What Noise Annoys an Oyster?

Oysters with Acceleratometers
(photo by Jean-Charles Massabuau)

When the ocean noise pollution issue came up on everybody’s sonar, the main concern was about the impact of noise on whales and dolphins – what we in our industry refer to as “charismatic megafauna.” There are a number of reasons for our prioritizing large marine mammals – mostly springing out of the public interest in critters that we find complex and lovable. And face it; WWF would not be half the organization it is today if their logo was a hagfish.

But our amplified care for marine mammals doesn’t mean that nature finds them any more important than animals further down on the trophic tree. Nor does it imply that marine mammals are more subject to the torments of anthropogenic noise than other marine life.

Early on in my excavation of noise impacts on the marine environment I published a “lit review” on “Fish, Mollusks, and other Sea Animals’ use of sound” which opened up this discussion bit. Knowing that the ocean is as much an acoustical environment as the land is a visual one, it is pretty obvious that most animals evolving in seawater for the last billion years probably have some interesting adaptations to sound and sound perception.

We are slowly excavating these adaptations, and increasingly studies are revealing that animals we may not be so compassionate about are sound-sensitive – and thus potentially being damaged by human-generated noise.

A study released this October revealed that oysters will “clam up” when exposed to low frequency tones. This could be problematic inasmuch as oysters feed and respire when open – so oyster health is correlated to how much time they spend with their shells open. Thus exposing them to noise is probably not so good for them.

A paper published in August indicates that seismic airgun surveys physiologically compromise adult scallops, and another paper from a few years back correlates noise exposure with scallop larva deformations. Although this last paper was a “playback” experiment in small tanks, which would not directly replicate field exposures, “it doesn’t take a weatherman to tell you it’s raining.”

These noise studies were focused on economically important invertebrates – scallops and oysters. But a recent study implicates how noise negatively impacts the behavior of invertebrates that don’t end up on our diner plates – a North Sea Langostine and a brittle star. What we are finding when scientists dig into a broader array of marine taxa is that most are subject to negative impacts from noise exposure.

This has pretty far-reaching implications on the health of the ocean – as broad-band human-generated noise reaches further out into what are increasingly more stressed and compromised ocean habitats. And it seems that all we need to do to find out is to look.