The ocean is salty.

And dumping manure on a field can prevent growth, if you do too much.

So I would think some degree of dilution would be a good idea before dumping it in the ocean.

even if you "scorch" a field with too much manure one year, that field is going to come back with a vengeance at some point. There are all sorts of natural disasters that scar the forest (like fire), but it is a renewing process