Marine fungi and other understudied pico-, nano-, and micro-eukaryotes—including labyrinthulomycetes, MAST lineages, etc—are now recognized as pivotal yet enigmatic players in ocean ecosystems. Though increasingly implicated in critical processes such as organic matter cycling, carbon degradation, and microbial network regulation, their ecological and biogeochemical roles remain poorly understood. Persistent methodological challenges and conceptual gaps have hindered progress, leaving these organisms at the margins of marine science. This session will showcase cutting-edge research on these overlooked microbial eukaryotes, fostering interdisciplinary dialogue to unravel their functions and integrate them into our understanding of ocean processes.

We welcome contributions on:

• Ecological dynamics: Fungal and pico-, nano- and/or micro-eukaryote contributions to food webs, symbioses, and parasitism.
• Biogeochemical impacts: Degradation of simple to complex organic matter substrates (e.g., lignin, plastics), and influence on marine carbon/nutrient fluxes.
• Innovative tools: Omics, single-cell techniques, imaging, and isotope tracers to uncover their diversity and function.
• Modeling approaches: Representing their roles in biogeochemical and ecosystem models.

By bridging field observations, lab experiments, and modeling, this session will illuminate the unseen microbial forces shaping ocean processes—from surface waters to the deep sea.

• Marine Ecology and Biodiversity -
• Ocean Biology and Biogeochemistry -