What will the future bring for biological invasions on islands? an expert-based assessment

Biological invasions are a major threat to global biodiversity with particularly strong implications for island biodiversity. Much research has been dedicated towards understanding historic and current changes in alien species distribution and impacts on islands and potential changes under future climate change. However, projections of how alien species richness and impacts on islands might develop in the future are still lacking. In the absence of reliable projections, expert-based assessments are a valuable tool to investigate the importance of different drivers and pathways and the distributions of potential impacts of future biological invasions. These insights can guide subsequent quantification efforts and inform invasive species management and policy. In this study, we performed a survey among 126 experts in invasion science ranging from scientists to managers and decision makers with a focus on island systems until the mid-21st century. The survey revealed that out of 15 drivers, six were considered important by almost all respondents (>90%). Of these, trade and transport was identified as most important at the introduction stage (99.2%) and land use/cover change as most important at the establishment (96.8%) and spread (95.2%) stage. Additionally, the experts considered that alien species were more likely to be introduced (93.7%) and spread (78.6%) as stowaways than through any other pathway. In general, respondents agreed that the impacts of alien species will increase on all types of islands, particularly on oceanic islands, followed by atolls and continental islands. Within islands, terrestrial ecosystems were assumed to be impacted more severely than marine ecosystems. Finally, the survey hints toward the potential for effective communication, scientific research and increased pro-active management of alien species on islands to reduce their future consequences. Given the major threat represented by invasive alien species on islands, these results provide crucial insights relevant for global and regional conservation efforts.info:eu-repo/semantics/publishedVersio

Effects of climate change on biodiversity

Nous traversons actuellement une crise de perte de la biodiversité sans précédant. La dégradation des sols et la perte d’habitat, la pollution, la surexploitation et les invasions biologiques contribuent à cette perte mondiale de biodiversité. Par ailleurs, le changement climatique et ses interactions avec les autres menaces, sont probablement l’un des défis majeurs des prochaines décennies pour la biodiversité. À l’heure actuelle, en raison de la multiplication des études et des approches employées, il est difficile d’avoir une vision synthétique des conséquences potentielles de ces changements sur la biodiversité. L’objectif principal de ce travail de thèse a été d’améliorer la caractérisation et la quantification des différents impacts des changements climatiques sur la biodiversité, à l’échelle mondiale par des approches de modélisations et de méta-analyses. Une première partie de mes travaux a ainsi porté sur les conséquences potentielles de la hausse du niveau des mers sur les hotspots insulaires, au cours de laquelle j’ai mis en évidence les conséquences majeures d’une telle hausse pour certains de ces hotspots. Je me suis ensuite intéressée à l’étude des effets conjugués des changements climatiques et des changements d’utilisation des sols sur les invasions biologiques à l’échelle mondiale. Cette partie a permis de mettre en évidence que les conséquences des changements climatiques et des changements d’utilisation des sols sur les espèces invasives dépendent de la région, du taxon et de l’espèce considérée. Ainsi, j’ai mis en évidence que certaines régions pourraient être moins favorables à la présence d’espèce invasives dans le futur. En outre, cette partie a également mis en évidence que les hotspots majoritairement composés d’îles étaient particulièrement favorables à la présence de ces espèces invasives. Finalement, dans une dernière partie, j’ai étudié les conséquences des menaces futures pour les hotspots de biodiversité dans une perspective de conservation. Cette partie a notamment permis d’établir des priorités de recherche et de conservation entre les hotspots de biodiversité en tenant compte des futures menaces qui pèsent sur la biodiversité à l’échelle des hotspots, mais également au sein même des hotspots de biodiversité. Cependant, la mise en œuvre de plans de gestion de sauvegarde d’habitats ou d’espèces ne pourra se faire qu’en intensifiant les collaborations avec l’ensemble des acteurs impliqués. Plus généralement, la mise en œuvre de stratégies d’atténuation et d’adaptation efficaces aux changements climatiques ne pourra pas avoir lieu sans un soutien du grand public.Global biodiversity is changing at an unprecedented rate due to loss of habitat, biological invasions, pollution, overexploitation. Furthermore, climate changes and their synergies with other threats will probably become the main drivers of biodiversity loss in the next century. Nowadays, the multiplicity of approaches and the resulting variability in projections make it difficult to get a clear picture of the future of biodiversity due to climate change. Yet, the majority of models indicate alarming consequences for biodiversity, with the worst- case scenarios leading to an increase of extinction rates. The aim of this thesis was to improve the knowledge about of the different consequences of climate change on biodiversity worldwide. To do that I mainly used modelisation and meta-analyses approaches. The first part of my work was to investigate the consequences of sea level rise for the ten insular biodiversity hotspot and their endemic species, during which I highlighted that between 6 and 19% of the islands would be entirely submerged. Then I studied the effects of climate and land use changes on biological invasions worldwide. The results showed that invasives species response to climate and land use changes depend on region, taxa and species considered. We also emphasized that some regions could lose a significant number of invasive alien species. Besides, we also found that hotspot that are mainly islands or group of islands are highly suitable for invasive species. Finally, in the last part, I quantified the exposure of biodiversity hotspots to the combined effects of climate change, land use change and biological invasions. This work highlighted the pressing need to consider different drivers of global change in conservation planning. In addition, we established some prioritization framework among the hotspot. Finally, conservation strategies to protect habitat and species under global changes, can only be achieved through closed collaboration with park managers. Overall, implementation of effective adaptation strategies to climate change can only succeed with public support

