Whales and dolphins use sound to communicate, navigate and detect prey, making them particularly vulnerable to noise pollution.
A team of scientists, students and a multimedia artist have just returned from a major expedition to investigate underwater noise disturbances and their effects on sea animals from the Strait of Gibraltar to Irish waters.
AMIGOS II (Acoustic Monitoring from Ireland to Gibraltar Oceanic Waters Survey) was a 10-day expedition to collect data for a four-year EU-funded project called STRAITS (Strategic Infrastructure for Improved Animal Tracking in European Seas), which aims to protect and conserve the habitats of sea animals and improve tracking in European waters.
This survey is the second to be led by Atlantic Technological University (ATU) marine scientist Dr María Pérez Tadeo, whose research currently focuses on acoustic monitoring of marine mammals and assessing noise levels at different sites across Europe.
The Strait of Gibraltar connects the Mediterranean Sea and the Atlantic Ocean and lies between southern Spain and north Africa. At the strait’s narrowest point, just 13km separates Spain from Morocco. It is an intensely busy and important shipping lane.
In this busy territory are also many varieties of aquatic life, including resident and migratory marine mammals, including short-beaked common, striped and bottlenose dolphins, long-finned pilot whales, sperm whales, killer whales, fin whales and Cuvier’s beaked whales.
“As cetaceans rely heavily on sound for communication, navigation and prey detection, they are especially vulnerable to anthropogenic ocean noise which can impair their hearing abilities and compromise their survival,” explained Pérez Tadeo.
Sighting of marine mammals, 8 October 25. Image: Lena Lingenfelder
The survey team, which included scientists and students from ATU, the University of Southampton, the Irish Whale and Dolphin Group, the Spanish Oceanographic Institute, consultancy Irwin Carr, and multimedia artist Simone Kessler, collected data by using a towed hydrophone and deploying acoustic devices including SoundTraps and F-PODs to assess underwater noise levels and detect the presence of cetaceans.
They also conducted visual surveys for marine mammals, other megafauna and seabirds, and measured oceanographic parameters such as temperature and salinity at different stations along the route.
Dr Joanne O’Brien, an MTU marine scientist and principal investigator on the STRAITS project, previously spoke to SiliconRepublic.com about the value of bioacoustic monitoring.
“We put a device out and we leave it there and walk away. So, we’re not having any impact on the animals. We’re not disturbing them and we’re not creating sound.
“It’s a really unique way to monitor,” she said, because you can get information about the animals and their environment, even at times when visual monitoring would not be possible, such as at night or during storms.
“It’s a really useful method and it has been shown to be successful across a whole range of species.”
Of the AMIGOS II survey, O’Brien said that “the knowledge the team gains is vital for protecting marine ecosystems while also supporting the sustainable use of our ocean resources”.
The first AMIGOS survey was conducted in October last year. At the time, Pérez Tadeo said that the data collected would provide a baseline of information allowing the researchers to compare noise levels across regions and assess the impact of human-made noise on marine life.
As well as the Strait of Gibraltar, STRAITS, which is led by the Loughs Agency, is monitoring marine animals off the north coast of Ireland, Denmark and Turkey.
Louise Constandt, a MSc student who took part in the survey, said, “Life at sea was incredible.
“It’s amazing to see all the equipment we’ve learned about these past years being used in real life such as watching the CTD, equipment used to collect oceanographic parameters, go into the water and then seeing the data appear on the screen right after and understanding what it means.”
While onboard, Constandt set herself the challenge of identifying different seabirds by their plumage, the way they fly and other details.
“The weather was great, and the sunsets over the Strait of Gibraltar, with dolphins swimming next to the boat felt like a dream,” she said.
The survey was conducted on board the RV Celtic Explorer, with ship time funded by a Marine Institute award.
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