Invasive aliens

Diabetic swine, green crabs, and exotic earthworms�research on invasive species figures prominently at scientific conference

"Historical changes in native clam traits after crab invasion," will be part of Oral Session #25: Invasive Species II: Aquatic Systems, held on Tuesday, August 5, 8 AM � 11:30 AM, SITCC, Meeting Room 205.

Between 1900 and 2000, an introduced predator, the European green crab, Carcinus maenas, spread northward along the coast of Maine, USA. One of the crab's preferred food choices are the area's native soft-shell clams, Mya arenaria. Lindsay Whitlow, of Bowdoin College, looked at aspects of the clams' shell morphology before and after the arrival of the crabs, examining clams from multiple sites along Maine's coast. Whitlow found that the scars on the shells, representing sizes of the clams' siphons and soft internal tissues, and the overall shell mass, all increased after the green crab arrived. According to Whitlow, the results suggest that the clams may have burrowed deeper to evade predation or that crabs may have eaten clams at shallower depths. Whitlow believes that the bivalves' increased shell mass may be the result of slower growth rates of deeper burrowing clams.

"Invasive aliens with thrifty genes: Diabetic feral swine on a southeastern coastal barrier island" will be part of Oral Session #42: Mammal Ecology: From Mice to Elephants, held Wednesday, August 6, 8 AM � 11:30 AM, SITCC, Meeting Room 104.

Somewhere over the course of the nearly 500 years in which they have roamed their island habitat, the wild swine of Ossabaw Island developed some unique traits that help them survive in an environment with fluctuating and unpredictable food sources. The feral pigs are not native to this island off the coast of Georgia; they were brought here centuries ago by early settlers, and as invasive aliens they pose a risk to other island creatures such as nesting sea turtles. However, in a fascinating twist, the swine's physiological ability to store fat is due to the same phenotype that causes such trouble in humans: type 2 diabetes. Yet the wild swine seem not to suffer from the usual problems associated with this phenotype. I. Lehr Brisbin of Savannah River Ecology Laboratory and colleague Michael Sturek of the University of Missouri will discuss their studies of the free-ranging swine and their potential to shed light on the evolutionary origin of type 2 diabetes, which has become an epidemic disease condition in the United States. The scientists point out that the Ossabaw Island swine present a unique challenge in juggling biomedical research interests with the ecological impacts of the pigs' presence on the island.

"Functional differences between exotic and native earthworm species in a California grassland," will be part of Oral Session #73: Invasive Species VI: Terrestrial, held on Thursday, August 7, 8 AM � 11:30 AM, SITCC, Meeting Room 204.

Although exotic earthworm species frequently displace native earthworms from managed California grasslands, understanding of the role they play in these ecosystems is still muddy. University of California--Davis researcher Thais Winsome and colleagues carried out experiments using a common exotic species, Aporrectodea trapezoides and a native, Argilophilus marmoratus, to shed some light on the earthworms' respective influence on nutrients and plants in the grassland system. Compared to the native species, the alien earthworm's activity promoted nutrient cycling and enhanced the growth of a fast-growing annual grass relative to slower-growing forbs and grasses. Meanwhile, the native earthworm fostered greater plant diversity and the retention of nutrients in the soil. The researchers believe that their findings may have important implications for restoring and conserving native grassland systems.

For more information on these events, or to find out more about the Ecological Society of America's 88th Annual Meeting, please visit our website http://www.esa.org/Savannah. Held at the Savannah International Trade and Convention Center August 3-8, 2003, in historic Savannah, Georgia, these sessions are part of a gathering of over 3,000 scientists and researchers. The theme of the meeting, "Uplands to Lowlands: Coastal Processes in a Time of Global Change," highlights the challenges facing ecological scientists, modelers, and policy makers.