APPENDIX ES-6: MEGALAGRION XANTHOMELAS CONSERVATION ES-6.1 BACKGROUND Megalagrion xanthomelas (Fig. 1) is one of 25 damselflies endemic to the Hawaiian Islands, all derived from a single radiation. Known as the orangeblack Hawaiian damselfly, it breeds in a wide variety of lentic aquatic habitats, including basal spring wetlands, brackish anchialine ponds, slow-moving streams, and various types of ponds, including taro loi and other artificial water bodies. Once widespread in the lowlands of all the main islands except Kauai, it has declined severely as wetlands have been disrupted and particularly due to the introduction of mosquitofish and other alien predatory fish. It was designated as a candidate for listing as endangered in 1994; it has not yet been listed, but is expected to be formally proposed soon. Five other Megalagrion damselflies are currently listed as endangered, including three endemic to Oahu. Although it occurs widely in scattered locations on Hawaii, M. xanthomelas was thought to be extirpated from Oahu until 1995. At that time, it was rediscovered on the grounds of Tripler Army Medical Center (TAMC) in a spring-fed stream that flowed permanently but only for a short distance, preventing fish from lower elevations from reaching it. The natural stream flow was later disrupted by construction at TAMC, and the population is now maintained as an artificial stream from a hose that is always kept on. The population has been monitored monthly by OANRP staff since October 2013; previously it was monitored weekly or biweekly from 2012-2013, and periodically prior to that, by Bishop Museum personnel under contract. During this time the population has stayed relatively stable, though the number observed fluctuates widely between visits (Fig. 2). They have survived in this situation for nearly 20 years, but since this is the only remaining Oahu population, it has long been considered a priority to establish at least one additional population elsewhere, Figure 1. Male Megalagrion xanthomelas, the orangeblack Hawaiian damselfly, at Tripler Army Medical Center. 2015 Makua and Oahu Implementation Plan Status Report 1
Figure 2. Megalagrion xanthomelas observations at TAMC over time. particularly in a more natural area managed for conservation. Translocations were attempted at Dillingham Military Reservation (1998), Makiki Stream (2003), Kalaeloa (2010), and Waimea Botanical Garden (2012), but all have failed so far for various reasons. All these sites are currently considered not suitable for long-term habitation by M. xanthomelas due to the presence of predators or degradation of the aquatic habitat. Therefore, we are still looking for a good reintroduction site. To this end, several potential reintroduction sites were visited by a group consisting of representatives from OANRP, DOFAW, USFWS, Honolulu Board of Water Supply, and the Bishop Museum. Sites were selected based on the collected knowledge of the group members and assessed for appropriateness of various characteristics, including water flow and depth, shade cover, lowest permanent reach, proximity to other water bodies, aquatic vegetation, abundance of potential prey items, and presence of alien aquatic predators. Land ownership and public accessibility were also secondary factors. ES-6.2 RESULTS Nine potential release sites were visited in Nov. Dec. 2014 and Feb. 2015. A brief summary of the results are in Table 1. The two windward Koolau sites were both permanent streams extending to the ocean, close to other water bodies, contained bullfrogs and mosquitofish (at least in the lower reaches), and are subject to frequent high-flow events during periods of high rainfall (one of which occurred during a visit). It is likely that all windward sites are similar, and thus no others were considered in this area. Still, some sites with isolated water features or slow side pools similar to the Onomea Bay streams of Hawaii may yet be found. The remaining sites were in the Waianae range. The previous reintroduction site above Dillingham airfield was revisited, as it had been considered to be one of the best locations. However, it was found to have significantly degraded over the past several years. Previously the presence of introduced crayfish and dense vegetation were thought to have been factors in the failure of M. xanthomelas to establish; now 2015 Makua and Oahu Implementation Plan Status Report 2
