Amsterdam Island Research Articles

Cladistic classification of Mecyclothorax Sharp (Coleoptera, Carabidae, Moriomorphini) and taxonomic revision of the New Caledonian subgenus Phacothorax Jeannel

The 15 species of Mecyclothorax Sharp precinctive to New Caledonia are revised and shown by cladistic analysis to comprise a monophyletic lineage, here treated as subgenus Phacothorax Jeannel. The New Caledonian species of subgenus Phacothorax include Mecyclothorax fleutiauxi (Jeannel), M. najtae Deuve, and 13 newly described species: M. jeanneli sp. n., M. laterobustus sp. n., M. laterorectus sp. n., M. laterosinuatus sp. n., M. laterovatulus sp. n., M. manautei sp. n., M. megalovatulus sp. n., M. octavius sp. n., M. paniensis sp. n., M. picdupinsensis sp. n., M. plurisetosus sp. n., and two jointly authored species; M. kanak Moore & Liebherr sp. n., and M. mouensis Moore & Liebherr sp. n.. subgenus Phacothorax is one of five subgenera recognized within genus Mecyclothorax based on cladistic analysis of 65 exemplar taxa utilizing information from 137 morphological characters. The four other monophyletic subgenera include the precinctive Australian Eucyclothorax subgen. n. (type species Mecyclothorax blackburni [Sloane]), the precinctive Queensland Qecyclothorax subgen. n. (type species Mecyclothorax storeyi Moore), the precinctive New Zealand Meonochilus Liebherr & Marris status n., and the geographically widespread and very diverse nominate subgenus, distributed from St. Paul and Amsterdam Islands, eastward across Australia and New Guinea, and in the Sundas, Timor Leste, Lord Howe and Norfolk Islands, New Zealand, and the Society and Hawaiian Islands. The biogeographic history of Mecyclothorax can be derived from the parsimony cladogram time-calibrated by times of origin of particular geographic areas inhabited by resident representative species. Based on sister-group status of subgenus Phacothorax and subgenus Mecyclothorax, and occupation of Lord Howe Island–an island originating no earlier than 6 Ma–by the earliest divergent lineage within subgenus Mecyclothorax, the ancestor of present-day Phacothorax spp. is hypothesized to have colonized New Caledonia 6 Ma, subsequent both to Cretaceous Gondwanan vicariance as well as any Oligocene submergence. Area relationships among the New Caledonian Phacothorax point to earliest diversification incorporating the northern massifs, and most recent diversification on the ultramafic volcanic substrates in the south of Grand Terre. Flight wing loss has played an important role in shaping the various island faunas, both in their morphology as well as their diversity. The retention of flight capability in only a few of the many hundred Mecyclothorax spp. is presented in light of how populations evolve from macropterous colonizing propagules to vestigially winged specialists. Interspecific differences in genitalic structures for the sister-species pair M. fleutiauxi + M. jeanneli are shown to involve functional complementarity of male and female structures. Extensive geographic variation of male genitalia is demonstrated for several New Caledonian Mecyclothorax spp. This variation deviates from the geographically uniform male genitalia exhibited by species in the hyperdiverse Mecyclothorax radiation of Haleakalā volcano, Maui, suggesting that extensive sympatry occurring among species in that diverse species swarm selects for stability within this mate recognition system. Conversely, lower levels of sympatry characterizing the depauperate New Caledonian radiation permit the presence of more extensive male genitalic variation, this variation not selected against due to the lower likelihood of interspecific mating mistakes.

