The impact of human activities on the oceans is not limited to microplastics causing harm to marine life. It also includes a factor that we may not have considered before. Pernille Sørensen, a scientist at the University of Bristol in England, conducted research on the effects of human activity on dolphins.

Her team's findings indicate that the noise pollution caused by human activities has made it so loud in the seas and oceans that dolphins are required to shout at each other to communicate effectively.

Have you ever been in a noisy bar or pub on a Friday night? Even if you're sitting next to someone, you have to raise your voice significantly to be heard. Similarly, dolphins also struggle to communicate in noisy environments, but instead of human conversation, they're affected by the noise from machines and ships.

Pernille Sørensen, a PhD student at the University of Bristol, conducted research to investigate how noise affects animals, and the findings were published in the scientific journal "Current Biology". The study revealed that dolphins need to shout at each other in order to communicate in noisy environments.

Two dolphins named Delta and Reese were the subjects of a study conducted at the Dolphin Research Center in the Florida Keys. The researchers placed them in an experimental lagoon and trained them to press a specially-prepared button. The objective was to test how the presence of noise affected the animals' task performance.

During the experiment, the dolphins had to cooperate to press the button, and the researchers tested how different intensities of sound affected their performance. In total, the dolphins performed 200 trials with varying sound intensities. The findings showed that with increased noise levels, the dolphins whistled louder to communicate with each other, essentially shouting. However, the louder it was, the more difficult it became for them to perform the task as well.

Dolphins use sound to communicate with each other and echolocation to hunt and navigate. This means that the volume of noise around them is crucial for their functioning. Unfortunately, commercial shipping, oil exploration and production, and military operations are the primary noise sources in non-experimental locations.

The noise levels generated by these activities can be as high as those experienced by marine animals through ships and drilling. If this noisy condition in the water persists, it could affect dolphins' ability to hunt and reproduce and ultimately lead to their extinction.

It's important to remember that humans have a history of making life difficult for animals, driving their populations to extinction. In fact, we are facing our sixth mass extinction, and according to the Living Planet Report 2022, which WWF publishes, wildlife populations surveyed worldwide have declined by an average of 69 per cent since 1970.

"The data in the document are not encouraging. They show that we are left with only 31 per cent. 'living planet', and the average decline in monitored wildlife populations between 1970 and 2018 was 69 per cent. The largest declines were in Central America and the Caribbean. Here, there was a 94 per cent decline in wildlife populations over the 48 years considered," reads tech.wp.pl.