Economist: HUMANS, being a terrestrial species, are pleased to call their home Earth. A more honest name might be Sea, as more than seven-tenths of the planets surface is covered with salt water. Moreover, this water houses algae, bacteria (known as cyanobacteria) and plants that generate about half the oxygen in the atmosphere. And it also provides seafood--at least 15% of the protein eaten by 60% of the planets human population, an industry worth $218 billion a year. Its well-being is therefore of direct...