For dolphins living along Florida’s Atlantic coast, the ocean is far more than a physical landscape. It is an acoustic environment shaped by whistles, echolocation clicks, fish calls, waves, currents and the increasingly persistent noise of ships. By listening to that underwater soundscape, researchers from Florida Atlantic University’s Harbor Branch Oceanographic Institute have identified distinct acoustic patterns that may reveal where dolphins socialize, hunt and respond to the animals around them. The findings suggest that dolphin habitat is not defined only by depth, temperature or geography, but also by the sounds present in the water.
The study, published in PeerJ, used an autonomous wave glider equipped with an underwater acoustic recorder to monitor the East Florida Shelf for two months. The wave-powered platform traveled through coastal waters while continuously recording sounds, creating a mobile listening station that could operate for much longer than a conventional boat-based survey. In total, the instrument captured nearly 62 hours of underwater sound, and dolphins were detected in more than 1,600 recordings. The researchers then compared dolphin vocalizations with environmental variables such as water depth, temperature, salinity, currents, chlorophyll-a concentration, biological productivity and human-generated noise.
Dolphin sounds provide researchers with a window into behavior that is often impossible to observe directly. Whistles are generally associated with communication and social activity. Individual dolphins can produce distinctive signature whistles that help them maintain contact, while groups may exchange calls as they travel, coordinate behavior or interact. Echolocation operates differently. Dolphins emit rapid sequences of broadband clicks and interpret the returning echoes to determine the location, distance, size and movement of objects. This biological sonar allows them to navigate in darkness and locate prey even when visibility is poor.
The Florida recordings revealed that these two acoustic behaviors were associated with different parts of the coastal environment. Whistle activity was detected more often in nearshore waters and was influenced by location, temperature, overall sound levels and chlorophyll-a concentration. Chlorophyll-a is commonly used as an indicator of microscopic plant productivity in the ocean. Areas with higher productivity can support more complex food webs, potentially affecting where fish gather and where dolphins encounter favorable conditions for social activity. The analysis identified two especially prominent zones of predicted whistle activity near St. Augustine and Ponce Inlet, with additional areas near Melbourne Beach and north of Ponce Inlet.
Echolocation produced a contrasting pattern. Dolphin clicks were concentrated in waters extending from Melbourne to Ponce Inlet and offshore toward Long John Reef. These areas also contained abundant sound-producing fish, raising the possibility that dolphins were using acoustic information generated by their prey while hunting. Many marine fish produce sounds through movements of muscles, bones or swim bladders, and those signals can travel through the water. If dolphins can detect such sounds, they may be able to use them as cues to locate productive feeding areas before prey comes into view. The overlap does not prove that dolphins were deliberately tracking fish sounds, but it provides a compelling direction for future research.
The study also found mismatches between fish acoustic activity and dolphin detections. Such mismatches may indicate that fish reduce or alter their sound production when dolphins are nearby, creating a form of acoustic concealment. In this underwater version of a surveillance game, predators may listen for prey while prey listen for predators. “Everybody is snooping on everybody else,” said Greg O’Corry-Crowe, a research professor at FAU Harbor Branch and a National Geographic Explorer. The observation raises a broader question about marine communication: whether dolphins are eavesdropping on fish and whether fish can recognize the acoustic presence of dolphins well enough to change their behavior.
The timing of detections varied as well. Dolphin activity was higher in March than in April, potentially reflecting seasonal movements of different populations along Florida’s Atlantic coast. The researchers caution that acoustic detections alone cannot identify every species, group size or specific behavior with certainty. Nevertheless, repeated patterns across space and time can reveal where dolphins are likely to spend energy communicating, traveling or searching for prey. Combining acoustic observations with oceanographic data gives scientists a way to estimate habitat use even when animals remain submerged and out of sight.
Human noise complicates this acoustic world. Vessel traffic can mask dolphin whistles, reducing the distance over which calls can be detected by other dolphins. The same masking effect can also make it harder for researchers to identify animals in acoustic recordings. Some areas with high predicted whistle activity overlapped with waters experiencing substantial vessel noise, suggesting that important social habitat may also be exposed to persistent disturbance. When communication becomes less reliable, dolphins may need to call more loudly, repeat signals or change the timing of their interactions, potentially increasing the energetic cost of maintaining contact.
Autonomous platforms such as wave gliders offer a powerful way to investigate these challenges. Unlike short boat-based surveys, which provide snapshots of animal activity, a wave glider can remain at sea for weeks and sample broad areas with relatively limited human intervention. Its recorder effectively extends the researcher’s hearing into an environment that humans cannot directly experience. “The ocean is filled with sounds that humans rarely hear,” said Laurent Chérubin, a research professor at FAU Harbor Branch and the study’s senior author. Continuous monitoring can expose patterns that would otherwise disappear between occasional observations, helping scientists distinguish persistent habitat preferences from brief encounters.
The researchers say that acoustic monitoring could ultimately support marine conservation by identifying dolphin feeding grounds, social areas and regions where human activity creates the greatest risks. The approach may be especially valuable in coastal waters, where dolphins, fish, shipping and recreation overlap within a limited space. By combining dolphin vocalizations with prey sounds and measurements of the physical ocean, scientists can begin to map habitat from the animals’ perspective. Every whistle, click and fish call becomes part of a larger ecological signal—one that could help determine where protection, vessel-management measures or further study are most urgently needed.
Subject of Research: Animals
Article Title: Differential acoustic habitat use in delphinids along the Florida Atlantic coast
News Publication Date: 31-Jul-2026
Web References: Florida Atlantic University Harbor Branch Oceanographic Institute; PeerJ article; https://doi.org/10.7717/peerj.21547
References: Carvalho et al., “Differential acoustic habitat use in delphinids along the Florida Atlantic coast,” PeerJ, DOI: 10.7717/peerj.21547
Image Credits: W. Noke Durden, NOAA Fisheries
Keywords
Dolphins, bioacoustics, echolocation, marine mammals, acoustic habitat, dolphin communication, fish sounds, marine conservation, autonomous wave glider, Florida Atlantic coast, vessel noise, foraging ecology, coastal ecosystems
Tags: autonomous underwater acoustic monitoringDolphin acoustic communicationdolphin social and hunting hotspotseffects of ocean noise pollution on marine lifeFlorida Atlantic University marine researchimpact of ship noise on dolphinslong-term underwater sound recording technologymarine biodiversity monitoring using acoustic datamarine mammal habitat mappingsound-based habitat identificationunderwater echolocation and whistlesunderwater soundscape analysis
