LIHUE — Coral spawning is close at hand, but reef experts are anticipating a slow season for the little critters.
“There’s a decline in coral, therefore a decline in coral spawning,” said Don Heacock, aquatic biologist with Hawaii’s Department of Land and Natural Resources.
On Hawaii, the coral spawning begins in April and winds down in September. It’s the way the little creatures that make up coral reef reproduce. Most coral are hermaphroditic in that they both produce eggs and sperm that meet in the water.
Once the eggs and sperm meet, they form a tiny coral baby that floats through the water, looking for a place to attach.
“It needs hard rock and then it starts growing into coral,” Heacock said.
The trend on Kauai lately, he explained, is that there is more sediment being deposited in the near-shore environments around Kauai and baby corals can’t attach to sand.
Harry Rabin, board director for Reef Guardians Hawaii and documentary filmmaker, said he’s noticed a decline in spawning over the past three or four years.
“It’s not (spawning) nearly as much,” Rabin said. “It’s drastically reduced most definitely.”
While there is a decline in spawning due to the decline in actual coral, Heacock said researchers who monitor reef recruitment in Hanalei Bay for the past decade haven’t seen a change in the level of baby corals that are settling into the bay.
What has changed, Heacock pointed out, is the amount of sea level rise, ocean acidification and coastal erosion on Kauai, as well as the amount of wastewater that’s being discharged into the ocean — wastewater that contains antibiotics and pharmaceuticals that don’t break down during treatment.
“Many of these compounds and pharmaceuticals (in treated wastewater), they stay the same, there’s no significant attenuation of those things,” Heacock said. “That’s a direct discharge of those.”
Discharge into the ocean is a problem for coral because the animals thrive in nutrient-low environments.
“They like a crystal clear environment with no nutrients,” Heacock said. “They’re not adapted to antibiotics and pharmaceuticals in the environment.”
More testing is needed to find out the details of the effects of antibiotics and pharmaceuticals on coral, but Heacock said “it’s certainly not benefiting them, we know that.”
Tom Woods, with Reef Guardians Hawaii, said that’s one of the things the organization hopes to study as it moves forward with its search for funding.