The Search for Slime Molds
Steve Stephenson was introduced to slime molds as a graduate student.
But it wasn’t exactly love at first sight.
“There was a single laboratory session devoted to slime molds that was included in a mycology course I was taking at Virginia Tech,” Stephenson said. “I didn’t instantly consider the possibility of studying them, but once I had become aware of these organisms, I began to notice them when I was out in the field carrying out my Ph.D. research. As I learned more about slime molds, but in particular a group of slime molds known as myxomycetes, my interest gradually increased.”
Especially after Stephenson, a research professor of biological sciences at the University of Arkansas, found out that very little research had been done on the ecology of myxomycetes.
“We didn’t know very much about what myxomycetes were doing in nature and why some species were found one place and not another,” he said. “They truly are fascinating organisms.”
Since his first collecting trip to India in 1987, Stephenson has traveled around the world to find and record slime molds, which are abundant and integral to the functioning of our ecosystems, but rarely given a second glance on a nature hike.
Slime molds are not plants or animals but they share the characteristics of both. They feed on the microorganisms associated with dead plant material, especially bacteria and fungi, and they play an important role in vital ecosystem processes such as nutrient cycling. Myxomycetes, are commonly found in soil and on dead wood and leaves on the forest floor. However, a few species can be found in an ordinary lawn.
Stephenson has collected and identified myxomycetes in the frigid landscapes of Antarctica, the dense temperate rainforests of southern New Zealand and the jungles of Southeast Asia, in addition to his decades of fieldwork in the United States. His work has drawn the attention of The New York Times.
Now he can add the Namib Desert in southern Africa to his atlas of discovery.
Stephenson is one of the world’s leading experts on myxomycetes. He led an expedition in March to Namibia, where an international team of scientists discovered myxomycetes in what is thought to be the oldest desert on Earth.
“Myxomycetes are usually associated with moist habitats, but we managed to collect approximately 50 specimens representing the first records from Namibia and the largest series of specimens known from any desert in Africa,” Stephenson said. “The most important scientific aspect of our expedition was to document the occurrence of myxomycetes in yet another region of the world. We also collected a large series of samples of dead plant material, from which we will isolate additional specimens of myxomycetes in the laboratory.”
The team was based at the Gobabeb Research and Training Center, an internationally recognized center for dry-land training and research.
“Gobabeb is located at the intersection of tall red sand dunes with virtually no vegetation and gravel plains with only scattered plants,” Stephenson said. “The region receives only about an inch of rain each year.”
Stephenson’s program of research has been supported by a series of grants from the National Science Foundation and the National Geographic Society, which funded the Namibia trip. Stephenson is the author or co-author of seven books and more than 300 book chapters and papers published in peer-reviewed journals. And he’s working on three more books.
Arturo Estrada-Torres from Mexico, Carlos Lado from Spain, Diana Wrigley de Basanta from the United Kingdom and Randy Darrah from the United States accompanied Stephenson. Darrah is one of his former students.
Several years ago, the same team surveyed myxomycetes in the mountains of the south-central portion of Cuba, and Stephenson has collaborated with the three international members of the group on surveys carried out in such places as the deserts of Mexico, the Patagonia region of Argentina and the Andes Mountains of Peru.
“Even after doing this for almost 30 years, I still find going to a new place very compelling, and there are certainly a number of places left on my ‘bucket list’ that I hope to visit before I retire,” Stephenson said.
In addition to their myxomycete research in Namibia, the team also observed Welwitschia, one of the most bizarre plants in the world. The plant, which is thought to be able to live up to 2,000 years, has only two leaves that slowly grow non-stop during the life of the plant.
“This plant is pretty much considered as a mecca for botanists, few of whom ever have an opportunity to visit the small region of south-western Africa where it occurs,” Stephenson said. “We got a real thrill out of seeing it.”