Renowned ichthyologist's research in Africa spans three decades

October 09, 2009

University Park, Pa. -- When Jay Stauffer began studying fish in Africa's huge Lake Malawi back in the early 1980s, it was really all about the finned creatures. He didn't recognize the immense social and economic implications of his research until later.

After three decades of work -- which has generated 68 scientific papers in refereed journals and has created a basis for addressing a growing public health crisis in central Africa -- the Penn State distinguished professor of ichthyology is trying again to focus on the fishes. Along the way, he has become an adjunct professor at the University of Malawi, has graduated three African doctoral students -- one from Zambia and two from Malawi -- and advised 31 master's and doctoral students at Penn State.

Lake Malawi (also known as Lake Nyassa) has always been the ideal subject for a scientist obsessed by fish species. Located in subequatorial Africa and bordered by the countries of Malawi, Mozambique and Tanzania, it is the third largest lake in Africa and the world's ninth largest lake by surface area and third largest by water volume. But most important to Stauffer -- its waters teem with more fish species than any other lake on Earth.

"That's why I initially decided to do research at Lake Malawi," Stauffer said. "If you are going to study freshwater fishes, this is Mecca. The lake is half a mile deep, there are more fish species there than in all of the waters on the North American continent combined, and about half of those species are still not yet described -- not named, categorized or familiar to scientists. Over 98 percent of the fish in Lake Malawi are endemic to that lake."

When Stauffer began studying Lake Malawi's fish, he was only vaguely aware of the problems with schistosomiasis (also known as Bilharzia), a major parasitic disease infecting humans that is caused by several species of flukes. The World Health Organization estimates that up to 200 million people are infected in parts of South America, Africa and Asia.

Aquatic snails of various genera act as intermediate hosts for schistosomes, so the prevalence of snails determines the distribution of the disease. The ailment long has been a problem in Lake Malawi. Parasitic eggs get into the water via human urine and defecation, and after a period of multiplication in the snails, an aquatic larval stage emerges and infects humans by direct penetration of the skin. It is a nasty cycle.

After conducting research for several years, Stauffer became aware of a change in Lake Malawi, in which he was a frequent scuba diver. The seminal event for him occurred in 1987, when he was infected by schistosomiasis. "We had been doing hundreds of hours of diving, and I got the disease, and so did every member of my crew," he said. "It came home to roost with me when I got infected because I got pretty sick. We knew something different was happening, so we started looking at snail data, trying to find out what was allowing snails to inhabit the open waters of the lake."

Snails had always been present in the lake's shallows, but after studying fish predation and snail movement, it became apparent that the bivalves were able to invade the open, shallower waters because of depleted populations of predators that formerly kept snail numbers in check. Stauffer and his peers were able to determine that the snail-eating fish, members of the cichlid family, were being overharvested in the shallows.

"We have seen a direct correlation between the decrease in the number of snail-eating fish and the increase in the incidence of schistosomiasis in humans," Stauffer said. 

For years Stauffer and other scientists have tried to work with African leaders to cut down on the harvest of snail-eating fish in Lake Malawi's shallow waters -- accomplished by small-boat-borne villagers using fine-mesh nets -- with varying degrees of success. "It is frustrating," he said. "When we convinced the elders of one village not to allow the taking of snail-eating fish from the shallow waters, populations began to rebound, but then fishermen from another village came and harvested them. 

"Our work has been noticed by African officials, but whether they will do anything is the question," Stauffer added. "We experimented with barriers to be placed in the shallows to prevent fishing, but whether they ever will be built or placed is doubtful. There is just no money." 

In recent years, Stauffer's research has shown that the problem is not so simple and involves a number of previously unsuspected snail and cichlid varieties. As recently as March of this year, he published a paper on a kind of snail, Bulinus globosus, that is newly involved in the schistosome equation, making the problem worse. 

"Our most recent work shows that the same schistosome can be hosted by several snail species, in completely different lineages," he said. "If we have one generalized shistosome that can use a variety of different hosts, the possibility or likelihood of spreading urinary schistosomiasis throughout Africa is greatly increased. This could signal a public health catastrophe." 

The key to preventing the spread of more disease in central Africa, Stauffer not surprisingly believes, lies with the fishes. "We think we can use fish as a biological control," he said. "We would have to find an indigenous cichlid that would serve that purpose. 

"My passion is to work out alpha-level taxonomy, identifying the fish species and determining their relationship to each other," Stauffer added. "We would not want to introduce any exotic fish into Lake Malawi -- we simply need to know more about the fishes that are there now, and that is where I am concentrating my work." 

The complicating factor for relying on fish to be the critical biological control of snail populations and to reduce schistosomiasis, Stauffer said, is their nutritional value to Africans. "Fish provide 70 percent of all the animal protein for people in Malawi," he said. "If fishes are to be managed in Lake Malawi for maximum sustainable yield and snail control, we need to know much more than we do now about growth and reproductive rates." 

Stauffer suggests that his biggest contribution has been educating Africans who live along the shore of Lake Malawi about schistosomiasis, the disease's relationship to snails and the overharvest of cichlids in shallow waters. "They really didn't understand," he said. "We published a brochure in English for the tourists to warn them about the disease, but then we printed a version in the Chechewe language, which is the main language for the Malawians, that was widely distributed and well received." 

Looking forward, Stauffer sees his role as continuing to educate about Lake Malawi. "I want to continue to expand the understanding of the taxonomy of the fishes and to make Africans aware of this great resource they have," he said.

  • Jay Stauffer diving in Lake Malawi.

    IMAGE: Penn State

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Last Updated November 18, 2010