Okay, I will make a little premise/context to give the question a decent background. I know that the scenario could look rather "handwavy", but take it as the framework on which the answer should be given (I will elaborate more on the causes, but this is not necessary inside this post).
Oceans and seas have become higly corrosive. This seems to affect almost every metal, plastic, organic and biological compounds but seems to arbitrarily spare some minerals and hydrocarbons to certain degrees (i.e. no dissolution of the oceanic floor), nothing - however - that could be shaped effectively for practical uses. As a result, 99% of the sea life died and boat travels are no more feasible due to the short duration of the hulls. For unknown reasons, fresh water is not affected, nor it is rain (lakes, rivers, glaciers "work" as usual).
So, how would this affect our world? I have thought of several things:
- The complete lack of fish / sea food would cause problems for all those regions which consistently live on fish (see list of most important fish-exporting countries and this page which pretty sums up a FAO report).
- Travels between continents would only be feasible by airplane; also, all the goods which are usually transported by cargo ships would have to be moved by airplane - or not to be moved at all, since if we consider only Europe and only short range transportations, we are talking about more than 1.5 billion tonnes of stuff.
- Submarine cables would be destroyed, cutting most of communications (see this map just to have an idea -> the only alternative would be satellite communications or radio waves.
- Oil extraction platforms would collapse and couldn't be used anymore, thus reducing oil extraction by approximately 30% and force the use of other resources or extraction sites.
- People from small islands without or with only one airport per several islands (e.g. Fær Øer islands) should be evacuated, since they would not be able to get by in any other way.
- Sea/oceanic water couldn't be used anymore as a coolant for thermal power plants.
- Economic crisis for most sea/ocean turistic places.
- Seaside cities would be mostly abandoned or "moved back" to the inland.
- Sea birds would either die of starvation or massively change their diet / habitat.
- Last but not the least, oxygen production would drop due to the disappearance of almost all phytoplankton (50 to 85% of the total oxygen produced by our own world). Since this would be pretty world-ending, either assume that the population of phytoplankton decreases enough to cause "massive human casualties" but not enough to completely wipe out the world population (yes, this is contrast with the opening, but a "everyone dies" answer is not exactly constructive - so let's handwave it a bit more :P) or that we have some other ways of supplying a decent quantity of oxygen to the atmosphere - which one you prefer.
Quite a bunch of stuff, huh? But I still feel like I am missing something. So, now the question:
Aside from the points listed, what would be the major effects of the described scenario on a contemporary/near-future-like world?
If the question is too broad, I will try to stretch it to the bones :D
N. B. This is not a question on the feasibility of the scenario, this is a question on the consequences of such scenario ;)
EDIT: since it looks like my last bullet point would have killed everyone on the planet just by itself, I have edited it ^_^