Subantarctic Campbell Island Research Articles

Dietary evidence of trophic segregation between Campbell albatross Thalassarche impavida and grey-headed albatross T. chrysostoma at subantarctic Campbell Island

Dietary evidence of trophic segregation between Campbell albatross Thalassarche impavida and grey-headed albatross T. chrysostoma at subantarctic Campbell Island

Taxonomic and biogeographical analysis of diatom assemblages from historic bryophyte samples from Campbell Island (sub-Antarctic)

Background and aims – The past two decades, the non-marine diatom flora in the sub-Aantarctic region has been intensively revised. Historic collections provide excellent tools for answering taxonomic, community-related, and biogeographical questions. This study analysed the moss-inhabiting diatom flora from sub-Antarctic Campbell Island in samples collected in 1969–1970 and retrieved from the British Antarctic Survey herbarium (Cambridge, UK). With this study we attempt to expand our, till now sparse, knowledge on the moss-inhabiting diatom flora in the southern Pacific Ocean.Material and methods – In total, the diatom composition in 32 moss samples has been analysed using Light Microscopy (LM) and Scanning Electron Microscopy (SEM). A biogeographical analysis and community analysis of the Campbell Island diatom flora were conducted.Key results – Analysis of the Campbell Island diatom flora revealed the presence of 141 taxa belonging to 45 genera. The species composition in the dominant genera Planothidium, Humidophila, and Psammothidium, the presence of Epithemia, Rhopalodia, Cocconeis, uncommon in the sub-Antarctic region, and many unidentified taxa point to the uniqueness of the Campbell Island diatom flora. The biogeographical analysis showed an overall low similarity with the other sub-Antarctic and the Maritime Antarctic islands. Four different diatom assemblages were distinguished following the community analysis. Moisture level and habitat type seem to be the main factors shaping the Campbell Island diatom assemblages.Conclusion – The results of the Campbell Island diatom analysis highlight the importance of historic herbarium material. Since the examined flora is largely composed of unknown (presumably new) species, it is vital to analyse additional (historic) samples to complete the assessment of the moss diatom assemblages from Campbell Island.

Revision of the non-marine centric diatom flora (Bacillariophyta) of the sub-Antarctic Campbell Island (southern Pacific Ocean) with the descriptions of five new species

During a survey of the moss-inhabiting diatom flora of the sub-Antarctic Campbell Island, located in the southern Pacific Ocean, several unknown centric diatoms were observed that could not be identified using the currently available literature. Detailed light and scanning electron microscopical observations and comparisons with the characters of several species of Melosira, Angusticopula, Ferocia and Arcanodiscus worldwide indicated that five of them should be described as new to science: Angusticopula cosmica Goeyers & Van de Vijver sp. nov., Arcanodiscus crawfordianus Goeyers & Van de Vijver sp. nov., A. indistinctus Goeyers & Van de Vijver sp. nov., A. saundersianus Goeyers & Van de Vijver sp. nov. and Ferocia houkiana Goeyers & Van de Vijver sp. nov. A sixth species, Angusticopula chilensis, was illustrated for the first time using SEM and as a result is considered to differ sufficiently from A. dickiei to warrant epitypification as A. chilensis. The new species were first described in genera that formerly were included within the genus Melosira. All six species are morphologically characterized and compared with similar species within their respective genera. Their presence and distribution on Campbell Island are discussed based on the observations made in the available samples.

<p><strong><em>Frankophila dalevittii</em></strong><strong>, a new freshwater diatom (Bacillariophyta) from Campbell Island</strong></p>

During a survey of the freshwater diatom flora of the sub-Antarctic Campbell Island, located in the southern Pacific Ocean, an unknown freshwater diatom was observed forming long colonies using linking spines. Detailed morphological analysis based on light and scanning electron microscopical observations and comparison with all known Frankophila taxa worldwide justified the description of this unknown taxon as a new species within the genus Frankophila: Frankophila dalevittii Van de Vijver & Goeyers sp. nov. The new taxon is characterized by the presence of well-developed linking spines, the absence of external raphe slits and the presence of internal raphe slits, biseriate striae composed of relatively large areolae and a large axial area. Despite the absence of the external raphe slits, the species is best placed within the genus Frankophila. The new species is described and illustrated and compared with all other Frankophila taxa.

