Wow a lot is going on in Fishman island.
1. The undersea blockade maintained jointly by the NFP's kraken and Vander Decken's umibozou has now been lifted thanks to Luffy ramming through, allowing for pirates to once again pass through FI. Shyar mentioned how no pirates had visited the island recently and how business was picking up again. This is evidence that the NFP and Vander Decken are allied, an considering how these actions would align with WG interests makes me suspicious of foreign intervention.
2. Fishman island shows a disturbing degree of "humanization" in how consciously the wealthy class try to mimic dry land human culture. Mermaids are the fastest and most agile of sea creatures and to see mermaids virtually wheelchair bound because all of the rich districts are above water demeans them. It's like the entire area from the docks though the candy factory and on to gyoverly hills are designed for the convenience of human visitors and not fishmen. That shows a real lack of racial pride among the fishmen elite. No wonder obesity seems so common for fishmen and older mermaids in that area: they never swim.
3. The "god" neptune and his sons seem like total jokes. If they wanted to stop being attacked by humans, all they would have to do is flood most of the bubble. Pirates don't breathe underwater and their DF powers are nullified. That kind of reformation would allow them to defend themselves and not rely on kaidou protection.
4. If luffy is considered a threat to the continued existence of FI, then it will be Big Mama's obligation as the protector of FI to confront him. She'll show up with her crew during this arc to attack Luffy. I have trouble telling if the object on her crest is a tree, a torch, or cotton candy though.
5. Shyar's foretelling occurred when she was looking into Luffy's future. So, he's unequivocally the guilty party while Vander Decken is merely a red herring. It's far too early to consider his motivations or rationale for such destruction, however the depiction of the damage inside the bubble brings to mind the effect of Shanks' royal haki on whitebeard's ship.
6. Hyouzou's a cool character. There are a couple of interesting notes about the Blue Ringed octopus that might be relevant: They can change color at will, they are among the most poisonous species in the world, and their poison is produced in special saliva glands. This means that Hyouzou poisoned luffy by spitting, biting, or with that toothpick he's always chewing on. That's pretty impressive work while he defended himself with that driftwood scabbard blade. http://en.wikipedia.org/wiki/Blue-ringed_octopus