The introduction of energy into the marine environment, especially in the form of noise, has an important impact on many species. The cetaceans (dolphins, whales, killer whales, sperm whales, etc.) are the group of animals most affected by these alterations as they depend 100% on sound. In the case of the bottlenose dolphins (Tursiops truncates), they live at a close distance from the coast, which means that they have to co-exist in the marine area with greatest human presence with an acoustic impact of a multitude of boats.
Underwater noise, together with fishing and chemical pollution, make the bottlenose dolphins the most harmed cetacean species in the Mediterranean.
Consequently we want to obtain a global view of the situation regarding acoustic contamination and the correlation with cetaceans, and to do this we need to install 3 hydrophones. One situated in the Northeast of the island, another in the natural reserves “Es Vedrà, Es Vedranell i els Illots de Ponent”, and the last one between Ibiza and Formentera (known as “els Freus d’Eivissa i Formentera” given the intense human presence in this area.
The EAR (Ecological Acoustic Recorder) are underwater hydrophones connected to a computer programme which specifically records underwater sounds. It is correctly installed towards near the seabed and is periodically visited in order to download the hard drive and replace the batteries. We then filter and process the sounds to be able to carry out the identification, quantification, and analysis of the recorded sounds. The research requires 12 months of data collection.
The sea surrounding the island of Ibiza is a hot spot for the presence of boats. The area between Ibiza and Formentera, also known as the “els Freus”, is the location in the Balearic islands that concentrate the greatest density of boats and it, probably, is within the whole western Mediterranean. Given the nature of the impact and the bottlenose dolphin, the acoustic analysis is the ideal technique to monitor the correlation between their presence and noise.
The uncontrolled increase in human activities during the summer, especially with regards to navigation, causes a great intensification in noise pollution, among others. This pollution has harmful effects on different marine organisms, especially cetaceans, which because of their way of life depend 100% on sounds.
The bottlenose dolphin is protected by several laws and regulations, both nationally and internationally. The introduction of noise in the marine environment is included as part of the description of the environmental status in the European policy known as “Marine Strategies”. In a place like Ibiza where both noise and dolphins coincide, it is essential to obtain data to understand what impact one has over the other in order to achieve a sustainable environmental management of our human activities.
Valorar la contaminación acústica marina en Ibiza y su posible incidencia en la presencia de delfines.
Los objetivos de Tursiops incluyen, no solo la investigación, sino que especialmente difundir los conocimientos adquiridos. Por esta razón también se han programado actividades para dar a conocer la situación y la presencia sobre estas especies en general.
La gran ventaja de los estudios acústicos del medio marino va ligada a la robusteza y riqueza de los datos que proporcionan. Los hidrófonos tienen la capacidad de grabar sistemáticamente un amplio espectro de señales acústicos a cualquier hora del día, cualquier día del año, por lo cual constituye el sistema de monitoreo más eficaz y efectivo. La instalación para la grabación de cetáceos y ruido a la vez es relativamente sencillo pero los resultados de los estudios pueden llevar a un impacto en la sostenibilidad medioambiental considerable.
