Determining host plant preferences for the critically endangered Lord Howe Island stick insect (<Emphasis Type="Italic">Dryococelus australis</Emphasis>) to assist reintroduction

The Lord Howe Island stick insect (Dryococelus australis) is one of the world’s rarest insects. However, the opportunity to reintroduce the species to Lord Howe Island, and commence the path to recovery, may occur within the next 5 years. Understanding the insect’s host plant and habitat preferences on Lord Howe Island is critical to maximising the likelihood of reintroduction success. However, very little ecological information was documented before the species became extinct on the island in the 1930s. Here we examine the Lord Howe Island stick insect’s preference for potential host plants, a key aspect of habitat suitability. We conducted preference trials using 15 common plant species found on Lord Howe Island. Both nymphs and adults consumed some but not all of these plant species. Nymphs were able to survive on 7 of these 15 plants for the duration of the 26-day trials although failed to survive on some of the plants most preferred by adults. Overall, these data reveal that there are numerous plants on Lord Howe Island that the stick insect can consume, though their suitability varies with different developmental stages of the insect. These data are encouraging for any future reintroduction attempts and would greatly aid the selection and monitoring of release sites.     

The recovery programme for the Lord Howe Island Phasmid (Dryococelus australis) following its rediscovery

Summary   Until its rediscovery on Balls Pyramid in February 2001, the Lord Howe Island Phasmid or Stick Insect ( Dryococelus australis ) was thought to be extinct. It disappeared from Lord Howe Island soon after the accidental introduction of the Ship Rat ( Rattus rattus ) in 1918. In this paper, we report on the recovery actions undertaken for this critically endangered species since its rediscovery. Monitoring of the small surviving population on Balls Pyramid has shown it to fluctuate between about 9 and 35 adult individuals. As a safeguard against extinction, two adult pairs were removed from Balls Pyramid in February 2003 to establish captive populations in Melbourne and Sydney. Although all four founders bred readily in captivity, one pair died only a month after capture. The second female would have also died soon after capture had it not been for veterinary intervention using novel untested techniques. The single surviving pair bred successfully but the hatch rate of eggs was poor. For the next generation, both fecundity and hatch rates were low. The lack of knowledge regarding the specific husbandry requirements of this particular species undoubtedly contributed to these problems. Careful management, together with a cautious scientific approach, eventually led to all problems being resolved. Presently, there are more than 700 individuals and 14 000 eggs in captivity. Approximately 80% of incubated eggs are expected to hatch. To establish additional captive colonies, adults and eggs have been sent to other institutions, both within Australia and overseas. Now that the species is reasonably secure in captivity, the opportunity exists to reintroduce this iconic insect back onto Lord Howe Island, but this can occur only after the introduced rodents have been removed. A programme to eradicate both the Ship Rat and the House Mouse ( Mus musculus ) from Lord Howe Island is currently being developed.     

The Micro-caddisflies of Lord Howe Island (Hydroptilidae: Trichoptera: Insecta)

Hydroptilid species are described from Lord Howe Island for the first time. All four species are in the endemic Australian genus Orphninotrichia, and all are endemic to Lord Howe Island. Modifications exhibited by these new species to the normally conservative Orphninotrichia features are suggestive of sympatric speciation and, for several, of a shift in larval niche.     

Population genetic and behavioural variation of the two remaining colonies of Providence petrel (<Emphasis Type="Italic">Pterodroma solandri</Emphasis>)

