In the oceans, where distances can be long and visibility can be short, many animal species rely on sound to communicate, navigate, and monitor their surroundings. The haunting cries and clicks of whales are both beautiful and vital to their survival. Using "songs" cetaceans can communicate with one another across several hundred kilometers of ocean. Whale sonar allows the animals to find food, safely travel along irregular coastlines, and migrate to and from breeding and feeding grounds. Some whales uses bursts of loud noise to drive and confuse their prey.
These activities are becoming more and more difficult as manmade noise in the sea has increased dramatically. Ship traffic, oil and gas exploration, scientific research activities, and the use of military sonar and communications equipment have caused an increase in ambient marine noise of two orders of magnitude in the last 60 years.
Recent studies suggest that noise pollution can harm whales directly by damaging their hearing, and in extreme cases, causing internal bleeding and death. More commonly, it appears that excessive or prolonged noise can cause behavioral changes that interfere with the health and survival of the animals.
In this activity, you will consider one type of whale behavior that has been linked to manmade noise, stranding. When whales strand, or beach themselves, they often die. Death may be due to the factors that drove them ashore initially, or to exposure and dehydration and organ damage caused by the unsupported weight of their own bodies.
A group of whales—mothers and their calves—is migrating along a coastline. Using sonar and song, they are keeping in touch with one another and away from shallow water. Their journey is uneventful, until human and natural activity causes underwater noise levels to rise.
Add noise to the marine environment by clicking on the boxes one by one, and observe how whale behavior is affected. Once you have seen the combined results of noise pollution on this group of whales, answer the questions that follow.
Climate researchers are using a technique called acoustic thermometry to track changes in ocean conditions due to global warming. Since the speed of sound in water varies with temperature, by transmitting and measuring low frequency sounds across ocean basins, scientists can monitor water temperature. But while this research may ultimately help protect ocean ecosystems, it may harm sound-sensitive animals like whales in the process. How should scientists balance the potential hazard to whales against the possible benefit to the marine environment?
Scientists seek to understand and explain how the natural world works. Many of the questions raised in this endeavor have no absolute answers.
The scientists should conduct experiments to determine how whales might be affected before the system is widely deployed. Perhaps there are frequencies or sound intensities that would minimize harm and yet still be effective in monitoring temperature.
If the only way to track ocean climate change does threaten whales, then it is a very difficult decision. Whales are among the most endangered and most beloved marine animals. It would be very hard to get popular or political support for research that risks their already uncertain future. But global warming could disrupt the entire ocean ecosystem. Are whales more important than all the other species? And it seems likely that if research is halted and environmental changes aren't tracked and possibly avoided, the whales will suffer anyway.