Temperature, Wind, Cloud, and the Postglacial Tree Line History of Sub-Antarctic Campbell Island

Campbell Island, which is 600 km south of New Zealand, has the southernmost tree line in this ocean sector. Directly under the maximum of the westerlies, the island is sensitive to changes in wind strength and direction. Pollen records from three peat cores spanning the tree line ecotone provide a 17,000-year history of vegetation change, temperature, and site moisture. With postglacial warming, tundra was replaced by tussock grassland 12,500 years ago. A subsequent increase of shrubland was reversed at 10,500 years ago and wetland-grassland communities became dominant. Around 9000 years ago, trees spread, with maximum tree line elevation reached around 6500 to 3000 years ago. This sequence is out of step with Southern Ocean sea surface temperatures, which were warmer than 12,500 to 9000 years ago, and, subsequently, cooled. Campbell Island tree lines were decoupled from temperature trends in the adjacent ocean by weaker westerlies from 12,500 to 9000 years ago, which leads to the intrusion of warmer, cloudier northern airmasses. This reduced solar radiation and evapotranspiration while increasing atmospheric humidity and substrate wetness, which suppressed tree growth. Cooler, stronger westerlies in the Holocene brought clearer skies, drier air, increased evapotranspiration, and rising tree lines. Future global warming will not necessarily lead to rising tree lines in oceanic regions.

Growth response of an invasive alien species to climate variations on subantarctic Campbell Island

Growth response of an invasive alien species to climate variations on subantarctic Campbell Island

Demography and ecology of southern right whales Eubalaena australis wintering at sub-Antarctic Campbell Island, New Zealand

Since the decimation of the southern right whale Eubalaena australis population in New Zealand by whaling, research on its recovery has focused on the wintering ground at the Auckland Islands, neglecting potentially important wintering habitat at Campbell Island. For the first time in 20 years we conducted an expedition to sub-Antarctic Campbell Island to document and describe E. australis occupying this wintering habitat. We used a variety of methods including photo-identification, genetic and stable isotope analyses of tissue samples, and visual surveys of abundance and distribution, to provide details on the demography, population connectivity and ecology of E. australis wintering at Campbell Island. Our primary findings include (1) a lack of calves observed at Campbell Island, (2) an age-class bias toward sub-adults encountered at Campbell Island, (3) nine photo-identification matches between individuals observed at Campbell Island and previously documented elsewhere in New Zealand, (4) no genetic differentiation between E. australis at Campbell Island and the broader New Zealand population, (5) increased abundance estimates of E. australis at Campbell Island over the last 20 years, and (6) indications that E. australis forage within the sub-Antarctic region based on stable isotope analyses. Our results confirm that the Auckland Islands are currently the only significant calving area for E. australis in New Zealand, and therefore previous abundance estimates based on demographic data from the Auckland Islands are applicable to the entire New Zealand population of E. australis. However, future periodic surveys to Campbell Island are recommended to monitor population recovery and expansion.

Population dynamics of Eastern Rockhopper Penguins on Campbell Island in relation to sea surface temperature 1942–2012: current warming hiatus pauses a long-term decline

Major population changes of marine mega-fauna are ongoing as global warming, and other anthropogenic drivers affect prey availability. The historical stronghold of the Eastern Rockhopper Penguin (Eudyptes chrysocome filholi) was New Zealand’s sub-Antarctic Campbell Island, but the population declined by 94 % between 1942 and 1984. The apparent mechanism of collapse was warm ocean temperatures causing an inadequate food supply. Eudyptes penguin population declines are ongoing at some breeding sites, highlighting the need to investigate the population trend on Campbell Island since 1984. We estimated the Eastern Rockhopper Penguin breeding population size through physical and photo-counts of birds and nests in 2012, and changes in colony area relative to 1984 and 1996 photographs. We estimated the 2012 population size at 33,239 breeding pairs, a 21.8 % decrease from an (adjusted) estimate of 42,528 pairs in 1984. Although substantial, the recent 1984–2012 decline occurred at a much slower rate (λ = 0.991) than the 1942–1984 decline (λ = 0.940). Despite great variation in trends between colonies ostensibly linked to differences in predation rates, the recent decline occurred primarily between 1984 and 1996, and thereafter the overall population grew. A 100-year time series of extended reconstructed sea surface temperatures (ERSST) confirmed that the population declined during warm periods and increased during cool periods, but that the initial decline began before increases in regional ERSST. Population growth after 1996 appears related to the current global warming hiatus, lower ERSST, and increased abundance of a key prey species. We predict a continuation of the long-term population decline after warming resumes.

