Little is known about the specific population sizes of this species.[3] Researchers have documented a decline in Pacific Hawaiian damselfly populations since 1905. This is likely as a result of the introduction of several nonnative species. One example includes the invasive Mexican molly (Poecilia mexicana). This nonnative species was introduced in Hawaii in 1984.[5] Nonnative species such as this one are predators that threaten Pacific Hawaiian damselfly naiads. This threat comes mostly during the larval growth of naiads. There is correlation between the presence of nonnative fish predation and damselfly population decline. But, there are no calculations of how many Pacific Hawaiian damselflies currently exist. There are also no reports that show how many damselflies have existed historically.[3]
In the past, Pacific Hawaiian damselflies were known to populate all of the main Hawaiian Islands at lower elevations, except Kahoolawe and Niihau. These populations would occur below 610 meters (2,000 feet) along streams. Since 1994, this species has been completely wiped out of Oahu, Kauai, and Lanai Islands. Today, fewer than six populations exist on the islands of Maui and Molokai. There are only a few across very specific ranges along seven streams in Molokai and 14 in Maui. Existing adult populations remain rooted close to these specific breeding areas along streams.[1]
Humans introduced nonnative bullfrogs (Rana catesbeiana) to the Hawaiian Islands between 1940 and 1990. Bullfrogs are an additional threat to the Pacific Hawaiian Damselfly populations.[6] This species of damselfly and bullfrogs both prefer habitats in calm water. Adult bullfrogs, and some tadpoles, feed on larvae and adult damselflies. Humans introduced another species of frog, Coqui frogs (Eleutherodactylus coqui) to the Hawaiian Islands in the 1980s. It is incredibly invasive and could begin to disrupt Pacific Hawaiian damselfly populations as well through predation.[3]
Nonnative ants are another immediate threat to the naiads of Pacific Hawaiian damselflies. The damselfly larvae leave the water when becoming adults. Their life cycle overlaps with several species of predatory, aggressive, invasive ant species. These ant species prey upon the young adult damselflies. Some species of threatening ants on the Hawaiian Islands can live up to 610 meters (2,000 feet) in elevation. These species include the big-headed ant (Pheidole megalocephala), the long-legged ant (Anoplolepis gracilipes), the Argentine ant (Linepithema humile), and the Papuan thief ant (Solenopsis papuana).[3]
Invasive aquatic insects, such as backswimmers (Notonectidae maculata), also threaten Pacific Hawaiian damselflies. They are predators of naiads in streams and calm water areas on almost all of the Hawaiian Islands.[3]
The State Water Code of Hawaii serves to protect all species and habitats within surface water. Unfortunately, this code is not well enforced or followed by the people of Hawaii. The government is not controlling the transfer of nonnative species between island water sources. The lack of governmental enforcement serves as another threat to populations of Pacific Hawaiian damselfly.[3]
Agricultural and urban expansion on the Hawaiian Islands have resulted in a 30% loss of Hawaiian wetlands. Historically, increased human expansion has threatened Hawaiian insects with habitat loss. The invasive grass (Urochloa mutica) grows along marshlands. The species converts marshes into grassy areas and changes habitats of the damselflies. In the mid-1900s, "amateur collectors" took samples of the damselfly species. Damselflies, butterflies, and dragonflies are the most popular insect species to collect. Researchers believe that this has also contributed to the reduction of Pacific Hawaiian damselflies.[3]
Climate change, stream alteration, urban development, and stochastic events also disrupt the Pacific Hawaiian damselfly populations. The populations of this species are sensitive and small. Therefore, a large disruption, such as a hurricane, could wipe out the entire population. Overall, the major threats to this species are nonnative species, lack of governmental regulation, and human disruption.[3]
The Megalagrion pacificum was listed as an endangered species under the Endangered Species Act beginning on July 26, 2010. This species is considered endangered on the islands of Maui, Molokai, and Hawaii.[4] The Pacific Hawaiian damselfly was first petitioned on May 11, 2004, to be listed under the Endangered Species Act.[1]
Initiation of the 5-year review was published on 1/22/2018. The 5-year review was published on 06/25/2021.[1] No new information about the Pacific Hawaiian Damselfly was published in the 5-year review.[3]
There is currently no Species Status Assessment for this species.[1]
The earliest delisting for the Pacific Hawaiian damselfly is expected to be 2051. The recovery plan was established on November 17, 2021, and has not yet been updated for this species.
In order to down-list the Pacific Hawaiian damselfly, three criteria need to be met. The first requires that all current populations of the species are found. Once found, they must be identified and considered evenly distributed as a population on at least one Hawaiian Island. On islands where the damselfly species historically existed, there should be at least 10 populations. Surveys should show that there is a consistent increase in all populations over five consecutive years or more. Next, all habitats in which the species is found need to be stable and supportive of breeding. This would include protections in place to prevent environmental disturbances that could decrease damselfly populations. Finally, these habitats need predation monitoring over five consecutive years. For three or more of these years, there need to be no nonnative predators, minimal predation, and minimal competition for the damselfly species. The major threats to the Pacific Hawaiian damselfly populations need to be stabilized or removed for the species to be down-listed.
To delist the Pacific Hawaiian Damselfly from the Endangered Species List, three additional criteria (including those listed above) must be met. Significant increases in the abundance of the species across all islands (Kaua'i, O'ahu, Moloka'i, Lana'i, Maui, and Hawaiʻi) must occur over 10 years. Strong increases in the population need to occur for at least 7 of the 10 years. Additionally, damselfly populations need to continue to breed and sustain themselves. Damselfly breeding must occur successfully on a repetitive basis. These populations of damselfly must, then, be able to withstand ecosystem disturbances. Finally, nonnative species need to be absent from these habitats. No significant predation or competition rates should harm damselfly populations. If these criteria are met, the Pacific Hawaiian damselfly can be delisted from the Endangered Species List.[7]
There are other suggestions for the recovery of this species. One suggestion includes using surveys to better determine distribution and population sizes. These surveys could also be used to stabilize the existing population of Pacific Hawaiian damselfly. Additionally, the U.S. Fish and Wildlife Services suggests focusing on nonnative predator management, documentation, surveying, studying, and extermination. The U.S. Fish and Wildlife Services also suggests studying the habitat requirements of the Pacific Hawaiian Damselfly. Depending on the habitat needs of the species, it may be possible to transport them to other areas with human intervention. New, suitable locations might provide habitats for growth and population restoration.[3]
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