The Extreme Life of the Sea by Palumbi Stephen R. Palumbi Anthony R

Author:Palumbi, Stephen R., Palumbi, Anthony R. [R. Palumbi, Stephen and R. Palumbi, Anthony]
Language: eng
Format: epub, mobi
Publisher: Princeton University Press
Published: 2014-04-09T16:00:00+00:00

Corals, warmth, and death

Picture a secluded stretch of Samoan coast. Classic palm trees break up the sandy beach’s blinding white, and behind them loom craggy volcanic hills. Warm, placid lagoon water laps at your ankles. A few hundred yards out in the water, tall rollers sputter their lives out in torrents of white foam. The submerged barriers sapping their strength can be seen from the beach: dark, amorphous forms. It’s a coral reef, built over millennia into massive offshore walls. Coral polyps—tiny flower-like animals that clone themselves to form the living tissue of a coral—spread with an industrious passion unrivaled in the sea, every day secreting thin undercoats of enduring limestone.20

Over countless years, those microscopic films pile up into structures capable of feeding and sheltering thousands of other species. And even when the coral animals are dead and gone, the built-up limestone remains. The hard coral head cast up on a tropical beach is made of this limestone. Australia’s Great Barrier Reef, one of the world’s most spectacular natural wonders, is made of this limestone. Millions of years in the making, it is the only natural biological structure visible from space. The end result of industrious coral construction is the closest thing to a structured city you’ll see beneath the waves.

Live reefs are magnificent to behold. Stunning blues and yellows and pinks and greens flash across the reef: fish, urchins, shrimp, and snails with a huge variety of body shapes and lifestyles. Worms huddle in their secret tubes, poking feathery heads out to troll the currents. Spires and walls of corals gradually rise from the ocean floor until the city hosts millions of creatures.21 Even the white-sand beaches on tropical shores are mostly coral, ground to flecks over years by relentless waves and gnawing fish.

But for all their towering accomplishments, corals are disturbingly fragile. A temporary rise in temperature of only a few degrees can set off a major mortality event, wiping out whole swaths of polyps. Large cyclic heat waves in the Pacific, called El Niño weather, can devastate them. In 1998, this phenomenon killed up to 90% of the live polyps on some reefs.22 In the past century, global warming from atmospheric carbon build-up has raised water temperature over a degree (Fahrenheit) in the tropics. That doesn’t sound like much, but it spells trouble for such sensitive and foundational animals.

Corals feed themselves mostly by farming photosynthetic single-celled algae named Symbiodinium. Living inside the coral polyps’ own body cells, they need plenty of sunlight and warm water to be productive. Thus, corals must live close to the surface in waters clear of cloudy sediment. These conditions are rarely found far from the equator, so that is where the overwhelming balance of corals live.23 There is in fact a set distance from the equator—named to honor Charles Darwin’s studies of coral reefs—beyond which corals can no longer build substantial reefs. The Darwin Point is located at about the latitude of Midway Atoll in the North Pacific, and just south of the Cook Islands in the South Pacific.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.