Cladistic classification of Mecyclothorax Sharp (Coleoptera, Carabidae, Moriomorphini) and taxonomic revision of the New Caledonian subgenus Phacothorax Jeannel

The 15 species of Mecyclothorax Sharp precinctive to New Caledonia are revised and shown by cladistic analysis to comprise a monophyletic lineage, here treated as subgenus Phacothorax Jeannel. The New Caledonian species of subgenus Phacothorax include Mecyclothoraxfleutiauxi (Jeannel), M.najtae Deuve, and 13 newly described species: M.jeanneli sp. n., M.laterobustus sp. n., M.laterorectus sp. n., M.laterosinuatus sp. n., M.laterovatulus sp. n., M.manautei sp. n., M.megalovatulus sp. n., M.octavius sp. n., M.paniensis sp. n., M.picdupinsensis sp. n., M.plurisetosus sp. n., and two jointly authored species; M.kanak Moore & Liebherr sp. n., and M.mouensis Moore & Liebherr sp. n.. subgenus Phacothorax is one of five subgenera recognized within genus Mecyclothorax based on cladistic analysis of 65 exemplar taxa utilizing information from 137 morphological characters. The four other monophyletic subgenera include the precinctive Australian Eucyclothorax subgen. n. (type species Mecyclothoraxblackburni [Sloane]), the precinctive Queensland Qecyclothorax subgen. n. (type species Mecyclothoraxstoreyi Moore), the precinctive New Zealand Meonochilus Liebherr & Marris status n., and the geographically widespread and very diverse nominate subgenus, distributed from St. Paul and Amsterdam Islands, eastward across Australia and New Guinea, and in the Sundas, Timor Leste, Lord Howe and Norfolk Islands, New Zealand, and the Society and Hawaiian Islands. The biogeographic history of Mecyclothorax can be derived from the parsimony cladogram time-calibrated by times of origin of particular geographic areas inhabited by resident representative species. Based on sister-group status of subgenus Phacothorax and subgenus Mecyclothorax, and occupation of Lord Howe Island–an island originating no earlier than 6 Ma–by the earliest divergent lineage within subgenus Mecyclothorax, the ancestor of present-day Phacothorax spp. is hypothesized to have colonized New Caledonia 6 Ma, subsequent both to Cretaceous Gondwanan vicariance as well as any Oligocene submergence. Area relationships among the New Caledonian Phacothorax point to earliest diversification incorporating the northern massifs, and most recent diversification on the ultramafic volcanic substrates in the south of Grand Terre. Flight wing loss has played an important role in shaping the various island faunas, both in their morphology as well as their diversity. The retention of flight capability in only a few of the many hundred Mecyclothorax spp. is presented in light of how populations evolve from macropterous colonizing propagules to vestigially winged specialists. Interspecific differences in genitalic structures for the sister-species pair M.fleutiauxi + M.jeanneli are shown to involve functional complementarity of male and female structures. Extensive geographic variation of male genitalia is demonstrated for several New Caledonian Mecyclothorax spp. This variation deviates from the geographically uniform male genitalia exhibited by species in the hyperdiverse Mecyclothorax radiation of Haleakalā volcano, Maui, suggesting that extensive sympatry occurring among species in that diverse species swarm selects for stability within this mate recognition system. Conversely, lower levels of sympatry characterizing the depauperate New Caledonian radiation permit the presence of more extensive male genitalic variation, this variation not selected against due to the lower likelihood of interspecific mating mistakes.

The genus Luticola (Bacillariophyta) on Ile Amsterdam and Ile Saint-Paul (Southern Indian Ocean) with the description of two new species

Five species of the terrestrial diatom genus Luticola D.G.Mann were found during a taxonomic survey of two small volcanic islands, Ile Amsterdam and Ile Saint-Paul (Southern Indian Ocean). Apart from the two already known Luticola species L. beyensii Van de Vijver et al. and L. subcrozetensis Van de Vijver et al., two new species are described: L. ivetana Chattová & Van de Vijver sp. nov. and L. vancampiana Chattová & Van de Vijver sp. nov. Finally, one, up to now unknown, Luticola species is briefly discussed and illustrated. Detailed morphological descriptions of these taxa are provided based on both light and scanning electron microscopy observations. Morphological features of the new species are compared to morphologically similar taxa, and notes on their ecology and biogeography are added.