Importance of metapopulation dynamics to explain fish persistence in a river system

International audienc

Effets des changements climatiques sur la biodiversité

Nous traversons actuellement une crise de perte de la biodiversité sans précédant. La dégradation des sols et la perte d habitat, la pollution, la surexploitation et les invasions biologiques contribuent à cette perte mondiale de biodiversité. Par ailleurs, le changement climatique et ses interactions avec les autres menaces, sont probablement l un des défis majeurs des prochaines décennies pour la biodiversité. À l heure actuelle, en raison de la multiplication des études et des approches employées, il est difficile d avoir une vision synthétique des conséquences potentielles de ces changements sur la biodiversité. L objectif principal de ce travail de thèse a été d améliorer la caractérisation et la quantification des différents impacts des changements climatiques sur la biodiversité, à l échelle mondiale par des approches de modélisations et de méta-analyses. Une première partie de mes travaux a ainsi porté sur les conséquences potentielles de la hausse du niveau des mers sur les hotspots insulaires, au cours de laquelle j ai mis en évidence les conséquences majeures d une telle hausse pour certains de ces hotspots. Je me suis ensuite intéressée à l étude des effets conjugués des changements climatiques et des changements d utilisation des sols sur les invasions biologiques à l échelle mondiale. Cette partie a permis de mettre en évidence que les conséquences des changements climatiques et des changements d utilisation des sols sur les espèces invasives dépendent de la région, du taxon et de l espèce considérée. Ainsi, j ai mis en évidence que certaines régions pourraient être moins favorables à la présence d espèce invasives dans le futur. En outre, cette partie a également mis en évidence que les hotspots majoritairement composés d îles étaient particulièrement favorables à la présence de ces espèces invasives. Finalement, dans une dernière partie, j ai étudié les conséquences des menaces futures pour les hotspots de biodiversité dans une perspective de conservation. Cette partie a notamment permis d établir des priorités de recherche et de conservation entre les hotspots de biodiversité en tenant compte des futures menaces qui pèsent sur la biodiversité à l échelle des hotspots, mais également au sein même des hotspots de biodiversité. Cependant, la mise en œuvre de plans de gestion de sauvegarde d habitats ou d espèces ne pourra se faire qu en intensifiant les collaborations avec l ensemble des acteurs impliqués. Plus généralement, la mise en œuvre de stratégies d atténuation et d adaptation efficaces aux changements climatiques ne pourra pas avoir lieu sans un soutien du grand public.Global biodiversity is changing at an unprecedented rate due to loss of habitat, biological invasions, pollution, overexploitation. Furthermore, climate changes and their synergies with other threats will probably become the main drivers of biodiversity loss in the next century. Nowadays, the multiplicity of approaches and the resulting variability in projections make it difficult to get a clear picture of the future of biodiversity due to climate change. Yet, the majority of models indicate alarming consequences for biodiversity, with the worst- case scenarios leading to an increase of extinction rates. The aim of this thesis was to improve the knowledge about of the different consequences of climate change on biodiversity worldwide. To do that I mainly used modelisation and meta-analyses approaches. The first part of my work was to investigate the consequences of sea level rise for the ten insular biodiversity hotspot and their endemic species, during which I highlighted that between 6 and 19% of the islands would be entirely submerged. Then I studied the effects of climate and land use changes on biological invasions worldwide. The results showed that invasives species response to climate and land use changes depend on region, taxa and species considered. We also emphasized that some regions could lose a significant number of invasive alien species. Besides, we also found that hotspot that are mainly islands or group of islands are highly suitable for invasive species. Finally, in the last part, I quantified the exposure of biodiversity hotspots to the combined effects of climate change, land use change and biological invasions. This work highlighted the pressing need to consider different drivers of global change in conservation planning. In addition, we established some prioritization framework among the hotspot. Finally, conservation strategies to protect habitat and species under global changes, can only be achieved through closed collaboration with park managers. Overall, implementation of effective adaptation strategies to climate change can only succeed with public support.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Data from: Biotic and abiotic drivers of species loss rate in isolated lakes

