Swimming with Mushrooms (or, the Fungal Life Aquatic)
|February 17, 2010||Posted by Philip under Info, Review|
Word has been floating around the mycological community for awhile now about the discovery of mushrooms developing submerged in a fresh water stream in Oregon. Now the research on these mushrooms has come to full light with the publication of a paper in Mycologia:
Jonathan L. Frank, Robert A. Coffan and Darlene Southworth, (2010), Aquatic gilled mushrooms: Psathyrella fruiting in the Rogue River in southern Oregon, Mycologia 102 (1): 93-107.
The paper describes the observation and analysis of a species of mushroom fruiting over an extended period in shallow flowing water. The authors of the paper suggest that this is a new species with the proposed name Psathyrella aquatica.
According to the paper’s abstract:
A species of Psathyrella (Basidiomycota) with true gills has been observed fruiting underwater in the clear, cold, flowing waters of the upper Rogue River in Oregon. Fruiting bodies develop and mature in the main channel, where they are constantly submerged, and were observed fruiting over 11 wk. These mushrooms develop underwater, not on wood recently washed into the river. Substrates include water-logged wood, gravel and the silty riverbed. DNA sequences of the ITS region and a portion of the ribosomal large subunit gene place this fungus in Psathyrella sensu strictonear P. atomata, P. fontinalis and P. superiorensis. Morphological characters distinguish the underwater mushroom from previously described species.
Discovering an Aquatic Mushroom
This certainly is an interesting find. I asked the corresponding author, Dr. Darlene Southworth of Southern Oregon State University, if she was sure this was a new species and not a freak occurrence of some sort. She was quite sure. “A single mutation likely would not be sufficient to change the preferred habitat or even to widen the range of a habitat, nor to form a new species. A new species description requires morphological and genetic differences. We showed that in our paper.”
Southworth went on to add, “Many species of fungi, plants, and animals live in local areas as endemics so narrowness of sites does not prevent it from being a new species. It probably makes it more likely. We have found these fungi over a quarter mile stretch of the river above and below a waterfall so it is not likely to be all one ‘colony,’ that is, all connected by hyphae.”
One logical next step would be to attempt to complete the fungus’s life cycle both in the air and underwater in a laboratory setting. According to Southworth, her team intends to do just that and she finds the prospect “pleasing.” This will probably take some time to work out. In the mean time, what’s next?
“One interesting next step is to find other sites, so wading upstream in the same river and its tributaries would be a task for next summer, ” she says. “We also welcome observations from other river waders. We have followed up three reports of underwater fungi, but none have been Psathyrella. It’s just a matter of time.”
Another Mycologist’s Opinion
Britt Bunyard, Ph.D, consulting mycologist and editor of Fungi, had this to say about the research. “This is a great paper and the authors did everything exactly right in working up this fungus and didn’t rush to press. In the words of the great Orson Miller: one specimen is interesting; two is more interesting; three is a collection. Science should be based on collections; too often we have a “new species” named from a single specimen. These authors did everything right. They collected it many times over three years (at least); did the morphological work and did a good job with the DNA analysis. From ALL of this they determined this to be a new species.”
Dr. Bunyard goes on to wonder, “How does the fungus get upstream? Shedding spores in a swift flowing stream would mean you’re quickly going to migrate downstream and out of the stream. So, maybe there are aquatic invertebrates or other animals that carry them upstream. Perhaps the fungus relies entirely on animals for spore dispersal (zoochory) and frankly, it would not surprise me.”
“A lot of aquatic invertebrates are grazers and “shredders” of organic material and fungi have been shown to be key parts of their diet or to be key in transforming the organic material into something they can use… maybe some of these creatures ingest the spores and vector them about in the aquatic environment. My own research has shown this to be case with some terrestrial mushrooms.”
Could There be Other Aquatic Mushrooms?
Overall, Dr. Bunyard agrees that this is an interesting report. Perhaps it will open up a whole new field of research in the way C.T. Ingold did with his discovery of aquatic hyphomycetes. “Maybe there are lots more aquatic mushrooms,” says Bunyard, “…but, we simply never foray in the water. Psathyrella–again, the authors point this out–would be a good candidate genus to put forth as an aquatic species as there are many members in the genus that live in wet areas very near to water.”