Japan attempts to restore coral reef by raising Acropora from spawn

by Owen James

The Hindu, one of India’s national newspapers, has a cracking article on restoring coral reefs through transplantation.

Of particular interest is the bit on Dr. Makoto Omori and his researchers at the Akajima Marine Science laboratory in Japan, who’ve raised Acropora from the egg-and-spawn stage:

Mass spawning of Acropora corals occurs around the full moon on early summer nights. Bundles of eggs and sperm are released together at night. Fertilization between different colonies takes place immediately below the sea surface soon after. Countless fertilized and unfertilized eggs aggregate and drift in the form of a slick the morning after spawning. The eggs and embryos are then collected from for mass coral culture. Alternatively, the bundles are collected by net underwater and fertilization immediately induced in the laboratory after spawning.

Five to six days after fertilization, the planulae swim down to the bottom to look for suitable places to settle. Searching for places to attach, planulae follow special chemical signals emitted by certain bacteria and crustose coralline algae on substratum. The larvae are induced to settle onto ceramic tiles that are placed on the seabed more than one month beforehand to grow algae and bacterial films on their surfaces. On the tile, each planula metamorphoses into a polyp (juvenile coral). These polyps multiply by producing clones to form a colony. The juvenile corals are then cultured in cages held by floating frames and suspended at 1.5 to 3 m depth into the sea. Though many planulae settle on the upper surface of a tile in the sea, sediments or algae overgrowth can easily discourage coral development. Tiles were hence vertically placed in the cage.

At this stage, the algae-eating juvenile top-shell snail, Trochus niloticus is introduced at the rate of 100 snails per cage Although only one to two percent of juvenile colonies generally survive, the yielding of a maximum of 10 colonies out of 700 polyps on a tile proved sufficient in this case.

Exciting stuff. Two things spring to mind:

  1. Why don’t we get articles like this in The Sunday Times? It beats celebrity gossip and whining about how rubbish Britain is.
  2. Why doesn’t someone start doing this with expensive corals like trachyphilia? Reports like this one from a coral wholesaler in Vietnam scare and depress me. There simply isn’t enough colourful LPS coral out there for everyone in Indonesia to take up reefkeeping with the carelessness we in the West have for years (and with their coral, for that matter).

Read the Ultimate Secrets To Saltwater Fish And Invertebrates.

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