Adaptations of a native Subantarctic flightless fly to dehydration stress: more plastic than we thought? ( Short Communication)

Water conservation is a critical aspect affecting the survival, distribution and abundance of terrestrial arthropods. In this study we investigate mechanisms of dehydration tolerance of the native, flightless fly, Calycopteryx moseleyi, inhabiting contrasting environments at two localities in the Kerguelen Islands. We compare the survival abilities and management of body water content of adult flies from two different ecophenotypes when exposed to conditions of low relative humidity. Our results suggest a broad plasticity in the responses of C. moseleyi to desiccation, showing distinct local adaptations to environmental conditions

Une gamme d'îles de référence, un atout majeur pour l'évaluation de programmes de restauration dans l'archipel de Kerguelen

The Kerguelen Archipelago is constituted by a main island (6 500 km2) and about sixty secondary islands (1-200 km2). Somee of these islands are pristine, while some others have been colonized by introduced plants, invertebrate species and, in some cases, by one or several alien mammals. Programs of ecological restoration began in 1992 on three islands, Verte I., Guillou I. and Cochons I. (respectively 150, 145 and 165 ha) damaged by the presence of mammals (rabbits, rabbits-cats-mice, rabbits-mice). The management action was the eradication of rabbits by poisoning. Due to the existence of reference islands (with or without introduced mammals), and of control islands (presence of rabbits), the Kerguelen Archipelago offers an unusual opportunity to distinguish the effects of the management intervention from those of other factors. For example, synchronised vegetation monitoring of habitats on a control island (Cimetière I., colonized by rabbits) has shown the role of this mammal in controlling one introduced Asteraceae (Taraxacum officinale). After rabbit eradication, this plant drastically increased in cover on the three experimental islands. Moreover, results from Mayes I. (without herbivores) and from the 4 other islands studied, emphasized the impact of the present climatic changes on the evolution of plant communities. This factor explains most of the decrease in cover of several native species, especially Acaena magellanica, with the timing of Dandelion's success linked to open land appearance. These observations confirmed the value of contemporary reference sites to analyze the advantages of restoration programs and to conduct future actionsL'archipel de Kerguelen est constitué d'une île principale (6 500 km2) et d'une soixantaine d'îles secondaires (1-200 km2). Certaines sont totalement indemnes d'espèces introduites, d'autres ont été colonisées par des espèces végétales et des invertébrés allochtones, et d'autres encore sont occupées, de plus, par un ou plusieurs mammifères introduits. Un programme de restauration écologique concernant trois îles (145 à 165 ha) dégradées par la présence de mammifères (lapin, lapin-souris, lapin-chat-souris) a été initié en 1992 par éradication du lapin. Par la présence d'îles de référence (sans herbivore introduit) et d'îles témoin (avec lapin), l'archipel de Kerguelen offre une situation exceptionnelle permettant de distinguer les effets de l'intervention de ceux d'autres facteurs. Le suivi synchronique de la végétation de différentes îles a permis de mettre en évidence, par exemple, le rôle du lapin sur le contrôle d'une Astéracée introduite (Taraxacum officinale) et l'importance des changements climatiques sur les trajectoires d'évolution des communautés végétales. Ces observations ont confirmé l'intérêt de disposer de références contemporaines pour analyser les bénéfices d'opérations de restauration et pour orienter les actions à veni

Spotlight on the invasion of a carabid beetle on an oceanic island over a 105-year period island

The flightless beetle Merizodus soledadinus, native to the Falkland Islands and southern South America, was introduced to the sub-Antarctic Kerguelen Islands in the early Twentieth Century. Using available literature data, in addition to collecting more than 2000 new survey (presence/absence) records of M. soledadinus over the 1991–2018 period, we confirmed the best estimate of the introduction date of M. soledadinus to the archipelago, and tracked subsequent changes in its abundance and geographical distribution. The range expansion of this flightless insect was initially slow, but has accelerated over the past 2 decades, in parallel with increased local abundance. Human activities may have facilitated further local colonization by M. soledadinus, which is now widespread in the eastern part of the archipelago. This predatory insect is a major threat to the native invertebrate fauna, in particular to the endemic wingless flies Anatalanta aptera and Calycopteryx moseleyi which can be locally eliminated by the beetle. Our distribution data also suggest an accelerating role of climate change in the range expansion of M. soledadinus, with populations now thriving in low altitude habitats. Considering that no control measures, let alone eradication, are practicable, it is essential to limit any further local range expansion of this aggressively invasive insect through human assistance. This study confirms the crucial importance of long term biosurveillance for the detection and monitoring of non-native species and the timely implementation of control measures

C3PO: A Network and Application Framework for Spontaneous and Ephemeral Social Networks