Map removed to protect rare resources. Available upon request Figure 3. Potential reintroduction sites for Megalagrion xanthomelas in the Waianae (left) and Koolau (right) ranges visited during the current survey year. Table 1. Site characteristics. Site Water Type Predators Habitat Waihee permanent flowing stream bullfrogs, fish heavily shaded, subject to frequent flash flooding Ahuimanu permanent flowing stream bullfrogs, fish heavily shaded, subject to frequent flash flooding Punanaula spring-fed slow stream wrinkled frogs small, narrow stream, confined by guinea grass; may be restored for taro production Honua permanent flowing stream none observed stream is relatively fast-flowing Makaha - Glover permanent flowing stream bullfrogs? may be restored for taro production Makaha stream intermittent with perm. pools bullfrogs Kapuna seep spring-fed slow stream bullfrogs M. hawaiiense present at seep, stream below very small Kapuna stream intermittent with perm. pools bullfrogs shady, moderately deep gulch Dillingham spring-fed slow stream none highly degraded, stream channel disrupted by pig digging extensive pig digging has levelled the stream channel into a flat, muddy bed, and no aquatic animals and little vegetation are present. Two sites were visited in Makaha Valley, in the upper valley above the bend and lower at Glover tunnel. The former had bullfrog tadpoles present and the streambed appeared relatively bare, suggesting few food resources. The latter appeared more suitable but is slated to be restored to taro production, and likely contains bullfrogs if the upper area does. 2015 Makua and Oahu Implementation Plan Status Report 3
Punanaula spring on the west side of Waianae Valley produces a small permanent stream that flows for a relatively short distance, and has only small wrinkled frogs present. However, it too is likely to be restored to taro production, and the area of available habitat is extremely small. Honua Stream on the east side is much larger but flows through a steep area, resulting in a high flow rate. While no predators were observed, it appears to flow continuously to low elevations so frogs may be present. At Kapuna Gulch in Pahole NAR, a seep feeds a small permanent stream that flows for a short distance above Mokuleia Trail. Megalagrion hawaiiense is found breeding at the seep itself, but bullfrog tadpoles were found in the stream pools below. Further down the gulch, the stream is intermittent but groundwater keeps at least some pools permanent, and bullfrogs were again present. Figure 4. Drainage ditch around the Tripler heating/cooling plant, inhabited by M. xanthomelas. ES-6.3 CONCLUSIONS All of the sites found so far were not high quality habitat for reintroduction of M. xanthomelas. Most had bullfrog tadpoles present, which are known to be predators of naiads though it is uncertain if they completely exclude Megalagrion, as they apparently formerly occurred at Tripler. The best site in terms of physical and biological environment was Punanaula, but the available area was very small and reservation of the site for agricultural use will likely result in increased disturbance. There may be additional sites available in Waianae Valley, including in the branches of Honua and Hiu streams, that have not yet been investigated. Portions of these are diverted for human use, but excess flow or even leakage from water pipes may provide sufficient habitat for damselflies. Historically it was recorded breeding in sugar plantation reservoirs in Waianae. The ideal site, where predators are not present or could be eliminated, would be something similar to the pre-disturbance state of the Tripler stream a spring-fed stream that originates in a relatively dry lowland area, flows a relatively short distance, and then usually dries up before connecting to any permanent water 2015 Makua and Oahu Implementation Plan Status Report 4
body. It would be extremely surprising if there were no other examples on Oahu, but we have been unable to find any. This may be due in part to the long history of hydrological alteration, including stream diversion and tunnel boring that has lowered perched aquifers. The recent discovery of M. xanthomelas breeding in a drainage ditch around a building at TAMC (Fig. 4) suggests that another solution may be to establish populations in relatively small, artificial sites. This was previously done at TAMC during construction, and the damselflies have essentially already done this themselves on other islands. On Lanai, there were no historic records of M. xanthomelas, but they were discovered on the island in 1993 breeding in golf course water traps and a leaking water pipe. Given its known adaptability M. xanthomelas was described as being a common insect in Honolulu gardens and very numerous under conditions changed from the natural by Perkins in 1913, prior to the introduction of most alien aquatic predators restoring it to formerly abundant artificial habitats may be the best option for increasing the population. 2015 Makua and Oahu Implementation Plan Status Report 5