Higher trophic level prey does not represent a higher quality diet in a threatened seabird: implications for relating population dynamics to diet shifts inferred from stable isotopes

Diet quality is a key determinant of population dynamics. If a higher trophic level, more fish-based diet is of higher quality for marine predators, then individuals with a higher trophic level diet should have a greater body mass than those feeding at a lower trophic level. We examined this hypothesis using stable isotope analysis to infer dietary trophic level and foraging habitat over three years in eastern rockhopper penguins Eudyptes chrysocome filholi on sub-Antarctic Campbell Island, New Zealand. Rockhopper penguins are ‘Vulnerable’ to extinction because of widespread and dramatic population declines, perhaps related to nutritional stress caused by a climate-induced shift to a lower trophic level, lower quality diet. We related the stable nitrogen (δ15N) and carbon (δ13C) isotope values of blood from 70 chicks, 55 adult females, and 55 adult males to their body masses in the 2010, 2011, and 2012 breeding seasons and examined year, stage, age, and sex differences. Opposite to predictions, heavier males consumed a lower trophic level diet during incubation in 2011, and average chick mass was heavier in 2011 when chicks were fed a more zooplankton-based, pelagic/offshore diet than in 2012. Contrary to the suggested importance of a fish-based diet, our results support the alternative hypothesis that rockhopper penguin populations are likely to be most successful when abundant zooplankton prey are available. We caution that historic shifts to lower trophic level prey should not be assumed to reflect nutritional stress and a cause of population declines.

Floral biology and flower visitors on subantarctic Campbell Island

Island plants often show reduced floral pigmentation and display size compared with mainland relatives, which is commonly thought to relate to a lack of specialized pollinators. Some species on New Zealand's subantarctic islands have spectacular, highly pigmented inflorescences, yet the depauperate insect fauna provides little apparent opportunity for biotic pollination. We document breeding systems and floral visitors for six Campbell Island species. All species tested had lipid-rich rather than starchy pollen and some produced nectar. Pleurophyllum hookeri appeared to be self-incompatible, but P. criniferum, Veronica benthamii and Damnamenia vernicosa were all capable of selfing. Daytime floral visitors were predominantly small Diptera and the flightless Muscid, Coenosis filipennis. The nocturnal wētā, Notoplectron campbellensis (Orthoptera), visited V. benthamii flowers and carried pollen between male and female plants of Anisotome latifolia and Bulbinella rossii. Biotic pollination might be more important in the subantarctic than previously thought and wētā are possibly key flower visitors.

Environmental barcoding of the ectomycorrhizal fungal genus Cortinarius

Understanding the role of ectomycorrhizal fungi in plant communities is hampered by a lack of knowledge about fungal diversity. DNA barcoding of the ectomycorrhizal fungal genus Cortinarius was used to compare fungal diversity in soil from four plant communities: (i) Nothofagus forest (where Cortinarius is common and diverse), (ii) Kunzea forest (where Cortinarius is present but with low diversity), (iii) a Pinus radiata plantation (Cortinarius is not thought to be present) and (iv) a sub-Antarctic island (where known ectomycorrhizal hosts are absent). PCR primers specific for the ITS region of Cortinarius species were developed. Specificity was tested in vitro and in silico against DNA from basidiocarps of Cortinarius and non-Cortinarius species. The primers were tested for their ability to amplify Cortinarius DNA in soil from forests of the three ectomycorrhizal forest communities and a range of soils from the ectomycorrhiza-free subantarctic Campbell Island. High diversity of Cortinarius was associated with soil of all three ectomycorrhizal communities, despite Cortinarius being previously unrecorded from Pinus. Soil from all three communities share some ectomycorrhizal fungi (including fungi shared between native and exotic hosts), having implications for community succession, introduction of exotic fungi and biodiversity assessment. No Cortinarius was detected from Campbell Island samples. The validated molecular protocol assessed species diversity in a rapid and cost effective way. Baseline biodiversity assessment based on DNA barcoding is more effective at detecting diversity than traditional methods, but requires careful consideration of the difference between ectomycorrhizal fungal diversity in soil versus root-tips.