Knowledge of the dispersal capacity of species is crucial to assess their extinction risk, and to establish appropriate monitoring and management strategies. The Providence petrel (Pterodroma solandri) presently breeds only at Lord Howe Island (~32,000 breeding pairs) and Phillip Island-7 km south of Norfolk Island (~20 breeding pairs). A much larger colony previously existed on Norfolk Island (~1,000,000 breeding pairs) but was hunted to extinction in the 18th Century. Differences in time of return to nesting sites are presently observed between the two extant colonies. Information on whether the Phillip Island colony is a relict population from Norfolk Island, or a recent colonization from Lord Howe Island, is essential to assess long-term sustainability and conservation significance of this small colony. Here, we sequenced the mitochondrial cytochrome b gene and 14 nuclear introns, in addition to genotyping 10 microsatellite loci, to investigate connectivity of the two extant P. solandri populations. High gene flow between populations and recent colonization of Phillip Island (95 % HPD 56–200 ya) are inferred, which may delay or prevent the genetic differentiation of these insular populations. These results suggest high plasticity in behaviour in this species and imply limited genetic risks surrounding both the sustainability of the small Phillip Island colony, and a proposal for translocation of Lord Howe Island individuals to re-establish a colony on Norfolk Island.     

Recruitment patterns of scleractinian corals in an isolated sub-tropical reef system

The density of recruits of scleractinian corals on settlement plates at Lord Howe Island, a small isolated sub-tropical island 630 km off the Australian coastline, was within the range of values reported for comparable studies on the Great Barrier Reef. However, there was a difference in the relative abundance of taxonomic groups, with recruitment at Lord Howe Island during the summer of 1990/91 dominated by corals from the Family Pocilloporidae, Family Poritidae, and sub-genus Acropora (Isopora) (in order of abundance). By contrast, on the Great Barrier Reef, recruits are generally predominantly species from the Family Acroporidae (other than the Acropora (Isopora) group). Both the recruits and the established coral communities at Lord Howe Island are dominanted by corals which release brooded planulae, as opposed to the pattern of mass-spawning with external fertilisation more typical of Great Barrier Reef corals. I hypothesise that the release of brooded planulae would be advantageous in an isolated reef community because (a) brooded larvae can travel large distances and survive the journey to the isolated reef and/or (b) brooded larvae have a shorter period before they are competent to settle and are therefore more likely to be retained on the parental reef once a population has been established.     

Molecular phylogeny of the scincid lizards of New Caledonia and adjacent areas: evidence for a single origin of the endemic skinks of Tasmantis

We use approximately 1900bp of mitochondrial (ND2) and nuclear (c-mos and Rag-1) DNA sequence data to recover phylogenetic relationships among 58 species and 26 genera of Eugongylus group scincid lizards from New Caledonia, Lord Howe Island, New Zealand, Australia and New Guinea. Taxon sampling for New Caledonian forms was nearly complete. We find that the endemic skink genera occurring on New Caledonia, New Zealand and Lord Howe Island, which make up the Gondwanan continental block Tasmantis, form a monophyletic group. Within this group New Zealand and New Zealand+Lord Howe Island form monophyletic clades. These clades are nested within the radiation of skinks in New Caledonia. All of the New Caledonian genera are monophyletic, except Lioscincus. The Australian and New Guinean species form a largely unresolved polytomy with the Tasmantis clade. New Caledonian representatives of the more widespread genera Emoia and Cryptoblepharus are more closely related to the non-Tasmantis taxa than to the endemic New Caledonian genera. Using ND2 sequences and the calibration estimated for the agamid Laudakia, we estimate that the diversification of the Tasmantis lineage began at least 12.7 million years ago. However, using combined ND2 and c-mos data and the calibration estimated for pygopod lizards suggests the lineage is 35.4-40.74 million years old. Our results support the hypothesis that skinks colonized Tasmantis by over-water dispersal initially to New Caledonia, then to Lord Howe Island, and finally to New Zealand.     

