# Mycoloop
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{{Short description|Trophic pathway in aquatic food webs}}
{{Use British English|date=September 2025}}
{{Use dmy dates|date=September 2025}}
{{plankton sidebar|trophic}}
The '''mycoloop''' is a trophic pathway in aquatic food webs where [parasitic fungi](/source/parasitic_fungi), particularly [chytrid](/source/chytrid)s, facilitate the transfer of nutrients and energy from large, inedible [phytoplankton](/source/phytoplankton) (algae) to [zooplankton](/source/zooplankton). This process enhances [nutrient cycling](/source/nutrient_cycling) and supports higher [trophic level](/source/trophic_level)s in [aquatic ecosystem](/source/aquatic_ecosystem)s.
Chytrids infect large, inedible phytoplankton, such as [diatom](/source/diatom)s or [cyanobacteria](/source/cyanobacteria), and produce [zoospore](/source/zoospore)s (free-living, motile spores, 2–5 μm in diameter).
These zoospores are rich in nutrients like [polyunsaturated fatty acid](/source/polyunsaturated_fatty_acid)s (PUFAs) and [cholesterol](/source/cholesterol), making them an excellent food source for zooplankton, such as ''[Daphnia](/source/Daphnia)'' and [rotifers](/source/rotifers). By consuming the zoospores or fragmented phytoplankton, zooplankton gain access to nutrients that would otherwise be unavailable from inedible phytoplankton, creating the trophic link called the ''mycoloop''. In this manner, the mycoloop channels [carbon](/source/carbon), [phosphorus](/source/phosphorus), and other nutrients from phytoplankton to zooplankton, bypassing the limitations of inedible phytoplankton.
The mycoloop can influence phytoplankton blooms by reducing host populations (via parasitism) and supporting zooplankton growth, potentially stabilizing aquatic food webs.
It can also influence the [carbon cycle](/source/carbon_cycle) by altering [carbon flux](/source/carbon_flux)es, reducing the sinking of large phytoplankton and redirecting carbon to higher trophic levels.
The concept of the mycoloop was developed by Maiko Kagami et al. in 2007.[{{cite journal | last1=Kagami | first1=Maiko | last2=von Elert | first2=Eric | last3=Ibelings | first3=Bas W | last4=de Bruin | first4=Arnout | last5=Van Donk | first5=Ellen | title=The parasitic chytrid, Zygorhizidium, facilitates the growth of the cladoceran zooplankter, Daphnia, in cultures of the inedible alga, Asterionella | journal=Proceedings of the Royal Society B: Biological Sciences | volume=274 | issue=1617 | date=2007-06-22 | issn=0962-8452 | pmid=17439852 | pmc=2176168 | doi=10.1098/rspb.2007.0425 | doi-access=free | pages=1561–1566 }}] The term "mycoloop" combines ''myco'' (referring to fungi, specifically chytrids) with ''loop'' (referring to the cycle of nutrient transfer). The discovery of the mycoloop, and its potential impact on nutrient cycling indicates the importance of fungal-algal interactions in natural systems. Chytrids have also been reported to stabilize food webs, while also reducing the amount of organic material that reaches benthic environments.[{{cite journal | last1=Grami | first1=Boutheina | last2=Rasconi | first2=Serena | last3=Niquil | first3=Nathalie | last4=Jobard | first4=Marlène | last5=Saint-Béat | first5=Blanche | last6=Sime-Ngando | first6=Télesphore | title=Functional Effects of Parasites on Food Web Properties during the Spring Diatom Bloom in Lake Pavin: A Linear Inverse Modeling Analysis | journal=PLOS ONE | volume=6 | issue=8 | date=2011-08-22 | issn=1932-6203 | pmid=21887240 | pmc=3161741 | doi=10.1371/journal.pone.0023273 | doi-access=free | article-number=e23273 | bibcode=2011PLoSO...623273G }} 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 International License].][{{cite journal | last1=Danz | first1=August | last2=Quandt | first2=C. Alisha | title=A review of the taxonomic diversity, host–parasite interactions, and experimental research on chytrids that parasitize diatoms | journal=Frontiers in Microbiology | volume=14 | date=2023-10-30 | issn=1664-302X | pmid=38029223 | pmc=10643281 | doi=10.3389/fmicb.2023.1281648 | doi-access=free | article-number=1281648 }} 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 International License].]
==Background==
Most food web studies do not incorporate what is perhaps the most common trophic interaction - [parasitism](/source/parasitism).[{{cite journal | last1=Marcogliese | first1=David J. | last2=Cone | first2=David K. | title=Food webs: a plea for parasites | journal=Trends in Ecology & Evolution | volume=12 | issue=8 | date=1997 | doi=10.1016/S0169-5347(97)01080-X | pages=320–325 | pmid=21238094 | bibcode=1997TEcoE..12..320M | url=https://linkinghub.elsevier.com/retrieve/pii/S016953479701080X | access-date=2025-08-18| url-access=subscription }}] Despite their ubiquity, parasites are often overlooked because of their [cryptic nature](/source/Crypsis), the difficulties in quantifying their effects, and their assumed low [biomass](/source/Biomass_(ecology)).[{{cite journal | last1=Lafferty | first1=Kevin D. | last2=Allesina | first2=Stefano | last3=Arim | first3=Matias | last4=Briggs | first4=Cherie J. | last5=De Leo | first5=Giulio | last6=Dobson | first6=Andrew P. | last7=Dunne | first7=Jennifer A. | last8=Johnson | first8=Pieter T. J. | last9=Kuris | first9=Armand M. | last10=Marcogliese | first10=David J. | last11=Martinez | first11=Neo D. | last12=Memmott | first12=Jane | last13=Marquet | first13=Pablo A. | last14=McLaughlin | first14=John P. | last15=Mordecai | first15=Erin A. | last16=Pascual | first16=Mercedes | last17=Poulin | first17=Robert | last18=Thieltges | first18=David W. | title=Parasites in food webs: the ultimate missing links | journal=Ecology Letters | volume=11 | issue=6 | date=2008 | issn=1461-023X | doi=10.1111/j.1461-0248.2008.01174.x | doi-access=free | pages=533–546 | pmid=18462196 | pmc=2408649 | bibcode=2008EcolL..11..533L }}] However, they can account for greater biomass than predators[{{cite journal | last1=Kuris | first1=Armand M. | last2=Hechinger | first2=Ryan F. | last3=Shaw | first3=Jenny C. | last4=Whitney | first4=Kathleen L. | last5=Aguirre-Macedo | first5=Leopoldina | last6=Boch | first6=Charlie A. | last7=Dobson | first7=Andrew P. | last8=Dunham | first8=Eleca J. | last9=Fredensborg | first9=Brian L. | last10=Huspeni | first10=Todd C. | last11=Lorda | first11=Julio | last12=Mababa | first12=Luzviminda | last13=Mancini | first13=Frank T. | last14=Mora | first14=Adrienne B. | last15=Pickering | first15=Maria | last16=Talhouk | first16=Nadia L. | last17=Torchin | first17=Mark E. | last18=Lafferty | first18=Kevin D. | title=Ecosystem energetic implications of parasite and free-living biomass in three estuaries | journal=Nature | volume=454 | issue=7203 | date=2008-07-24 | issn=0028-0836 | doi=10.1038/nature06970 | pages=515–518 | pmid=18650923 | bibcode=2008Natur.454..515K | url=https://www.nature.com/articles/nature06970 | access-date=2025-08-18| url-access=subscription }}] and participate in the majority of [trophic links](/source/Food_chain).[{{cite journal | last1=Amundsen | first1=Per-Arne | last2=Lafferty | first2=Kevin D. | last3=Knudsen | first3=Rune | last4=Primicerio | first4=Raul | last5=Klemetsen | first5=Anders | last6=Kuris | first6=Armand M. | title=Food web topology and parasites in the pelagic zone of a subarctic lake | journal=Journal of Animal Ecology | volume=78 | issue=3 | date=2009 | issn=0021-8790 | doi=10.1111/j.1365-2656.2008.01518.x | doi-access=free | pages=563–572 | pmid=19175443 | bibcode=2009JAnEc..78..563A }}] Parasites can modulate trophic flows in a number of ways. They can drive reductions in [host](/source/Host_(biology)) biomass, not only by increasing host mortality rates, but also by influencing growth, fecundity, nutritional status, susceptibility to predation, or behaviour.[{{cite journal | last1=Selakovic | first1=Sanja | last2=de Ruiter | first2=Peter C. | last3=Heesterbeek | first3=Hans | title=Infectious disease agents mediate interaction in food webs and ecosystems | journal=Proceedings of the Royal Society B: Biological Sciences | volume=281 | issue=1777 | date=2014-02-22 | issn=0962-8452 | pmid=24403336 | pmc=3896020 | doi=10.1098/rspb.2013.2709 | doi-access=free | article-number=20132709 | bibcode=2014PBioS.28132709S }}] While their role as consumers is better known, parasites can also be prey for other organisms. They can be consumed together with their host (i.e. concomitant predation) or as free living life stages. Given the enormous reproductive output of parasites, free living infecting stages potentially constitute a significant nutrient source and can account for a substantial transfer of material and energy to higher [trophic level](/source/trophic_level)s.[{{cite journal | last1=Johnson | first1=Pieter T.J. | last2=Dobson | first2=Andrew | last3=Lafferty | first3=Kevin D. | last4=Marcogliese | first4=David J. | last5=Memmott | first5=Jane | last6=Orlofske | first6=Sarah A. | last7=Poulin | first7=Robert | last8=Thieltges | first8=David W. | title=When parasites become prey: ecological and epidemiological significance of eating parasites | journal=Trends in Ecology & Evolution | volume=25 | issue=6 | date=2010 | doi=10.1016/j.tree.2010.01.005 | pages=362–371 | pmid=20185202 | bibcode=2010TEcoE..25..362J | url=https://linkinghub.elsevier.com/retrieve/pii/S0169534710000340 | access-date=2025-08-18| url-access=subscription }}][{{cite journal | last1=Thieltges | first1=David W. | last2=Amundsen | first2=Per-Arne | last3=Hechinger | first3=Ryan F. | last4=Johnson | first4=Pieter T. J. | last5=Lafferty | first5=Kevin D. | last6=Mouritsen | first6=Kim N. | last7=Preston | first7=Daniel L. | last8=Reise | first8=Karsten | last9=Zander | first9=C. Dieter | last10=Poulin | first10=Robert | title=Parasites as prey in aquatic food webs: implications for predator infection and parasite transmission | journal=Oikos | volume=122 | issue=10 | date=2013 | issn=0030-1299 | doi=10.1111/j.1600-0706.2013.00243.x | doi-access=free | pages=1473–1482 | bibcode=2013Oikos.122.1473T | hdl=10037/11842 | url=https://pure.au.dk/portal/files/79580627/ParasitesAsPrey_Thieltges_2013_OIKOS.pdf | access-date=2025-08-18}}][{{cite journal | last1=Agha | first1=Ramsy | last2=Saebelfeld | first2=Manja | last3=Manthey | first3=Christin | last4=Rohrlack | first4=Thomas | last5=Wolinska | first5=Justyna | title=Chytrid parasitism facilitates trophic transfer between bloom-forming cyanobacteria and zooplankton (Daphnia) | journal=Scientific Reports | volume=6 | issue=1 | date=2016-10-13 | issn=2045-2322 | pmid=27733762 | pmc=5062065 | doi=10.1038/srep35039 | doi-access=free | url=https://www.nature.com/articles/srep35039.pdf | access-date=2025-08-12 | article-number=35039 | bibcode=2016NatSR...635039A }} 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 International License].]
[Chytrid](/source/Chytrid)s are a type of microscopic fungi belonging to the phylum [Chytridiomycota](/source/Chytridiomycota). These fungi are primarily aquatic or found in moist environments.[{{cite book | last=Barr | first=D. J. S. | title=Systematics and Evolution | chapter=Chytridiomycota | publisher=Springer Berlin Heidelberg | publication-place=Berlin, Heidelberg | date=2001 | isbn=978-3-642-08193-4 | doi=10.1007/978-3-662-10376-0_5 | chapter-url=http://link.springer.com/10.1007/978-3-662-10376-0_5 | access-date=2025-08-27 | pages=93–112}}] Chytrids can be [saprophytic](/source/saprophytic) (decomposing organic matter), [parasitic](/source/parasitic) (infecting plants, algae, or animals), or [mutualistic](/source/Mutualism_(biology)), and play key ecological roles in breaking down organic material and nutrient cycling.