International audienceThe C3PO project promotes the development of new kind of social networks called Spontaneous and Ephemeral Social Networks (SESNs) dedicated to happenings such as cultural or sport events. SESNs rely on both opportunistic networks formed dynamically by the mobile devices of event attendees, and on an event-based communication model. Therefore, user can exchange digital contents with the other members of their SESNs, even without Internet access. This paper presents the framework developed in the C3PO project to provide network and application supports in such challenged networks. This framework exploits the different wireless interfaces of the mobile devices to interconnect them and to disseminate content through the resulting opportunistic network. At the application layer, this framework is composed of plugins that process locally the data stream to offer generic features, or to easily build applications dedicated to specific happenings

Résilience des communautés insulaires subantarctiques : facteurs influençant la vitesse de restauration écologique après éradication de mammifères introduits

Cattle were introduced to Amsterdam Island in 1871 and rabbits to the Kerguelen Archipelago in 1874. These herbivorous mammals caused severe damage to these terrestrial ecosystems. Two ecological restoration programs were implemented: cattle eradication from the southern part of Amsterdam Island (55 km2) in 1988 and rabbit eradication from three small islands (145 to 165 ha) at Kerguelen from 1992. On Amsterdam Island, in a temperate climate, the recovery of vegetation depended on the degree of damage caused to the environment by cattle. On the Jess eroded organic soils, recovery of native vegetation (e. g. Poa novarae, Blechnum penna-marina) was observed 10 years after cattle eradication. Conversely, on the thin and eroded mineral soils, an irreversible level of disturbance occurred: vegetation recovery was very slow and introduced plant species (e.g. Holcus lanatus) remained dominant while the cover of autochtonous species (Scirpus nodosus, Blechnum penna-marina) increased very slowly. Due to the cooler climate, ecological restoration processes were slower at Kerguelen than at Amsterdam Island. For some autochtonous species, such as Pringlea antiscorbutica and Azorella selago , presence of refuge areas on cliffs inaccessible to rabbits was important for colonization after rabbi! eradication. Vegetation changes depended greatly on the climatic changes recently recorded (characterised by a slight increase in temperature and more frequent summer drought). In contrast to the autochtonous species, most of the alien plants ( Taraxacum officinale, Senecio vulgaris...), originating from temperate regions, were favoured by these climatic changesL'introduction de bovins en 1871 sur l'île Amsterdam et de lapins en 1874 dans l'archipel de Kerguelen a eu un impact considérable sur les écosystèmes terrestres. Deux programmes de restauration écologique ont été mis en place, l'un en 1988 par élimination des bovins de la partie sud de l'île Amsterdam (55 km2), le second à partir de 1992 par éradication des lapins sur trois îles (1,45 à 1,65 km2) à Kerguelen. Sur l'île Amsterdam, les capacités et la vitesse de restauration des communautés dépendent du niveau de la perturbation des milieux engendrée par les bovins. Alors qu'une dizaine d'années a suffi à la restauration des communautés végétales sur certains secteurs dont les sols étaient peu dégradés, l'évolution est lente et les espèces introduites restent dominantes sur de larges secteurs où l'érosion du sol atteint un seuil d'irréversibilité. A Kerguelen, les processus de restauration, plus lents, ont été de plus fortement influencés et limités par les changements climatiques récents (sécheresse estivale de plus en plus fréquente) qui bénéficient aux espèces introduites, originaires de régions plus tempérées, et pénalisent les espèces locales pour lesquelles ces conditions sont entièrement nouvelle

Impact des changements climatiques et de la fréquentation humaine sur la biodiversité des îles subantarctiques françaises

L’invasion des écosystèmes par des espèces exotiques constitue, en conjonction avec les changements climatiques, une des plus grandes menaces pour la biodiversité mondiale, après la destruction des habitats. Même dans les régions antarctiques et subantarctiques, des espèces étrangères à la faune et à la flore locales ont été introduites dès la fin du 18e siècle. La majorité de ces introductions sont associées à la fréquentation humaine et aux visites des navires. Par ailleurs, comme le prédisent la plupart des modèles, les régions de hautes latitudes sont les plus sensibles aux changements climatiques. Les observations faites à Kerguelen confirment cette tendance et attestent de l’impact déjà bien visible des augmentations de température (1,3°C depuis le milieu des années 1960) et des déficits hydriques estivaux récurrents ces dernières années. Avec ces changements climatiques rapides, une augmentation du nombre d’introductions d’espèces et de leur succès d’établissement est attendue, de même que la fragilisation de la faune et la flore locales, d’où de notables conséquences prévisibles quant à la biodiversité de ces régions très particulières.Biological invasions, in connection with climate changes, are amongst the most significant threats to biodiversity worldwide. Even in antarctic and subantarctic regions, alien species arrived since the end of the 18th century. Most of these introductions are obviously associated with human activities and ship landings. Otherwise, as predicted by many global circulation models, rates of warming are expected to be stronger at higher latitudes. Our study on the Kerguelen Islands confirms this trend and demonstrates that the effects of warming (+ 1.3°C since the mid 1960s) and summer droughts on plants and invertebrates are now visible. With climate change occurring rapidly, both the numbers of introductions and the success of colonisation by alien species are likely to increase, with as consequence subsequent impacts on the entire ecosystem

