Appendix ES-7 Hawaiian Tree Snail Propagation Summary
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Appendix ES-7 Hawaiian Tree Snail Propagation Summary Hawaiian Tree Snail Conservation Laboratory Pacific Biosciences Research Center PI: Brenden Holland Annual Report – October 2015 TREE SNAIL PROPAGATION SUMMARY The UH Tree Snail Conservation Lab currently houses and cares for about 400 snails in 10 endemic Hawaiian achatinelline species, all of which are listed as federally endangered. The tree snails are housed in 28 cages of three different sizes, maintained in environmental chambers. Conditions in chambers are intended to mimic natural conditions of mid-elevation Hawaiian rain forest. Chambers have temperature and light control, on a 12 hour cycle. Temperatures are held at 20 or 21°C for during daylight, and 16°C or 17 during the night. Sprinkler timers are set to water cages each 8 hours, 6 days per week. There has historically been a one day no water period, again to mimic natural conditions. Tasks for lab personnel include weekly scheduled cage changes, removal of old leaves and branches and replacing with fresh leaves of native tree and plant species. We also count births, measure newborn snails and remove, measure and preserve any dead individuals, and note percent cultured fungus consumed. Following removal of old leaves, cages are cleaned with hot water and detergent, sterilized with ethanol, air-dried, and snails are replaced along with fresh foliage. Members of our group hike Oahu trails weekly to collect fresh leaves, providing food for the snails in the form of surface growing arboreal fungus from leaves and tree bark. In addition culture medium is autoclaved weekly, and 45 plates are poured and inoculated with lab stock fungus. Cultured fungus has been used as a dietary supplement in the lab for a number of years. 1 Appendix ES-7 Hawaiian Tree Snail Propagation Summary Table A. Population status summary for the Waianae species, Achatinella mustelina from most recent cycle (period ending July 1, 2015). Population source # of snails Juvenile Subadult Adult Peacock Flats 3 1 2 0 Bornhorst 1 0 1 0 Ekahanui Honouliuli 11 11 0 0 Palikea Gulch 2 0 0 2 Makaha 1 1 0 0 Schofield West 7 6 1 0 Makaleha 11 9 1 1 Totals 36 28 5 3 Table B. Population status summary for the Koolau species, Achatinella lila from most recent cycle (period ending July 1, 2015). # of Species Cage Births Deaths snails Juvenile Subadult Adult A. lila Pop 1 1 0 25 9 11 5 Pop 2 1 0 38 16 16 6 Pop 3 0 0 35 20 5 10 Pop 4 0 0 33 20 6 7 Pop 5 3 2 35 22 5 8 Pop 6 0 0 25 14 5 6 Pop 7 0 1 15 12 0 3 Pop 8 2 0 21 14 3 4 Totals 7 3 227 127 51 49 There is a long-standing plan to release a subsample of the total 227 Achatinella lila currently housed in the lab, into a recently constructed predator exclusion fence in the central Koolau Mountains at a site called Poamoho. This translocation effort has been delayed due first to climatic conditions leading to complete destruction, due to high wind velocity, of the first steel walled structure. The structure was then completely redesigned 2 Appendix ES-7 Hawaiian Tree Snail Propagation Summary and replaced with a wooden version by OANRP staff. Currently the fence structure itself is intake and completed, but the persistence of predatory rodents (rats) in the interior, and uncertainty as to whether rats are able to gain access from outside of the fence has delayed this action. Chamber temperature calibrations During this period we tested all internal chamber temperatures using Hobo data- loggers and analog thermometers. We found that three of the chambers were operating a few degrees (average 2.3° C) below the control panel settings. Therefore we have adjusted panel setting to maintain internal temperatures within day/night target ranges. It is our hope that keeping more precise chamber temperatures might help stabilize reproductive rates and survival for captive species. Figure A. Electronic and analog means to monitor temperatures in environmental chambers. 3 Appendix ES-7 Hawaiian Tree Snail Propagation Summary New Tree Snail Population Data Entry System Together with SEPP staff, USFWS, and intern Ryan Pe’a, we have implemented a new data entry system. The new system uses a Weekly Master Update, and will improve data recording consistency, legibility, ability to share, and will be contiguous. HAWAIIAN SNAIL PREDATOR STUDIES This section of the draft report includes summaries of ongoing and recently completed efforts aimed at obtaining management relevant biological data during this funding cycle. The projects summarized share the objective of understanding and ultimately controlling invasive predators that are known or suspected to impact endangered species on Army lands, including two projects (sections D & E) that were recently submitted for peer- reviewed publication. Recent OANRP-funded studies conducted in our lab over the past few years have resulted a number of scientific publications concerning: 1.) The first detection of impacts on endemic fauna, including the Oahu tree snail Achatinella mustelina (Holland, Costello & Montgomery 2010). 