[{{cite journal | last1=Gleason | first1=Frank H. | last2=Scholz | first2=Bettina | last3=Jephcott | first3=Thomas G. | last4=van Ogtrop | first4=Floris F. | last5=Henderson | first5=Linda | last6=Lilje | first6=Osu | last7=Kittelmann | first7=Sandra | last8=Macarthur | first8=Deborah J. | title=Key Ecological Roles for Zoosporic True Fungi in Aquatic Habitats | journal=Microbiology Spectrum | volume=5 | issue=2 | date=2017-03-10 | issn=2165-0497 | doi=10.1128/microbiolspec.FUNK-0038-2016 | article-number=5.2.17 | pmid=28361735 | pmc=11687468 }}] Notably, the chytrid ''[Batrachochytrium dendrobatidis](/source/Batrachochytrium_dendrobatidis)'' causes [chytridiomycosis](/source/chytridiomycosis), a deadly disease in amphibians, contributing to global population declines.[{{cite journal | last1=Berger | first1=Lee | last2=Speare | first2=Rick | last3=Daszak | first3=Peter | last4=Green | first4=D. Earl | last5=Cunningham | first5=Andrew A. | last6=Goggin | first6=C. Louise | last7=Slocombe | first7=Ron | last8=Ragan | first8=Mark A. | last9=Hyatt | first9=Alex D. | last10=McDonald | first10=Keith R. | last11=Hines | first11=Harry B. | last12=Lips | first12=Karen R. | last13=Marantelli | first13=Gerry | last14=Parkes | first14=Helen | title=Chytridiomycosis causes amphibian mortality associated with population declines in the rain forests of Australia and Central America | journal=Proceedings of the National Academy of Sciences | volume=95 | issue=15 | date=1998-07-21 | issn=0027-8424 | pmid=9671799 | pmc=21197 | doi=10.1073/pnas.95.15.9031 | doi-access=free | pages=9031–9036 | bibcode=1998PNAS...95.9031B }}][{{cite journal | last1=Fisher | first1=Matthew C. | last2=Garner | first2=Trenton W.J. | last3=Walker | first3=Susan F. | title=Global Emergence of Batrachochytrium dendrobatidis and Amphibian Chytridiomycosis in Space, Time, and Host | journal=Annual Review of Microbiology | volume=63 | issue=1 | date=2009-10-01 | issn=0066-4227 | doi=10.1146/annurev.micro.091208.073435 | pages=291–310 | pmid=19575560 | url=https://www.annualreviews.org/doi/10.1146/annurev.micro.091208.073435 | access-date=2025-08-27| url-access=subscription }}] They are unusual among fungi in that they reproduce with motile [spore](/source/spore)s, driven by [flagella](/source/flagella), called [zoospore](/source/zoospore)s.[{{cite book | author=Sparrow, F.K. | year=1960| title=Aquatic Phycomyete | edition=2nd | publisher=The University of Michigan Press | place=Ann Arbor, MI }}][{{cite journal | last1 = Hibbett | display-authors = etal | year = 2007 | title = A higher-level phylogenetic classification of the Fungi | journal = Mycologia | volume = 111 | issue = 5 | pages = 509–547 | pmid = 17572334 | doi = 10.1016/j.mycres.2007.03.004 | s2cid = 4686378 }}] Most chytrids do not sexually reproduce. [Asexual reproduction](/source/Asexual_reproduction) occurs through the release of zoospores.[
File:Chytrid diagram.jpg
[[File:Chytrid zoospores.jpg|thumb|upright=1.2|Chytrid zoospores are tiny fungal [spore](/source/spore)s which in the ocean can have densities up to a billion per litre.][{{cite journal |last1=Frenken |first1=Thijs |last2=Alacid |first2=Elisabet |last3=Berger |first3=Stella A. |last4=Bourne |first4=Elizabeth C. |last5=Gerphagnon |first5=Mélanie |last6=Grossart |first6=Hans-Peter |last7=Gsell |first7=Alena S. |last8=Ibelings |first8=Bas W. |last9=Kagami |first9=Maiko |last10=Küpper |first10=Frithjof C. |last11=Letcher |first11=Peter M. |last12=Loyau |first12=Adeline |last13=Miki |first13=Takeshi |last14=Nejstgaard |first14=Jens C. |last15=Rasconi |first15=Serena |last16=Reñé |first16=Albert |last17=Rohrlack |first17=Thomas |last18=Rojas-Jimenez |first18=Keilor |last19=Schmeller |first19=Dirk S. |last20=Scholz |first20=Bettina |last21=Seto |first21=Kensuke |last22=Sime-Ngando |first22=Télesphore |last23=Sukenik |first23=Assaf |last24=Van De Waal |first24=Dedmer B. |last25=Van Den Wyngaert |first25=Silke |last26=Van Donk |first26=Ellen |last27=Wolinska |first27=Justyna |last28=Wurzbacher |first28=Christian |last29=Agha |first29=Ramsy |title=Integrating chytrid fungal parasites into plankton ecology: Research gaps and needs |journal=Environmental Microbiology |date=2017 |volume=19 |issue=10 |pages=3802–3822 |doi=10.1111/1462-2920.13827 |pmid=28618196 |bibcode=2017EnvMi..19.3802F |hdl=20.500.11755/2135e790-9a9a-48b1-b4b9-5edb7084beb9 |hdl-access=free }}. 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].]]]
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[[File:Pennate diatom infected with two chytrid-like fungal pathogens.png|thumb|upright=1.2|right| [Pennate diatom](/source/Pennate_diatom) from an Arctic [meltpond](/source/meltpond), infected with two [chytrid-like](/source/Chytridiomycota) [zoosporangium](/source/zoosporangium) fungal pathogens (in false-colour red). Scale bar = 10 μm.[{{cite journal |doi = 10.1038/s42003-020-0891-7|title = Chytrid fungi distribution and co-occurrence with diatoms correlate with sea ice melt in the Arctic Ocean|year = 2020|last1 = Kilias|first1 = Estelle S.|last2 = Junges|first2 = Leandro|last3 = Šupraha|first3 = Luka|last4 = Leonard|first4 = Guy|last5 = Metfies|first5 = Katja|last6 = Richards|first6 = Thomas A.|journal = Communications Biology|volume = 3|issue = 1|page = 183|pmid = 32317738|pmc = 7174370|s2cid = 216033140}} 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].]]]
[Saprotrophic](/source/Saprotrophic) chytrids decompose inedible [organic matter](/source/organic_matter) releasing zoospores that [zooplankton](/source/zooplankton) consume, further contributing to [nutrient cycling](/source/nutrient_cycling). Zooplankton grazing on zoospores may suppress chytrid outbreaks, regulating parasite populations. The mycoloop can stabilise ecosystem by alleviating competition among phytoplankton and supporting zooplankton production, especially in nutrient-rich environments.[{{cite journal | last1=Danz | first1=August | last2=Quandt | first2=C. Alisha | title=A review of the taxonomic diversity, host–parasite interactions, and experimental research on chytrids that parasitize diatoms | journal=Frontiers in Microbiology | volume=14 | date=2023-10-30 | issn=1664-302X | pmid=38029223 | pmc=10643281 | doi=10.3389/fmicb.2023.1281648 | doi-access=free | article-number=1281648 }} 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 International License].]