Description of two new species of the genus Priolepis from the Indo-Pacific with redescription of Priolepis profunda and Priolepis psygmophilia

Priolepis akihitoi is described as new from Australia, New Caledonia and Japan. The species is distinctive in having a transverse papilla pattern, second dorsal rays usually I, 11, predorsal fully scaled and dark bars dorsally on the caudal fin. Priolepis cyanocephala is described as new from eastern Australia and Lord Howe Island. It differs from other species in having a reduced transverse papilla pattern, second dorsal rays I, 10, predorsal largely naked and head with vertical bands, but no bands on the body. Priolepis profunda is redescribed based on material from northwestern Australia and Thailand, and photos of specimens from Indonesia, New Guinea and the Philippines. Priolepis psygmophilia is redescribed based on recently obtained material from the Kermadec Islands and other material from Lord Howe Island, Easter Island and Rapa Island.     

Abundance,diversity, and feeding behavior of coral reef butterflyfishes at Lord Howe Island

Endemic species are assumed to have a high risk of extinction because their restricted geographic range is often associated with low abundance and high ecological specialization. This study examines the abundance of Chaetodon butterflyfishes at Lord Howe Island in the south‐west Pacific, and compares interspecific differences in local abundance to the feeding behavior and geographic range of these species. Contrary to expected correlations between abundance and geographic range, the single most abundant species of butterflyfish was Chaetodon tricinctus, which is endemic to Lord Howe Island and adjacent reefs; densities of C. tricinctus (14.1 ± 2.1 SE fish per 200m²) were >3 times higher than the next most abundant butterflyfish (Chaetodon melannotus), and even more abundant than many other geographically widespread species. Dietary breadth for the five dominant butterflyfishes at Lord Howe Island was weakly and generally negative correlated with abundance. The endemic C. tricinctus was a distinct outlier in this relationship, though our extensive feeding observations suggest some issues with the measurements of dietary breadth for this species. Field observations revealed that all bites taken on benthic substrates by C. tricinctus were from scleractinian corals, but adults rarely, if ever, took bites from the benthos, suggesting that they may be feeding nocturnally and/or using mid‐water prey, such as plankton. Alternatively, the energetic demands of C. tricinctus may be fundamentally different to other coral‐feeding butterflyfishes. Neither dietary specialization nor geographic range accounts for interspecific variation in abundance of coral reef butterflyfishes at Lord Howe Island, while much more work on the foraging behavior and population dynamics of C. tricinctus will be required to understand its’ abundance at this location.     

Re-Examining Mortality Sources and Population Trends in a Declining Seabird: Using Bayesian Methods to Incorporate Existing Information and New Data

The population of flesh-footed shearwaters (Puffinus carneipes) breeding on Lord Howe Island was shown to be declining from the 1970''s to the early 2000''s. This was attributed to destruction of breeding habitat and fisheries mortality in the Australian Eastern Tuna and Billfish Fishery. Recent evidence suggests these impacts have ceased; presumably leading to population recovery. We used Bayesian statistical methods to combine data from the literature with more recent, but incomplete, field data to estimate population parameters and trends. This approach easily accounts for sources of variation and uncertainty while formally incorporating data and variation from different sources into the estimate. There is a 70% probability that the flesh-footed shearwater population on Lord Howe continued to decline during 2003–2009, and a number of possible reasons for this are suggested. During the breeding season, road-based mortality of adults on Lord Howe Island is likely to result in reduced adult survival and there is evidence that breeding success is negatively impacted by marine debris. Interactions with fisheries on flesh-footed shearwater winter grounds should be further investigated.     

Genetic divergence between colonies of Flesh-footed Shearwater <Emphasis Type="Italic">Ardenna carneipes</Emphasis> exhibiting different foraging strategies