Algal Parasite Herpodiscus durvillaeae (Phaeophyceae: Sphacelariales) Inferred to have Traversed the Pacific Ocean with its Buoyant Host.

The parasitic phaeophycean endophyte Herpodiscus durvillaeae (Lindauer) G. R. South has previously only been recorded from New Zealand, in association with a single host species, Durvillaea antarctica (Chamisso) Hariot (southern bull-kelp). Here we use DNA sequence data from plastid and nuclear markers (chloroplast rbcL, ribosomal LSU, and a nuclear pseudogene copy of COI) to test for the presence of H.durvillaeae beyond the New Zealand region, and on host species other than D.antarctica. Analyses of samples from the Falkland Islands confirm the first record of H.durvillaeae from the Atlantic Ocean. We report that Falkland Islands H.durvillaeae are genetically indistinguishable from samples of this species from New Zealand's sub-Antarctic Campbell Island, suggesting recent dispersal of the parasite across the Pacific Ocean, presumably by rafting with its buoyant macroalgal host. We also here record H.durvillaeae from New Zealand endemics Durvillaea poha Fraser etal. and D.willana Lindauer.

Hermaphroditism and dichogamy in Stilbocarpa polaris (Araliaceae) on Campbell Island

Since its scientific discovery in 1844, the breeding system of Stilbocarpa polaris (Araliaceae) has been described as polygamo-dioecious with either unisexual or hermaphroditic and female flowers. A short study of flower sex expression, on subantarctic Campbell Island, found evidence that all flowers are cosexual, protandrous and strictly dichogamous, such that whole inflorescences are either presenting pollen or stigmas. Circumstantial evidence also suggests that S. polaris is self-compatible but self-fertilisation would be largely avoided by this synchronous dichogamy. Pollination is most likely effected by small diptera which congregate on inflorescences.

Past diversity of Proteaceae on subantarctic Campbell Island, a remote outpost of Gondwana

Twelve fossil species of Proteaceous pollen, predominantly attributable to Proteacidites and Beaupreaidites, were recovered from the Maastrichtian–Paleocene sedimentary succession of the Garden Cove Formation on Campbell Island, the southernmost landmass of the Zealandia continent. Among these are two new species, Proteacidites campbellensis and Proteacidites hortisinus. The high diversity of Proteaceae pollen in the sediments encompassing the Cretaceous–Paleogene boundary on Campbell Island is consistent with the fossil record from neighbouring landmasses but strongly contrasts with the impoverished record of the family in the extant New Zealand flora. Examples of Beauprea- and Knightia-like pollen in the Campbell Island assemblages confirm the presence of these lineages on Zealandia by the end of the Cretaceous and suggest that their present endemism in New Caledonia and New Zealand can be explained in terms of relictual vicariant distributions, perhaps modified by northward tracking of warmer climates on Zealandia through the Cenozoic.

New Zealand sub-Antarctic phytoliths and their potential for past vegetation reconstruction

AbstractPhytoliths in the modern vegetation of sub-Antarctic Campbell Island are compared with those in the soil beneath to assess the accuracy of vegetation reconstructions made from dispersed phytolith assemblages. The soil phytoliths alone suggest the source vegetation is a grassland association for all study sites, which reflects none of the herb, fern or shrub component of the overlying vegetation. It is concluded that at this locality dispersed phytoliths on their own are not reliable indicators of source vegetation and should be used with caution in this context for palaeoecological studies. However, they can provide useful botanical information where all other organic material is absent. With further research, based on the abundance and diversity of Poaceae phytoliths observed in this and other studies, dispersed phytoliths from the fossil record have the potential to contribute significantly to the understanding of grassland ecosystem development in the geological past.