Studies show chytrid zoospores, which can have densities up to a billion spores per litre, are a high-quality food source, doubling zooplankton feeding rates compared to uninfected phytoplankton. The mycoloop is significant both in freshwater lakes and marine environments, with chytrids like ''Zygorhizidium'' facilitating nutrient transfer from algae like ''[Asterionella](/source/Asterionella)'' to zooplankton like [Daphnia](/source/Daphnia).[{{cite journal | last1=Maier | first1=Michelle A. | last2=Peterson | first2=Tawnya D. | title=Observations of a Diatom Chytrid Parasite in the Lower Columbia River | journal=Northwest Science | volume=88 | issue=3 | date=2014 | issn=0029-344X | doi=10.3955/046.088.0306 | pages=234–245 | bibcode=2014NWSci..88..234M | url=http://www.bioone.org/doi/abs/10.3955/046.088.0306 | access-date=2025-08-08| url-access=subscription }}][{{cite book | veditors = Jones EG, Hyde KD, Pang KL |url=https://books.google.com/books?id=mXfnBQAAQBAJ |title=Freshwater Fungi: and Fungal-like Organisms |date=2014-08-27 |publisher=Walter de Gruyter GmbH & Co KG |isbn=978-3-11-033348-0 |language=en}}][{{cite book | vauthors = Jones EG, Hyde KD, Pang KL |url=https://books.google.com/books?id=RcF97cHppPsC |title=Marine Fungi: and Fungal-like Organisms |date=2012-08-31 |publisher=Walter de Gruyter |isbn=978-3-11-026406-7 |language=en}}][{{Cite journal |last1=Sen |first1=Kalymani |last2=Sen |first2=Biswarup |last3=Wang |first3=Guangyi |date=May 8, 2022 |title=Diversity, Abundance, and Ecological Roles of Planktonic Fungi in Marine Environments |journal= Journal of Fungi|volume=8 |issue=5 |page=491 |doi=10.3390/jof8050491 |doi-access=free |pmid=35628747 |pmc=9147564 }}] They are composed of [filamentous](/source/Filamentous_fungus) free-living [fungi](/source/Fungus) and yeasts that are associated with planktonic particles or [phytoplankton](/source/phytoplankton).[{{cite journal | vauthors = Wang X, Singh P, Gao Z, Zhang X, Johnson ZI, Wang G | title = Distribution and diversity of planktonic fungi in the West Pacific Warm Pool | journal = PLOS ONE | volume = 9 | issue = 7 | article-number = e101523 | date = 2014-07-03 | pmid = 24992154 | pmc = 4081592 | doi = 10.1371/journal.pone.0101523 | bibcode = 2014PLoSO...9j1523W | doi-access = free }}] Similar to [bacterioplankton](/source/bacterioplankton), these aquatic fungi play a significant role in [heterotroph](/source/heterotroph)ic [mineralization](/source/Mineralization_(soil_science)) and [nutrient cycling](/source/nutrient_cycling).[{{cite book |date=2012 | veditors = Raghukumar C | title = Biology of Marine Fungi | series = Progress in Molecular and Subcellular Biology | volume = 53 |language=en |doi=10.1007/978-3-642-23342-5 | isbn = 978-3-642-23341-8 | s2cid = 39378040 |issn=0079-6484}}] Mycoplankton can be up to 20 mm in diameter and over 50 mm in length,[{{cite journal | vauthors = Damare S, Raghukumar C | title = Fungi and macroaggregation in deep-sea sediments | journal = Microbial Ecology | volume = 56 | issue = 1 | pages = 168–177 | date = July 2008 | pmid = 17994287 | doi = 10.1007/s00248-007-9334-y | bibcode = 2008MicEc..56..168D | s2cid = 21288251 }}] though mostly they are microscopic.[{{cite journal | last1=Cudowski | first1=A. | last2=Pietryczuk | first2=A. | title=Biodiversity of mycoplankton in the profile of eutrophic lakes with varying water quality | journal=Fungal Ecology | volume=48 | date=2020 | doi=10.1016/j.funeco.2020.100978 | article-number=100978 | bibcode=2020FunE...4800978C | url=https://linkinghub.elsevier.com/retrieve/pii/S1754504820300908 | access-date=2025-08-26| url-access=subscription }}][{{cite journal | last1=Sen | first1=Kalyani | last2=Sen | first2=Biswarup | last3=Wang | first3=Guangyi | title=Diversity, Abundance, and Ecological Roles of Planktonic Fungi in Marine Environments | journal=Journal of Fungi | volume=8 | issue=5 | date=2022-05-08 | issn=2309-608X | pmid=35628747 | pmc=9147564 | doi=10.3390/jof8050491 | doi-access=free | page=491}}] A typical litre of seawater contains between one- and ten-million fungal cells.[{{cite journal | vauthors = Kubanek J, Jensen PR, Keifer PA, Sullards MC, Collins DO, Fenical W | title = Seaweed resistance to microbial attack: a targeted chemical defense against marine fungi | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 100 | issue = 12 | pages = 6916–6921 | date = June 2003 | pmid = 12756301 | pmc = 165804 | doi = 10.1073/pnas.1131855100 | bibcode = 2003PNAS..100.6916K | doi-access = free }}][{{cite journal | vauthors = Jobard M, Rasconi S, Sime-Ngando T |date=2010-06-01 |title=Diversity and functions of microscopic fungi: a missing component in pelagic food webs |journal=Aquatic Sciences |language=en |volume=72 |issue=3 |pages=255–268 |doi=10.1007/s00027-010-0133-z |bibcode=2010AqSci..72..255J |s2cid=36789070 |issn=1420-9055}}] The greatest diversity and number of species of mycoplankton is found in [surface waters](/source/Coastal_ecosystems) (< 1000 m), and the [vertical profile](/source/Water_column) depends on the abundance of [phytoplankton](/source/phytoplankton).[{{cite journal | vauthors = Gao Z, Johnson ZI, Wang G | title = Molecular characterization of the spatial diversity and novel lineages of mycoplankton in Hawaiian coastal waters | journal = The ISME Journal | volume = 4 | issue = 1 | pages = 111–120 | date = January 2010 | pmid = 19641535 | doi = 10.1038/ismej.2009.87 | s2cid = 2395339 | doi-access = free | bibcode = 2010ISMEJ...4..111G }}][{{cite journal | vauthors = Panzer K, Yilmaz P, Weiß M, Reich L, Richter M, Wiese J, Schmaljohann R, Labes A, Imhoff JF, Glöckner FO, Reich M | display-authors = 6 | title = Identification of Habitat-Specific Biomes of Aquatic Fungal Communities Using a Comprehensive Nearly Full-Length 18S rRNA Dataset Enriched with Contextual Data | journal = PLOS ONE | volume = 10 | issue = 7 | article-number = e0134377 | date = 2015-07-30 | pmid = 26226014 | pmc = 4520555 | doi = 10.1371/journal.pone.0134377 | bibcode = 2015PLoSO..1034377P | doi-access = free }}] Furthermore, this difference in distribution may vary between seasons due to nutrient availability.[{{cite journal |date=2004 |title=First record of flamentous fungi in the coastal upwelling ecosystem off central Chile |journal=Gayana (Concepción) |volume=68 |issue=2 |doi=10.4067/s0717-65382004000200001 |issn=0717-6538|doi-access=free }}] Aquatic fungi survive in a constant oxygen deficient environment, and therefore depend on oxygen diffusion by [turbulence](/source/turbulence) and oxygen generated by [photosynthetic organisms](/source/Phototroph).[{{cite book |title=Plankton Dynamics of Indian Waters |vauthors=Sridhar KR |date=January 2009 |publisher=Pratiksha Publications |location=Jaipur, India |pages=133–148 |chapter=Aquatic fungi – Are they planktonic? |chapter-url=https://www.researchgate.net/publication/267452832}}]
Aquatic fungi consist mostly of tiny [mycoplankton](/source/mycoplankton) ([microfungi](/source/microfungi)), [yeast](/source/yeast), or mobile [zoospore](/source/zoospore)s, that can recycle organic matter through the mycoloop process, which involving parasiting plankton.[[https://ungc-communications-assets.s3.amazonaws.com/docs/publications/PlanktonManifesto_MG_DIGITAL-2.pdf Plankton Manifesto] ''Ocean Stewardship Coalition'' of the [United Nations Global Compact](/source/United_Nations_Global_Compact), published September 2024.]
