By Asher Price
AMERICAN-STATESMAN STAFF
Published: 7:06 p.m. Saturday, Aug. 6, 2011
IPSWICH, Mass. — Gray upon gray, slosh upon slosh, acre after acre of marsh. Early on a wet dog of a Saturday morning, I had wriggled my way into a pair of extra-large waterproof waders and set out with a team of journalists and scientists onto a portion of the foggy bog north of Boston known as the Great Marsh .
Salt marsh was the more technical term: We were between land and sea, in a cracked, muddy landscape, riven with tidal waters. Centuries before, New Englanders had harvested the grasses as hay. Now this marsh, 20,000 acres stretching roughly from Gloucester to Salisbury, is largely a preserve, visited only by intrepid birders, the occasional dog walker and scientists.
Beginning in 2004 , researchers with the Marine Biological Laboratory have conducted experiments on the effects of fertilizer on the salt marsh system here. They have essentially polluted a 15-acre section of the system daily from May through October . A water tank they call "the brain" drips a solution containing 40 50-pound bags' worth of fertilizer a week into a creek — the equivalent of the flushed wastewater and lawn fertilizer runoff from 1,000 houses. Linda Deegan , a lead scientist on the project, prefers to call the creek "nutrient-enriched"; think of it as introducing cancer cells in mice to come up with a cure for humans.
I was there as a Logan Science Journalism Fellow at the Marine Biological Laboratory, a program to get journalists to play scientist and thus to become more effective at explaining science to readers.
Five years before, when my editors at the American-Statesman asked me to cover environmental issues, I had hesitated. I grew up a city boy; wasn't the environmental beat about trees and the animals that love them? I brought my misgivings to my colleague Ralph Haurwitz, who had written about the environment for the newspaper in the 1990s. His counsel: Environmental issues intersect with anything else that interests you. With that advice in mind, I took the beat — and have found Ralph's words to be true. Even as I've grown more interested in environmental topics, I've found the gap between my knowledge and the scientists' a real challenge to overcome.
So off I went to take water and soil samples on the marshland of coastal Massachusetts. We were far from Texas, but some of the same problems are playing out on the Gulf Coast. Scientists trace so-called dead zones, where a lack of oxygen in the water has suffocated fish and plants, to fertilizer that washes off farms into the great rivers like the Mississippi that empty into the Gulf of Mexico.
After a couple of days on the marsh this past May, we took our work, including bottles full of coffee bean snails and tiny crustaceans known as isopods, data on soil respiration and water quality, and diagrams and data on the slopes of the marsh banks, back to the Marine Biological Laboratory in Woods Hole , a picturesque town of fishing trawlers and high-end lobster shacks on the southwestern tip of Cape Cod. Its unofficial slogan: A small town with big science.
Our lab work, which involved carefully measuring snails, weighing grass samples and performing chemistry analyses on our water samples, compared findings in the polluted creek with a reference creek. In particular, we learned about how nitrogen, a major ingredient of fertilizer and a basic element found in all plants, was shaping the marsh ecosystem.
Nitrogen is a chief factor in the growth rates of plants and is typically the most abundant ingredient in fertilizer. For eons, bacteria in oceans and plants had converted a certain amount of nitrogen into a form that would benefit plants. But human activities have rapidly raised the amount of this converted nitrogen available to plants. Practices such as the laying of fertilizer, the burning of fossil fuels, and the widespread planting of legumes like soybeans that are necessary for feeding cattle and are plentiful with the bacteria used to convert nitrogen have doubled the amount of plant-available nitrogen on the planet since World War II , says Chris Neill , the affable senior scientist at the Marine Biological Laboratory who led the environmental journalism program.
In Massachusetts, one reason high levels of nitrogen wind up in marshlands is that "you've had soybeans fed to beef, the beef is then trucked to Massachusetts, it's fed to people, it's excreted and ends up in the marsh," Neill said.
So were marshes overdosing on nitrogen? And if so, what were the consequences?
How much could the marshes absorb, and what happens to the nitrogen that's not absorbed? What would be the consequences for carbon dioxide release, landscape change and affects on the food web?
Even from our small sample size, we observed that the banks of the nitrogen-rich creek have slumped. Indulged with easy access to nutrients, salt grasses along these creeks do not bother shooting down deep roots to get nutrients; top-heavy, they topple, and the soil has little to hold it in place. As the marsh declines, it becomes more susceptible to the rising seawaters that already flood it.
We also found that the outgoing tide was carrying with it nitrogen — significantly more than scientists had seen in the early years of the investigation, suggesting the marsh has reached a saturation point.
"Requires further study" was one of the jokes we gave at our end-of-week presentations, but scientists working there longer than we were have found wider evidence of the trends we picked up.
Worryingly, excessive nitrogen has had serious consequences in the Gulf and the ocean beyond. In Texas waters, nutrients flooding in from farms lead to algae blooms. As they sink to the seafloor, microbes feed on them, using up oxygen that's necessary for sealife, says Wes Tunnell, a biologist and associate director of the Harte Research Institute for Gulf of Mexico Studies in Corpus Christi.
A resulting dead zone that forms each summer near the mouth of the Mississippi River and typically stretches west to Galveston had grown to more than 6,700 square miles in late July, Louisiana university researchers reported last week. With the help of nutrient-laden Mississippi floodwaters, this year's zone has been expected to break the 2002 record of 8,500 square miles. Tropical Storm Don is believed to have helped stall the dead zone's growth, the researchers reported, noting that its size might have been underestimated because of rough water and would be remeasured in coming weeks.
Oceanwide, scientists draw a dire picture: Stresses on ocean life, including nutrient runoff, algae blooms and dead zones, have increased the risk that many marine species could be extinct within a generation, according to a report from an international group of sciences released last month.
Peering closely enough at the Massachusetts mud, in other words, one could see something of the grave future of the world's oceans.
This email address is being protected from spambots. You need JavaScript enabled to view it.; 445-3643
web site design by Zoom Consulting