Projects and People
Chris Craft in the field...
What are you working on right now?
We are working on a project funded by an EPA STAR (Science to Achieve Results) grant, looking at the effects of climate change on the ecosystem services provided by tidal wetlands. Services like water quality improvement, carbon sequestration, habitat for birds and small fish, and shoreline protection potential.
Shoreline protection must be a huge issue after Hurricane Katrina.
Tidal marshes serve as the first line of defense against storms, depending on how wide the marsh is, as marsh vegetation buffers wind and wave action. Obviously, vegetation will not provide a buffer against 150-mile-an-hour winds, but there is evidence that when you have a lot of marsh, some of that energy, especially the storm surge, will get dissipated by the plants. Also, the plant roots hold soils and sediments in place so the land doesn’t get washed away. And the flat topography of the marsh makes it a good place to store floodwaters. The combination of these three factors makes tidal marshes an ideal defense against storms. Besides, what else are you going to do with the marshes? You can’t develop marshland because it is wet and flood-prone.
Where’s all this taking place?
Our study sites are in coastal Georgia—the Altamaha, Satilla, Ogeechee Rivers and estuaries. As part of the project we will expand the study area so that it covers the southeast coast from South Carolina to Florida, more than 300 miles of coastal shoreline.
What else is happening?
We study nutrient enrichment and eutrophication of wetlands.
That’s when water bodies receive excessive nutrients, nitrogen and phosphorus, stimulating algae and plant growth. It’s a problem in rivers, streams, lakes, and wetlands. Basically, it’s too much of a good thing. Determining whether a river is eutrophic is not so difficult; you take a sample of the water and measure the chlorophyll content, which is an index of phytoplankton/algae growth. But how do you measure eutrophication in wetlands? Some wetlands don’t have surface water, just squishy soil, so you can’t use measurements in the water as an index of enrichment.
So what do you use?
Vegetation and soils. Plants respond to the nutrients by growing more, so you measure the productivity and growth of emergent vegetation. And soils sometimes sorb more nutrients, especially phosphorus, in response to nutrient enrichment.
Was this another Georgia coastline project?
No. It spanned three geographic regions in Indiana. We sampled wetlands in southern Indiana, in the northeast near Angola and Pigeon River where they have a lot of bogs and lakes, and north of Lafayette in the eastern Corn Belt region. These three areas of the state differ in climate, geology, topography, and land use, so we expect the wetlands to vary in the degree of enrichment from one region to another. EPA funded this study also through its Washington, D.C. headquarters and through Region 5 in Chicago.
Which indicators did you look at?
Well, soils aren’t a good indicator because they vary so much depending on geology. We needed something that responds across a range of geographic conditions. We concluded that plants like cattail (Typha spp.) and reed canary grass (Phalaris arundinacea) make the best indicators. Both are aggressive, fast-growing, weedy wetlands plants that outcompete other plants in nutrient-enriched situations.
Where does wetland restoration fit into your work?
One hundred to 200 years ago, much more of the American landscape was wetland. But it was drained for agriculture and other uses. Today, many agencies and organizations such as the U.S. Fish and Wildlife and the Nature Conservancy are interested in restoring some of this land back to wetlands. In addition to restoring habitat for wetland dependent species such as waterfowl, these restored wetlands can be used to reduce eutrophication. If you convert farmland to wetland you are no longer fertilizing that land—you’re not adding nutrients— so it goes from being a source of nutrients to being a sink as plants and other organisms assimilate nitrogen and phosphorus.
If you can restore wetlands like this, how much nitrogen and phosphorus—the two major constituents in fertilizer—can the wetlands trap every year? That’s one question we’re looking into with the Nature Conservancy at Upper Klamath Lake, Oregon. In Oregon, phosphorus is the problem nutrient whereas in the Midwest it’s nitrogen. Both are necessary to life. They’re essential elements but too much is not good.
