Crozet Islands Research Articles

Population and survival trends of Wandering Albatrosses (Diomedea exulans) breeding on Macquarie Island

Wandering Albatrosses (Diomedea exulans) are globally threatened owing to declines in populations, and the breeding population of Macquarie Island is particularly vulnerable as it comprises fewer than 20 breeding pairs. We describe population trends of Macquarie Island Wandering Albatrosses between 1955 and 2004, combining long-term population data with demographic data collected between 1995 and 2004. Rates of annual breeding effort and survival varied markedly over time and breeding numbers declined from a peak in 1968 to near extinction in the mid-1980s. Underlying this decline was a significant decrease in juvenile survival and, to a lesser extent, adult survival. These changes in survival coincided with changes in long-line fishing effort in the Southern Ocean. Breeding numbers slowly recovered on Macquarie Island through the late 1980s and 1990s, reaching a total of 19 breeding pairs in the mid-1990s. The population remained at about this level in 2004. Relative trends in numbers and survival in the population are similar to those observed in other populations in the Indian Ocean, including Marion Island and Iles Crozet.

Fault dynamics of Indian Ocean earthquakes derived from the array analysis of T-waves

The Great Sumatran earthquake of 26 December 2004 generated some of the largest and longest T-waves ever recorded, and certainly the largest T-waves recorded on modern high-dynamic range hydrophones. For example, the recordings at the Diego Garcia hydroacoustic array indicate a T-wave duration of approximately 15 min. Array processing of these signals by many investigators indicates that the T-wave generation started near the earthquake epicenter and propagated northwest along the trench for nearly 600 km. This corresponds to the faulting zone defined by the aftershock distribution. A dataset of T-wave recordings of Indian Ocean earthquakes has been examined, covering the period 2001 to the present, including events on the oceans ridges and trenches, as well as some interplate events. The recordings were made at Diego Garcia, Cape Leeuwin, and Crozet Island. Event sizes range from magnitude 4 to 8. Bearing versus time is derived via intersensor cross correlations with a time resolution of 0.010 s, corresponding to a bearing resolution of 0.4 deg. Examples of events along the Sumatran Trench are shown with extended T-wave source areas, from which estimates of fault length and rupture velocity are made. These studies further demonstrate the utility of T-phases for understanding seismic source dynamics.

Massive breeding failures following a tsunami in a colonial seabird

Natural catastrophic events such as tsunamis may induce drastic decreases in breeding success of animal populations. We evaluate the impacts of flooding on the reproductive success of king penguins (Aptenodytes patagonicus) in the Crozet Archipelago. On 26 December 2004, a magnitude-9 earthquake created a large tsunami that flooded a colony at 6,500 km from the epicentre of the earthquake. On 30 January 2005, severe waves again flooded the colony. About 17–20% of the surface of the colony was impacted during each flood and 44% of the breeding birds abandoned their egg or chick following the two floodings. Although about 11% of birds laid another egg after the tsunami, none reproduced again after the second flood that happened later in the breeding season. Our results show that the tsunami directly affected the reproductive success of seabirds nesting near the coast.

Influence of substratum on the degradation processes in diesel polluted sub-Antarctic soils (Crozet Archipelago)

Biodegradation by naturally occurring populations of microorganisms is a major mechanism for the removal of oil hydrocarbons from the environment. Therefore, follow-up of bacterial populations and chemical indices of biodegradation are important components of contaminated site assessment studies. Over a 4-year period following an accidental diesel contamination of the sub-Antarctic Crozet Archipelago (51°51′E–46°25′S), a field study was carried out in the contaminated area that is located in a transition zone between an arid fell-field (upstream) and a wet vegetated area (downstream). This study included a monitoring of heterotrophic and hydrocarbon-degrading bacterial abundance and chemical analysis of the remaining hydrocarbons. Significant higher number of heterotrophic and hydrocarbon-degrading bacterial counts revealed a rapid acclimation of sub-Antarctic microbial soil communities to the diesel fuel contamination. A chemical survey conducted during the last 2 years (2002 and 2003) showed that the total extractable hydrocarbons (TPH) content in arid fell field was reduced to ≤50% of their value while it was reduced only to ≤65% in vegetated soil. In addition, the decrease of TPH was always higher in the presence of fertilizer in the arid contaminated area, while fertilizer addition was almost inefficient in the wet contaminated one. All these results demonstrate a serious influence of the soil properties on the degradation rate. However, all chemical indices showed a significant reduction of alkanes and light aromatics in both contaminated area confirming a regular oil degradation process.

