Black Reefs–When the Ship Hits the Reef

Enric Sala  –

The first time I dived at the remote Kingman Reef, in 2005, I thought I found paradise. In the middle of the Pacific Ocean, almost 2000 km south of Hawaii, lies a pristine coral reef, covered with colorful corals and a carpet of giant clams with unbelievable electric blues and greens. When I returned in 2007, I thought I had entered the dark land of Mordor.

The healthy corals of the windward side of Kingman Reef, permanently washed by the breaking waves, had died, and the reef shifted into a carpet of dark slime – filamentous algae and microbes. The former crystal clear waters were now murky like a swimming pool after turning off the filtration system. We called it the ‘black reef.’

What was the reason for such a shift – from pristine to degraded? We found the answer right away: the wreck of a teak-hulled fishing vessel filled with iron-rich compressors, engines and unidentifiable machinery. We will never know who the ship belonged to, and what happened to her crew. All we know is that that vessel wasn’t there two years earlier. The ship is a ghost, killing the reef around it little by little.

A scientific study published today at The ISME Journal shows that the shipwreck is releasing iron slowly into the surrounding waters, thus fertilizing the iron-poor waters of Kingman Reef and causing a population explosion of algae, and microbes. The result is the killing of one km of reef in less than three years.

Linda Wegley of San Diego State University (SDSU) and lead author of the study says that ” the black reefs show that a very small amount of some pollutant (in this case iron) can kill a large area of a pristine reef.”

Full story…