Our pollutants can alter the behavior of aquatic creatures

Environmental pollution in its various forms from air pollution to water pollution can have harmful effects on human health. Yet it isn’t just people who end up suffering the consequences of pollutants. Wildlife does too.

The scientific field of behavioral toxicology focuses on understanding and measuring the precise effects pollution has on wild animals. A team of scientists from the University of Portsmouth has developed new scientific tests to do just that.

It’s well attested scientifically that pollutants like airborne and waterborne toxics can affect animal behavior in marked ways. These pollutants may reduce certain species’ ability to escape predators or obtain vital nutrients. The team of researchers, led by Professor Alex Ford and PhD student Shanelle Kohler, set out to design experiments whereby they could test how amphipods (small shrimp-like crustaceans) respond to increased toxicity levels in their environment.

What they found, according to a paper published in the journal PeerJ, was that the size and shape of water tanks where the small creatures were kept affected their exploratory behaviors by influencing how much time they spent by the side of the tank and how fast they swam around in search of food.

For a second set of experiments, whose results were published in Aquatic Toxicology, the researchers examined how two related species, one marine and one freshwater amphipod, reacted to stimuli from light. They found that they did so in very different ways when subjected to two-minute bursts of light.

These discoveries aren’t groundbreaking, yet they do indicate what biologists have long been observing in the wild: that even relatively minor changes can have significant behavior-altering effects on various species.

In another recent study, for instance, scientists in England explained that the estrogen content of contraceptives that leaks into streams and rivers (via women’s urine through toilets) affected the gender expression of as many as a fifth of male fish at as many as 50 locations in certain rivers in the UK by turning them transgender (neither fully male nor fully female).

Many male freshwater fish such as river roach have started displaying female characteristics; some of them have even started producing low-quality eggs. The chemicals that trigger these reactions in male fish are also found in cosmetics, drugs like antidepressants and cleaners.

“[S]ome of these chemicals can have much wider health effects on fish that we expected,” explained Prof. Charles Tyler, of the University of Exeter, who led the research. “Using specially created transgenic fish that allow us to see responses to these chemicals in the bodies of fish in real time, for example, we have shown that estrogen found in some plastics affect the valves in the heart.”

The researchers have identified over 200 chemicals that have escaped from sewage plants untreated into local water sources and that have estrogen contents or can produce the hormone’s effects, thereby altering the natural behavior of fish.