Ferocia gen. nov., a new centric diatom genus (Bacillariophyceae) from the sub-Antarctic region

A new centric diatom genus, Ferocia Van de Vijver & Houk gen. nov. is described based on Melosira setosa Greville. Several samples collected in lava tunnels on Ile Amsterdam, a small isolated, volcanic island in the southern Indian Ocean where the latter taxon dominated the diatom flora, were investigated. The new genus is characterized by having heavily silicified, spherical frustules, connected into long chains by large, complex linking spines. Valves are dome-shaped with a high mantle with rounded to irregularly shaped areolae. Numerous small rimoportulae forming a marginal ring are present near the mantle edge. The cingulum is composed of a large number of narrow, open copulae. A second species, Ferocia ninae Van de Vijver & Houk sp. nov., is described from the nearby Crozet archipelago. Besides the typical features of the genus Ferocia, the rimoportulae in F. ninae are almost equidistant, the valves have a relatively low valve height and the spines are relatively small. Both F. ninae and F. setosa were found in shaded lava tunnels with a sparse moss vegetation. The two species are illustrated and discussed based on detailed LM and SEM observations.

Rapid Dwarfing of an Insular Mammal \u2013 The Feral Cattle of Amsterdam Island

The island rule describes a graded trend in insular populations of vertebrates from gigantism in small species to dwarfism in large species. The dwarfing of large mammals on islands has been observed both in the present fauna and in the fossil record. Elephants, hippopotami, deer, and other species became dwarfed on islands scattered all over the world, from the Mediterranean Sea to Indonesia, from the Eastern to Western Pacific Ocean, from the Caribbean to Canary Islands. The most rapid and well documented cases of island dwarfing known thus far took place over thousands of years. Here, we describe a rapid example of dwarfing of a large mammal - the feral cattle of Amsterdam Island, southern Indian Ocean, which dwarfed to about three quarters of its body size in slightly more than one century. This population provides us with a rare opportunity to assess the rapidity of demographic, life history, and morphological responses of large mammals to a very isolated and ecologically simple, insular environment.

From Antarctica to the subtropics: Contrasted geographical concentrations of selenium, mercury, and persistent organic pollutants in skua chicks (Catharacta spp.)

Seabirds integrate bioaccumulative contaminants via food intake and have revealed geographical trends of contamination in a variety of ecosystems. Pre-fledging seabird chicks are particularly interesting as bioindicators of chemical contamination, because concentrations in their tissues reflect primarily dietary sources from the local environment. Here we measured 14 trace elements and 18 persistent organic pollutants (POPs) in blood of chicks of skuas that breed in four sites encompassing a large latitudinal range within the southern Indian Ocean, from Antarctica (Adélie Land, south polar skua Catharacta maccormicki), through subantarctic areas (Crozet and Kerguelen Islands, brown skua C. lonnbergi), to the subtropics (Amsterdam Island, C. lonnbergi). Stables isotopes of carbon (δ13C, feeding habitat) and nitrogen (δ15N, trophic position) were also measured to control for the influence of feeding habits on contaminant burdens. Concentrations of mercury (Hg) and selenium (Se) were very high at all the four sites, with Amsterdam birds having the highest concentrations ever reported in chicks worldwide (4.0 ± 0.8 and 646 ± 123 μg g−1 dry weight, respectively). Blood Hg concentrations showed a clear latitudinal pattern, increasing from chicks in Antarctica to chicks in the subantarctic and subtropical islands. Interestingly, blood Se concentrations showed similar between-population differences to Hg, suggesting its involvement in protective mechanisms against Hg toxicity. Chicks’ POPs pattern was largely dominated by organochlorine pesticides, in particular DDT metabolites and hexachlorobenzene (HCB). Skua chicks from subantarctic islands presented high concentrations and diversity of POPs. By contrast, chicks from the Antarctic site overall had the lowest concentrations and diversity of both metallic and organic contaminants, with the exception of HCB and arsenic. Skua populations from these sites, being naturally exposed to different quantities of contaminants, are potentially good models for testing toxic effects in developing chicks in the wild.