Climate, fire, farming and the recent vegetation history of subantarctic Campbell Island

ABSTRACTCampbell Island is a small, uninhabited peat-covered island lying in the cool southern ocean 600 km south of the New Zealand mainland. Dracophyllum scrub is the main cover from sea level to 200 m, above which tussock grassland, macrophyllous forbs and tundra dominate. Seven peat profiles from sea level to the tundra zone provide an elevational transect for pollen and charcoal records spanning the last 500 years. Scrub density was relatively low between 200 and 400 cal yrs BP, possibly due to Little Ice Age cooling, but had recovered by the time Europeans discovered the island in AD 1810. Burning and grazing during a brief farming episode (AD 1895–1931) severely reduced scrub and palatable grasses and forbs. Vegetation recovery is now well advanced following cessation of farming and the later elimination of all feral grazing animals, cats and rats. Climates were cool in the southwest Pacific during the farming period, and since AD 1970 the island has warmed by c. 0·5°C. However, there has been no upwards movement of the scrubline despite vigorous regeneration of scrub at lower altitudes. The island's cloudy, highly oceanic climate appears to offset increasing summer warmth, and scrubline is likely to rise only if clearer and less windy, as well as warmer, summers eventuate.

Phytoliths from subantarctic Campbell Island: plant production and soil surface spectra

Phytolith (plant opal) production, and its preservation within the soil surface, is described for the first time in the subantarctic region from Campbell Island, ca. 600 km south of New Zealand, forming the basis for a new modern reference collection for the region. Plant samples (many from species endemic to the island and vegetation community dominants) were sourced from Campbell Island and from gardens in New Zealand. Short and long cell phytoliths are described from four graminoids ( Chionochloa antarctica, Poa litorosa and Poa sp. (Poaceae), Carex trifida (Cyperaceae)), four forbs ( Acaena minor var. antarctica and Acaena anserinifolia (Rosaceae), Myosotis capitata (Boraginaceae), Anaphalioides bellidioides (Asteraceae)) and a shrub ( Hebe elliptica (Plantaginaceae)) from 23 analysed taxa. The remainder were found to be non-producers, including the distinctive macrophyllous forbs or ‘megaherbs’. Soil surface samples collected with 11 of the plants from Campbell Island contain abundant, predominantly graminoid-type phytoliths. Two-sample Kolmogorov-Smirnov tests indicate the soil surface assemblages beneath different vegetation community types are nevertheless similar to each other. This is interpreted to be a direct result of widespread grasses in the island's vegetation that produce abundant phytoliths of robust morphology. The over-representation of grass phytoliths in the soils may also be explained by the absence of other non-grass phytolith producer taxa in the vicinity of the collection locality, or the dissolution or fragmentation in the soil of fragile forms. Localised concentrations of sedge ‘hat-shaped’ phytoliths in two soil surface samples result in significantly different assemblages from the other collection sites, suggesting that despite the high proportion of grass-type phytoliths, there is still potential for differentiating vegetation community types on Campbell Island on the basis of the dispersed soil surface assemblages. With further knowledge about modern phytolith production in the subantarctic, this technique may then be applied to regional fossil assemblages. The predominantly grass-type phytoliths described during this pilot study differ significantly from the Oligocene and Miocene tree/shrub-dominated assemblage of the Cape Roberts Project cores from the Ross Sea region of Antarctica, interpreted to have been sourced from a vegetation growing in similar, but less oceanic, climatic conditions. The reasons for this disparity, reflected by the terrestrial palynomorph records of previous studies undertaken on the Cape Roberts Project cores and present day Campbell Island pollen rain, remain unclear, but may involve differences in the growing environment or different continental origins of elements of the vegetation.

Recent spread of Dracophyllum scrub on subantarctic Campbell Island, New Zealand: climatic or anthropogenic origins?

