Coral Spawning

Scientists know more complex reef habitats tend to recover faster after disturbances.  But, until now, they didn’t know why.

New findings published in Scientific Reports this week found the improved recovery of complex reef systems is largely due to the fact these structures trap more coral larvae.

“Storms, floods, and coral bleaching damage coral reefs,” Professor Andrew Baird from the ARC Centre of Excellence for Coral Reef Studies at James Cook University said.

“As reefs recover from these events, they depend on free-swimming coral larvae to attach to a hard surface, grow, and replenish the area.”

Why complexity matters

Reefs, coral colonies and crevices create complex underwater structures. When turbulence is generated by these structures, it creates eddies that catch the baby corals.

“Coral larvae can’t swim fast enough to get to suitable settlement sites on their own,” Prof. Baird said.

“They depend on the structures that help shape these eddies, otherwise they are essentially lost at sea.”

More research required on reef recovery

According to the study, there is an urgent need to improve our understanding of the mechanisms underlying different reef recovery scenarios.

This is particularly important in the wake of two back-to-back coral bleaching events earlier this year.

The scientists involved in the study said corals are suffering from repeated environmental disturbances.  They said climate change only compounds the effects of these disturbances.

Dr. Joshua Madin from Macquarie University adds that ‘reef complexity’ can be easily and cheaply gauged by using new technologies that capture 3D structures.  These images could then be added to reef monitoring programs.

How you can help reefs recover

Current management actions to help reefs recover after damage, and protect reef complexity, include:

  • limiting fishing and tourism practices that directly damage corals and the structures around them, and
  • encouraging algae-eating fish to the area to prevent algae from growing and smothering corals.

This article first appeared on James Cook University.

Read the paper, ‘Coral larvae are poor swimmers and require fine-scale reef structure to settle’.



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