What happens when one adheres to the seemingly unexciting reminder of alcohol advertisements about drinking moderately? Surprisingly it does well, at least for the zebrafish. In fact, when they are drunk, they can be quite influential to their peers.
Past studies have already been conducted on zebrafish to determine the intricacy of the correlations between alcohol and social behavior. These zebrafish (Danio rerio) are relatively convenient to use, since they are cheaper to maintain, their genomes are well-understood, and they do great in interacting with other fish in schools or shoals. Dubbed as the "new lab rats," the zebrafish became a trend after the altering of their DNA structures became possible in 1988.
To date, zebrafish, when used in alcohol-related studies, are usually observed through a traditional paradigm that makes use of the whole school and scientists would subsequently analyze their behavior as a group. True to form, some studies revealed that like any drunk human, zebrafish tend to become slower in movement as their alcohol intake increases. Also, the group's unity falters when each fish in the group is under the influence of alcohol.
Zebrafish are found to be ideal subjects in studying emotions too, namely anxiety and fear. Another study, which was led by Maurizio Porfiri, an associate professor at the New York University (NYU) Polytechnic School of Engineering, revealed that these one-inch-long fish, when intoxicated, can become bolder and more daring when confronted with its main predator, the Indian leaf fish.
Out of curiosity and keen interest with drunk zebrafish's behavior, Porfiri came up with another remarkable study that veered away from the traditional method of observing the behavior of zebrafish. This time though, Porfiri and his team at the NYU school monitored the inebriation of a single zebrafish and how it would interact with its sober peers, a first of its kind.
Initially, they predicted that being drunk may vary depending on whether the zebrafish is with its sober peers or just alone. What caught them off guard was the reverse of what they had anticipated. It was the drunk zebrafish that even influenced all of its teetotal comrades.
"These results were very surprising," said Porfiri, who is also the director of the school's Dynamical Systems Laboratory. "It is clear that the untreated fish were matching the swimming speed of the alcohol-exposed fish, and this correlation was especially strong at an intermediate level of alcohol exposure. At very high or low levels, the influence decreases."
In the latest study published in the journal Alcoholism: Clinical and Experimental Research, the researchers dropped a single zebrafish each into the four aquariums that had a different concentration of ethanol, which ranged from 0.25 percent to 1 percent. Afterwards, the exposed fish were dropped into aquariums with sober zebrafish and their behaviors were monitored via a custom tracking algorithm they developed.
After five minutes, the zebrafish under the moderate influence of alcohol swam faster amid a school of non-exposed peers than being alone. Meanwhile, the drunkest one slowed down and trailed behind instead of being at the frontlines because of the sedative effects of high concentrations of alcohol that must have settled in, Porfiri pointed out.
Researchers deduced that moderate exposure made the fish hyperactive or tipsy, while the environment filled with other fish excited them further. Drunk zebrafish whizzed past other fish fearlessly and they are more confident in swimming, echoing that findings in Porfiri's previous study.
This euphoric behavior of buzzed zebrafish exhibited a similar quality seen generally in leaders of a pack, which may have prompted the non-exposed fish to follow suit. The drunk zebrafish has even encouraged its sober shoal mates to swim three times faster than normal just to keep up.