Increasing evidence suggests foraging segregation as a key mechanism promoting genetic divergence within seabird species. However, testing for a relationship between population genetic structure and foraging movements among seabird colonies can be challenging. Telemetry studies suggest that Flesh-footed Shearwater Ardenna carneipes that breed at Lord Howe Island or New Zealand, versus southwestern Australia or Saint-Paul Island in the Indian Ocean, migrate to different regions (North Pacific Ocean and northern Indian Ocean, respectively) during the non-breeding season, which may inhibit gene flow among colonies. In this study, we sequenced a 858-base pair mitochondrial region and seven nuclear DNA fragments (352–654 bp) for 148 individuals to test genetic differentiation among colonies of Flesh-footed Shearwaters. Strong genetic divergence was detected between Pacific colonies relative to those further West. Molecular analysis of fisheries’ bycatch individuals sampled in the Sea of Japan indicated that individuals from both western and eastern colonies were migrating through this area, and hence the apparent segregation of the non-breeding distribution based on telemetry is invalid and cannot contribute to the population genetic structure among colonies. The genetic divergence among colonies is better explained by philopatry and evidence of differences in foraging strategies during the breeding season, as supported by the observed genetic divergence between Lord Howe Island and New Zealand colonies. We suggest molecular analysis of fisheries’ bycatch individuals as a rigorous method to identify foraging segregation, and we recommend the eastern and western A. carneipes colonies be regarded as different Management Units.     

Pelagic larval duration is similar across 23° of latitude for two species of butterflyfish (Chaetodontidae) in eastern Australia

Duration of the pelagic phase of benthic marine fishes has been related to dispersal distance, with longer pelagic larval duration (PLD) expected to result in greater dispersal potential. Here, we examine PLDs of 2 species of coral-reef butterflyfish (Chaetodon auriga and C. flavirostris) across latitudes (14°S–37°S) along the Great Barrier Reef into south-eastern Australia; we predict that PLD will be higher for fish collected below the breeding latitudes of 24°S. For C. auriga, apart from significantly longer PLDs at Lord Howe Island and Jervis Bay (means of 54 and 52 days, respectively), all locations had similar PLDs (mean 41 days). For C. flavirostris, there was no significant location effect on PLD (mean 41.5 days); however, PLD at Lord Howe Island was 58 days with high variance precluding significance. Also, there was no significant variation in PLD among years for either species despite considerable variation in East Australian Current strength.     

Notes on the biology, captive management and conservation status of the Lord Howe Island Stick Insect (Dryococelus australis) (Phasmatodea)

The Lord Howe Island Stick Insect (Dryococelus australis: Phasmatodea: Phasmatidae: Eurycanthinae) is a large, flightless stick insect once thought to be extinct but rediscovered on an island (Balls Pyramid) near Lord Howe Island in 2001. A captive population at Melbourne Zoo is now in its fourth generation and aspects of the biology of the species are discussed. Observations focussed on the eggs as indicators of the health of the population and inbreeding depression, but included data on the juveniles where possible. Behavioural observations reveal that this species is very different from other Australian stick insects, but similar in many ways to overseas members of the Eurycanthinae. Veterinary interventions and post mortems have provided substantial information about the captive population and its environmental stresses, and have wider implications for captive invertebrate populations, particularly those involved in conservation programs. Evidence of inbreeding and the conservation significance of this species is discussed in context with other programs and their implications.     

Rediscovery of the ‘extinct’ Lord Howe Island stick-insect (Dryococelus australis (Montrouzier)) (Phasmatodea) and recommendations for its conservation

The Lord Howe Island Stick-insect (Dryococelus australis) was formerly abundant on Lord Howe Island, Australia, but was extirpated by Black Rats (Rattus rattus) in the 1920s. The species was thought to be extinct, until freshly dead remains were found by climbers on Balls Pyramid during the 1960s. In February 2001, a survey of Balls Pyramid led to the discovery of a small population of D. australis on a precipitous terrace 65 m above sea level. Two adults and one nymph (all females) were located feeding on an endemic tea-tree (Melaleuca howeana). An accumulation of plant debris at the base of the shrub, kept moist by water seepage, provided the insects with damp hollows suitable for use as daytime refugia. All evidence indicated that the species was confined to this single small terrace. A second survey, in March 2002, located a total of 24 D. australis. Twelve individuals were in the same shrub as that occupied the previous year, and 12 were dispersed among five nearby, smaller shrubs. Ten individuals were able to be sexed – eight females and two males. A number of threats to the population of D. australis on Balls Pyramid are identified and several management actions are proposed to ensure the conservation of the species.     