Antarctic environmental protection: Strengthening the links between science and governance

The Antarctic has significant environmental, scientific, historic, and intrinsic values, all of which are worth protecting into the future. Nevertheless, the area is subject to an increasing level and diversity of human activities that may impact these values within marine, terrestrial and cryosphere environments. Threats to the Antarctic environment, and to the aforementioned values, include climate change, pollution, habitat destruction, wildlife disturbance and non-native species introductions. Over time, a suite of legally binding international agreements, which form part of the Antarctic Treaty System (ATS), has been established to help safeguard the Antarctic environment and provide a framework for addressing the challenges arising from these threats. Foremost among these agreements are the Protocol on Environmental Protection to the Antarctic Treaty and the Convention on the Conservation of Antarctic Marine Living Resources. Many scientists working in Antarctica undertake research that is relevant to Antarctic environmental policy development. More effective two-way interaction between scientists and those responsible for policy development would further strengthen the governance framework, including by (a) better communication of policy makers’ priorities and identification of related science requirements and (b) better provision by scientists of ‘policy-ready’ information on existing priorities, emerging issues and scientific/technological advances relevant to environmental protection. The Scientific Committee on Antarctic Research (SCAR) has a long and successful record of summarizing policy-relevant scientific knowledge to policy makers, such as through its Group of Specialists on Environmental Affairs and Conservation (GOSEAC) up to 2002, currently the SCAR Standing Committee on the Antarctic Treaty System (SCATS) and recently through its involvement in the Antarctic Environments Portal. Improvements to science-policy communication mechanisms, combined with purposeful consideration of funding opportunities for policy-relevant science, would greatly enhance international policy development and protection of the Antarctic environment

An integrated palaeoenvironmental investigation of a 6200 year old peat sequence from Ile de la Possession, Iles Crozet, sub-Antarctica

International audienceA 6200 year old peat sequence, cored in a volcanic crater on the sub-Antarctic Ile de la Possession (Iles Crozet), has been investigated, based on a multi-proxy approach. The methods applied are macrobotanical (mosses, seeds and fruits) and diatom analyses, complemented by geochemical (Rock-Eval6) and rock magnetic measurements. The chronology of the core is based on 5 radiocarbon dates. When combining all the proxy data the following changes could be inferred. From the onset of the peat formation (6200 cal yr BP) until ca. 5550 cal yr BP, biological production was high and climatic conditions must have been relatively warm. At ca. 5550 cal yr BP a shift to low biological production occurred, lasting until ca. 4600 cal yr BP. During this period the organic matter is well preserved, pointing to a cold and/or wet environment. At ca. 4600 cal yr BP, biological production increased again. From ca. 4600 cal yr BP until ca. 4100 cal yr BP a “hollow and hummock” micro topography developed at the peat surface, resulting in the presence of a mixture of wetter and drier species in the macrobotanical record. After ca. 4100 cal yr BP, the wet species disappear and a generally drier, acidic bog came into existence. A major shift in all the proxy data is observed at ca. 2800 cal yr BP, pointing to wetter and especially windier climatic conditions on the island probably caused by an intensification and/or latitudinal shift of the southern westerly belt. Caused by a stronger wind regime, erosion of the peat surface occurred at that time and a lake was formed in the peat deposits of the crater, which is still present today

Threat management priorities for conserving Antarctic biodiversity

Antarctic terrestrial biodiversity faces multiple threats, from invasive species to climate change. Yet no large-scale assessments of threat management strategies exist. Applying a structured participatory approach, we demonstrate that existing conservation efforts are insufficient in a changing world, estimating that 65% (at best 37%, at worst 97%) of native terrestrial taxa and land-associated seabirds are likely to decline by 2100 under current trajectories. Emperor penguins are identified as the most vulnerable taxon, followed by other seabirds and dry soil nematodes. We find that implementing 10 key threat management strategies in parallel, at an estimated present-day equivalent annual cost of US$23 million, could benefit up to 84% of Antarctic taxa. Climate change is identified as the most pervasive threat to Antarctic biodiversity and influencing global policy to effectively limit climate change is the most beneficial conservation strategy. However, minimising impacts of human activities and improved planning and management of new infrastructure projects are cost-effective and will help to minimise regional threats. Simultaneous global and regional efforts are critical to secure Antarctic biodiversity for future generations