Sorry to troll, but are you guys really engineers?? Surely you understand the concept of a decimal point? Yes coral reefs have been around for 1000's years, but CO2 normally fluctuates over a period of millions of years.

It's like when you try to measure a signal on an oscilloscope and instead of the nice sine or square wave you were expecting you get a flat line and you think there must be something wrong - then you you crank the sample rate knob over to the right and try again -lo and behold, your sine wave appears. We are all living in the trough of a sine wave :-)

Some thoughts:
I'm no shark expert, but I do happen to know that gray nurse sharks look pretty scary, but are actually quite harmless, while great whites, well... I suspect these sharks were the former.

Also I strongly suspect there was something seriously wrong with the shark in the vid. Don't sharks need to keep moving to breath? Just perhaps that individual had a parasite in its head that had eaten most if its brain away!