==Mycoloop dynamics==
Parasitic [chytrid](/source/chytrid)s can transfer material from large inedible phytoplankton to zooplankton. Chytrids [zoospore](/source/zoospore)s are excellent food for zooplankton in terms of size (2–5 μm in diameter), shape, nutritional quality (rich in [polyunsaturated fatty acid](/source/polyunsaturated_fatty_acid)s and [cholesterol](/source/cholesterol)s). Large colonies of host phytoplankton may also be fragmented by chytrid infections and become edible to zooplankton.[{{cite journal |last1=Kagami |first1=Maiko |last2=Miki |first2=Takeshi |last3=Takimoto |first3=Gaku |title=Mycoloop: Chytrids in aquatic food webs |journal=Frontiers in Microbiology |date=2014 |volume=5 |doi=10.3389/fmicb.2014.00166|doi-access=free |pmid=24795703 |pmc=4001071 }}. 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 International License].]
[Parasitic](/source/Parasitic) fungi, as well as [saprotrophic](/source/saprotrophic) fungi, directly assimilate phytoplankton organic carbon. By releasing [zoospore](/source/zoospore)s, the fungi bridge the trophic linkage to [zooplankton](/source/zooplankton), known as the mycoloop. By modifying the [particulate](/source/particulate_organic_carbon) and [dissolved organic carbon](/source/dissolved_organic_carbon), they can affect bacteria and the [microbial loop](/source/microbial_loop). These processes may modify [marine snow](/source/marine_snow) chemical composition and the subsequent functioning of the [biological carbon pump](/source/biological_carbon_pump).[{{cite journal |last1=Amend |first1=Anthony |last2=Burgaud |first2=Gaetan |last3=Cunliffe |first3=Michael |last4=Edgcomb |first4=Virginia P. |last5=Ettinger |first5=Cassandra L. |last6=Gutiérrez |first6=M. H. |last7=Heitman |first7=Joseph |last8=Hom |first8=Erik F. Y. |last9=Ianiri |first9=Giuseppe |last10=Jones |first10=Adam C. |last11=Kagami |first11=Maiko |last12=Picard |first12=Kathryn T. |last13=Quandt |first13=C. Alisha |last14=Raghukumar |first14=Seshagiri |last15=Riquelme |first15=Mertixell |last16=Stajich |first16=Jason |last17=Vargas-Muñiz |first17=José |last18=Walker |first18=Allison K. |last19=Yarden |first19=Oded |last20=Gladfelter |first20=Amy S. |title=Fungi in the Marine Environment: Open Questions and Unsolved Problems |journal=mBio |date=2019 |volume=10 |issue=2 |article-number=e01189-18 |doi=10.1128/mBio.01189-18 |doi-access=free |pmid=30837337 |bibcode=2019mBio...1089.18A |pmc=6401481 }}. 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].][{{Cite journal |last1=Gutiérrez |first1=Marcelo H. |last2=Jara |first2=Ana M. |last3=Pantoja |first3=Silvio |date=May 2016 |title=Fungal parasites infect marine diatoms in the upwelling ecosystem of the Humboldt current system off central Chile |url=https://sfamjournals.onlinelibrary.wiley.com/doi/10.1111/1462-2920.13257 |journal=Environmental Microbiology |language=en |volume=18 |issue=5 |pages=1646–1653 |doi=10.1111/1462-2920.13257 |pmid=26914416 |bibcode=2016EnvMi..18.1646G |issn=1462-2912|url-access=subscription |hdl=10533/148260 |hdl-access=free }}]
[[File:Parasitic chytrids as a mycoloop.jpg|thumb|upright=1.5|left| {{center| '''Diagram of a mycoloop (fungus loop)'''}} Parasitic [chytrid](/source/chytrid)s can transfer material from large inedible phytoplankton to zooplankton. Chytrids [zoospore](/source/zoospore)s are excellent food for zooplankton in terms of size (2–5 μm in diameter), shape, nutritional quality (rich in [polyunsaturated fatty acid](/source/polyunsaturated_fatty_acid)s and [cholesterol](/source/cholesterol)s). Large colonies of host phytoplankton may also be fragmented by chytrid infections and become edible to zooplankton.[{{cite journal |last1=Kagami |first1=Maiko |last2=Miki |first2=Takeshi |last3=Takimoto |first3=Gaku |title=Mycoloop: Chytrids in aquatic food webs |journal=Frontiers in Microbiology |date=2014 |volume=5 |page=166 |doi=10.3389/fmicb.2014.00166|doi-access=free |pmid=24795703 |pmc=4001071 }}. 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 International License].]]]
thumb|upright=1.5|right| {{center| '''Possible other mycoloops in aquatic environments'''}} Saprotrophic chytrids may also play important roles in aquatic food webs, by decomposing inedible organic material such as pollens. Zoospores released from pollen may be consumed by zooplankton, functioning as another "mycoloop." In addition to chytrids, other zoosporic fungi or fungal-like protists, such as Cryptomycota and Labyrinthulomycota, can infect phytoplankton or consume large inedible organic material, which may be grazed by zooplankton in freshwater and marine environments.[{{cite journal |last1=Frenken |first1=Thijs |last2=Alacid |first2=Elisabet |last3=Berger |first3=Stella A. |last4=Bourne |first4=Elizabeth C. |last5=Gerphagnon |first5=Mélanie |last6=Grossart |first6=Hans-Peter |last7=Gsell |first7=Alena S. |last8=Ibelings |first8=Bas W. |last9=Kagami |first9=Maiko |last10=Küpper |first10=Frithjof C. |last11=Letcher |first11=Peter M. |last12=Loyau |first12=Adeline |last13=Miki |first13=Takeshi |last14=Nejstgaard |first14=Jens C. |last15=Rasconi |first15=Serena |last16=Reñé |first16=Albert |last17=Rohrlack |first17=Thomas |last18=Rojas-Jimenez |first18=Keilor |last19=Schmeller |first19=Dirk S. |last20=Scholz |first20=Bettina |last21=Seto |first21=Kensuke |last22=Sime-Ngando |first22=Télesphore |last23=Sukenik |first23=Assaf |last24=Van De Waal |first24=Dedmer B. |last25=Van Den Wyngaert |first25=Silke |last26=Van Donk |first26=Ellen |last27=Wolinska |first27=Justyna |last28=Wurzbacher |first28=Christian |last29=Agha |first29=Ramsy |title=Integrating chytrid fungal parasites into plankton ecology: Research gaps and needs |journal=Environmental Microbiology |date=2017 |volume=19 |issue=10 |pages=3802–3822 |doi=10.1111/1462-2920.13827 |pmid=28618196 |bibcode=2017EnvMi..19.3802F |hdl=20.500.11755/2135e790-9a9a-48b1-b4b9-5edb7084beb9 |hdl-access=free }}. 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].]]]
