Too much sand in water leads to dead coralsOctober 9th, 2008 - 12:10 pm ICT by IANS
Sydney, Oct 9 (IANS) Startling evidence has emerged from new research to show that when fishes get a mouthful of sand, the days of coral reefs are numbered. “We’ve known for a while that having a lot of sediment in the water is bad for corals and can smother them,” said David Bellwood, professor at the ARC Centre of Excellence for Coral Reef Studies (CoECRS) and James Cook University.
The killer blow for a degraded coral reef is a thick mat of sand and weeds that shrouds the rocky surfaces on which the corals would normally grow, preventing them from re-establishing. This gritty algal ‘turf’ has shown itself to be remarkably hardy and, once in place, makes it almost impossible for the corals to return.
If sea levels rise, then the smothered reef ‘drowns’ and never recovers, Bellwood said. “We know this from geological history, at the time of previous sea level rises. The reason we are doing the work is to see whether or not coral reefs will be able to keep up with rising sea levels under climate change.”
But Bellwood and colleague Chris Fulton from the Australian National University have also uncovered a remarkable link in the chain which explains why the algal turf can win in its ‘turf war’ with the corals, according to an ARC press release.
When the water is thick with sediment and it settles on the seaweeds, herbivorous reef fish turn up their noses at the gritty food, much as humans disdain a sandwich that has been dropped on a sandy beach.
“Remarkably we found that when there is little sediment around and plenty of fish, the fish ‘mowed’ the weeds very fast, eating two thirds of their length in about four hours. This action by fish in keeping the algal turf down gives the corals a chance to re-establish” said Fulton.
“But if there is a lot of sediment in the water, the fish go off their feed, the weeds grow, more sand settles - and the murky shroud that smothers the reef becomes more stable, often permanent. Then, when sea levels rise, the reef drowns.”
- Excess sediment in waters bad for coral health - Oct 09, 2008
- Parrotfish play vital role in preserving coral reefs - Dec 12, 2011
- Weed-eating fish key to reef's survival - Mar 11, 2011
- Fish learn to cope with high CO2 in oceans - Jul 03, 2012
- Weed-eating fish 'vital to coral reefs' survival' - Mar 11, 2011
- Could corals survive more acidic oceans? - Apr 02, 2012
- Humans increasingly poisoned by reef fish - Sep 11, 2012
- More warm, acidic oceans will require greater reef care - Feb 15, 2011
- Seaweed released chemicals stunting coral growth - Sep 02, 2008
- CO2 threatens fish's very survival in oceans - Jan 16, 2012
- Tropical fish adapt to rising sea temperatures - Dec 06, 2011
- Overgrown algae smothering coral reef - Sep 20, 2012
- Seaweeds fast endangering coral reefs - Jan 07, 2010
- Sea cucumbers could protect endangered corals - Feb 01, 2012
- Oz scientist discovers world's rarest coral in Pacific - Jul 30, 2010