Fungi in the Marine Environment: Open Questions and Unsolved Problems.

Anthony S Amend ,Joseph Heitman ,Erik Hom ,Giuseppe Ianiri ,Jason E Stajich ,Gaëtan Burgaud ,Cassandra L Ettinger ,C Alisha Quandt ,Kathryn T Picard ,Oded Yarden ,Meritxell Riquelme ,José M Vargas-Muñiz ,Seshagiri Raghukumar ,Michael Cunliffe ,Maiko Kagami ,Adam C Jones ,Allison K Walker ,Virginia P Edgcomb ,Marcelo H Gutiérrez ,Amy S Gladfelter

doi:10.1128/mbio.01189-18

Abstract

Terrestrial fungi play critical roles in nutrient cycling and food webs and can shape macroorganism communities as parasites and mutualists. Although estimates for the number of fungal species on the planet range from 1.5 to over 5 million, likely fewer than 10% of fungi have been identified so far. To date, a relatively small percentage of described species are associated with marine environments, with ∼1,100 species retrieved exclusively from the marine environment. Nevertheless, fungi have been found in nearly every marine habitat explored, from the surface of the ocean to kilometers below ocean sediments. Fungi are hypothesized to contribute to phytoplankton population cycles and the biological carbon pump and are active in the chemistry of marine sediments. Many fungi have been identified as commensals or pathogens of marine animals (e.g., corals and sponges), plants, and algae. Despite their varied roles, remarkably little is known about the diversity of this major branch of eukaryotic life in marine ecosystems or their ecological functions. This perspective emerges from a Marine Fungi Workshop held in May 2018 at the Marine Biological Laboratory in Woods Hole, MA. We present the state of knowledge as well as the multitude of open questions regarding the diversity and function of fungi in the marine biosphere and geochemical cycles.

Highlights

Terrestrial fungi play critical roles in nutrient cycling and food webs and can shape macroorganism communities as parasites and mutualists
The first records of marine fungi came from 19th century studies which utilized microscopy- and culture-dependent approaches, such as growing organisms on prepared media or on incubated samples collected from the marine environment [1,2,3]
We discuss the known and postulated functional roles for fungi throughout the marine environment with an eye toward understanding the colonization of marine habitats by fungi and their contributions to the ecology of the sea. This perspective emerges from a Marine Fungi Workshop held in May 2018 at the Marine Biological Laboratory in Woods Hole, MA

Summary

Introduction

Terrestrial fungi play critical roles in nutrient cycling and food webs and can shape macroorganism communities as parasites and mutualists. Molecular-based inventories of marine fungal diversity have recovered novel OTUs (operational taxonomic units) allied to known plant- and animal-associated lineages from seawater and marine sediments [9, 14, 15, 68, 69], suggesting that the myriad symbiotic interactions observed in terrestrial fungi—and their critical roles in ecosystem functioning—are likely present, or at least have correlates, in marine habitats as well.

Results

Conclusion