Earthquakes and ecology: What might these earth-shaking events mean for aquatic organisms?

After the startling article in The New Yorker about how a large earthquake would devastate the Pacific Northwest, it is worth reflecting on how our aquatic friends might fare.  There is some evidence that animals can predict an earthquake, which may be an evolved behaviour.  Dogs barking is one commonly cited response, but other changes may precede an earthquake.  For example, toads in Italy stopped spawning five days before an earthquake and only resumed several days after the shock.  There is also evidence of changes in the physiology and behaviour of animals following earthquakes.  For instance, mice that experienced the Great East Japan earthquake in 2011 responded with longer swimming distances and faster swim times.

Common toads changed their reproductive behaviour five days before an earthquake.

Common toads changed their reproductive behaviour five days before an earthquake.

These internal responses are fascinating, but what about the significant physical and chemical disturbances that accompany the earthquake?  Returning to the Japanese earthquake and tsunami of 2011, researchers found that macroinvertebrate communities in tsunami-inundated rivers were devastated: >90% reductions in abundance and loss of over half of the diversity.  Recovery of these communities was slow, even 16 months after the event – though species that were strong swimmers did show better recovery than other species.  Similarly, the diversity of marine invertebrates in the intertidal region was significantly reduced (30-80%, depending on which group), and again, more mobile species fared better than their less mobile peers.  Both studies observed new species that were transported by the tsunami.  Indeed, marine species from Japan are still turning up on the Pacific coast of North America, more than four years after the earthquake and tsunami.

Marine debris found at Lakewood, OR.  Photo courtesy of NOAA's Marine Debris Blog.

Marine debris found at Lakewood, OR. Photo courtesy of NOAA’s Marine Debris Blog.

Though concern for human safety is of utmost concern, understanding how organisms deal with earthquakes and tsunamis is important to determining how ecosystem recovery may proceed, making us all a little more prepared for what the future may hold.

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