OUr Aquatic Projects

Invasive Octocoral

There are two (2) species of invasive octocorals in Pearl Harbor. Unomiastolonifera (also known as pulse coral) and Capnellaspicata(also known as Kenya green tree coral) are present in the Bishop Point area. Colonies of Unomiastoloniferahave also been identified at Lima Landing and KapilinaMarina. These are both popular aquarium species native to the Indo-Pacific and have not been observed elsewhere in Hawaii.

What are octocorals?

Octocoralsare a fast-growing type of soft coral. Octocorals are related to stony corals but lack a hard skeleton and so they do not contribute to reef building. They are colonial and are made up of polyps. They can reproduce by spawning but can also spread through fragmentation. Fragmentation occurs when a piece of the polyp breaks off, settles elsewhere, and begins to grow. Reproduction through fragmentation means these species can spread very quickly.

Why are these invasive?
These species are considered invasive because they are not native to Hawaii and may have catastrophic impacts on Hawaii’s coral reef ecosystems. These two species have been observed attaching to and growing on hard substrates, including stony corals. Because they can reproduce quickly and do not have natural predators in Hawaii they can quickly grow and smother Hawaiian coral reefs.

What effects can they have on local species?
These octocorals can grow over and smother hard corals and seagrass. In Venezuela, invasive Unomiastoloniferais now covering 1.2 million square miles of what used to be coral reef. In areas where octocorals dominates that marine habitat, there are a lower density and diversity of fish.

How and when did they get to Pearl Harbor?
These species are popular in home aquaria because of their heartiness and charismatic appearance. They are not typical vessel biofouling species. It is most likely that these species were initially introduced into Pearl Harbor by an unauthorized aquarium dump near the Hickam Fishing Pier.
They were first discovered during marine surveys in late 2020. These surveys were not focused on these octocorals but did make note of them and estimated the area in which they were observed. Recent surveys have documented these species in a much larger area and indicate they were most likely present prior to 2019.