It’s one thing for consumers to know intellectually that our gas-guzzling, polluting ways are taking their toll on the planet. It’s another thing to connect all the dots in terms of actions and consequences. Yet, even as we continue to drive SUVs and convert wilderness areas into housing developments, we hold out hope that the environment will rebound.
Unfortunately, for coral reefs, it’s going to take a lot more than hope, says Todd LaJeunesse , assistant professor of biology at Penn State.
Coral reefs are suffering from overfishing and other types of resource exploitation, LaJeunesse explains. In addition, they are being degraded by pollution from sewage and agricultural runoff, and by increasing sea-surface temperatures and acidification as a result of global warming.
"Coral reefs are important not only for the beauty they provide to snorkeling tourists, but for the ecosystem services they provide to us all," says LaJeunesse. "They protect coastal areas by buffering the effects of hurricanes; they serve as habitat for food fish and other edible animals; and they are sources of medicines."
According to the National Oceanic and Atmospheric Administration , reef-supported tourism alone generates an estimated $30 billion annually, with additional environmental and economic benefits valued at ten times that amount.
LaJeunesse’s own research focuses on the relationship between corals -- which are animals -- and the symbiotic algae, known as zooxanthellae, that live inside their cells. The photosynthetic algae provide food and energy to the corals, while the corals, in turn, provide a safe home for the algae.
"Heat disrupts the association between corals and their symbionts," explains LaJeunesse, "and this causes the algae to be expelled from the corals, leaving behind a dead, bleached skeleton."
Because of the barrage of human-induced pressures on corals, most places in the world have seen significant declines in coral cover over the last couple of decades, he adds. "Our own Florida Keys has been among the hardest hit. The area used to be covered with corals of all shapes, sizes, and colors; now there is just a whole lot of dead coral."
Many of the reefs in the Caribbean Ocean have taken a turn for the worse, adds LaJeunesse. "Elsewhere on the planet, they seem to be doing a little better -- in the Indo-Pacific, for example -- but scientists think those reefs are just a couple decades behind the Caribbean in their decline."