Tuesday, June 15, 2010

Eyeing coral spawn

This week, corals are spawning all over Hawai'i, but where do those drifting coral larvae go?

This year, someone is watching.

(Image: This digital photo shows the release of larvae from reef-building corals off Maui. Credit: John Gorman, 2003, Maui Ocean Center.)

Corals spawn very predictably, and the rice corals (genus Montipora) are doing their thing during the second week of June.

This year, as the eggs and larvae are released into the water column, satellite tracking devices will accompany them on their travels.

The idea is to help find out why some reefs are growing well and some not. It may have to do with how well or how predictably new coral larvae settle back on those reefs, to replace old, dying corals.

The satellite tracking effort is a joint project of the U.S. Geological Survey, the University of Hawai'i Kewalo Marine Laboratory and the conservation group Malama Maunalua. They will release satellite drifters that presumably will drift along the same ocean routes that the coral larvae do.

One question: when corals spawn on south O'ahu's Maunalua Bay, do they stay in Maunalua Bay or do they drift away to populate other reefs?

“Once scientists understand the circulation, larval dispersal patterns, and 'connectivity' between reefs, managers can identify where recovery efforts should be focused,” said a news release from the University of Hawai'i.

The drifters are orange, about 8 inches in diameter, and there are also yellow floats that mark the location of instrument clusters. If you're swimming in the bay during the next few days, watch for and avoid them.

For more RaisingIslands posts on corals, see here.

© Jan TenBruggencate 2010

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