Table Of Content

Memoirs of"the Museum ofVictoria 56(2):431-433 (1997) A CONSERVATION PROGRAMME FOR THE PARTULID TREE SNAILS OF THE PACIFIC REGION Paul Pearce-Kelly. Dave Clarke, Craig Walker and Paul Atkin Invertebrate Conservation Centre, Zoological Society ofLondon. Regent's Park. London NW1 4RY, UK Abstract Pearce-Kelly,P.,Clarke,D.,Walker,C.andAtkin,P., 1997.Aconservationprogrammefor thepartulidtreesnailsofthePacificregion. MemoirsoftheMuseumofVictoria 56(2):431- 433. ThroughoutthePacificnumerousendemicmolluscspecieshaveeitherbecomeextinct in the wild or are currently facing the threat ofextinction as a result ofintroduction ofthe predatory snail Euglandina rosea and the New Guinea flatworm Platyclemus manokwari. Without determined conservation efforts, including the establishment ofexsitu breeding programmes, much ofthe region's endemic snail fauna will be lost. Since 1986 a collabor- ative international conservation programme has been in place forpartulid treesnails. The > participating institutions currently maintain a total of33 taxa in culture (comprising 12 000snails).Theconservationstatusofall 1 17partulidspecieshasbeenassessedusingthe Conservation Action Management Plan (CAMP) process. Target ex situ population sizes required to maintain 90% ofstarting heterozygosity over 100 years have been calculated usingthe analytical model programmeCAPACITY (Pearce-Kelly et al., 1994)Thegenetic management requirementsofthebreedingprogramme have necessitated the development ofacolonymanagementcomputerdatabaseenablingdemographicmanagementandanaly- sisofthepopulations.Theabilityoflongtermcaptive-bredsnailstoreadapttonatural field conditions was investigated using a trial release and monitoring experiment at Kew Gardens. Field introduction trials via the construction ofpredator-proofforest reserves, were commenced in 1994. Introduction dae. Euglandina paid scant attention to its intended Achatina target preferring to prey on An ill-conceivedattempt at biologicalcontrolof the smaller endemic snails. Extensive field sur- the African land snailAchatinafulica(usingthe veys have determined that many partulid snail predator Euglandina rosea and the New species have been preyed toextinction through- Guinea flatworm Platydemus manokwari) has out their natural range (Murray and Clarke, resulted in large numbers of endemic mollusc 1984; Pearce-Kelly et al., 1994). speciesbecomingextinct, or facingthe threat of In 1986 the international zoo community, in extinction, throughout the Pacific region. With- association with IUCN's Captive Breeding out the establishment of ex situ breeding pro- Specialist Group, devised an international con- grammes many of these endemic species will servation programme to establish viable exsitu face extinction. populations of as many endangered partulid The 1 17 species of Polynesian tree snails of species as possible. The programme iscurrently the family Partulidae once spread over a wide maintaining in culture 33 taxa (totalling groupofvolcanicislandsofthewest,centraland > 12 000 individuals) in 18 collections in south Pacific. Each island had its own endemic Europe and North America. species, which were often further restricted to A workshop in 1994 used the Conservation individualvalleys.Theproductofextraordinary ActionManagementPlan (CAMP)process(Seal selectivepressures,Partula(thelargestandmost et al., 1994) to assess the conservation status of studied genus of the Partulidae) has provided everyspecies withinthe Partulidae. Thisreview researchers with an invaluable insight to the determined that no species could be considered mechanisms behind speciation (Johnson et al., as being less than endangered and identified 53 1995). In addition totheirscientific importance species as being in need of urgent captive- many species ofPartulidae are valued elements breeding assistance (Pearce-Kelly et al., 1994). ofthe region's rich cultural heritage. Because of the intensive culture requirements TheintroductionofEuglandinahashadadis- associatedwiththe Partulidae, togetherwiththe astrous effect on the region's species ofPartuli- large number of species requiring captive- 431 432 P. PEARCE-KELLY ET AL. breedingassistance,theworkshopcalculatedthe Kew Gardens. This 16 month trial suggested target population sizes required to maintain that longterm captive-bred Partula populations 90% of starting heterozygosity over 100 years haveretainedtheirabilitytoreadapttoanatural using the analytical model programme environment and diet (Pearce-Kelly et al., CAPACITY (Flesnessand Mace, 1988; Souleet 1995). The latest development has been the al., 1986) The results ofthis exercise suggested commencement of reestablishment on the that a minimum of 250 adults, together with French Polynesian island of Moorea (Murray, their associated young, need to be maintained 1995). Because of continued predator threat, for each species in the breeding programme. this aspect ofthe programme has involved the construction ofa predator-proof reserve, 20 m The demographic labyrinth X 20 m, built with cheap locally available