Recent 210Pb, 137Cs and 241Am accumulation in an ombrotrophic peatland from Amsterdam Island (Southern Indian Ocean)

Over the past 50 years, 210Pb, 137Cs and 241Am have been abundantly used in reconstructing recent sediment and peat chronologies. The study of global aerosol-climate interaction is also partially depending on our understanding of 222Rn-210Pb cycling, as radionuclides are useful aerosol tracers. However, in comparison with the Northern Hemisphere, few data are available for these radionuclides in the Southern Hemisphere, especially in the South Indian Ocean. A peat core was collected in an ombrotrophic peatland from the remote Amsterdam Island (AMS) and was analyzed for 210Pb, 137Cs and 241Am radionuclides using an underground ultra-low background gamma spectrometer. The 210Pb Constant Rate of Supply (CRS) model of peat accumulations is validated by peaks of artificial radionuclides (137Cs and 241Am) that are related to nuclear weapon tests. We compared the AMS 210Pb data with an updated 210Pb deposition database. The 210Pb flux of 98 ± 6 Bq·m−2·y−1 derived from the AMS core agrees with data from Madagascar and South Africa. The elevated flux observed at such a remote location may result from the enhanced 222Rn activity and frequent rainfall in AMS. This enhanced 222Rn activity itself may be explained by continental air masses passing over southern Africa and/or Madagascar. The 210Pb flux at AMS is higher than those derived from cores collected in coastal areas in Argentina and Chile, which are areas dominated by marine westerly winds with low 222Rn activities. We report a 137Cs inventory at AMS of 144 ± 13 Bq·m−2 (corrected to 1969). Our data thus contribute to the under-represented data coverage in the mid-latitudes of the Southern Hemisphere.

Early‐life density‐dependence effects on growth and survival in subantarctic fur seals

AbstractUnderstanding the regulation of natural populations has been a long‐standing research program in ecology. Current knowledge on marine mammals and seabirds is biased toward the adult component of populations and lacking are studies investigating the juvenile component. Our goal was to estimate demographic parameters on the pre‐weaning stage of a subantarctic fur seal (Arctocephalus tropicalis) population on Amsterdam Island, suspected to be regulated by density‐dependence. The influence of abundance on growth parameters (length and weight) and survival was assessed over a study period spanning 16 years. We evidenced a negative trend in population growth rate when density increased. Density‐dependence models were favored for pup body size and mass growth. Abundance had a clear influence on body length at high population‐density, pups grew slower and were smaller at weaning than pups born in years with low population density. Abundance partly explained pup body mass variation and a weak effect was detected on pre‐weaning survival. The causal mechanisms may be increased competition for food resources between breeding females, leading to a reduction of maternal input to their pups. Our results suggested that pup favored survival over growth and the development of their diving abilities in order to withstand the extreme fasting periods that are characteristic of this fur seal population. This analysis provides significant insight of density‐dependent processes on early‐life demographic parameters of a long lived and top‐predator species, and more specifically on the pre‐weaning stage with important consequences for our understanding of individual long‐term fitness and population dynamics.

Particulate-phase mercury emissions from biomass burning and impact on resulting deposition: a modelling assessment.