Alloparental feeding in the king penguin

We investigated allofeeding (feeding of offspring by adults other than their own parents) in the king penguin, Aptenodytes patagonicus, a long-lived pelagic bird that faces severe food shortages during its reproduction and in which parents leave their fasting chick in dense creches. A 1-year monitoring of 103 breeding pairs and 70 chicks was carried out in a colony in the Crozet Archipelago. We examined whether allofeeding was common enough to alter survival costs or benefits for both the allofed chicks and the allofeeders. Twenty-two per cent of marked adults allofed more than 65% of all the chicks without repeatedly feeding the same chick. Allofeeding in king penguins benefited allofed chicks by increasing their survival, yet little or no fitness cost was detected among allofeeders. We identified proximal factors affecting allofeeding: (1) the breeding conditions of the population were not unusual; (2) allofeeding occurred mostly when parental provisioning was low; (3) alloparents did not respond to increased begging by regurgitating more meals; (4) allofeeders were mostly failed breeders, although successful breeders occasionally allofed; (5) when the colony was no longer organized into breeder territories, allofeeders preferentially fed chicks that had been reared by close neighbours at the time of brooding.

A new species of the genus Paralomis (Crustacea: Decapoda: Lithodidae) from the Spiess seamount near Bouvet Island (Southern Ocean), with notes on habitat and ecology

A new species of the genus Paralomis, Paralomis elongata, has been collected from the Spiess seamount near Bouvet Island in the Southern Ocean. The species shows close affinity with P. anamerae Macpherson, 1988, from the Patagonian Shelf, P. africana Macpherson, 1987, from the south-western African shelf, and P. aculeata Henderson, 1888, from Crozet Islands. Morphological differences among the species and ecological characteristics are discussed.

Albatross Long-Distance Navigation: Comparing Adults And Juveniles

Albatrosses are known for their extreme navigation performance enabling them to locate isolated breeding islands after long-distance migrations across open seas. Little is known about the migration of young albatrosses and how they reach the adults' navigation and foraging skills during the period of immaturity lasting several years and spent permanently flying across the open ocean. We tracked by satellite telemetry the dispersal and migration of 13 juvenile wandering albatrosses from the Crozet Islands during their first year at sea. The young albatrosses covered an average distance of 184,000 km during the first year, restricting their dispersal movement to the unproductive and low wind subtropical Indian Ocean and Tasman Sea. The juveniles initiated the migration by an innate phase of rapid dispersal encoded as a fixed flight direction assisted by southerly winds towards north and northeast. Thereafter each individual restricted its movement to a particular zone of the ocean that will possibly be used until they start breeding 7–10 years later and return in contact with breeding adults. This dispersal in young birds corresponds well with movements observed for adult non-breeding wandering albatrosses. The results show clearly an inherited ability to navigate back to already visited areas in young wandering albatrosses. The juvenile dispersal behaviour and migration at sea suggest a genetically based migration program, encoding navigation to a destination area used throughout the life.

Genetic affinities of newly sampled populations of Wandering and Black-browed Albatross

This study extends previous phylogeographic genetic studies of the Black-browed and Wandering Albatross species complexes through the addition of newly acquired genetic data from wandering-type albatrosses on Macquarie Island and Black-browed Albatrosses (Thalassarche melanophrys) on Macquarie Island and the Chilean islands of Diego de Almagro and Ildefonso. DNA sequencing of Domain I of the mitochondrial control region showed that the wandering-type albatrosses on Macquarie Island belong to the Diomedea exulans group and show close genetic affinity to populations on the Prince Edward and Crozet Islands. The populations of Black-browed Albatrosses on Diego de Almagro, Ildefonso and Macquarie Islands all fell into a distinct grouping that also included birds from Diego Ramirez, South Georgia and Kerguelen Islands. Both the Wandering and Black-browed species complexes show multiple distinct lineages, some with disjunct geographical distributions. We suggest that this is a consequence of prolonged isolation of populations during the Late Pleistocene followed by range expansion of D. exulans and T. melanophrys after glacial retreat from many subantarctic islands. Both species most likely dispersed from populations centred in the southern Indian Ocean.

