Sea floor ‘dying’ along with coral

US GOVERNMENT scientists have found a dramatic impact from the continuing decline of coral reefs: the sea floor around them is eroding and sinking, deepening coastal waters and exposing nearby communities to damaging waves that reefs used to weaken.

The new study, conducted by researchers with the US Geological Survey, examined reefs in Hawaii, the Florida Keys and the US Virgin Islands, finding sea floor drops in all three locations. Near Maui, where the largest changes were observed, the researchers found that the sea floor had lost so much sand that, by volume, it would be the equivalent of 81 Empire State Buildings.

“We knew that coral reefs were degrading, but we didn’t really know how much until we did this study,” said USGS oceanographer Kimberly Yates. “We didn’t really realise until now that they’re degrading enough that it’s actually affecting the rest of the sea floor as well.”

The study, published in the journal Biogeosciences, found that in some places, the sea floor dropped by as much as 4m – particularly striking when considered in the context of today’s rising seas. While the current rate of annual sea level rise is estimated at a little above 3mm, the study calculated sea floor elevation loss rates that were sometimes double that – or even higher in Maui.

The upshot is that natural reef growth in these areas will not be able to keep up with sea level rise – rather, the reefs will fall well behind it and coastal waters will keep growing deeper and deeper.

“This shows that we are not only losing living corals, but also that reefs are being eroded away around the world,” said marine scientist Michael Beck.