[[File:Mycoloop with diatom and rotifer.webp|thumb|upright=1.5|left| {{center| '''Mycoloop with diatom and rotifer'''}} The food web system includes the inedible [diatom](/source/diatom) (''Synedra''), the [obligate](/source/obligate) parasitic consumer of the diatom ([chytrid](/source/chytrid)) with a [sessile](/source/Sessility_(motility)) ([sporangium](/source/sporangium)) and a motile (zoospore) life stage, and the [rotifer](/source/rotifer) (''Keratella''), which can consume the chytrid zoospores but not the host diatom. While ''Synedra'' is inedible to ''Keratella'', its nutrients may still be transferred to the rotifer via infection propagules (zoospores).[{{cite journal |last1=Sánchez Barranco |first1=Virginia |last2=Van Der Meer |first2=Marcel T. J. |last3=Kagami |first3=Maiko |last4=Van Den Wyngaert |first4=Silke |last5=Van De Waal |first5=Dedmer B. |last6=Van Donk |first6=Ellen |last7=Gsell |first7=Alena S. |title=Trophic position, elemental ratios and nitrogen transfer in a planktonic host–parasite–consumer food chain including a fungal parasite |journal=Oecologia |date=2020 |volume=194 |issue=4 |pages=541–554 |doi=10.1007/s00442-020-04721-w |pmid=32803339 |pmc=7683484 |bibcode=2020Oecol.194..541S }}. 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].]]]
[[File:Central role played by pelagic fungi in the mycoloop and microbial loop.jpg|thumb|upright=1.5|right|The central role played by [pelagic fungi](/source/Marine_fungi), both parasitic and [saprotrophic](/source/saprotrophic) in the mycoloop, and saprotrophic fungi as active contributors to the [microbial loop](/source/microbial_loop). The activity of heterotrophic microbes, including pelagic fungi, has far-reaching global implications for fisheries (i.e., the amount of carbon that will ultimately flow to higher trophic levels) and climate change (i.e., the amount of carbon that will be sequestered in the ocean or respired back to CO2 and the release of other greenhouse gases; e.g., N2O.[{{cite journal | last1=Breyer | first1=Eva | last2=Baltar | first2=Federico | title=The largely neglected ecological role of oceanic pelagic fungi | journal=Trends in Ecology & Evolution | volume=38 | issue=9 | date=2023 | doi=10.1016/j.tree.2023.05.002 | doi-access=free | pages=870–888 | pmid=37246083 | bibcode=2023TEcoE..38..870B | url=http://www.cell.com/article/S0169534723001258/pdf | access-date=2025-07-27}}]]]
[{{clear}}
==Parasites and food webs==
Parasites are rarely included in food web studies, although they can strongly alter trophic interactions.
In aquatic ecosystems, poorly grazed cyanobacteria often dominate phytoplankton communities,
leading to the decoupling of primary and secondary production.[{{cite journal | last1=Brett | first1=M T | last2=Goldman | first2=C R | title=A meta-analysis of the freshwater trophic cascade. | journal=Proceedings of the National Academy of Sciences | volume=93 | issue=15 | date=1996-07-23 | issn=0027-8424 | pmid=11607694 | pmc=38814 | doi=10.1073/pnas.93.15.7723 | doi-access=free | pages=7723–7726 | bibcode=1996PNAS...93.7723B }}] One reason for this is that most food web studies do not incorporate what is perhaps the most common trophic interaction - parasitism.[{{cite journal | last1=Markensten | first1=Hampus | last2=Moore | first2=Karen | last3=Persson | first3=Irina | title=Simulated lake phytoplankton composition shifts toward cyanobacteria dominance in a future warmer climate | journal=Ecological Applications | volume=20 | issue=3 | date=2010 | issn=1051-0761 | doi=10.1890/08-2109.1 | pages=752–767 | pmid=20437961 | bibcode=2010EcoAp..20..752M | url=https://esajournals.onlinelibrary.wiley.com/doi/10.1890/08-2109.1 | access-date=2025-08-19| url-access=subscription }}][{{cite journal | last1=Paerl | first1=Hans W. | last2=Huisman | first2=Jef | title=Climate change: a catalyst for global expansion of harmful cyanobacterial blooms | journal=Environmental Microbiology Reports | volume=1 | issue=1 | date=2009 | issn=1758-2229 | doi=10.1111/j.1758-2229.2008.00004.x | pages=27–37 | pmid=23765717 | bibcode=2009EnvMR...1...27P | url=https://sfamjournals.onlinelibrary.wiley.com/doi/10.1111/j.1758-2229.2008.00004.x | access-date=2025-08-19| url-access=subscription }}] cyanobacteria often develop into blooms that severely disrupt ecosystem functioning and raise health concerns due to the production of diverse toxins[{{cite journal | last1=Codd | first1=Geoffrey A. | last2=Morrison | first2=Louise F. | last3=Metcalf | first3=James S. | title=Cyanobacterial toxins: risk management for health protection | journal=Toxicology and Applied Pharmacology | volume=203 | issue=3 | date=2005 | doi=10.1016/j.taap.2004.02.016 | pages=264–272 | pmid=15737680 | bibcode=2005ToxAP.203..264C | url=https://linkinghub.elsevier.com/retrieve/pii/S0041008X04002418 | access-date=2025-08-19| url-access=subscription }}][{{cite journal | last1=Zillén | first1=L. | last2=Conley | first2=D. J. | title=Hypoxia and cyanobacteria blooms - are they really natural features of the late Holocene history of the Baltic Sea? | journal=Biogeosciences | volume=7 | issue=8 | date=2010-08-31 | issn=1726-4189 | doi=10.5194/bg-7-2567-2010 | doi-access=free | pages=2567–2580 | bibcode=2010BGeo....7.2567Z }}] Cyanobacteria display high resistance to grazing, which often leads to the decoupling of primary and secondary production and inefficient carbon transfer to zooplankton.[De Bernardi, R. d. & Giussani, G. Biomanipulation Tool for Water Management: Proceedings of an International Conference held in Amsterdam, 8–11 Aug 1989, pp. 29–41.] The inability of zooplankton to exert
