What kind of feelings does the word “mosquito” bring up for you? Chances are they aren’t very positive feelings and are more along the lines of “annoyance,” or “irritation.” So, it shouldn’t be surprising to find out that the aquatic creature that bears the word “mosquito” in its name is also a vexatious presence.
The mosquitofish is a harmful invasive species that overwhelms native fish and other aquatic life by rendering them incapable of feeding themselves. How do the mosquitofish manage to do this? Just as mosquitos disturb us with their bites, mosquitofish also nip away at the tails of their victims until the tail is just a stub that renders the native fish unable to swim. This means that they can’t access food sources such as insect larvae, which the mosquitofish are then free to feast on.
The native creatures, on the other hand, end up starving to death. Mosquitofish also deplete other local populations of fishes and frogs by consuming their eggs, too.
Solutions to control the mosquitofish such as manually netting them out are too time-consuming and labor-intensive, however, a team of scientists hailing from Australia, Italy, and America has come up with an innovative solution: a robotic largemouth bass.
The largemouth bass is one of the chief natural predators of the mosquitofish, but introducing real bass into lakes and ponds plagued with mosquitofish might disrupt the ecological balance of the environment. So the team decided to create a robotic one.
The idea is for the bass-like robot, which is mounted on a transparent vertical shaft with a magnet at the bottom, to be moved with another magnet placed underneath. The team tested the system out by placing the rubber bass into a water-filled tank and engaged the magnet on the robot through the bottom of the tank with the other magnet. Using stepper motors and other tools, the scientists were able to drag the robot through the tank back and forth.
To further test the robot, the team placed groups of six wild-caught mosquitofish and six wild-caught Australian motorbike frogs (Litoria moorei) into the tank for one-hour periods, with two overhead webcams monitoring their movements. If the mosquitofish were seen approaching the tadpoles, the robot bass was sent to the area to scare the mosquitofish away.
Over the five-week testing period, the team observed that the mosquitofish became more reluctant to approach the tadpoles compared to a control group that wasn’t chased away. This effect lasted even after the robot was removed from the tank.
The mosquitofish who were chased by the robot also demonstrated signs of weight loss, skinnier body shapes, and fertility reduction, all of which would negatively affect their survival as a species in the local environment. The tadpoles, on the other hand, seemed unbothered by the robot bass.
The magnet-based system wouldn’t work for natural bodies of water, but the data from this study support the notion that a self-propelled autonomous robotic bass could make a huge difference in protecting native species in these environments.
Source Study: iScience—Ecology of fear in highly invasive fish revealed by robots
