Have you ever wondered how the subtle hums and rumbles beneath the ocean’s surface—sounds we humans might find calming or stressful—affect the creatures that call it home? From the rhythmic crash of waves to the mechanical drone of ships and wind turbines, low-frequency sounds (0.05–50 Hz) and infrasound play a crucial role in marine ecosystems. Building on our discussions about human perceptions, let’s dive into the scientific studies exploring these effects on tuna, marine mammals, and other species. Drawing from lab experiments, field observations, and reviews, we’ll uncover behavioral disruptions, physiological stress, and potential long-term consequences. This isn’t just academic—it’s vital for conservation in an increasingly noisy ocean.

Studies on Tuna: Disrupted Schooling and Migration

Tuna, like bluefin (Thunnus thynnus) and yellowfin (Thunnus albacares), are highly migratory predators sensitive to low-frequency cues for navigation and communication. Research shows they produce and detect sounds in the 20–130 Hz range, often linked to swim bladder contractions or ”coughing” behaviors. But anthropogenic noise from boats, offshore wind farms, and seismic surveys can interfere.

A 2021 study monitored caged bluefin tuna exposed to ship and wind turbine noises (30 Hz–10 kHz, peaks at 50 Hz, levels 120–182 dB re 1 μPa). Over 10–15 minute exposures, tuna exhibited abrupt dives, school contractions (vertical span reduced by ~30%), faster swimming, and disorientation at higher intensities (>150 dB). Longer sessions delayed reactions but caused persistent shallower positioning, with habituation noted after repeats—suggesting adaptation in captivity but potential migration risks in the wild.

Earlier field work in 2007 observed bluefin tuna in Mediterranean traps reacting to boat noise (70–6000 Hz, up to 135 dB at 200–400 m). Schools showed increased vertical movements, direction changes, and dispersion, disrupting homing and foraging. No long-term physiological damage was found, but chronic exposure could elevate stress, mirroring broader fish responses like behavioral changes and hearing loss.

These findings highlight tuna’s vulnerability, with implications for fisheries: noise could reduce catch rates by 50–90% in affected areas.

Studies on Marine Mammals: From Stress to Strandings

Marine mammals, including whales, dolphins, and seals, rely on low-frequency sounds for communication, echolocation, and sensing their environment. Baleen whales are particularly attuned to infrasound (down to 7–30 Hz), making them susceptible to shipping, sonar, and seismic noise.

A 1994 NRC review synthesized effects from low-frequency sources (12–300 Hz, 115–170 dB), noting avoidance in 50% of baleen whales at >120 dB—gray whales altered paths, bowheads displaced 10–30 km from drillships, and vocalizations decreased. Potential masking of calls and temporary hearing shifts (TTS) were inferred, with chronic stress linked to elevated glucocorticoids.

Updated 2019 guidelines set TTS thresholds at 168–183 dB SEL for low-frequency cetaceans, with behavioral changes like strandings from sonar exposures (minutes-long, mid/low-freq). Ship noise causes vocal modifications, respiration changes, and habitat abandonment, with knowledge gaps in long-term population impacts. High-level tones (>1 hour) can damage sensory cells, leading to hearing loss.

Overall, effects include anxiety, panic, and ecosystem disruptions, with calls for better mitigation like quieter vessels.

Effects on Other Marine Species: From Fish to Plankton

Beyond tuna and mammals, low-frequency noise impacts diverse species, often through vibrations detected by lateral lines, statocysts, or shells.

For other fish like cod and herring, seismic air guns (<100 Hz, 160–255 dB) cause fleeing, hemorrhaging, and 50–90% catch drops, with cortisol spikes and barotrauma. Sharks avoid boat noise (10–500 Hz), showing reduced prey capture.

Crustaceans (crabs, lobsters) exhibit tail-flips and elevated heart rates from impulses (<100 Hz, 180–210 dB), with chronic shipping noise (hours-days) increasing oxygen use and mortality risk. Mollusks like squid suffer statocyst damage from seismic sounds, leading to erratic behavior and metabolic shifts. Bivalves close valves and reduce filtration under pile-driving (1–100 Hz).

Plankton and larvae face migration alterations and 20–50% mortality from pulses (<50 Hz), potentially cascading through food webs.

Wrapping Up: A Call for Quieter Oceans

These studies reveal a noisy underwater world where low-frequency sounds can stress, injure, or displace marine life, from tuna’s disrupted migrations to plankton’s foundational impacts. While natural sounds like waves may harmonize, man-made noise demands action—think reduced vessel speeds or acoustic barriers. More research is needed on cumulative effects, but one thing’s clear: protecting these species safeguards our oceans. What do you think—should we prioritize quieter tech? Share below!

Sources: Compiled from recent reviews and experiments as of 2025.