Navigating the microbial seas: a global analysis of gut microbiota in marine mammals

Abstract The gastrointestinal microbiota of mammals plays a crucial role in host health, influencing nutrient absorption, lipid metabolism, and immune system regulation. This study examines the current state of research on gut microbiota in pinnipeds and cetaceans, significant indicators of ocean health. To this end, a bibliometric and an in-depth analysis was conducted using the Scopus database. A total of 83 articles published between 1994 and 2023 were found on this topic. In this period, publications showed a 6.9% annual increase, reflecting a growing interest in this field. The USA and China lead in research output, reflecting their high investment in research funding. Study topics were classified in characterization, characterization and comparison, bacterial isolation, and others. Regarding the origin of the samples, faecal samples predominated over gastrointestinal tissues and oral swabs. The most abundant bacterial phyla were Firmicutes, Proteobacteria, Fusobacteria, and Bacterioidetes. The research also highlights the presence of pathogenic bacteria underscoring the need to better understand the health implications for these species. The analysis also reveals that studies focus on a few species, such as Phoca vitulina (Harbor seal) and Tursiops truncatus (Bottlenose dolphin), reflecting a bias towards more accessible and studied species. To advance in this area, it is recommended to broaden the range of species and countries studied, improve sampling methodologies, and foster international collaborations. Research on marine mammal gut microbiota remains an expanding field, offering significant insights into the biology and ecology of these animals.