not been well studied. Here, we comparatively studied the gut microbiota of diverse amphipod species inhabiting from coastal to hadopelagic zones. The results showed that four phyla, including Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteriota, occupied more than 90% of the total microbes in the studied amphipod guts, with Firmicutes being dominant in the hadal amphipods. The gut microbiome of amphipods from the hadal zone displayed the lowest richness, lowest diversity, and shared few microorganisms with the surrounding seawater compared to others. Amphipods in different inhabiting regions have discriminant taxa for their gut microbial communities. Taken together, amphipod gut microbiota was affected by both biological and abiotic factors, yet these factors are not independent. This article provides us with a further understanding of the structure and characteristics of the gut microbiota of invertebrate organisms.