Invasive Plants
Mokauea Island is overgrown with the following invasive species:
• Long thorn kiawe
• Mangrove
• Pickleweed
• Limu
On June 16, 2007, Kai Makana and its volunteers began to remove the long thorn kiawe and mangrove along the coast as well as the invasive limu and mangrove in the fishpond. Pickleweed removal is also being done, particularly in the areas identified as the stock planting area for native Hawaiian plants. Significant long thorn kiawe, mangrove, and pickleweed exist on the western side of Mokauea Island and removal of these invasive plants remains as one of the major project challenges. Kai Makana will continue to remove the long thorn kiawe and pickleweed along the coast and replant with native Hawaiian plants. We will continue to monitor and mitigate the re-growth of the invasive plants.
Limu (Invasive)
On May 20, 2007, Daniel Amato, a Graduate Assistant in Marine Botany at the University of Hawaii conducted an assessment of the island's limu population. Mr. Amato identified the following native and invasive species (listed from most to least abundant):
1. Spyridia filamentosa (native)
2. Acanthophora spicifera (invasive)
3. Padina gymmospora (native)
4. Hypnea spinella (native)
5. Enteromorpha flexuosai (native)
6. Gayralia oxysperma (native)
7. Gracilaria salicornia (invasive)
8. Chondria simpliciuscula (native)
It was concluded that two invasive species were of major concern for Mokauea Island's ecosystem. Gracilaria salicornia was especially abundant on the rocky substrate near the dwellings and at the entrance to the fishpond. This highly invasive limu was also found within the fishpond among the invasive red mangrove (Rhizophora mangle) stands.
On June 16, 2007, the removal of this invasive limu from the fishpond entrance and near the dwelling was performed by Kai Makana volunteers. The volunteers removed the invasive limu and placed it into mesh bags. The limu was then dumped into a pile and was manually sorted by other volunteers to remove invertebrates and fish. Approximately 500 pounds of the invasive limu were removed in this one day of work, with the help of a Department of Land and Natural Resources (DLNR) boat.
Limu restoration feasibility studies are planned for Mokauea Island. In addition, removal of the invasive Gracilaria salicornia will be an ongoing project and serve as an education tool for students visiting Mokauea Island.
Long Thorn Kiawe
Long thorn kiawe (Prosopis juliflora or LTK), is designated a noxious weed. LTK has thorns which can grow up to three inches in length. Removal of the LTK from the island remains as a significant challenge for the project. Seeds produced by LTK are disbursed by ocean currents and propagate along Hawaii’s shoreline. The Oahu Invasive Species Committee (OISC) assessed Mokauea's Island's LTK growth on April 14, 2007 and LTK removal operations commenced on June 16, 2007 with the help of over 140 volunteers from the community as well as State, Federal, and City and County of Honolulu governments.
On July 12, 2007, employees from the Department of Agriculture and the Department of Land and Natural Resources, - Division of Forestry and Wildlife notched and applied herbicide to over 90 LTK trees. This notching technique is very effective at killing the LTK trees.
On September 8, 2007, the OISC and volunteers removed 86 LTK plants. Kai Makana will continue LTK removal operations and replant former LTK growth areas with native Hawaiian plants that are being grown in a stock area on the island.