Spartina Fungus Gone Haywire
Fungus outbreak hits Alabama marshes
A widespread fungal outbreak is affecting one of Alabama’s key marsh grass species, potentially rendering much of this year’s seed crop sterile, according to scientists.
While the fungus is always present in coastal marshes, scientists speculated that repeated exposure to oil sheens from the Gulf of Mexico spill floating on Mississippi Sound and Mobile Bay this spring and summer might have played a role in the outbreak by reducing the natural resistance of the marsh plants to the disease. It is also possible that other factors, such as an ongoing drought, played a more important role than oil, they said.
There are records of the fungus in Alabama and Mississippi marshes dating to 1895, and the scientific literature describes some years where every seed was lost to the fungus, said Judy Stout, who has studied the Gulf’s coastal marshes since 1972.
“The marshes and barrier islands were the areas that took the brunt of the oil and sheens,” said Judy Haner, marine conservation director with the Alabama office of The Nature Conservancy. “This infection raises the possibility that our marsh system is more vulnerable because it has been stressed. This wasn’t like a hurricane, over and done. This area was subjected to months of repeated exposure.”
A BP spokesman said that if federal damage assessments found problems in the marshes related to the spill, the company would act appropriately.
Affecting Spartina alterniflora, one of the two main grasses in Gulf Coast salt marshes, the fungus produces deep purple shafts that protrude from individual plant seeds like cat claws coming out of a paw. The fungus, Claviceps purpurea, does not kill the adult plants.
The Press-Register documented the presence of the fungus in marshes along West Fowl River, Portersville Bay, Heron Bay, Raccoon Island and portions of lower Mobile Bay during a survey of 20 miles of shoreline. None of the scientists contacted by the newspaper have surveyed the marshes for the presence of the fungus since the spill. They examined photographs taken by the Press-Register.
“Other than removing the seeds as a source of recolonization for spartina, it’s of little consequence to the plant itself. And spartina spreads readily without seeds,” Stout said, adding that she was unsure whether oil exposure would act as a source of stress. “Moisture versus dryness and varying degrees of salinity this year might be more important conditions.”
Stands of spartina grass along Fowl River itself appeared to be largely free of the fungus, while marshes on the Mississippi Sound were the most affected.
The sound was subject to repeated exposure to oil sheens, as documented in satellite photographs and by Press-Register reporters and oil recovery workers.
This, scientists said, could be the first sign of many subtle problems potentially related to exposure to oil.
Haner said the numerous fungi present in natural systems are normally held in check by plants that are robust enough to fend them off.
“When a system is knocked out of balance, we can see things take off like this,” Haner said. “The difficulty will come in quantifying the loss we’ve suffered. A stressed plant is not something you can easily detect, the way we can see the thousands of pencil eraser-sized tarballs still floating around in our system.”
Haner speculated the disease could leave delicate coastal marshes more vulnerable to erosion, as spartina is one of the main plants holding the soft marsh mud in place. In Alabama, spartina is often present at the fringes of the marsh, as it is better able to withstand oncoming waves. Spartina often provides shelter to the black needle rush grass that makes up the bulk of the marsh.
Stan Senner, who served as Alaska’s science coordinator following the Exxon Valdez spill and is now the director of conservation science for the Ocean Conservancy, likened the situation in the Gulf to a human immune system affected by stress.
“It is certainly reasonable that exposure to oil may have weakened these plants and made them vulnerable to this fungus or other diseases,” Senner said. “People talk about the collapse of the herring population years after Exxon Valdez. Well, one of the agents of that collapse was a fungus that struck the fish. Exposure to oil (for fish born the year of the spill) made them more vulnerable to the fungus.”
Senner said the potential link between the fungus and the spill suggests that similar, seemingly unrelated problems may crop up for years to come.
“This story will play out over several years,” he said. “Anyone who thinks we have dodged all the bullets in terms of impacts from the spill is being way too premature.”
Ray Melick, a BP spokesman, said the spill has heightened awareness of the environment, which may breed questions about the oil’s effects. “We have complete faith in the scientists who have spent their lives studying this region,” he said. “If it is related to the spill, that’s part of what the Natural Resources Damages Assessment process is there to determine, and we are committed to that process.”
“There are many reasons plants get infected by disease, but I was stunned by how pervasive this seems to be this year,” Finch said. “That raises questions about spartina being able to recover from the spill, and it raises questions about the relationship with the spill and the outbreak. We need to investigate whether the unusual events of the past year might have stressed the plants and left them more vulnerable.”
Ben Raines of the Press-Register wrote this report