Invasive Algae

Invasive algae or seaweed threatens the health of the corals. Introduced algae can grow rapidly to cover corals and native algae. The loss of biodiversity of algae and coral leads to the loss of fish and invertebrate diversity.

Gorilla ogo (Gracilaria salicornia) was probably accidentally introduced to Hilo Bay in the 1970s by a ship from the Philippines. It was later brought to O‘ahu as an experimental aquaculture crop. Gorilla ogo is edible and very nutritious, like its endemic Hawaiian cousin limu manauea, or ogo (Gracilaria parvispora). The gorilla ogo grows faster than most native algae, and can quickly take over an area, smothering native algae and coral.

Leather mudweed (Aurainvillea amadelpha) is another problematic algae. It was first reported on O‘ahu in the 1980s. It forms dense mats of spoon shaped blades that smother other algae. The tightly grouped blades trap sediments that create a layer of mud around them.

Careful and persistent efforts to control the spread of invasive algae has made progress toward limiting the damage they create. Additionally, it’s important to protect and cultivate native species of algae.

Hawaiians used to have many large fishponds covering many acres, where fish and algae were cultivated. Many of these fishponds have been abandoned, drained, and buried under houses and urban buildings. Some of the remaining fishponds are beginning to be restored and made operational again.

The effects of a functioning fishpond go far beyond its walls. The healthy ecosystem of the fishpond makes the surrounding coast more abundant. A healthy fishpond also requires a healthy freshwater source. People who see the value of fishponds are motivated to do a better job of managing a clean healthy upland aquatic environment.