Impact of Salinity Stress on Growth and Development of Aquatic Fungi

Abstract

In most ecosystems salinity shapes biotic assemblages, representing a key environmental factor. This variable is regarded as a major threat to microbial commu- nities in terrestrial systems, modifying considerably a number of important ecosystem processes, including turnover of organic matter and nutrients acquisition. However, complex effects ofsalinity remain poorly understood, especially for non-model aquatic microbial assemblages, which account for most of the biodiversity in natural systems. Aquatic fungi are a widespread and phylogenetically heterogeneous group of micro- organisms, occurring in marine, estuarine, and freshwater systems. These osmotrophs are completely adapted to rapidly colonize, grow, and reproduce in aquatic systems, where salinity represents a frequently fluctuating environmental variable. Some inves- tigations have approached aquatic fungal response to salinity, suggesting that despite these microorganisms are able to survive under osmotic stress conditions, this variable may select for distinctive community compositions. At large, fungal responses to salinity stress are determined by taxon-specific underlying physiological traits, leading to distinctive tolerance thresholds. Herein, we review the impact of salinity on growth and development of aquatic fungi, integrating literature reports on marine and fresh- water species, and recent advances introducing molecular techniques to provide better understanding of the phenomenon of aquatic fungal salinity tolerance.