Reassembling island ecosystems: the case of Lord Howe Island

Exotic species that invade remote islands, usually following human settlement, have had catastrophic effects on native biota. However, on islands it is increasingly feasible to eradicate key exotic species allowing extant native species to recover in situ or to return naturally. The practice of marooning threatened species on islands where the threat is absent, irrespective of whether the threatened species once occurred on the island, is well established. However, less focus has been given to the 'island' as the management unit on which to return extirpated species or related surrogates for extinct species. We use the example of Lord Howe Island as a case study to explore options for island restoration should the remaining critical exotic pests (rodents and perhaps owls in this case) be eradicated as planned. Lord Howe Island, in the south-west Pacific Ocean, is remote, biologically diverse, has a high degree of endemism, and was only discovered by humans in 1778. Consequently, the original and exotic biota and their interactions are all better known than for many islands with a more ancient human history. Two species of plants, nine terrestrial birds, one bat and at least four invertebrates have been lost from the island since 1778. One plant and two invertebrates could be returned as conspecifics. One plant and all the terrestrial birds that are extinct could be replaced by closely related species from elsewhere in the Pacific Ocean. Decisions on replacing extinct species with surrogates should be based on the taxonomic relatedness of the candidates for reintroduction: the same species before subspecies before genera, with functional replacement being a further filter on candidates that are not the same species. In our opinion, taxa with functional equivalence but without taxonomic relatedness would not be acceptable candidates for reintroduction.     

Latitudinal variation in thermal tolerance thresholds of early life stages of corals

Organisms living in habitats characterized by a marked seasonal temperature variation often have a greater thermal tolerance than those living in more stable habitats. To determine the extent to which this hypothesis applies to reef corals, we compared thermal tolerance of the early life stages of five scleractinian species from three locations spanning 17° of latitude along the east coast of Australia. Embryos were exposed to an 8 °C temperature range around the local ambient temperature at the time of spawning. Upper thermal thresholds, defined as the temperature treatment at which the proportion of abnormal embryos or median life span was significantly different to ambient controls, varied predictably among locations. At Lizard Island, the northern-most site with the least annual variation in temperature, the proportion of abnormal embryos increased and life span decreased 2 °C above ambient in the two species tested. At two southern sites, One Tree Island and Lord Howe Island, where annual temperature variation was greater, upper temperature thresholds were generally 4 °C or greater above ambient for both variables in the four species tested. The absolute upper thermal threshold temperature also varied among locations: 30 °C at Lizard Island; 28 °C at One Tree Island; 26 °C at Lord Howe Island. These results support previous work on adult corals demonstrating predictable differences in upper thermal thresholds with latitude. With projected ocean warming, these temperature thresholds will be exceeded in northern locations in the near future, adding to a growing body of evidence indicating that climate change is likely to be more detrimental to low latitude than high latitude corals.     

Coral growth in subtropical eastern Australia

 Extension rates of corals at two sites in subtropical eastern Australia (Solitary Islands and Lord Howe Island) were measured to determine whether growth was low relative to tropical locations. Growth was measured using alizarin staining of skeletons and X-radiographic analysis, and was compared between colonies, species, and sites. Linear extension of individual Pocillopora damicornis colonies averaged 12.4 to 16.1 mm per year at Solitary Islands and Lord Howe Island respectively, which is 50% to 80% of published values for this species at tropical sites. Similarly, average extension of most massive faviid species examined at these sites was between 2.6 mm and 4.6 mm per year, considerably lower than most values reported from lower latitudes (generally 6 mm to 10 mm per year). However, growth rates of Acropora yongei, Turbinaria frondens, and Porites heronensis were close to those of closely-related taxa from the tropics. Causal links between latitude, growth rates of coral colonies, and the potential for reef accretion remain unclear. Accepted: 22 April 1999     