A new application for transponders in studying penguins

Abstract We developed an identification setup enabling automatic detection of the passage of free-living King Penguins implanted with small radio frequency transponders at Possession Island, Crozet Archipelago. An unique feature of the system is the use of antennas allowing automatic detection and identification on pathways up to 8-m wide without the use of flipper bands. We present results on demographic parameters of the King Penguin, and we found an unexpectedly survival rate of immature penguins. Such an identification system can be used for other birds, mammals, or reptiles that use regular pathways.

Differences in foraging strategy and maternal behaviour between two sympatric fur seal species at the Crozet Islands

Marine top-predators such as marine mammals forage in a heterogeneous environment according to their energetic requirements and to the variation in environmental characteristics. In this study, the behaviour of breeding females in 2 sympatric fur seal species, Antarctic fur seal Arctocephalus gazella and Subantarctic fur seal A. tropicalis, was investigated in relation to foraging effort. Foraging effort was hypothesised to be greater in Antarctic fur seal than in Subantarctic fur seal due to their shorter lactation period. Using satellite telemetry, time-depth recorders and satellite images of sea-surface temperature and chlorophyll a concentration, the foraging grounds, the at-sea activity budgets and the environmental features were determined for both species breeding on the Crozet Archipelago. Foraging cycle duration was similar for the 2 species, and the seals exhibited similar at-sea activity budgets. Only the proportion of time spent at sea was higher in Antarctic fur seals. Separate foraging areas were identified for the 2 species. Antarctic fur seal distribution was related to bathymetric features, while we did not find any direct relationship between chlorophyll a concentration and seal foraging areas. Our results suggest that Antarctic fur seals tend to respond to the higher needs of their pups by having a higher foraging efficiency and concentrating their foraging activity in the most productive areas.

Mercury concentrations in king penguin (Aptenodytes patagonicus) feathers at Crozet Islands (sub‐Antarctic): Temporal trend between 1966–1974 and 2000–2001

Remote sub-Antarctic islands and their wildlife may be contaminated by mercury via atmospheric and oceanic currents. Because of mercury's high toxicity and its capacity to be biomagnified in marine food chains, top predators like seabirds may be threatened by secondary poisoning. The present study provides data regarding mercury concentrations in breast feathers sampled in 2000 and 2001 on king penguins (Aptenodytes patagonicus) living at Crozet Islands. These contemporary concentrations were compared to those measured in feathers of king penguins sampled in the same colony between 1966 and 1974 and preserved in a museum (1970s sample). The average concentration of the contemporary sample is 1.98 microg g(-1) (dry mass) and is significantly different than the concentrations reported in some other penguin species. The concentration of the contemporary sample is significantly lower than the concentration of the 1970s sample (2.66 microg g(-1)). This suggests that mercury concentrations in southern hemisphere seabirds do not increase, which conflicts with the trends observed in the northern hemisphere. This difference in temporal trends between the northern and southern hemispheres usually is attributed mainly to a higher degree of pollutant emission in the northern hemisphere. Parameters that may explain the interspecies differences in mercury concentrations are discussed. These first results may constitute a basis for further ecotoxicological and/or biomonitoring studies of king penguins in these remote ecosystems.

Freshwater Testate Amoebae Communities from Île de la Possession, Crozet Archipelago, Subantarctica

An ecological study of the freshwater testate amoebae (Protozoa, Rhizopoda) on the subantarctic island Île de la Possession (Crozet Archipelago) revealed 85 taxa, belonging to 21 genera. Twenty-two taxa belonged to the genus Difflugia, typical for freshwater habitats whereas the genus Trinema showed the highest relative abundance. A cluster analysis revealed two communities: a Difflugiella crenulata assemblage and a Trinema lineare–T. enchelys assemblage. These communities, together with the results of a RDA analysis, represented a clear geographical separation on the island. The Difflugiella crenulata assemblage typified locations, with a high specific conductance and neutral to alkaline pH values, on the western part of the island. Aquatic habitats in the larger valleys on the eastern side of Île de la Possession, with a low conductivity and slightly acid pH values, were characterized by the Trinema assemblage. Weighted averaging and calibration were used to develop a statistical transfer function to infer the pH of freshwater bodies from the testate amoebae assemblages. The model is usable over a pH range of 5 to 9.

