Tuesday, April 1, 2008

fungus among us

As the planet continues to experience rapid climate change due to human actions, the potential impact on the microbiotic community is little understood. Despite the overwhelming diversity, biomass, and ecological importance of bacteria, archaebacteria, and fungus we spend very little time worrying about their long-term stability... except when they start killing bigger things.

two cases in particular. the frogs of central & south america, and the oaks of northern california. both are being laid low by a fungus. in the case of the frogs it is a chytrid fungus, Batrachochytrium dendrobatidis, the oaks Phytothphora ramorum, an oomycete.

P. ramorum (oak killer) was first reported in 1995 along the hills of the northern California coast, where it rapidly began infecting large populations of the coastal live oak and black oak, once infected mortality is assured. Oozing black cankerous sores, wilting leaves, beetle infestations, and then death mark the disease. In Europe a similar afflication was identified as being P. ramorum shortly after it was found in the U.S. The fungus also infects many different host tree species, such as rhododendrons, but does not cause mortality, using the host instead as a spore factory that can spread the fungus via water or wind to new oaks. The origin of P. ramorum is not understood.

B. dendrobatidis (frog killer), on the other hand is a well known disease of amphibians but usually only effects a small percentage of any given community. However, during the 1980's and 1990's two thirds of the 110 harlequin frog species vanished, even those in remote mountainous areas, driven extinct by the fungus. The scientists were stumped until long-term climate data was analyzed for the cloudy rainforests where the frogs live. They realized that due to global warming the forests weren't getting as cold during the night, but were getting cooler during the day, constricting the temperature range. Without the extreme temperatures to limit it, B. dendrobatidis flourished, the infection rates in the frogs bounded upward, and species began dying off.

I believe that a similar process is at work in the oak death, a climate threshold was crossed and the California coast became a more suitable habitat for P. ramorum, perhaps latent in host species it proliferated and began attacking the oaks. As global climate changes we would expect to see corresponding shifts in the microbiota as the new conditions favor a different set of species that come into the population forefront while others step back or go extinct.

Temperatures continue to creep higher, and there is no telling what kind of organism may begin multiplying into the warm, moist air or water. The frogs and the oaks are obvious examples, but other inexplicable die-offs may be related. the Colony Collapse Disorder afflicted honeybees were full of fungus, bacteria, and viruses. More recently the sudden decimation of the bat populations in the eastern U.S. was marked by a white fungus that grew on the bat's noses just before death.

Two points make a line, three a plane, and a pattern emerges. While the polar bears stuck on ice flows get the press the real consequences of climate change may be more subtle, yet much deadlier. if you're interested in purchasing a fungal spore-proof respirator visit the merchandise area of my blog-world. best of luck buddies!






1 comment:

John Lambert Pearson said...

oh didn't you hear?
i cured sudden oak death and colony collapse disorder in chip's drawing class.