While scientists initially speculated that exposure to oil might have weakened marsh plants and left them more vulnerable to a fungus now widespread in Alabama and Mississippi, some now suggest it is equally plausible that the oil may have acted as a sort of fertilizer, helping the fungus grow.
The fungus, Claviceps purpurea, renders the seeds of one of the Gulf Coast’s primary marsh grasses sterile. It was present in both Alabama and Mississippi marshes during several inspections by the Press-Register in November and December.
The fungus is a normal part of marshes the world over, but it typically affects about 10 percent of the seeds in a given year, according to a U.S. Fish & Wildlife paper about the marsh communities of the Gulf Coast.
In marshes surveyed by the newspaper this year, infection rates appeared much higher – at times seeming to affect every seed head.
Past outbreaks have been linked to various environmental factors, such as drought, that cause stress to marsh grasses and leave them more vulnerable to infection. But with the summer’s Gulf spill, scientists said, other stress factors must be considered.
Some fungi in the Claviceps genus are known to be able to degrade oil, according to a survey of scientific publications. “There is a fairly substantial body of evidence in the literature,” said Scott Milroy, a University of Southern Mississippi marine biologist specializing in ecological modeling.
Milroy, who said he was not an expert in marine fungi, speculated that some species might benefit from the summertime infusion of oil into the marshes.
“If you are the only one that can access this new food resource, then it is a boom time for you,” Milroy said. “The law of unintended consequences plays out all the time….We should be looking for this type of thing.”
Milroy noted that the microbial community in Gulf waters is believed to have degraded a substantial amount of oil after the spill.
The Claviceps fungus is most recognizable after it has infected a plant, producing long, black structures that protrude from the seed heads like claws coming out of a cat paw. The window for surveying Gulf marshes for the fungus is rapidly closing, as Gulf populations of the affected plant, Spartina alterniflora, typically set seeds in October and November.
Several scientists said the National Oceanic and Atmospheric Administration had circulated the newspaper’s earlier report on the spread of the fungus and asked for their comments.
“Whether what you saw is a function of the oil spill, I don’t know. It’s probably worth looking into,” said Irv Mendelssohn, a marsh plant expert at Louisiana State University.
Mendelssohn said he has seen past outbreaks of this fungus that affected nearly every plant in an area, raising the possibility that oil had nothing to do with this year’s episode. He also noted that the signs of infection are fairly subtle and would likely escape notice unless someone knew what they were looking for. He said he planned to look for it during his next trip into the marsh.
“It’s an interesting observation, and it is very easy when you have a massive spill like this to question whether it is related. This is certainly a reasonable question,” Mendelssohn said. “The (Natural Resources Damage Assessment) people that are trying to assess the impact, it would be very interesting to see if they have noticed anything like this.”
Federal officials in charge of the NRDA process did not return calls seeking comment.
