Darwin's
Dreampond: Drama in Lake Victoria.
1996. Tijs Goldschmidt (translated
by Sherry Marx-Macdonald). The MIT Press, Cambridge and London.
276 pp. hardbound, $25.
The cichlid fish of Africa's Lake Victoria were so little known to scientists when Tijs Goldschmidt and a group of Dutch biologists set out to study them that "There was no reason. . .to go to libraries and read volumes of tedious articles. We would write these ourselves later." Undoubtedly Goldschmidt has written some tedious articles for scientific journals, but you couldn't tell on the evidence of Darwin's Dreampond. This is a very good book.
When raising the alarm on rainforest destruction and other unnatural disasters, conservationists often decry the loss of species not yet known to science. But these unknown species are theoretical. We have no idea what they might have been, only that they must have been. Not so for the loss of unknown species of furu, as Lake Victoria's cichlids are called. We know that unknown furu went extinct in full view of the scientists, like Goldschmidt, who were trying to catalog them. In fact, as the author recounts, after seeing one too many furu on a collecting trip, he himself "threw back" a furu never seen before or since.
Goldschmidt and his fellow Dutch biologists hit the Tanzanian shores of Lake Victoria in 1981, and found a gold mine of furu. (A somewhat mixed blessing to the biologist, who notes that "Nothing is more stultifying than discovering something new every week.") In virtually no time at all, they'd found more than 300 species of furu in one small bay of this huge lake (which is larger than the state of Maryland), fully half of which were previously undescribed.
These brightly colored small fish, ranging from two to ten inches in length, were a marvelously diverse bunch, more easily differentiated by their habitat and feeding adaptations than by morphological differences. Among the furu were multiple species of insect-eaters and prawn-eaters, mud-biters and algae-scrapers, snail-crushers and snail-shellers, leaf-choppers and zooplankton-eaters, cleaners and scale-scrapers, fish-eaters galore, and a group of 13 species know as pedophages, "child-eaters," dining on the embryos or fry of other furu. Within each group even more narrow specialties emerge. Among the pedophages, for instance, some are rammers, which bash a mouth-brooding female so she opens her mouth and releases her young to be gobbled up. One species rams the female by approaching at an angle from below her; another blasts straight up; a third rams from above. This enormous diversity within a single group is unparalleled, putting Darwin's Galapagos finches with their paltry 14 species to shame. The story of this spectacular evolution of furu was the subject of Goldschmidt's science, and forms the "Darwin's Dreampond" part of his book.
By 1985, about 200 of these species were extinct, victims of a single large species of fish-eater, the Nile perch. Nile perch were introduced--at first surreptitiously by "one man with a bucket" in the early 1950s and officially in the 1960s--to provide much-needed protein for people living around the lake and to form the basis for a fishing industry as well. Judged solely on these merits, the introduction has to be deemed a success, at least so far. But the consequences for the furu were devastating. Moreover, the ecology of the lake is irrevocably changed. This story, to which Goldschmidt was a witness, and which turned him into a somewhat reluctant conservationist, comprises the "Drama in Lake Victoria" part of the book.
Tying these parts together is Goldschmidt's own story of life as a Western fish biologist working in a Tanzania of warm beer and malaria, of long lines and even longer waits for planes that never arrive, of petty bureaucrats and nosy policemen, and of patient fisherman who humor Goldschmidt as he collects tiny furu when there are, quite literally, bigger fish to fry and who become his friends and confidants. Goldschmidt writes with a wry sense of humor and possesses an ability, rare among scientists, to poke fun at himself.
Most intriguing is Goldschmidt's balance and optimism. Even while watching the species of his life's work disappear into the guts of Nile perch, he appreciates how the Nile perch has filled the guts of many, many people who now have a life's work. And, in the furu species that do remain, he sees potential for new species to emerge. The first hint of this comes at the end of the book, when a Japanese scientist finds possibly new species in the same bay so carefully combed just a few years earlier by Goldschmidt's team. More recently, in another part of the lake, another survey team found about 60 species of furu, about half of which were previously unknown. Are these simply species previously overlooked or new species, recently evolved in Lake Victoria's changed environment? Some of both? We may never know, but as Goldschmidt makes happily clear, the drama in Darwin's Dreampond is far from over.
--Susan Lumpkin
(ZooGoer 26(2) 1997.Copyright 1997 Friends of the National Zoo. All rights reserved.)
