wild kin. rediscovering Mangarahara cichlids in Madagascar could one day provide a companion for this male ( left ) to the London Zoo.
(left) London Zoo; (Right) Brian Zimmerman
Boston- Dude, check out these European perch. After swimming in water laced with a common anti-anxiety medication, fins goldfish shed their inhibitions and swallow prey at a much faster pace, according to a new study presented today at the annual meeting of the American Association for the advancement of science (editor science NOW). The animals acting strangely, even after being exposed to low concentrations of the drug found in rivers around the world, suggesting that the drug and others like it could affect fish behavior and ecology, even small doses.
Hundreds of different pharmaceuticals are able to slip beyond the conventional treatment plants and sewage in our waterways, said Jerker Fick, a toxicologist at the University of Umeå Sweden and co-author of the new study. "They mysteriously do not disappear after we excrete." Scientists have long known that many pharmaceuticals can persist in rivers and streams, and have effects on the behavior of aquatic species in high doses, he said ;. however, to determine if more dilute concentrations have an effect is more difficult to establish
thereseveral years Fick and his colleagues found a common psychoactive drug called oxazepam in water samples river Fyris, which flows through Uppsala, the fourth largest city in Sweden. Oxazepam belongs to a class of drugs that make them less excitable neurons and slower to transmit signals in the brain and is a treatment "essential" for attacks panic and other severe anxiety disorders, said Fick. Although the authors describe the drug concentration-0.58 micrograms per liter -1 -like "abnormally high", they also say that is comparable to levels found in rivers in other countries; however, there is not enough research to know with certainty the extent of the drug is. "It is not a particularly Swedish problem," says lead author Tomas Brodin of Umeå University.
Fish sequester toxic chemicals in their muscle tissue, which makes it even dilute concentrations in potentially dangerous water, said Environmental Specialist and co-author Jonatan Klaminder, also from Umeå. In the drawn pole Fyris the river, the team found concentrations of oxazepam up to six times higher in muscle tissue than in water. To determine whether this level of exposure could affect fish behavior, scientists have raised the juvenile perch under three different conditions with a twice the level of oxazepam as that found in the river, with a 500 times that level and a drug-free control. (They do not use the actual level of the drug found in the river because they were concerned they would not see an effect, the authors say. However, such high levels were reported in other rivers , they argue, and amount of drug that fish finally imprisoned in his body, and not the level of exposure, is what influences behavior.)
Three striking changes in behavior stood in the perch exposed to oxazepam, the authors reported today at the meeting and also online science . First, the fish stopped "shoaling" -the social behavior which keeps schools of fish together and protects them from predators and swam solo instead. Second, fish exposed to very high levels of the drug has become risk takers, venture into new environments through a trap much more readily than their sober peers. Finally, fish feeders at both doses were much more greedy and more efficient, darting after water fleas fat belly vigorously while drug-hooked fish back. Because it binds to GABA receptors, cell signaling mechanism found in many different species, the drug is likely to affect the behavior of other fish, say the authors.
Further research is needed to determine whether oxazepam and similar drugs are actually causing the fish to change their behavior in the wild. If yes, the deep ecological effects might result, say the authors. For example, fish relieved of their normal stress say, being eaten, could wipe out the population of algae water fleas room, which could lead to a proliferation of algae. On the other hand, fish without anxiety are likely to be much more vulnerable to predators, Brodin said, suggesting that the overall effect will probably depend on the perch are the predator in their environment.
"A large number of toxicological studies are conducted these days exhibits that simply are not realistic," said Heiko Schoenfuss, a toxicologist at the University of Saint Cloud, Minnesota. He described the new study as "really exciting" because the authors "have gone to great pains" to ensure that drug levels anxiolytic that have accumulated in fish tissues were relevant to those found in the river Fyris . to his knowledge, no research has focused on how the feed rate may be affected by other traits like courage, he adds, describing the results of the team as "conclusive." Now, he says -he, currently no legal framework to regulate the potential behavioral effects of pollutants. It hopes that this study will help to change this situation, and "calm skeptics who think that the study of fish behavior is a rather esoteric way spend your time. "
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