Coral reefs are under increasing threat by human development, pollution and rising ocean temperatures.

It was assumed that isolated reefs were most vulnerable, because following damage, recovery involves migration of species from nearby reefs to recolonise and rebuild them.

For isolated reefs, this would be slower or not occur at all.

Here they studied the recovery of the isolated Scott reefs off Western Australia, which were badly bleached by hot weather in 1998.

They found that the reef system had rapidly recovered within 12 years.

It might have been even more pronounced if it wasn’t for 2 cyclones, a disease outbreak and another bleaching.

This suggests that isolation is not a disadvantage for coral reefs.

In fact, they benefit from being a long way from their most serious threat – humans.

 

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Background

Coral reefs are under increasing threat by human development, pollution and rising ocean temperatures.

What is the best way to protect them?

It was assumed that isolated reefs were most vulnerable, because following damage (e.g. cyclone), recovery involves migration of species from nearby reefs to recolonise and rebuild them. For isolated reefs, this would be slower or not occur at all.

Here they investigated this question using a damaged coral reef off the coast of WA.

Materials and Methods

The Scott system of reefs is 250 km off the coast of WA in the Indian Ocean. It is also 250 km away from the nearest reef and 1000 km from the nearest large city. There is very little fishing or other human pressures. Extreme water temperatures caused bleaching in 1998, killing up to 90% of the corals. Recovery of the reef was monitored over the next 12 years.

Results

Following bleaching damage to the reef in 1998, there was a surprisingly rapid recovery.

Within 12 years, the coral cover increased from 9% to 44%.

This was not due to migration of corals from other reefs (too isolated). Rather, the recovery was driven by the growth of remnant corals that survived the bleaching.

The recovery might have been even more pronounced if it wasn’t for 2 cyclones, a disease outbreak and a second bleaching within the 12-year recovery period.

Discussion

Isolation was not a disadvantage for coral reefs.

This is good news for coral protection, since following damage they can quickly recover (at least quicker than previously thought).

In fact, the isolation seems to be an advantage, since they are further away from interference, especially from humans.

Article

Recovery of an isolated coral reef system following severe disturbance

Gilmour et al., 2013 Science 340:69-71

Keywords

Ecosystem, ecology, biodiversity, coral, reef, ocean, Australia, bleaching, recovery

Subject

Science, geography, biology, ST1-10LW, ACSSU030, ST1-11LW, ACSSU211, ST2-8ES, ACSSU075, ST2-11LW, ACSSU073, ST3-11LW, ACSSU094, SC4-13ES, ACSSU222, SC4-15LW, ACSSU112, SC5-13ES, ACSSU189, SC5-14LW, ACSSU176