Mercury (Hg) emissions from biomass burning (BB) are an important source of atmospheric Hg and a major factor driving the interannual variation of Hg concentrations in the troposphere. The greatest fraction of Hg from BB is released in the form of elemental . However, little is known about the fraction of Hg bound to particulate matter (HgP) released from BB, and the factors controlling this fraction are also uncertain. In light of the aims of the Minamata Convention to reduce intentional Hg use and emissions from anthropogenic activities, the relative importance of Hg emissions from BB will have an increasing impact on Hg deposition fluxes. Hg speciation is one of the most important factors determining the redistribution of Hg in the atmosphere and the geographical distribution of Hg deposition. Using the latest version of the Global Fire Emissions Database (GFEDv4.1s) and the global Hg chemistry transport model, ECHMERIT, the impact of Hg speciation in BB emissions, and the factors which influence speciation, on Hg deposition have been investigated for the year 2013. The role of other uncertainties related to physical and chemical atmospheric processes involving Hg and the influence of model parametrisations were also investigated, since their interactions with Hg speciation are complex. The comparison with atmospheric HgP concentrations observed at two remote sites, Amsterdam Island (AMD) and Manaus (MAN), in the Amazon showed a significant improvement when considering a fraction of HgP from BB. The set of sensitivity runs also showed how the quantity and geographical distribution of HgP emitted from BB has a limited impact on a global scale, although the inclusion of increasing fractions HgP does limit availability to the global atmospheric pool. This reduces the fraction of Hg from BB which deposits to the world’s oceans from 71 to 62 %. The impact locally is, however, significant on northern boreal and tropical forests, where fires are frequent, uncontrolled and lead to notable Hg inputs to local ecosystems. In the light of ongoing climatic changes this effect could be potentially be exacerbated in the future.

Records of pinnipeds in the Mascarene Islands, 1996 - 2014

While no populations of seals are resident in the tropical Indian Ocean, vagrant animals are occasionally sighted in the region. Here we detail two new sightings of pinnipeds in the Mascarene Islands (Mauritius, Reunion and Rodrigues) since 1996 and review a further 15. These include nine records of southern elephant seals ( Mirounga leonina ) and eight of Subantarctic fur seals ( Arctocephalus tropicalis ). A possible increase in the number of vagrants over time may be partially due to changes in sighting effort. The majority of sightings for both species were in the austral winter, the period during which vagrants were most commonly recorded elsewhere. The most recent sightings were a juvenile Subantarctic fur seal on the south east coast of Mauritius in July 2013 and another on La Reunion in August 2014. These animals were underweight and in poor condition, as were most Subantarctic fur seal vagrants to the region. This contrasts with the apparently healthy condition of vagrant southern elephant seals. The origin of vagrants to the Mascarene Islands is unknown but the Iles Kerguelen is a likely source of the southern elephant seals, and Ile Amsterdam and Prince Edward Islands for the Subantarctic fur seals, due to the proximity, the size of their populations and the direction of flow of oceanic currents.

Geographic variation in subantarctic fur seal pup growth: linkages with environmental variability and population density

Abstract Marine predator populations are sensitive to temporal variation in prey availability, but prey dynamics are often difficult to quantify. Long-term measures of offspring growth is a useful performance attribute to gauge the potential demographic direction for such predator populations, especially where other metrics (e.g., population size estimates) are lacking. Subantarctic fur seal ( Arctocephalus tropicalis ) females are central place foragers during a protracted lactation period, and their foraging success determines the growth and vitality of their offspring. Using data spanning over 2 decades, we assessed geographic and temporal variation in growth rates and weaning mass of subantarctic fur seal pups at 2 of the species’ principal populations (Gough and Marion islands) and identified environmental conditions that may, through assumed bottom-up mechanisms, affect body mass at weaning. While Marion Island pups grew at an average rate of between 0.040 and 0.067kg/day early in lactation (comparable to conspecific growth at Amsterdam Island), the mean growth rate at Gough Island (approximately 0.030kg/day) was lower than the growth rate represented by the bottom 5% of the body mass distribution at Marion Island. Notwithstanding substantial interannual variability, we found support for a negative trend in weaning mass at both populations, suggesting a rise in limiting factors that is hypothesized to relate to concurrent local population size increases. Weaning mass tended to be higher when sea surface temperatures were warmer (with a stronger positive effect at Gough Island) and during positive phases of the Southern Oscillation Index (La Niña events), with a stronger positive effect in males. Given the low weaning mass of Gough Island fur seal pups, continued population growth here seems unlikely. While density-dependent regulation appears to have increased in strength at Marion Island, terminating rapid population growth, current weaning weights remain above the physiological limits of growth in subantarctic fur seals.

