Learn & Explore/Species/Introduced & Invasive/Gorilla Ogo

Gorilla Ogo

Category: Invasive

A brittle invasive seaweed that forms dense mats, covering reefs and crowding out native algae and marine life.

Gorilla Ogo (Gracilaria salicornia) ​

  • Small, solid, brittle, cylindrical to compressed, irregular branches with segmentation on each branch 2,4

  • Varies in color, from a bright yellow at the tips to orange, green, or brown at the base 4

  • Has been found to reproduce sexually and asexually 2

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Photo: DAR

Habitat

  • Grows in close proximity with neighboring benthic organisms to create thick mats and clumps that can be up to 30 centimeters (cm) or more across, and up to 40 cm thick 2, 3

  • Typically found in tidepools and on reef flats, up to four meters underwater 2

Impacts & Concern

  • Widespread dispersal mainly through fragmentation 2, 3

  • Fragments are heavy and tend to sink rapidly but remain viable after more than 6 hours desiccation 1

  • Overgrows and outcompetes native algae and coral, shading it from light 3

  • Can cause ecosystem changes by shifting Hawaiian reefs from coral dominated to algae dominated, leading to low biodiversity 3

  • Loss of the ecosystem services and structure provided by live coral 3

Gorilla ogo
Photo: DAR

Introduction

  • First identified in 1971 on Hawai’i Island in Hilo Bay, where it was likely unintentionally introduced by shipping vessels originating from the Philippines 2, 3

  • In April 1971, G. salicornia was transported intentionally from Hilo to Waikīkī

  • In September 1978 it was transferred to Kāne‘ohe Bay on O‘ahu for aquaculture projects that were later abandoned 2

Distribution in Hawaiʻi

  • Kauaʻi: Not documented

  • O‘ahu: Waikīkī, Pearl Harbor, Maunalua Bay, and Kāne‘ohe Bay

  • Molokaʻi: Present, Specific Areas Unknown

  • Lānaʻi: Not documented

  • Maui: Not documented

  • Hawaiʻi (the Big Island): First discovered in Hilo Harbor, now spread south along the coast

Map - Gorilla Ogo distribution

Related AIS Team Management Projects

Invasive Algae Project

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Other Introduced & Invasive

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Marine

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Freshwater

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Brackish

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Seaweed/Algae

References

  1. Smith, J., Hunter, C., & Conklin, E. (2004). Ecology of the Invasive Red Alga Gracilaria salicornia (Rhodophyta) on O‘ahu, Hawai‘i. Pacific Science, 58(2), 325-343.

  2. UH Mānoa. (2001). Gracilaria salicornia. Marine Algae of Hawaiʻi. https://www.hawaii.edu/reefalgae/invasive_algae/rhodo/gracilaria_salicornia.htm

  3. CABI. (2019). Gracilaria Salicornia. In: Invasive Species Compendium. Wallingford, UK: CAB International. https://www.cabi.org/isc/datasheet/107771

  4. Eyes of the Reef (EOR). (2015). Gorilla Ogo (Gracilaria Salicornia). Eyes of the Reef Hawaiʻi. https://eorhawaii.org/education/marine-invasive-species/gorilla-ogo/