2.) Impact projections, estimates and overall threat assessment via gut content analyses and ingestion frequency (Chiaverano & Holland 2014). 3.) We have characterized movement behavior and establishment of home range in various forest habitats (Chiaverano, Wright & Holland 2014) using radio-transmitter tracking studies in the field. 4.) We discovered consistent, statistically significant differences in head morphology (size) and invertebrate prey utilization among different Hawaiian islands correlated with differences in bite force due to diet differences and rainfall (Van Kleeck, Chiaverano & Holland in press, summarized below). For the predatory invasive wrinkled frog, we have submitted our findings for publication (summarized in section D below). 4 Appendix ES-7 Hawaiian Tree Snail Propagation Summary A) Chameleon dissection results: We euthanized and dissected 21 adult field collected Jackson’s chameleons during this period, all cleared from the Puu Hapapa site, outside of the snail exclosure in the native forest. The most significant result was one large male was found to have consumed 16 native helicarionid snails, all present in its gut, of various sizes, presumably all were the same species Philonesia harmanni. Jackson’s chameleons continue to pose an immediate threat to the persistence of native Hawaiian invertebrates on Army managed lands. No additional A. mustelina have been observed in chameleon stomachs. B) Jackson’s Chameleon control feasibility trial based on comparison to Brown Tree Snake management on Guam Ecosystem damage by the introduction of the Brown Tree Snake (BTS) (Boiga irregularis) in the 1950’s on the island of Guam (US Territory) has resulted in the devastation of the island wildlife, particularly the native and naturalized avifauna. In fact 11 of the 18 native birds have been extirpated and all of the remaining taxa severely depleted (by over 90%), and 12 resident species have been extirpated. Following introduction of very few specimens (1998) the BTS spread rapidly, within a few years reaching densities of 12,000 per square mile, resulting in thousands of hospitalizations due to bites in the past two decades, and regular, electrical outages caused by BTS (about 1.5 hrs every other day) (Burnett et al 2008). Several decades and millions of dollars have been invested in attempted control, and have proven largely unsuccessful. Targeted management efforts to date have mainly consisted of baited minnow traps that use live mice, and are placed along residential fence lines and around utilities and power generating stations. There has been a concerted effort both on Guam and at Honolulu International Airport, to prevent transfer of this devastating invasive reptile to the Hawaiian Islands. Although Hawaii has no invasive snakes, at the present time, there are 26 established predatory invasive reptiles and amphibians in the islands. The Jackson’s chameleon 5 Appendix ES-7 Hawaiian Tree Snail Propagation Summary (Trioceros jacksoni xantholophus) is the most ecologically damaging species of invasive herpetofauna in Hawaii, for which the threat and impact has been characterized to date. Relative to the density recorded for BTS, of 12,000 snakes per mi2, Jackson’s chameleons have been observed at a density of six times this, or 72,000 per mi2 (45 per 0.4 acres = 72,000 per mi2). Our concern is that predatory activity of Jackson’s chameleons on Oahu could cause the extinction of tree snails in areas where the species overlap in habitat, as has occurred on Guam with the invasive BTS and native birds. In a sense, the Jackson’s chameleon could be considered Hawaii’s BTS, and it warrants immediate control efforts. Recent innovative field trials on the island of Guam, aimed at control of BTS conducted by the USGS and USDA, appear to be having the desired impact, namely a reduction of the population density of snakes. In this trial the commercially available analgesic Tylenol®, or generic name acetaminophen, is delivered via placement in the esophagus of a dead mouse, at a dosage of 80 mg/kg. This dose has been tested in the laboratory and shown to be lethal to all size classes, even the largest adult snakes, with little or no secondary or non-target impacts. We are interested in investigating the possibility of adopting this strategy for Jackson’s chameleons in Hawaii. We have recently received IACUC protocol approval to test acetaminophen on chameleons in the laboratory. Once approval was received for lab testing, we started trials immediately, and preliminary results are definitive: this product is toxic to Jackson’s chameleons at same dosage as used for BTS in Guam (80 mg acetaminophen/kg body weight). We will continue to test the same dosages per body weight as were done with BTS lab trials.