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Coral Spawning in Hawaii

by Mary Hagedorn on May 2nd, 2008   Comments [0]

Spring is here in Hawaii and the water is getting warmer. It is about 75°F (24 °C) in Kaneohe Bay now. One of the first corals to spawn in the Bay is the Cauliflower Coral, Pocillopora meandrina (Fig. 1).

Fig. 1: The pink coral in the center is Pocillopora meandrina,
the Cauliflower Coral.

In Hawaii, this coral spawns in the early morning during April and May on or shortly after the full moon. Amy Apprill, Ginnie Carter, Clarke Hagedorn and I combined efforts to collect egg/sperm bundles to produce larvae (Fig. 2 and 3).

Fig. 2: Ginnie Carter and Clarke Hagedorn watch as Amy
Apprill collects eggs and sperm from the spawning
P. meandrina early in the morning.


Fig. 3: The tube on the left has nothing in it to contrast with
the tube on the right that has suspended brownish eggs
and sperm. Some eggs have settled on the bottom of the
right tube.

One of the main things we examine when first working with a new coral species is how to optimally rear the larvae, so that we can have large number of larvae to work on. Since we had never reared this coral, we wanted to observe how the coral behaved and how it swam. We have developed a number of rearing chambers for coral larvae. One in particular we thought would work well for this species, was a 75-liter conical chamber (Fig. 4).

Because P. meandrina is a slow-swimming larvae that tends to hover near the bottom, most of the larvae died in this chamber. Our larval rearing chamber has jets (Fig. 4, see dye injection) towards the bottom that move the water and larvae up from the bottom. This works fairly well for larvae, such as Fungia scutaria, that are neutrally buoyant and active swimmers. We are designing a different rearing chamber for P. meandrina for next month’s spawn.



Fig. 4: Coral larval rearing chamber shows
movement of pink dye, moving larvae in
an upwards-motion through the seawater.

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