Index Fungorum, Species Fungorum and MycoBank are the key fungal nomenclature and taxonomic databases that can be sourced to find taxonomic details concerning fungi, while DNA sequence data can be sourced from the NCBI, EBI and UNITE databases. Nomenclature and ecological data on freshwater fungi can be accessed on http://fungi.life.illinois.edu/ , while http://www.marinespecies.org/provides a comprehensive list of names of marine organisms, including information on their synonymy. Previous websites however have little information on marine fungi and their ecology, beside articles that deal with marine fungi, especially those published in the nineteenth and early twentieth centuries may not be accessible to those working in third world countries. To address this problem, a new website www.marinefungi.org was set up and is introduced in this paper. This website provides a search facility to genera of marine fungi, full species descriptions, key to species and illustrations, an up to date classification of all recorded marine fungi which includes all fungal groups (Ascomycota, Basidiomycota, Blastocladiomycota, Chytridiomycota, Mucoromycota and fungus-like organisms e.g. Thraustochytriales), and listing recent publications. Currently, 1257 species are listed in the marine fungi website ( www.marinefungi.org ), in 539 genera, 74 orders, 168 families, 20 classes and five phyla, with new taxa continuing to be described. The website has curators with specialist mycological expertise who help to provide update data on the classification of marine fungi. This article also reviews knowledge of marine fungi covering a wide range of topics: their higher classification, ecology and world distribution, role in energy transfer in the oceans, origin and new chemical structures. An updated classification of marine fungi is also included. We would like to invite all mycologists to contribute to this innovative website.

The Chytridiomycota phylum contributes to nutrient cycling and the flow of energy between trophic levels in terrestrial and aquatic ecosystems yet remains poorly described or absent from publications discussing fungal communities in these environments. This study contributes to the understanding of three species of soil chytrids in vitro—Gaertneriomyces semiglobifer, Spizellomyces sp. and Rhizophlyctis rosea—in the presence of elevated concentrations of nitrogen and phosphorus and with different sources of nitrogen. Colony growth was measured after 4 weeks as dry weight and total protein. To determine the impacts on zoospore reproduction, motility, lipid content, and attachment to organic substrates, 4- and 8-week incubation times were investigated. Whilst all isolates were able to assimilate ammonium as a sole source of nitrogen, nitrate was less preferred or even unsuitable as a nutrient source for G. semiglobifer and R. rosea, respectively. Increasing phosphate concentrations led to diverse responses between isolates. Zoospore production was also variable between isolates, and the parameters for zoospore motility appeared only to be influenced by the phosphate concentration for Spizellomyces sp. and R. rosea. Attachment rates increased for G. semiglobifer in the absence of an inorganic nitrogen source. These findings highlight variability between the adaptive responses utilised by chytrids to persist in a range of environments and provide new techniques to study soil chytrid biomass and zoospore motility by total protein quantification and fluorescent imaging respectively.

Chytridiomycota (zoosporic true fungi) have a consistent presence in soils and have been frequently identified within many diverse terrestrial environments. However, Chytridiomycota and other early-diverging fungi have low representation in whole-genome sequencing databases compared to Dikarya. New molecular techniques have provided insights into the diversity and abundance of chytrids in soils and the changes in their populations both spatially and temporally. Chytrids complete their life cycle within rapidly changing soil environments where they may be more common within micropores due to protection from predation, desiccation, and extreme temperatures. Reproductive and morphological changes occur in response to environmental changes including pH, fluctuating nutrient concentrations, and metals at levels above toxic thresholds. Rhizoids share some features of hyphae, including the spatial regulation of branching and the ability to attach, adapt to, and proliferate in different substrates, albeit on a microscale. Soil chytrids provide a pool of novel enzymes and proteins which enable a range of lifestyles as saprotrophs or parasites, but also can be utilised as alternative tools with some biotechnological applications. Thus, 3D live-cell imaging and micromodels such as MicroCT may provide insight into zoospore functions and rhizoid plasticity, respectively, in response to various conditions. A combination of classical techniques of soil chytrid baiting with simultaneous molecular and ecological data will provide insights into temporal population changes in response to environmental change. The authors emphasise the need to review and improve DNA-based methodologies for identifying and quantifying chytrids within the soil microbiome to expand our knowledge of their taxonomy, abundance, diversity, and functionality within soil environments.

The diversity and abundance of zoosporic true fungi have been analyzed recently using fungal sequence libraries and advances in molecular methods, such as high-throughput sequencing. This review focuses on four evolutionary primitive true fungal phyla: the Aphelidea, Chytridiomycota, Neocallimastigomycota, and Rosellida (Cryptomycota), most species of which are not polycentric or mycelial (filamentous), rather they tend to be primarily monocentric (unicellular). Zoosporic fungi appear to be both abundant and diverse in many aquatic habitats around the world, with abundance often exceeding other fungal phyla in these habitats, and numerous novel genetic sequences identified. Zoosporic fungi are able to survive extreme conditions, such as high and extremely low pH; however, more work remains to be done. They appear to have important ecological roles as saprobes in decomposition of particulate organic substrates, pollen, plant litter, and dead animals; as parasites of zooplankton and algae; as parasites of vertebrate animals (such as frogs); and as symbionts in the digestive tracts of mammals. Some chytrids cause economically important diseases of plants and animals. They regulate sizes of phytoplankton populations. Further metagenomics surveys of aquatic ecosystems are expected to enlarge our knowledge of the diversity of true zoosporic fungi. Coupled with studies on their functional ecology, we are moving closer to unraveling the role of zoosporic fungi in carbon cycling and the impact of climate change on zoosporic fungal populations.

Zoosporic fungi (chytrids) are common soil saprotrophs and parasites and important organisms which decompose complex carbohydrates, yet little is known of their ability to colonise these substrates in the presence of toxic metals. Three saprotrophic isolates of zoosporic fungi from the soils of NSW, Australia, are examined here for their ability to adhere to cellulose and chitin in the presence of various concentrations of the toxic metal ions Cu (II), Pb (II) and Zn (II). Rhizophlyctis rosea and Gaertneriomyces semiglobifer showed significant reduction in the attachment rate at 60 ppm for Cu (II), while Chytriomyces hyalinus and G. semiglobifer declined significantly at 60 ppm Zn (II) and R. rosea and C. hyalinus at 100 ppm Pb (II). Rhizoids of R. rosea increased significantly both in number and length when incubated with 20, 30 and 60 ppm Pb (II). If these metals cause similar effects in soils, Cu (II), Pb (II) and Zn (II) are expected to reduce attachment rates of zoosporic fungi, thereby slowing the mineralisation of organic matter.