Underwater noise as a new threat to the marine environment, with special reference to marine mammals, mainly cetaceans

Abstract

In May 1996, several Cuvier' s beaked whales were found stranded along the coast of Gulf of Kyparissia in Ionian Sea, Greece. The necropsies consisted of a basic examination and did not lead to the discovery of the cause of death. In an attempt to find the cause of the fatal event, marine biologists examined potential options, including meteorological events, pollution, tectonic activity, but nothing seemed to have taken place in the area that could be related to the incident. A leading researcher, Frantzis came across a notice dating several months back from the Greek Hydrographic Service, which relayed a warning from NA TO that "sound detecting system trials" would performed by a research vessel in the area, including coordinates of the Gulf. Tests involved, a Low Frequency Active Sonar (LFAS). The researcher made a link between these two events, claiming that sonar resulted on these negatives effects on the marine mammals. Intense debate was ensued, between scientists and NATO. The strandings were seen as an international benchmark event, prompting the scientific community to deal with a new phenomenon, an environmental threat, namely underwater noise. Following this incident, many other cetacean strandings that took place around the world, for instance, in the Bahamas and the Canary Islands, alarmed the scientists. For the past 10 years, scientific community has attempted to understand better the problem, the effects on cetaceans and the precise reasons causing their deaths, in an attempt to regulate internationally this new threat to the marine environment. The significance of underwater noise lies on the fact that is the primary communication tool for marine mammals, which are based on sound for various needs, such as echolocation. In the marine environment, anthropogenic noise is a result of different sources, where shipping and seismic surveys are the main ones. In areas where the natural and anthropogenic signals meet, data collection has shown in many cases disturbance to marine mammals. Several regional frameworks attempt to deal with underwater noise, for instance in the United States and Europe. One very optimistic attempt is the Marine Strategy Framework Directive-MSFD- and decisions through ACCOBAMS. As underwater noise is a relatively recent issue in the scientific community, this study aims to bring noise to public awareness. Also, due to its interdisciplinary characteristics, the study attempts to provide the basic background, but in the same time the necessary depth to familiarize the readers with this new threat to the marine environment. Last but not least, this thesis aims to work as a bridge combining biological aspects, legal framework and policy making.