Q: If lightning strikes the ocean, do the marine animals get hurt or killed? (Sault Ste. Marie, Minn.
Honestly, I have never given this question any thought. Given that I am a biologist and not a physicist means I may not even be the best to answer it. The first question is obviously how often lightning strikes the ocean?
The map below assembled by a crack team of NASA scientists shows the number of flashes per km2 per year. You can see that most of the worlds oceans are at less than 2 strikes per year (light blue). Areas near the coast receive more but typically still less than 10 per year. However the Gulf of Mexico especially near the Gulf Coast of the US and Florida appears to be quite a hotspot.
What happens to the charge once the lightning makes contact with water? According to Don MacGorman, a physicist at the National Severe Storms Laboratory in Norman, Oklahoma.
“Basically lightning stays more on the surface of the water rather than penetrating it. That’s because water is a reasonably good conductor, and a good conductor keeps most of the current on the surface.”
So if I understand this correctly the surface is acting bit like the Gaussian surface of a Faraday cage. How far this charge carries across the surface likely depends on surface topography of the water, total power of the lightning, temperature, salinity, etc. Thus to the original question: what about the animals? If of course this is all true, and I know someone is out there waiting to pounce on this, then unless an organism breaks the surface it will not get electrocuted.
But what about the sound wave? A lightning strike at the surface generates up to 260 decibels at 1m away. That is about twice the decibels of a gun shot or firecracker. There is some evidence (Hasting and Popper 2004) that suggest hearing loss can occur in cod at 180 dB, with some other species closer to 220 dB. How many dB’s does it take to rupture a swim bladder or interfere with other organs?
Ultimately I am hoping some of the readers will chime in and provide a more solid answer.