Soundscapes of the Mediterranean Sea Episode 1: Bioacoustics

This series of three podcast episodes explores Soundscapes in the Mediterranean Sea, one of the world's major maritime transport areas. It represents only 1% of the Earth's marine surface, but 15% of the world's maritime activity is generated in its waters. The first episode focuses on bioacoustics and scientific data on the excess of underwater noise produced by maritime traffic. The second episode reports how cetaceans become disoriented, collide, and diminish their ecosystemic function. The third episode looks at some decisions at the political level that affect the soundscape of the Mediterranean. Between them, there is a project in the International Maritime Organization (IMO) that plans to reduce the speed of maritime traffic. On the other side, the Spanish government seeks the possibility of building a macro wind farm in the Gulf of Roses.

Bioacoustics, one of the most powerful tools to detect artificial sounds

But before getting to understand the marine world of cetaceans and the consequences of political decisions in this sea, the first episode of this podcast series is about bioacoustics, one of the most powerful tools to detect artificial sounds and assess the state of marine ecosystems threatened by all the human activity that is recorded daily, for example, in Mediterranean waters.

In this context, bioacoustics suggests the excess of noise in the sea is lethal for the marine environment. A large proportion of this noise comes from maritime traffic in the Mediterranean, one of the seas in the world with the most pressure from humans. According to data submitted by Spain, France, Italy, and Monaco to the International Maritime Organization as part of a project to reduce the speed of ships in the western Mediterranean Sea to 13 knots, this sea represents 1% of the earth's sea surface and is used by 15% of the world's shipping traffic.

However, we need to understand the bioacoustics world, so let's go back to the early 1990s, when the French scientist, Michel André, current director of the Laboratory of Bioacoustics Applications at the Polytechnic University of Catalonia (LAB), designed one of the first systems to alert ships about the presence of whales in their path.

At that time, the flow of vessels throughout the world's seas was increasing due to the global economic model based on free markets between countries. Since then, this economic activity has become one of the symptoms of the deterioration of marine ecosystems. Despite the fact that maritime traffic was not a topic of sufficient interest for policymakers to occupy the international agenda, the bioacoustics technology in the LAB and the experience of this scientist came together to create this laboratory that now has 15 researchers and 150 permanent observatories in the oceans of the planet.

How does it work? This complex system is nourished daily by the sounds of artificial origin captured by the hydrophones of this laboratory. According to Michel André, the noise of maritime traffic, for example, produces sound masking. This effect interrupts the transfer of auditory information between marine species as a consequence of exposure to one or more simultaneous sounds, which is fatal for all cetaceans living in the Mediterranean Sea. This overexposed noise causes them to collide with vessels; they also become disoriented and suffer various injuries. Many die and later are found anywhere along the Mediterranean coast.

According to Txema Brotons, scientific director of Tursiops, an organization located in the Balearic Islands and dedicated to studying cetaceans, their ecosystemic function is essential for the fight against climate emergency. So, their preservation consists in protecting their environment, based on the fact that hearing is their most precious sense. Through it, they obtain knowledge of the marine environment, communicate, and obtain the food they need daily. According to Txema, acoustics is everything they need to survive.

However, there are multiple activities of human origin that keep cetaceans under permanent threat in all the seas of the planet. One of them is the generation of noise due to the extraction of hydrocarbons in the oceans. Although there is a protected area of about 47,000 square kilometers in the Mediterranean Sea that prohibits this activity, starting in Denia (Alicante) and extending from the Balearic Islands and the coasts of Valencia and Catalonia to the Gulf of Roses, the Spanish government has not yet determined a comprehensive management plan for this area, according to Carlos Villa Bravo of the organization Ocean Care in Spain, in the third episode of this series of podcasts. This fact puts conservationist organizations on alert. They demand more and better action from the Spanish state institutions for the benefit of the executive conservation of the protected areas of the Mediterranean Sea.

In the end, all the political, social, economic, and environmental facts around the Mediterranean Sea have bioacoustics in common and, therefore, according to Michel André, director of the LAB, it is too late for to point an accusing finger at the promoters of this noise produced by maritime traffic. It is necessary for politicians, private companies, and all of us who consume the products transported on these huge ships to synchronize their priorities in order to conserve and protect marine life in the Mediterranean

You can listen to the full first episode in English:

And in Spanish: 

• Listen to Episode 2 of this podcast series. 

This story was produced with support from Internews' Earth Journalism Network. It was first broadcast in Carijonas on 29 March 2023 in Spanish; this version has been adapted by EJN's Mediterranean Media Initiative.

Banner image: Images of fishes underwater, Calafat, Spain, August 2022 / Credit: Clovis Wood via Unsplash.