The role of sexual and asexual reproduction in structuring high latitude populations of the reef coral Pocillopora damicornis

The genotypic composition of populations of the asexually viviparous coral Pocillopora damicornis varies in a manner that challenges classical models of the roles of sexual and asexual reproduction. On the geographically isolated Hawaiian reefs and high latitude reefs in Western Australia, P. damicornis populations are highly clonal although it has been argued that sexual reproduction via broadcast spawning generates widely dispersed colonists. In contrast, on eastern Australia's tropical Great Barrier Reef populations show little evidence of clonality. Here, we compare the genotypic diversity of adult and juvenile colonies of P. damicornis at seven sites on eastern Australia's high latitude Lord Howe Island reefs to determine if levels of clonality vary with habitat heterogeneity and age of colonies (as predicted by theory) or alternatively if clonality is again always high as for other isolated reef systems. We found 55-100% of the genotypic diversity expected for random mating at all seven sites and little evidence of asexual recruitment irrespective of habitat heterogeneity (sheltered versus wave exposed) or colony age. We found reduced levels of genetic diversity compared with tropical reefs (2.75 versus 4 alleles/locus), which supports earlier findings that Lord Howe Island is an isolated reef system. Furthermore, heterozygote deficits coupled with significant genetic subdivision among sites (FST=0.102+/-0.03) is typical of populations that have limited larval connections and are inbred. We conclude that the genetic structure of P. damicornis at Lord Howe Island reflects populations that are maintained through localised recruitment of sexually produced larvae.     

Longline Fisheries and Foraging Distribution of Flesh-Footed Shearwaters in Eastern Australia

ABSTRACT Incidental seabird mortality associated with bycatch during longline commercial fishing is a conservation concern. An initial step to estimating likelihood of seabird bycatch and conceiving conservation strategies is determining amount of overlap between foraging birds and commercial fishing effort, identifying oceanographic features associated with foraging birds, and quantifying dive characteristics. We tracked 24 adult flesh-footed shearwaters (Puffinus carneipes) breeding on Lord Howe Island located east of Australia during incubation and early and late chick-rearing periods from 6 January to 17 April 2005. At-sea foraging distribution of flesh-footed shearwaters was primarily confined within the jurisdictional Australian Fishing Zone. Foraging was strongly associated with sea-surface temperature >24°C. Spatial and temporal overlap of longline fishing with foraging shearwaters varied throughout the breeding season, but was greatest (63% overlap) during early chick-rearing. Mean maximum distance reached from the breeding colony during a foraging event was 804 km (SD = 280) from Lord Howe Island. Foraging behavior was strongly diurnal, with 91% of dives occurring during daylight, and most dives (77%) were <5 m. Given that longline fishing and flesh-footed shearwaters overlap substantially, the Australian Fisheries Management Authority should consider implementing additional regulations to further reduce bycatch. Conservation strategies such as setting longlines at nights may reduce flesh-footed shearwater bycatch.     

Sophora sect. Edwardsia (Fabaceae): further evidence from nrDNA sequence data of a recent and rapid radiation around the Southern Oceans

Phylogenetic relationships are inferred from nuclear ribosomal internal transcribed spacer sequences for species belonging to Sophora sect. Edwardsia from South America, New Zealand, Lord Howe Island, Hawai'i, La Réunion, Easter Island, and Raivavae Island (French Polynesia). Results support the monophyly of sect. Edwardsia , but relationships among the species from this section are poorly resolved due to most species having identical sequences. The origin of Sophora sect. Edwardsia is discussed, as competing hypotheses have proposed the group originated in South America from a North American ancestor, or in the north-west Pacific. We suggest sect. Edwardsia may have arisen in the north-west Pacific from a Eurasian ancestor.  © The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 435–441.