The subspecies of Antarctic Terns (Sterna vittata) wintering on the South African coast: evidence from morphology, genetics and stable isotopes

Five to seven subspecies of Antarctic Tern (Sterna vittata) are recognised, with at least three (S. v. vittata, S. v. tristanensis and S. v. sanctipauli) wintering in South Africa. Morphological characters used to define these subspecies are not perfectly reliable, but fidelity to nesting site suggests they could be genetically distinct. We used morphological data and DNA to investigate the validity of subspecies. We further used stable isotope analysis of feather samples collected from the non-breeding grounds in South Africa to attempt to ascertain the population of origin. Nuclear and mitochondrial DNA sequence data identified two major genetic clades: one mostly comprised individuals partially or completely matching the morphological description of S. v. tristanensis, the other included individuals from S. v. vittata and S. v. sanctipauli. Stable isotope values indicated that juveniles originated from at least three populations. Irrespective of their morphological and genetic characteristics, most immatures moulted in Antarctic waters, and adults moulted in various habitats. Their colony of origin could not therefore be inferred from stable isotope values from feathers. Results indicate that morphological groupings may reflect a north-south cline across the Indian Ocean. Adequate conservation strategies require rigorous reassessment of the currently accepted subspecies, including DNA analyses of samples from the breeding grounds, particularly on Amsterdam and St Paul Islands.

Atmospheric water-soluble organic nitrogen (WSON) over marine environments: a global perspective

Abstract. To obtain a comprehensive picture of the spatial distribution of water-soluble organic nitrogen (WSON) in marine aerosols, samples were collected during research cruises in the tropical and southern Atlantic Ocean and also in the southern Indian Ocean (Amsterdam Island) for a 1-year period (2005). Samples were analyzed for both organic and inorganic forms of nitrogen, and the factors controlling their levels were examined. Fine-mode WSON was found to play a significant role in the remote marine atmosphere with enhanced biogenic activity, with concentrations of WSON (11.3 ± 3.3 nmol N m−3) accounting for about 84 % of the total dissolved nitrogen (TDN). Such concentrations are similar to those observed in the polluted marine atmosphere of the eastern Mediterranean (11.6 ± 14.0 nmol N m−3). Anthropogenic activities were found to be an important source of atmospheric WSON as evidenced by the levels in the Northern Hemisphere (NH) being 10 times higher than in the remote Southern Hemisphere (SH). Furthermore, the higher contribution of fine-mode WSON to TDN (51%) in the SH, compared to the NH (13%), underlines the important role of organic nitrogen in remote marine areas. Finally, there was a strong association of WSON with dust in coarse-mode aerosols in the NH.

Comparison of mercury concentrations measured at several sites in the Southern Hemisphere

Abstract. Our knowledge of the distribution of mercury concentrations in air of the Southern Hemisphere was until recently based mostly on intermittent measurements made during ship cruises. In the last few years continuous mercury monitoring has commenced at several sites in the Southern Hemisphere, providing new and more refined information. In this paper we compare mercury measurements at several remote sites in the Southern Hemisphere made over a period of at least 1 year at each location. Averages of monthly medians show similar although small seasonal variations at both Cape Point and Amsterdam Island. A pronounced seasonal variation at Troll research station in Antarctica is due to frequent mercury depletion events in the austral spring. Due to large scatter and large standard deviations of monthly average median mercury concentrations at Cape Grim, no systematic seasonal variation could be found there. Nevertheless, the annual average mercury concentrations at all sites during the 2007–2013 period varied only between 0.85 and 1.05 ng m−3. Part of this variability is likely due to systematic measurement uncertainties which we propose can be further reduced by improved calibration procedures. We conclude that mercury is much more uniformly distributed throughout the Southern Hemisphere than the distributions suggested by measurements made onboard ships. This finding implies that smaller trends can be detected in shorter time periods. We also report a change in the trend sign at Cape Point from decreasing mercury concentrations in 1996–2004 to increasing concentrations since 2007.