Noise characterization at the international station of Crozet Islands (H04)

In the context of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), the hydroacoustic network gives the ability to state parties to check the natural and artificial activity in the oceans. To achieve this purpose, 11 hydroacoustic stations are going to be established. One of these stations has recently been launched by the CEA (France) near the Crozet Islands in the Indian Ocean. In this paper, we characterize the ambient noise of this new station. This study will enable one to estimate the detectability of the station. In this analysis, we associate the tide height with the noise level on the recorded signals. The lunar calendar perfectly matches the hydroacoustic noise variation. In addition, we will show the influence of this noise evolution on the rate of detection. In order to have a good statistic, we process a hundred days of data (recorded at 250 Hz). The tide heights supplied by ‘‘le Laboratoire de gophysique et Ocanographique de Toulouse,’’ are sampled with a 1-h step. Furthermore, the spectral characteristic of the ambient noise is also given. Finally, a comparison with other international stations, Diego Garcia (H08) and Cape Leeuwin (H01), is given.

The moss dwelling testacean fauna of Île de la Possession

An ecological study of the moss dwelling testacean fauna (Protozoa, Rhizopoda) on Ile de la Possession (Crozet Archipelago, sub-Antarctica) revealed 83 taxa, belonging to 21 genera. The moss flora was dominated by cosmopolitan and ubiquitous taxa, such as Trinema lineare, T. enchelys, Euglypha laevis and E. rotunda. A cluster analysis and a correspondence analysis identified three communities: (1) a Corythion dubium assemblage found in a drier, slightly acidic terrestrial moss vegetation, (2) the Arcella arenaria, and (3) the Difflugiella crenulata assemblages, both characteristic of wetter, circumneutral habitats. The latter typified submerged mosses growing in running water, while the A. arenaria assemblage seemed to prefer mosses in standing waterbodies. Moisture conditions appeared to play a key role in determining the distribution pattern of testacean communities, while pH was only a secondary factor. A logistic regression emphasised the effect of the habitat type in controlling the variance in testacean assemblages. Moreover, the close relationship between bryophyte species and habitat type had a significant influence on the distribution pattern of the testate amoebae. Weighted averaging and calibration were used to estimate moisture optima and tolerances of the testate amoebae.

Long-term trends in the population size of king penguins at Crozet archipelago: environmental variability and density dependence?

We examined the growth rate of the breeding population of king penguins of Crozet archipelago over 41 years. Most colonies showed positive growth rates from the 1960s. However, there was evidence for a decrease in the larger colonies since the early 1990s, and for lower growth rates in the smaller colonies during the 1990s. The overall population size was estimated using log linear models, and the average annual growth rate was +6.3% for the 41-year period. Four change points were detected in the annual growth rate: +21.1% during 1978-1985, +4.3% during 1985-1995, � 19.2% during 1995-1999, and +10.9% during 1999-2003. Time-series analyses of the population-size estimates and the rela- tionship between growth rate and population size both indicated density-dependence in population growth rate. Variations in population sizes are also discussed in relation to environmental fluctuations. Our results sug- gest that important changes occurred over the past 10 years.

Trichomycete symbiotes of Crozetia seguyi, a primitive black fly

Crozetia is a genus of black flies endemic to the Crozet Islands in the Indian Ocean. No internal symbiotes were previously known from Crozetia species. We report two species of trichomycete symbiotes Stachylina litoralis and Smittium culicisoides from Crozetia seguyi. Larvae of C. seguyi were examined from three sites. The infection rates for St. litoralis was 10.0–33.3% ( n = 47) of the larvae and Sm. culicisoides was 46.1–85.7% ( n = 47). No other symbiotes were discovered.

Spatial, Temporal and Interannual Variability of Methanesulfonate and Non-Sea-Salt Sulfate in Rainwater in the Southern Indian Ocean (Amsterdam, Crozet and Kerguelen Islands)

Methanesulfonate (MS−) and non-sea-salt sulfate (nss-SO42−), two of the major oxidation products of atmospheric dimethylsulfide (DMS), have been continuously measured in rainwater at three remote islands in the Southern Indian Ocean: Amsterdam since 1991, Crozet since 1992, and Kerguelen since 1993. The annual volume weighted mean (VWM) concentrations of nss-SO42− in rainwater were 3.19, 3.04 and 4.57 μ eq l−1 at Amsterdam, Crozet, and Kerguelen, respectively while the VWM of MS− were 0.24, 0.15 and 0.30 μ eq l−1, respectively. At all three islands, MS− presented a well-distinguished seasonal variation with a maximum during summer whereas the seasonal variation of nss-SO42− was less pronounced, possibly due to the increased anthropogenic influence during the winter period. Furthermore, MS− presented significant interannual variations, in particular at Amsterdam and Crozet, which is closely related to the sea-surface temperature (SST) anomalies). Finally, the nss-SO42− deposition at Crozet Island presented a decreasing interannual trend, reflecting probably reductions in sulfur emissions from Southern Africa. On the contrary no interannual tendency was observed in the nss-SO42− concentrations at Amsterdam Island, indicating that the biogeochemical sulfur cycle at this area is mainly influenced by biogenic emissions.

