Steven Pennings, Ph.D., is an expert in community ecology. He is a professor in the department of biology and biochemistry at the University of Houston. He conducts his research in the coastal wetlands. Pennings is currently conducting research on the impact of sea level rise and erosion on coastal salt marshes. He recently talked about the oil spill in the Gulf of Mexico and its potential impact on coastal wetlands.
Q: WHAT IS YOUR AREA OF EXPERTISE?
SP: My research is in the area of community ecology, so I study how plants and animals interact with each other and with the physical environment. I do most of my research in coastal wetlands, like salt marshes and mangroves. I've worked along the East Coast of the United States, the Gulf of Mexico, the Pacific Coast, and also in Europe and overseas.
Q: WHAT IMPACT MAY THIS OIL SPILL HAVE ON THE ECOLOGY?
SP: Salt marshes are very productive habitats, and they provide habitat for a lot of species. They are important nursery and feeding grounds for commercial shrimp, fish, crabs, and oysters. There are a lot of different types of wildlife in the marshes.
A lot of species are vulnerable. There has been a lot of work looking at the impacts of oil on salt marshes, and the more oil you dump on them, the worse off they are. Beyond that, it seems as though animals are more vulnerable than plants. It could lead to a situation where we are fooled - you might see the salt marshes being green and a lot of plants growing, but these animals might have mostly died. It would be a very affected system. The other thing is salt marshes occur where wave action is not very strong which means you are not going to have the waves breaking and dispersing the oil. So the oil just stays there once it's in the marsh. The studies have shown that the oil effects can remain for decades in salt marshes. It's not something like a rocky beach, where a few years later everything would have washed away.
Q: AS AN ECOLOGIST, WHAT IS YOUR BIGGEST CONCERN WITH THE OIL SPILL?
SP: The main concern is the enormous size of the spill, and because it's occurring in an area without much wave action, that oil is going to be in those habitats for decades.
Q: WHAT'S THE IMPACT ON CONSUMERS?
SP: The Gulf coast does produce a lot of seafood. You get shrimp, fish, oysters and crab from the gulf coast fisheries, and those are all at risk. I wouldn't worry about what you are buying in the grocery store, except that it might be more expensive in the future.
Q: WHAT IT IS THE PHYSIOLOGICAL IMPACT ON THE ANIMALS THAT CAN KILL THEM?
SP: Oil, a lot of it will float. You get a film on the water surface. Salt marshes are intertidal habitats, so as the tide rises they get covered, and as the tide falls they get exposed. The oil film will come into the marsh at high tide. It will stick to everything when the water goes at low tide. The oil will stay in the marsh because it's sticky, so it's going to accumulate in the marshes. Animals get killed when they get coated with oil. This disrupts their gills, their ability to breathe, or if they are a bird or a mammal their insulation. The volatile stuff gets into their lungs and affects breathing. The big tarry lumps are an unsightly nuisance, but they are not the main threat to animals.
ARE OIL SPILLS THE BIGGEST THREAT TO SEA MARSHES, OR ARE THERE OTHER ENVIRONMENTAL THREATS?
SP: The main threat to Gulf coast sea marshes is sea level rise and subsidence of the coast, so a lot of the coast is sinking because of extraction of oil or water from beneath the sediments. Along the Mississippi River you have a lot of the sediments which used to come off of the river that are being diverted offshore now. They are not getting out and building wetlands as they used to so marsh acreage is disappearing very rapidly, especially in Louisiana and the areas where the Mississippi River used to be feeding the marshes with sediment. The habitats are disappearing very quickly. They will cut channels to get oil rigs into places and that alters the water through the marsh and in ways that are sometimes destructive.
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