The rime of the modern mariner: evidence for capture of yellow-nosed albatross from Amsterdam Island in Indian Ocean longline fisheries

Commercial fisheries currently pose a serious threat at sea to the conservation of a number of pelagic seabirds. However, these interactions are complex, and reports on population-specific bycatch in the high seas are scarce. Here we report the case of an Indian yellow-nosed albatross Thalassarche carteri re-sighted on Amsterdam Island after an apparent capture by an Indonesian long-liner, as indicated by a message attached to the bird. This record demonstrates that Amsterdam birds may interact with long-liners indeed, at least during winter, and that such interactions are not systematically lethal. We suggest that bycatch sub-lethal effects should be investigated at colonies with high risks of individual capture at sea.

Global modelling of direct and indirect effects of sea spray aerosol using a source function encapsulating wave state

Abstract. Recently developed parameterizations for the sea spray aerosol source flux, encapsulating wave state, and its organic fraction were incorporated into the aerosol–climate model ECHAM-HAMMOZ to investigate the direct and indirect radiative effects of sea spray aerosol particles. Our simulated global sea salt emission of 805 Tg yr−1 (uncertainty range 378–1233 Tg yr−1) was much lower than typically found in previous studies. Modelled sea salt and sodium ion concentrations agreed relatively well with measurements in the smaller size ranges at Mace Head (annual normalized mean model bias −13% for particles with vacuum aerodynamic diameter Dva < 1 μm), Point Reyes (−29% for particles with aerodynamic diameter Da < 2.5 μm) and Amsterdam Island (−52% for particles with Da < 1 μm) but the larger sizes were overestimated (899% for particles with 2.5 μm < Da < 10 μm) at Amsterdam Island. This suggests that at least the high end of the previous estimates of sea spray mass emissions is unrealistic. On the other hand, the model clearly underestimated the observed concentrations of organic or total carbonaceous aerosol at Mace Head (−82%) and Amsterdam Island (−68%). The large overestimation (212%) of organic matter at Point Reyes was due to the contribution of continental sources. At the remote Amsterdam Island site, the organic concentration was underestimated especially in the biologically active months, suggesting a need to improve the parameterization of the organic sea spray fraction. Globally, the satellite-retrieved AOD over the oceans, using PARASOL data, was underestimated by the model (means over ocean 0.16 and 0.10, respectively); however, in the pristine region around Amsterdam Island the measured AOD fell well within the simulated uncertainty range. The simulated sea spray aerosol contribution to the indirect radiative effect was positive (0.3 W m−2), in contrast to previous studies. This positive effect was ascribed to the tendency of sea salt aerosol to suppress both the in-cloud supersaturation and the formation of cloud condensation nuclei from sulfate. These effects can be accounted for only in models with sufficiently detailed aerosol microphysics and physics-based parameterizations of cloud activation. However, due to a strong negative direct effect, the simulated effective radiative forcing (total radiative) effect was −0.2 W m−2. The simulated radiative effects of the primary marine organic emissions were small, with a direct effect of 0.03 W m−2 and an indirect effect of −0.07 W m−2.

