A global protist: dynamics of marine Labyrinthulomycetes across ecosystems

Abstract

Labyrinthulomycetes is a class of heterotrophic fungal-like protists (microbial eukaryote) that has been found in both aquatic and terrestrial ecosystems. In marine and estuarine environments, Labyrinthulomycetes are known for their saprotrophic lifestyle (feeding on detritus) and therefore have an important role in the degradation of phytoplankton litter. Despite their crucial role in the marine ecosystem, previous efforts in understanding their biogeography have been limited. This study aims to map out a global scale genetic diversity of Labyrinthulomycetes and their community structure across ecosystems and climates. To explore the biogeographical patterns of Labyrinthulomycetes genetic clades and to understand the ecosystem dynamics shaping its community structure, I will be analysing 59 publicly available metabarcoding studies (≈ 6000 samples) gathered in MetaPR2 database. Species richness, abundance and taxa dominance vary across the different ecosystems showing niche preference amongst the different clades. Coastal ecosystems were found to be associated with Thraustochytrids while oceanic ecosystems are associated with the Labyrinthulomycetes X undescribed environmental order. Dominant taxa associated with each climatic area are shaped by factors such as substrate preference and oceanic upwelling. Vertical community partitioning was observed too, suggesting the different roles each Labyrinthulomycetes clade has in the process of deep-sea carbon sequestration. Labyrinthulomycetes displayed clear patterns in their distribution, although the drivers of such niche partitioning remain unclear.