A new species and new records of lithodid crabs (Crustacea: Decapoda: Lithodidae) from the Crozet and Kerguelen Islands area (Subantarctica)

Four species of lithodid crabs from waters (240–2,005 m) in the Crozet and Kerguelen Islands area were studied. One new species, Neolithodes duhameli, is described. Three other species, N. capensis Stebbing, Paralomis anamerae Macpherson and P. birsteini Macpherson are reported for the first time from these localities. The new species, N. duhameli (620–1,500 m), is the fourth representative of the genus in Subantarctic waters and belongs to the group of species possessing a carapace, chelipeds and walking legs covered with numerous spinules or spiniform granules in addition to spines. However, the new species is distinguishable from others in the genus by the long, strong spines on the carapace and pereiopods. The finding of two species of Paralomis clearly extends their geographic ranges in the Southern Ocean: P. anamerae was previously known only in waters of the Falkland Islands and the circumpolar distribution of P. birsteini is supported. The observation of N. capensis also extends its previously described range from South Africa, in the Cape region, to Subantarctic waters. As a result of this study, 14 species of the family Lithodidae are now known from Antarctic and Subantarctic waters; and most can be considered endemic to these waters.

Annual energy budget and food requirements of breeding wandering albatrosses ( Diomedea exulans )

Energy budgets form an integral part of our understanding of animal energetics, particularly when presented in the context of reproduction. In this paper, I created a time-energy budget for a breeding pair of wandering albatrosses (Diomedea exulans) to estimate the annual breeding costs and food requirements of the population at Possession Island, Crozet Archipelago. For a breeding cycle that lasts 356 days on average, a pair uses 2,733 MJ to raise a single chick to fledging. This estimate is 1.21 times higher than previously calculated for wandering albatrosses breeding at Marion Island. Unlike the current analysis, the previous study assumed that foraging costs were constant across all stages of the breeding cycle. Recent evidence shows that foraging costs vary during breeding for wandering albatrosses at Crozet and this is probably true for all populations. Incubation costs have also been shown to be substantially lower than previously determined. Therefore, if a wandering albatross pair at Crozet uses a total of 2,733 MJ to breed, they would need to consume at least 1.7 kg bird−1 day−1 of fresh food, on average, to balance their own energy requirements and to provision a single chick for approximately 278 days. At this rate of food consumption, the breeding population at Crozet would consume approximately 340 tonnes of fresh food per breeding season.

Growth and energy expenditure of Wandering AlbatrossDiomedea exulanschicks

Wandering AlbatrossDiomedea exulanschicks require 9–10 months to achieve adult body size at fledging, at which time they are also sexually size dimorphic. Because the developmental period spans the winter season, chicks must endure severe winter conditions and variability in provisioning effort by their parents. Thus chicks may adjust their rate of energy utilization to accommodate variations in provisioning, but this has not previously been studied. We followed longitudinally the changes in growth, body composition and oxygen consumption of 10 chicks from the end of the brooding period until fledging on the Crozet Islands. Body mass, culmen length and wing length were measured every 10 days and total body water (TBW) and resting metabolic rate (RMR) were measured monthly. Overall growth followed a logistic curve for all chicks, and sexual dimorphism in body mass appeared as early as the second month of measurements (males being heavier than females). Absolute TBW followed a logistic increase like that of body mass and was significantly higher in males owing to the difference in body mass. Conversely, mass‐specific TBW (i.e. the proportion of body mass made up of water) did not differ significantly between male and female chicks. Absolute RMR peaked at 1.5 × adult basal metabolism in midwinter when chicks achieved maximum body mass, but decreased to adult levels by the time chicks fledged. The decrease in absolute RMR following attainment of peak mass is atypical of most seabird chicks (Procellariiformes) and may be explained partly by a reduction in size of the gut when parents reduce provisioning effort. The changes in mass‐specific RMR did not differ between sexes but male chicks, being heavier, had higher absolute oxygen consumption and therefore greater energy requirements.