A 2-year record of atmospheric mercury species at a background Southern Hemisphere station on Amsterdam Island

Abstract. Although essential to fully understand the cycling of mercury at the global scale, mercury species records in the Southern Hemisphere are scarce. Under the framework of the Global Mercury Observation System (GMOS) project, a monitoring station has been set up on Amsterdam Island (37°48´ S, 77°34´ E) in the remote southern Indian Ocean. For the first time in the Southern Hemisphere, a 2-year record of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particle-bound mercury (PBM) is presented. GEM concentrations were remarkably steady (1.03 ± 0.08 ng m−3) while RGM and PBM concentrations were very low and exhibited a strong variability (mean: 0.34 pg m−3, range: < detection limit–4.07 pg m−3; and mean: 0.67 pg m−3, range: < detection limit–12.67 pg m−3, respectively). Despite the remoteness of the island, wind sector analysis, air mass back trajectories and the observation of radonic storms highlighted a long-range contribution from the southern African continent to the GEM and PBM budgets from July to September during the biomass burning season. Low concentrations of GEM were associated with southerly polar and marine air masses from the remote southern Indian Ocean. This unique data set provides new baseline GEM concentrations in the Southern Hemisphere midlatitudes while mercury speciation along with upcoming wet deposition data will help to improve our understanding of the mercury cycle in the marine boundary layer.

Bryophytes of Île Amsterdam in the South Indian Ocean: 1. Liverworts

Abstract The liverworts of Ile Amsterdam are surveyed. On the basis of historical collections and specimens collected on the island in 2006 and 2007 some 29 species and one variety belonging to 18 families have been recorded. This means that in comparison with the last survey of the island's hepatics, in 2002, the number of taxa has been nearly doubled. Of these, eight taxa are recorded for the first time from the island, namely Kurzia capillaris (Sw.) Grolle subsp. Stephanii (Renauld ex Steph.) Pos, Adelanthus lindenbergianus (Lehm.) Mitt., Syzygiella colorata (Lehm.) K.Feldberg, Vaňa, Hentschel et J.Heinrichs, S. sonderi (Gottsche) K.Feldberg, Vaňa, Hentschel et J.Heinrichs, Cephaloziella varians (Gottsche) Steph., Anastrophyllum auritum (Lehm.) Steph., Andrewsianthus marionensis (S.W.Arnell) Grolle and Heterogemma patagonica (Herzog et Grolle) L.Soderstr. et Vaňa, whilst Aneura subcanaliculata R.M.Schust. is excluded from the island's hepatic flora. Two taxa, Kurzia capillaris subsp. Stephanii and Gymn...

Pollution, habitat loss, fishing, and climate change as critical threats to penguins.

Cumulative human impacts across the world's oceans are considerable. We therefore examined a single model taxonomic group, the penguins (Spheniscidae), to explore how marine species and communities might be at risk of decline or extinction in the southern hemisphere. We sought to determine the most important threats to penguins and to suggest means to mitigate these threats. Our review has relevance to other taxonomic groups in the southern hemisphere and in northern latitudes, where human impacts are greater. Our review was based on an expert assessment and literature review of all 18 penguin species; 49 scientists contributed to the process. For each penguin species, we considered their range and distribution, population trends, and main anthropogenic threats over the past approximately 250 years. These threats were harvesting adults for oil, skin, and feathers and as bait for crab and rock lobster fisheries; harvesting of eggs; terrestrial habitat degradation; marine pollution; fisheries bycatch and resource competition; environmental variability and climate change; and toxic algal poisoning and disease. Habitat loss, pollution, and fishing, all factors humans can readily mitigate, remain the primary threats for penguin species. Their future resilience to further climate change impacts will almost certainly depend on addressing current threats to existing habitat degradation on land and at sea. We suggest protection of breeding habitat, linked to the designation of appropriately scaled marine reserves, including in the High Seas, will be critical for the future conservation of penguins. However, large-scale conservation zones are not always practical or politically feasible and other ecosystem-based management methods that include spatial zoning, bycatch mitigation, and robust harvest control must be developed to maintain marine biodiversity and ensure that ecosystem functioning is maintained across a variety of scales.

First breeding record of the northern giant petrel Macronectes halli at Ile Amsterdam

First breeding record of the northern giant petrel <i>Macronectes halli</i> at Ile Amsterdam