effective top-down control on cyanobacterial populations has traditionally been linked to the poor edibility of cyanobacteria with colonial or filamentous morphologies, the production of toxic metabolites, and their low nutritional value.[{{cite journal | last1=Ger | first1=Kemal Ali | last2=Urrutia-Cordero | first2=Pablo | last3=Frost | first3=Paul C. | last4=Hansson | first4=Lars-Anders | last5=Sarnelle | first5=Orlando | last6=Wilson | first6=Alan E. | last7=Lürling | first7=Miquel | title=The interaction between cyanobacteria and zooplankton in a more eutrophic world | journal=Harmful Algae | volume=54 | date=2016 | doi=10.1016/j.hal.2015.12.005 | pages=128–144 | pmid=28073472 | bibcode=2016HAlga..54..128G | url=https://linkinghub.elsevier.com/retrieve/pii/S1568988315301475 | access-date=2025-08-19| url-access=subscription }}][{{cite journal |last1=Amend |first1=Anthony |last2=Burgaud |first2=Gaetan |last3=Cunliffe |first3=Michael |last4=Edgcomb |first4=Virginia P. |last5=Ettinger |first5=Cassandra L. |last6=Gutiérrez |first6=M. H. |last7=Heitman |first7=Joseph |last8=Hom |first8=Erik F. Y. |last9=Ianiri |first9=Giuseppe |last10=Jones |first10=Adam C. |last11=Kagami |first11=Maiko |last12=Picard |first12=Kathryn T. |last13=Quandt |first13=C. Alisha |last14=Raghukumar |first14=Seshagiri |last15=Riquelme |first15=Mertixell |last16=Stajich |first16=Jason |last17=Vargas-Muñiz |first17=José |last18=Walker |first18=Allison K. |last19=Yarden |first19=Oded |last20=Gladfelter |first20=Amy S. |title=Fungi in the Marine Environment: Open Questions and Unsolved Problems |journal=mBio |date=2019 |volume=10 |issue=2 |article-number=e01189-18 |doi=10.1128/mBio.01189-18 |doi-access=free |pmid=30837337 |pmc=6401481 |bibcode=2019mBio...1089.18A }}. 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].][{{cite journal | last1=Gutiérrez | first1=Marcelo H. | last2=Jara | first2=Ana M. | last3=Pantoja | first3=Silvio | title=Fungal parasites infect marine diatoms in the upwelling ecosystem of the Humboldt current system off central Chile | journal=Environmental Microbiology | date=2016 | volume=18 | issue=5 | pages=1646–1653 | doi=10.1111/1462-2920.13257 | pmid=26914416 | bibcode=2016EnvMi..18.1646G | hdl=10533/148260 | hdl-access=free }}]]]
[Marine microorganisms](/source/Marine_microorganisms) make up around 70% of the total marine biomass[{{cite journal | last1=Bar-On | first1=Yinon M. | last2=Phillips | first2=Rob | last3=Milo | first3=Ron | title=The biomass distribution on Earth | journal=Proceedings of the National Academy of Sciences | volume=115 | issue=25 | date=2018-06-19 | issn=0027-8424 | pmid=29784790 | pmc=6016768 | doi=10.1073/pnas.1711842115 | doi-access=free | pages=6506–6511 | bibcode=2018PNAS..115.6506B | url=https://www.pnas.org/content/pnas/115/25/6506.full.pdf | access-date=2025-08-14}}] and are involved in complex functional and phylogenetic networks with all three organismal domains of life and viruses.[{{cite journal | last1=Lima-Mendez | first1=Gipsi | last2=Faust | first2=Karoline | last3=Henry | first3=Nicolas | last4=Decelle | first4=Johan | last5=Colin | first5=Sébastien | last6=Carcillo | first6=Fabrizio | last7=Chaffron | first7=Samuel | last8=Ignacio-Espinosa | first8=J. Cesar | last9=Roux | first9=Simon | last10=Vincent | first10=Flora | last11=Bittner | first11=Lucie | last12=Darzi | first12=Youssef | last13=Wang | first13=Jun | last14=Audic | first14=Stéphane | last15=Berline | first15=Léo | last16=Bontempi | first16=Gianluca | last17=Cabello | first17=Ana M. | last18=Coppola | first18=Laurent | last19=Cornejo-Castillo | first19=Francisco M. | last20=d'Ovidio | first20=Francesco | last21=De Meester | first21=Luc | last22=Ferrera | first22=Isabel | last23=Garet-Delmas | first23=Marie-José | last24=Guidi | first24=Lionel | last25=Lara | first25=Elena | last26=Pesant | first26=Stéphane | last27=Royo-Llonch | first27=Marta | last28=Salazar | first28=Guillem | last29=Sánchez | first29=Pablo | last30=Sebastian | first30=Marta | last31=Souffreau | first31=Caroline | last32=Dimier | first32=Céline | last33=Picheral | first33=Marc | last34=Searson | first34=Sarah | last35=Kandels-Lewis | first35=Stefanie | author36=Tara Oceans coordinators | last37=Gorsky | first37=Gabriel | last38=Not | first38=Fabrice | last39=Ogata | first39=Hiroyuki | last40=Speich | first40=Sabrina | last41=Stemmann | first41=Lars | last42=Weissenbach | first42=Jean | last43=Wincker | first43=Patrick | last44=Acinas | first44=Silvia G. | last45=Sunagawa | first45=Shinichi | last46=Bork | first46=Peer | last47=Sullivan | first47=Matthew B. | last48=Karsenti | first48=Eric | last49=Bowler | first49=Chris | last50=de Vargas | first50=Colomban | last51=Raes | first51=Jeroen | title=Determinants of community structure in the global plankton interactome | journal=Science | volume=348 | issue=6237 | date=2015-05-22 | issn=0036-8075 | doi=10.1126/science.1262073 | doi-access=free | url=https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/197952/3/science.1262073.pdf | access-date=2025-08-15 |display-authors = 4 | article-number=1262073 | pmid=25999517 | hdl=2078.1/231553 }}] They harbor a set of genes responsible for driving major [redox](/source/redox) reactions that are crucial for controlling the [remineralization](/source/remineralization) of organic material.[{{cite journal | last1=Falkowski | first1=Paul G. | last2=Fenchel | first2=Tom | last3=Delong | first3=Edward F. | title=The Microbial Engines That Drive Earth's Biogeochemical Cycles | journal=Science | volume=320 | issue=5879 | date=2008-05-23 | issn=0036-8075 | doi=10.1126/science.1153213 | doi-access=free | pages=1034–1039 | pmid=18497287 | bibcode=2008Sci...320.1034F | url=https://eebweb.arizona.edu/faculty/saleska/Ecol596V/Readings/Falkowski.2008_Microbes.biogeochemistry_Science.pdf | access-date=2025-08-15}}] Most of the research on the role of microbes in the oceanic [nutrient cycling](/source/nutrient_cycling) has focused on [prokaryotes](/source/Marine_prokaryotes). Little is known on the role of [pelagic fungi](/source/pelagic_fungi) in the cycling of [organic matter](/source/organic_matter) in the ocean despite fungi being recognized as key elements in remineralizing nutrients and degrading organic matter in the terrestrial and freshwater environment.[{{cite journal | last1=Grossart | first1=Hans-Peter | last2=Van den Wyngaert | first2=Silke | last3=Kagami | first3=Maiko | last4=Wurzbacher | first4=Christian | last5=Cunliffe | first5=Michael | last6=Rojas-Jimenez | first6=Keilor | title=Fungi in aquatic ecosystems | journal=Nature Reviews Microbiology | volume=17 | issue=6 | date=2019 | issn=1740-1526 | doi=10.1038/s41579-019-0175-8 | doi-access=free | pages=339–354 | url=https://repository.publisso.de/resource/frl:6417101/data | access-date=2025-08-15 |display-authors = 4 | pmid=30872817 | hdl=10669/81667 | hdl-access=free }}] However, recent studies revealed that pelagic fungi were found to dominate the microbial biomass in deep-sea [marine snow](/source/marine_snow)[{{cite journal | last1=Bochdansky | first1=Alexander B | last2=Clouse | first2=Melissa A | last3=Herndl | first3=Gerhard J | title=Eukaryotic microbes, principally fungi and labyrinthulomycetes, dominate biomass on bathypelagic marine snow | journal=The ISME Journal | publisher=Oxford University Press (OUP) | volume=11 | issue=2 | date=2016-09-20 | issn=1751-7362 | doi=10.1038/ismej.2016.113 | doi-access=free | pages=362–373 | pmid=27648811 | pmc=5270556 | url=https://www.nature.com/articles/ismej2016113.pdf | access-date=2025-08-15}}] and exhibited biomass concentrations similar to that of prokaryotes during phytoplankton blooms.