Moving the Waters - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 107

The water within it is chilly. Humboldt, on his travels, himself had
measured it to be a full 7 degrees Celsius colder than water that was
farther offshore. Did it, he thought, therefore come from the south?
Indeed it does, and the cold water sucks moisture out of the air—
much as a cold windowpane does—to produce frequent mists and
fogs. As far as water goes, therefore, it receives rather than gives.
Hence, the adjoining coast is one of the driest on the planet, where the
Atacama Desert adjoins the sea.
The wind there blows offshore. It helps, thus, to combine the life-
giving sunlight in the surface waters with the nutrients stored in the
ocean below the thermocline, at depth. The wind pulls the surface
water away from the coastline, and deep, nutrient-rich water wells up
to replace it. This triggers an explosion of planktonic algae, fed upon
voraciously by swarming zooplankton, in turn devoured by fish. Four
species, in particular, run amok: anchovy, sardine, jack mackerel, and
chub pollock. Just in that small space—less than 1 per cent of the
world's ocean surface—they can make up to one-fifth of the world's
total fish catch.
These extraordinary fish populations have been a source of food
long before humans arrived on the scene. Larger fish and dolphins
joined in the feast, and so did seabirds—so prodigiously that the
excrement from their feasting could pile more than 20 metres thick
on the coast and adjacent islands. It was the perceptive Humboldt,
too, who recognized the significance of these guano deposits, and his
writings sparked off a large industry in the nineteenth century, ship-
ping this nitrogen- and phosphorus-charged stuff to the fertilizer-
starved farmers of Europe. Humboldt, a humanist to the core, would
have wept to see some of the human consequences of this industry,
which fed booming European populations with the oceans' bounty. It
was vile, arduous work to dig out the stinking guano (that had com-
pacted to rock-like consistency) in the infernal desert heat. The