Hungry Algae Eating Tiny Sea Urchins Could Save Hawaiian Reefs

Sea Urchins are small creatures with long spines – sort of like porcupines – and what’s really remarkable about them is that eat anything that happens to float by.

They have really sharp teeth that they use to scrape algae off of rocks and reefs. And that makes them pretty valuable especially in places like Hawaii where invasive algae species are threatening the coral reefs. In the summer of 2019, 500,000 of them were released to gobble-up the algae.

The issue started when non-native algae were introduced to the ecosystem of Kāneʻohe Bay, on the east side of Oʻahu in the 1970s and like other invasive species, and because it had no predators, it ended up taking over the bay according to the National Marine Fisheries Service (NOAA).

The algae smothered the coral and blocked sunlight from reaching them and that in turn affected the local fish because they changed the chemistry of the water. Solutions were found that included using a large vacuum that was called the “super sucker” to suck up the algae but it wasn’t enough.

That’s when the NOAA  turned to sea urchins that loved to devour the algae. But there weren’t enough of them and they had to grow to the size of a cherry tomato before they could be released.

Beginning in 2011, the NOAA and some partners have been growing and releasing sea urchins to eat the algae. Some of the funds are available due to an unfortunate incident. In 2005, the M/V Cape Flattey was grounded on a shallow reef off of Barbers Point in Oʻahu.

When the ship was removed, it was found to have damaged 20 acres of reef.  When there is environmental damage, the NOAA and other agencies that are called trustees, receive funds from the wrongdoers and the funds are used to restore the damage.

Some of the funds were used to do some emergency work at the accident location but the rest was used on other projects like the sea urchins. The state of Hawaii remodeled space in an unused hatchery to grow the urchins. When they are large enough, divers carefully place the prickly creatures on the reef and let nature take its course.

Algae isn’t the only thing that threaten the coral reefs. Climate change and the effects of fishing and tourism in the area also endanger the coral reefs. But letting nature take care of nature instead of man-made solutions seems like the best way to go. Who knew that hungry tiny sea urchins could do so much good?