Question about effect of tsunami on marine life

[Nancy]

What is the effect of a tsunami on marine life? Does it greatly disturb costal marine life - what about further out in the ocean?

We hear so much about the effect on people and property along the shore but never about the effect on the shore and its creatures, or on ocean inhabitants.

Nancy

 

[Steve O'Shea]

I don't know Nancy; I think it would be extremely, immediately disruptive (devastating) to coastal/intertidal life, but not-so-much that further offshore (at a guess 30+m depth); subsequent effects will likely include waters laden with earth and debris retreating, dumping tons of sediment at greater depth, smothering everything.

From memory, something I taught earlier on, a thin veneer of sediment 4mm deep deposited on the seabed in a coastal region around Auckland (New Zealand) caused complete annihilation of all infauna over a 7-day period. 4mm isn't a lot of sediment!

It's a tragic state of affairs, what has just happened. We had an 8.1 earthquake south of NZ a couple of days ago, but the tsunami was something like 20cm; to get two major earthquakes of this magnitude so close together is frightening!

 

[tonmo]

I would imagine that along with the giant waves themselves, the massive vibrations from the 9.0 earthquake would have shocked and devastated marine life quite a bit on its own.

One of these articles stated that tsunamis can travel up to 500km per hour. That's got to have quite an effect on currents, etc.!

 

[Snafflehound]

Waves on Coasts

Like ordinary waves, tsunamis have the greatest effects on coastlines. Out in the open ocean one may not even notice when a tsunami wave passes by.

 

[Phil]

I think it would be extremely, immediately disruptive (devastating) to coastal/intertidal life, but not-so-much that further offshore (at a guess 30+m depth); subsequent effects will likely include waters laden with earth and debris retreating, dumping tons of sediment at greater depth, smothering everything.

I would have thought that these conditions are perfect for fossil formation. Rapid deposition of silt and sediment onto the seafloor burying anything carried along with the retreating tidal waters or living at depth makes these conditions ideal. Animal and plant remains can be buried in oxygen-deficient silt at depths where bacteria may not survive and predators are unable to pick at carcasses. I'd imagine that such assemblages would be very jumbled in such strata and very mixed as to the animals and/or plants they contain.

There are extensive examples of these 'Tsunami Beds' recorded from the Gulf of Mexico, in places many metres thick, where the meteorite allegedly impacted 65mya probably causing the death of the dinosaurs. (Though these particular beds are not very fossiliferous).

 

[Colin]

We have work mates in Sri Lanka right now along with friends in Thailand, I hope they are okay.

I imagine that a lot of destruction will happen to coral reefs surrounding these land masses and islands. But this has been going on for millions of years and the animals and plats will be able to bounce back.

 

[tonmo]

We have work mates in Sri Lanka right now along with friends in Thailand, I hope they are okay.

Me too. The loss of human life in this catastrophe is unfathomable.

 

[cthulhu77]

watching cnn last night was horrific...watching people drown...horrible. simply horrible.

 

[atticus_finch]

IMHO, a major mitigating factor in human pursuit of knowledge of inner space (eg. the oceans), as well for outter space (eg. the universe) is our definition of space. IMHO, we are all too ready to assume that space means emptiness; that when matter is not observible empirically to the human eye, it denotes emptiness. IMHO, this is not the case. Both inner- and outter space are full of matter, and forces which move matter. We must desist from this approach if there is any hope of true knowledge. It has always been my view that life within the oceans is more complex and interesting than terrestial life. It holds the key for understanding of life, both inner- and outter.

JMO.. ~a.f.

 

[TPOTH]

*dredging memories from physics lessons*

The impact of a tsunami offshore is likely to be nil, iirc the product of depth and amplitude is a constant (Google could help us here) so above the abyssal plains (or any area 4000+m deep) the tsunami will have only a 1-2 meters amplitude (hence the reason why boats are safer at sea than in the narbour in times of tsunami)... actually you could hardly feel it. No more than a very "long" wave.
When approaching the coast, the depth decreases dramatically and thus the amplitude increases creating huge devastating waves.

I'm wondering if the Indonesian village on stilts i did my MSc project in is still standing The impact of the reef life must be huge as well. However I'm thinking that reefs and marine life as a whole have been around for a looong time so it feels unlikely that the tsunami/earthquake would wipe them out. Along the same line of thought, it's possible that recovery time after those events is extremely long (see bottom trawling impact) and thus in the light of human lifespan, marine ecosystems could be seen as annihlated....

TPOTH