1. Today, anthropogenic impacts are causing a serious crisis for global biodiversity, with rates of extinction increasing at an unprecedented rate. Extinctions typically occur after a certain delay and understanding the mechanisms causing delays is a key challenge for both fundamental and applied perspectives. 2. Here, we make use of natural experiments, the isolation of lakes by land up-lift in Northern Scandinavia, to examine how yearly extinction rates are affected by time since isolation and a range of abiotic and biotic factors. 3. In this aim, we adapted a model of delayed species loss within isolated communities to test the effects of time since isolation, area, pH, depth and presence/absence of piscivores on extinction rates. 4. As expected, we found that small and/or young lakes experience a higher annual rate of extinctions per species than larger and/or older ones. Compared to previous studies that were conducted for either young (few thousand years ago) or very old (>10 000 years ago) isolates, we demonstrated over a large and continuous temporal scales (50-5000 yr), similar relationship between extinction rates and age. We also show that extinction rates are modified by local environmental factors such as a strong negative effect of increasing pH. 5. Our results urge for the need to consider the time since critical environmental changes occurred when studying extinction rates. In a wider perspective our study demonstrates the need to consider extinction debts when modeling future effects of climate change, land-use changes, or biological invasions on biodiversity

Insular threat associations within taxa worldwide

International audienceThe global loss of biodiversity can be attributed to numerous threats. While pioneer studies have investigated their relative importance, the majority of those studies are restricted to specific geographic regions and/or taxonomic groups and only consider a small subset of threats, generally in isolation despite their frequent interaction. Here, we investigated 11 major threats responsible for species decline on islands worldwide. We applied an innovative method of network analyses to disentangle the associations of multiple threats on vertebrates, invertebrates, and plants in 15 insular regions. Biological invasions, wildlife exploitation, and cultivation, either alone or in association, were found to be the three most important drivers of species extinction and decline on islands. Specifically, wildlife exploitation and cultivation are largely associated with the decline of threatened plants and terrestrial vertebrates, whereas biological invasions mostly threaten invertebrates and freshwater fish. Furthermore, biodiversity in the Indian Ocean and near the Asian coasts is mostly affected by wildlife exploitation and cultivation compared to biological invasions in the Pacific and Atlantic insular regions. We highlighted specific associations of threats at different scales, showing that the analysis of each threat in isolation might be inadequate for developing effective conservation policies and managements

Future climate change vulnerability of endemic island mammals

International audienceDespite their high vulnerability, insular ecosystems have been largely ignored in climate change assessments, and when they are investigated, studies tend to focus on exposure to threats instead of vulnerability. The present study examines climate change vulnerability of islands, focusing on endemic mammals and by 2050 (RCPs 6.0 and 8.5), using trait-based and quantitative-vulnerability frameworks that take into account exposure, sensitivity, and adaptive capacity. Our results suggest that all islands and archipelagos show a certain level of vulnerability to future climate change, that is typically more important in Pacific Ocean ones. Among the drivers of vulnerability to climate change, exposure was rarely the main one and did not explain the pattern of vulnerability. In addition, endemic mammals with long generation lengths and high dietary specializations are predicted to be the most vulnerable to climate change. Our findings highlight the importance of exploring islands vulnerability to identify the highest climate change impacts and to avoid the extinction of unique biodiversity

Important characteristics determining the success of nonnative freshwater fish introduction, establishment, and impact.

AimThe invasion success of introduced freshwater fish is influenced by many factors, including ecological, species, and socioeconomic characteristics. Most studies that document the importance of one of these factors are conducted at a local scale and/or focus on a single step of the invasion process. Here, our aim is to identify the characteristics of successful invaders across the entire invasion process using ecological, species, and socioeconomic characteristics.LocationWorldwide.Time periodContemporary.Major taxa studiedFreshwater fish.MethodsWe conducted a worldwide analysis of 307 freshwater fish species and considered the number of countries in which each species was introduced, established, or had ecological impacts as a proxy of invasion step success. We applied generalized linear models to 20 variables relating to species morphology, ecology, and introduction pathways to determine the main characteristics associated with invasion success. By disentangling our results by pathways, we specifically explore the role played by aquaculture and ornamental trade pathways in the characteristic selection.ResultsWe found that non-native freshwater fish with a broad diet, high parental care, and multiple introduction pathways are the most widely introduced and established worldwide. The number of countries associated with impacts was best explained by the type of introduction pathway (i.e., aquaculture or fisheries). We also discovered that alien species introduced through aquaculture belonging to Cypriniformes and having a broad diet were the most widely introduced and established species. The same was observed for species introduced through ornamental pathways that were mainly native to tropical regions.Main conclusionsConsidering both intrinsic and extrinsic drivers is important when analyzing the invasion success of freshwater fish and disentangling the different invasion steps. These findings have strong implications for anticipating the profile of species with a high potential to invade a large number of countries