Pharmaceutical drugs in the ocean are affecting the behavior of fish, says a new study published in the journal Science. Medication is often flushed from our bodies intact, the paper says, and once these chemicals reach the ocean, it alters the behavior of fish.
The fish become fearless, gluttonous and exhibit asocial behavior, such as leaving their schools to search for food alone. This is dangerous because schooling is a behavior that evolved as a defense against predators — by traveling in groups, fish have a much lower chance of becoming prey.
This may not seem like much, co-author Michael Jonsson told Discovery, but if fish are eating more zooplankton and depleting their numbers, algae blooms become a risk because the population of the only organisms keeping the algae in check has been depleted. The risk of an algae bloom largely occurs when the algae die and begin to decompose — bacteria use up oxygen in the water to break down algae, leaving less for fish and potentially causing a fish kill.
Jonsson and his team focused on how a drug called Oxazepam, which is a medication for anxiety and insomnia, affect wild perch. They found traces of the drug in the fish while conducting a routine screening at the River Fyris in Sweden.
Fish often have the same drug receptors as people do, so many kinds of compounds from human medication could affect them. They also maintain equilibrium with the water, bioconcentrating the drugs in their gills: meaning they have the same concentration of drugs in their system as in the water around them.
The researchers emphasize that other marine life could also be impacted, although the effect would diminish in deeper waters, where concentration is lower.
Joakim Larsson, an associate professor at the University of Gothenburg's Institute of Biomedicine, suggests that to reduce the exposure of pharmaceuticals to the environment, better sewage filtration and treatment systems should be installed. None of the authors suggests banning or switching out drugs, because doing so could hurt people who need them.