[{{cite journal | last1=Gutiérrez | first1=M. H. | last2=Pantoja | first2=S. | last3=Tejos | first3=E. | last4=Quiñones | first4=R. A. | title=The role of fungi in processing marine organic matter in the upwelling ecosystem off Chile | journal=Marine Biology | volume=158 | issue=1 | date=2011 | issn=0025-3162 | doi=10.1007/s00227-010-1552-z | pages=205–219 | bibcode=2011MarBi.158..205G | url=http://link.springer.com/10.1007/s00227-010-1552-z | access-date=2025-08-15| url-access=subscription }}] Moreover, by infecting inedible phytoplankton, parasitic fungi are suggested to act as trophic bridge via the fungal shunt by producing zoospores that are consumed by zooplankton, a process defined as the "mycoloop".[{{cite journal | last1=Cleary | first1=Alison C. | last2=Søreide | first2=Janne E. | last3=Freese | first3=Daniela | last4=Niehoff | first4=Barbara | last5=Gabrielsen | first5=Tove M. | title=Feeding by Calanus glacialis in a high arctic fjord: potential seasonal importance of alternative prey | journal=ICES Journal of Marine Science | volume=74 | issue=7 | date=2017-10-01 | issn=1054-3139 | doi=10.1093/icesjms/fsx106 | doi-access=free | pages=1937–1946 | url=https://academic.oup.com/icesjms/article-pdf/74/7/1937/28658590/fsx106.pdf | access-date=2025-08-15}}][{{cite journal | last1=Klawonn | first1=Isabell | last2=Van den Wyngaert | first2=Silke | last3=Parada | first3=Alma E. | last4=Arandia-Gorostidi | first4=Nestor | last5=Whitehouse | first5=Martin J. | last6=Grossart | first6=Hans-Peter | last7=Dekas | first7=Anne E. | title=Characterizing the "fungal shunt": Parasitic fungi on diatoms affect carbon flow and bacterial communities in aquatic microbial food webs | journal=Proceedings of the National Academy of Sciences | volume=118 | issue=23 | date=2021-06-08 | issn=0027-8424 | pmid=34074785 | pmc=8201943 | doi=10.1073/pnas.2102225118 | doi-access=free |display-authors = 4 | article-number=e2102225118 | bibcode=2021PNAS..11802225K }}][{{cite journal | last1=Breyer | first1=Eva | last2=Zhao | first2=Zihao | last3=Herndl | first3=Gerhard J. | last4=Baltar | first4=Federico | title=Global contribution of pelagic fungi to protein degradation in the ocean | journal=Microbiome | volume=10 | issue=1 | date=2022-09-01 | issn=2049-2618 | pmid=36050758 | pmc=9434897 | doi=10.1186/s40168-022-01329-5 | doi-access=free | article-number=143 }} 50px Modified text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].]
Recent evidence also indicates that pelagic fungi play a potentially important role in the marine carbon cycle.[{{cite journal | last1=Morales | first1=Sergio E. | last2=Biswas | first2=Ambarish | last3=Herndl | first3=Gerhard J. | last4=Baltar | first4=Federico | title=Global Structuring of Phylogenetic and Functional Diversity of Pelagic Fungi by Depth and Temperature | journal=Frontiers in Marine Science | volume=6 | date=2019-03-19 | issn=2296-7745 | doi=10.3389/fmars.2019.00131 | doi-access=free | article-number=131 | bibcode=2019FrMaS...6..131M }}][{{cite journal | last1=Chrismas | first1=Nathan | last2=Cunliffe | first2=Michael | title=Depth-dependent mycoplankton glycoside hydrolase gene activity in the open ocean—evidence from the Tara Oceans eukaryote metatranscriptomes | journal=The ISME Journal | volume=14 | issue=9 | date=2020-09-01 | issn=1751-7362 | pmid=32494052 | pmc=7608184 | doi=10.1038/s41396-020-0687-2 | doi-access=free | pages=2361–2365 | bibcode=2020ISMEJ..14.2361C | url=https://www.nature.com/articles/s41396-020-0687-2.pdf | access-date=2025-08-15}}][{{cite journal | last1=Baltar | first1=Federico | last2=Zhao | first2=Zihao | last3=Herndl | first3=Gerhard J. | title=Potential and expression of carbohydrate utilization by marine fungi in the global ocean | journal=Microbiome | volume=9 | issue=1 | date=2021 | issn=2049-2618 | pmid=33975640 | pmc=8114511 | doi=10.1186/s40168-021-01063-4 | doi-access=free | article-number=106 }}] A global-ocean scale [multiomics](/source/multiomics) study reported a widespread and active role of fungi in degrading carbohydrates by studying the diversity and expression of carbohydrate-active enzymes phylogenetically affiliated to fungi.[{{cite journal | last1=Chen | first1=Ming | last2=Gao | first2=Honghui | last3=Zhang | first3=Jimin | title=Mycoloop: Modeling phytoplankton–chytrid–zooplankton interactions in aquatic food webs | journal=Mathematical Biosciences | volume=368 | date=2024 | doi=10.1016/j.mbs.2023.109134 | article-number=109134 | pmid=38158013 | url=https://linkinghub.elsevier.com/retrieve/pii/S0025556423001748 | access-date=2025-08-10| url-access=subscription }}][{{cite journal | last1=Klawonn | first1=Isabell | last2=Van den Wyngaert | first2=Silke | last3=Parada | first3=Alma E. | last4=Arandia-Gorostidi | first4=Nestor | last5=Whitehouse | first5=Martin J. | last6=Grossart | first6=Hans-Peter | last7=Dekas | first7=Anne E. | title=Characterizing the "fungal shunt": Parasitic fungi on diatoms affect carbon flow and bacterial communities in aquatic microbial food webs | journal=Proceedings of the National Academy of Sciences | volume=118 | issue=23 | date=2021-06-08 | issn=0027-8424 | pmid=34074785 | pmc=8201943 | doi=10.1073/pnas.2102225118 | doi-access=free |display-authors = 4 | article-number=e2102225118 | bibcode=2021PNAS..11802225K }}]
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==References==
{{reflist}}
{{aquatic ecosystem topics|expanded=none}}
{{modelling ecosystems}}
Category:Marine fungi
Category:Microbiology terms
Category:Environmental microbiology
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Adapted from the Wikipedia article [Mycoloop](https://en.wikipedia.org/wiki/Mycoloop) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Mycoloop?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.