I Contain Multitudes: The Microbes Within Us and a Grander View of Life

by Ed Yong

Corals have been building reefs for hundreds of millions of years but their days of underwater architecture may be drawing to a close. Caribbean populations have largely collapsed. Australia’s mighty Great Barrier Reef has lost most of its coral. A full third of reef-building coral species face extinction, imperilled by many threats. The carbon dioxide that humans unleash into the atmosphere warms the oceans by trapping the sun’s heat.

Coral death

They are called black reefs. They are a marine vision of Tolkien’s Mordor, and they happen when a boatload of iron lands in an ecosystem that is generally poor in nutrients. The iron acts as fertiliser for fleshy algae, which grow so vigorously that even grazing fish can’t trim them back fast enough. The algae then trigger Rohwer’s cycle: more DOC, more microbes, more pathogens, more disease, more dead corals.

Boats kill coral

a Grand Unified Theory of Coral Death. It shows how the largest sharks are connected to the smallest viruses.

The rise of Bd is a perfect example. Yes, it is virulent. Yes, it represses the immune systems of amphibians. But it’s still just a fungus, and amphibians have been dealing with fungi for some 370 million years. This isn’t their first rodeo. They are fumbling this particular ride because they have already been weakened by changing climate, introduced predators, and environmental pollutants.

There’s a popular saying among doctors: there’s no such thing as alternative medicine; if it works, it’s just called medicine.