AbstractAim The vegetation of subantarctic Campbell Island consists mainly of lowland Dracophyllum scrub and upland tussock grassland and tundra. Soon after the island was discovered in 1810, occupation by sealers and whalers led to localized burning and cutting of scrub. Further burning and cutting took place as a result of sheep farming between 1894 and 1931. Since the earliest photographs and vegetation descriptions of the island in the late nineteenth century, scrub cover has expanded markedly. Also, since the 1960s, the island has become warmer and drier. The aim of this paper is to quantify scrub changes as depicted in photo‐sequences from the island, and to establish if the spread of scrub is a result of the cessation of anthropogenic activities or a response to global warming.Location Campbell Island, an isolated island 600 km south of New Zealand mainland (52°33.7′S, 169°09′E).Methods Changes in scrub cover in the island were established through analysis of 33 photographic sequences in the island, the earliest photos dating back to 1888. Visual estimates were made of percentage woody cover in matching areas of repeat photographs, and of changes in scrub distribution with altitude and landscape type.Results Dracophyllum scrub was restricted at the time of the first photographs (1888) relative to its present extent, and earlier written observations suggest that there had been little change from the 1840s. Scrub cover has subsequently increased in most areas. Most of the spread occurred after the cessation of farming. Change has mostly consisted of a thickening and expansion of pre‐existing scrub patches. There is no indication that the upper elevational limit of scrub has increased.Main conclusions Initial reduction of scrub was probably due to anthropogenic fire in the early nineteenth century, although it is possible that less favourable climates had also restricted its distribution. Failure of the scrub to regenerate significantly between 1840 and c. 1895 may also have been a consequence of generally cooler, wetter climates at this time. Rapid scrub expansion began between the end of farming and burning in 1931 and 1988 when the remaining feral sheep were removed. Sheep grazing in the absence of fire reduced competition, and encouraged regeneration and growth of woody scrub. Spread was probably assisted by a pronounced shift to warmer, drier climates in the second half of the twentieth century. Upper elevational limits of scrub have not increased, suggesting that factors other than summer temperature are controlling scrub line in this superoceanic environment.

Zoosporic fungi from subantarctic Campbell Island

Eight species of zoosporic fungi (Catenophlyctis variabilis, Karlingia rosea, Cladochytrium tenue, Rhizophlyctis mastigotrichis, Chytriomyces hyalinus, Saprolegnia ferax, S. diclina, and Phythium monospermum) were isolated from soil and water samples collected on subantarctic Campbell Island. All are new records for the New Zealand subantarctic islands, and two (R. mastigotrichis and S. diclina) have not yet been recorded from mainland New Zealand.

From small Maria to massive Campbell: Forty years of rat eradications from New Zealand islands

Over the last four decades the eradication of rats from islands around New Zealand has moved from accidental eradication following the exploratory use of baits for rat control to carefully planned complex eradications of rats and cats (Felis catus) on large islands. Introduced rodents have now been eradicated from more than 90 islands. Of these successful campaigns, those on Breaksea Island, the Mercury Islands, Kapiti Island, and Tuhua Island are used here as case studies because they represent milestones for techniques used or results achieved. Successful methods used on islands range from bait stations and silos serviced on foot to aerial spread by helicopters using satellite navigation systems. The development of these methods has benefited from adaptive management. By applying lessons learned from previous operations the size, complexity, and cost effectiveness of the campaigns has gradually increased. The islands now permanently cleared of introduced rodents are being used for restoration of island‐seabird systems and recovery of threatened species such as large flightless invertebrates, lizards, tuatara, forest birds, and some species of plants. The most ambitious campaigns have been on remote subantarctic Campbell Island (11 300 ha) and warm temperate Raoul Island (2938 ha), aimed to provide long‐term benefits for endemic plant and animal species including land and seabirds. Other islands that could benefit from rat removal are close inshore and within the natural dispersal range of rats and stoats (Mustela erminea). Priorities for future development therefore include more effective methods for detecting rodent invasions, especially ship rats (Rattus rattus) and mice (Mus musculus), broader community involvement in invasion prevention, and improved understanding of reinvasion risk management.