Maintaining healthy genetic populations ofany materials, and containing three species ofcap- species over successive generations requires a tive-bred Partula snails (Murray, 1995). management protocol that takes account ofthe Forthe foreseeable future, it is not possible to major factors that lead to loss ofgenetic diver- progress beyond the predator-proof reserve sity. These factors aregenetic drift (the random strategy due to the high numbers of surviving process which results when a limited sample of Euglandinain thehabitat.TheseEuglandinaare genes from one generation is transmitted to the feeding on native micro-snails in the leaflitter next), inbreeding depression (mating between andwillcontinuetopreventthefullre-establish- relatives which can result in reduced characters ment of Partula into the wild until effective such asfertilityandgrowth rate), artificial selec- predator control measures are developed. tion (the disproportionate survival of individ- To ensure that the captive snails do not uals adapte—d to the prevailing environmental becomediseased, lose theirnatural resilienceto conditions in captivity selective pressures endemic micro-organisms, or introduce alien maydifferfromthoseinthewild)anddisease. In microbes when returned to theirnative habitat, order to balance these considerations the snail an extensive screening exercise is in place to cultures are maintained along inbred and out- determine the nature and levels of enteric gut bred lines with genetic drift and inbreeding fauna and flora in both the wild and captive depression beingminimised in theoutbred lines Partula populations. while the inbred lines best reduce the risks of selection pressures and disease. Other conservation initiatives Thetaxa in the Partulidae programme derive Educational material is being produced to help not only from different islands but from differ- raise public awareness ofthe ecological disaster eEnatchvaolfletyhsea>nd10c0ollceocltlieocntiosnitessitewsitrheipnrevsaelnltesysa. fPaacciifnigcthaendi,ndtiogeinloluusstrsantaeilhfoawunaPotlhyrnoeusgihaonustctahne geneticallyuniquepopulation which needstobe helppreventfurtherextinctionsofendemicmol- maintainedasaseparatebreedingline.Theneed luscs, legislation is being formulated to prohibit forgeneration separation and monitoringofthe furtherintroductionofalien speciesintoFrench fourdevelopmental stages(defined as newborn, Polynesia. These two initiatives are the most juvenile, subadult and adult) are further effective conservation action that can be taken management complications. These considera- to reducethelikelihood ofalien predators being tions are compounded by the need to maintain introduced to islands that havethus farescaped populations as colonies of up to 200 snails, of such disastrous importations. mixedagestructure. Thedevelopmentofacom- puterized colony database (CERCI) has, forthe Conclusion first time, enabled the detailed monitoring and analysis of demographic trends, and environ- The extinction of endemic species of mollusc mental and genealogical data in colony popula- throughout the Pacific is continuing. Without tions. concerted insituandexsituaction,ofthenature outlined above, it can only escalate. The signifi- Re-establishment cance for conservation of such action is high- Theeffectiveness ofthe breedingprogramme in alfigfhotreddedbay stehceonnducmhbaenrceooffsspuercviievsalcutrhrreonutglhy wm1aa9is9n4rtewaliheneaisnnegdaogvnrioatbuolpePoofplozyponuoel-saibtarineodnpslPaanrwttasuslgartoetwsateienndigatiaant cbpearnpoetgfiirvtaei-mnbmgreetsehdeairneignpdopitrveoingdturiaaallmmcteoasnr.sgeetrIvnasptaeidcodineistm,ioodnseulctsho CONSERVATION OF PARTULID TREE SNAILS OF THE PACIFIC REGION 433 for many of the more than1000 IUCN-listed Pearce-Kelly, P., Clarke, D. and Mace, G.M., 1994. threatened mollusc species. Partula '94:Anactionplanfortheconservation of thefamilyPartulidae. Zoological Society ofLon- don: London. References Pearce-Kelly, P., Mace, G. and Clarke, D., 1995. The Fleness,N. and Mace,G., 1988. Populationdatabases release of captive bred snails (Partula taeniata) and zoological conservation. International Zoo intoasemi-naturalenvironment.Biodiversityand Yearbook 27 44-49. Conservation 4: 645-663. Johnson, M.S., Murray,J.andClarke,B.C., 1993.The Seal, U.S., Foose, T.J. and Ellis, S., 1994. Conser- ecologicalgeneticsandadaptive radiation ofPar- vation assessment and man plans (CAMPS) and tula on Moorea. OxfordSurveys in Evolutionary Global captive action plans. Pp. 312-328 in: Biology 9: 167-238.' Olney, P.J., Mace, G.M. and Feistner, A.T.C. Murray, J. and Clarke, B., 1984. Movement and gene (eds), Creative conservation. Chapman and Hall: flow in Partula taeniata. Malacologia 25: 343- London. 348. Soule, M.E., Gilpin, M., Conway, W. And Foose, T., Murray, J., 1995. Conservation ofPacific landsnails: 1986. The millennium ark, how long a voyage, Monitoring and rescue ofendangered species. A how many state rooms, how many passengers? preliminary report to Flora and Flora Inter- Zoo Biology 5: 101-113. national, Cambridge, UK.