Upper Klamath Lake is a good example of the potential benefits of wetland restoration. Endangered fish, the Short-nosed Sucker and the Lost River Sucker, live in the lake and their populations are in decline. There are about 12 theories for why the fish are in decline. Excess phosphorus is one of them. When you have too much phosphorus, you get these giant algae blooms. The lake is 40 miles long, five to ten miles wide, and, in the summer, most of the lake is green with algae blooms. The excessive growth of the algae results in fish kills in the summer as the algae dies and is decomposed by bacteria that use up all of the oxygen in the water column. At Upper Klamath Lake, the goal of the restoration is to restore more than 5800 ha (about 13000 acres) of wetlands. If they are successful in restoring that much farmland back to wetland, instead of being a source of phosphorus to the lake, the land will become a sink for P as the plants take it up, die, and it becomes incorporated into the peat soil.
We are working to determine how much phosphorus is sequestered by restoring wetlands around the lake. In addition to phosphorus removal and water quality improvement for the endangered fish, the plan is to restore habitat for waterfowl, as the lake is an important stopover for migratory birds on the “Pacific flyway.”
What else keeps you busy these days?
Wetland restoration in the northeastern U.S. We are working to restore wetlands along the Woodbridge River in northern New Jersey. It’s part of the Hudson River and the New York/New Jersey Harbor, one of the most industrialized waterways in the world. Wetland restoration in urban landscapes like this is really difficult as the surrounding watershed is completely developed. While you can restore the on-site characteristics that make up a wetland—hydrology, vegetation, and soils—at a site like this, you have no control over what enters the wetland when it rains as runoff from urban landscapes, which, in addition to nutrients, contains toxic pollutants such as heavy metals and hydrocarbons. We are working with the New Jersey Office of Natural Resources Restoration, NOAA’s National Marine Fisheries Service, and the U.S. Fish and Wildlife Service at Woodbridge River to restore wetlands as compensation for natural resources damaged by an oil spill at the Exxon Bayway refinery in 1991.
The states of New York and New Jersey set up a trust to fund environmental restoration projects in the region. When there’s an environmental problem like an oil spill, the offending company pays a civil settlement for the damage, which goes into the trust fund. Woodbridge River in New Jersey is one of these sites. The wetland has a dike around it and they dug mosquito ditches 70 years ago to drain it. Also, the soils contain high levels of heavy metals. We submitted a proposal to study whether metal pollution has led to bioaccumulation in the wetland plants and animals. In addition, the site has been taken over by Phragmites, an invasive plant. Restoring wetlands at Woodbridge is a real challenge. But, as they say in New York, if we can make it—be successful—there, we can succeed anywhere.
With wetland restoration, there are so many things you need to do to get it right. You need to get the hydrology right—the depth, duration, and frequency of inundation—or you will not succeed. Successful restoration depends on restoring hydrology. Without the appropriate hydrology, you will not recreate the environmental conditions for plants and animals that rely on wetlands for habitat and reproduction. If you get the hydrology right, you can have wetland plants covering the site within two to three years. During my career, I have been involved in creating and restoring tidal marshes in North Carolina. Today, these marshes range in age from nine to 37 years old and they are some of the oldest created wetlands in the United States. What we know is that the wetland plant community develops in about three to five years after hydrology is restored and that the animal and microbial community develops after about five to 15 years. But wetland soil development is slow. Even after 30 years, the soils are not equivalent to what we find in a natural system.
So you’re working in New Jersey wetlands. Have you found any dead bodies swimming with the fishes?
No, we think Jimmy Hoffa may be buried there, but looking for his body is not part of our restoration monitoring plan.
Chris Craft is an associate professor at SPEA, IUB. His research focuses on biogeochemical linkages among vegetation, soils, and soil fauna, and the effects of human activities on these linkages. He particularly uses wetlands as model for these links. Craft received his Ph.D. from North Carolina State University in 1987.