Final Report Summary - LIAK&CC (IMPACT OF CLIMATE CHANGE ON WINTERING ARCTIC SEABIRDS – AN INTER-POPULATION STUDY ON LITTLE AUKS)
The North Atlantic, including the Atlantic sector of the Arctic, is one of the most important marine regions of the planet holding sensitive ecosystems. However, it is also one of the most perturbed regions by both anthropogenic activities and climate changes, which are predicted to increase during next decades and might therefore have devastating effects upon the state of marine resources and biodiversity. In this context, there is a pressing need to improve our understanding of how species of these regions will react to global changes and to predict the consequences of habitat modifications for their survival and population dynamics.
The main objective of this project was to perform a comprehensive study of the potential consequences of ongoing and future climate change upon seabirds during their inter-breeding period, by focusing on little auks (Alle alle). The study of seabirds is indeed essential as they are the most threatened group of birds in the world and play a key role in Arctic marine food webs. Moreover, seabirds potentially function as powerful ecological indicators of marine food webs, and such bio-indicators are extremely valuable in remote areas such as the North Atlantic and the Arctic where detailed at-sea investigations of ecological processes are costly and challenging. In this context, the little auk represents an interesting model species because they are the most abundant seabird in the Arctic and North Atlantic and have a wide distribution ranging from Canadian to Russian coasts, enabling the study of populations in different environmental conditions.
In order to establish predictive studies allowing to understand how climate change will affect little auks, it is first essential to have a good knowledge of their ecological niche. This basic information was nonetheless missing. The first objective of this project was therefore to define the non-breeding distribution of little auks at an inter-population level and to understand the ecological determinant of these distribution patterns. To this end, I first used miniaturized electronic devices to track the non-breeding distribution of little auks from four major colonies distributed throughout the North Atlantic. I highlighted two key hotspots used by this species: one located in the Greenland Sea and essentially used as a moulting ground and one off Newfoundland used as a winter quarter. Crucially, by combining this information with oceanographic and zooplankton data, I modelled the wintering niche of little auks and showed how the environmental conditions drive their migratory strategy and their distribution in the North Atlantic. Birds indeed select wintering areas according to different environmental parameters presumably to optimize their energy balance, by maximizing the energy intake (little auks favour patches of high copepod abundance) while minimizing thermal stress and energy expenditures (birds are distributed in a narrow thermal niche where air temperatures are comprised between 0ºC and 5ºC), in order to promote high winter survival. These results greatly advance our knowledge on critical areas and habitat preference of little auks and our understanding of seabird responses to extreme environmental conditions. They also provide essential information for future predictive studies aiming at understanding how climate change might impact this species by affecting the different components of their ecological niche.
Once this information acquired, the second objective was to predict how future climate change will impact the winter distribution of little auks by affecting their energetics and their ecological niche (prey availability and air temperature). This second part of the project is currently under process and I am now using the bioenergetics model Niche Mapper to model the most profitable places for wintering little auks throughout the North Atlantic under different environmental conditions. This will allow to predict future winter distribution of little auks under environmental changes.
Beyond the change of prey distribution and air temperature, Arctic species are facing a drastic and rapid decline of the sea-ice extent. However, sea-ice can represent an essential habitat for many Arctic species, including seabirds, and understanding the consequences of this change on the avian biodiversity is essential. The third objective of this project was therefore to estimate indirect impacts of climate change on little auks through sea-ice retreat. By the use of the biotelemetry, I first demonstrated the importance of the sea-ice for the little auk populations during both the breeding and the non-breeding seasons. During the non-breeding season, I showed that the distribution of birds breeding in Svalbard overlapped closely with the location of the ice edge, particularly in the Greenland Sea, the Barents Sea and the southwest Davis Strait. During the breeding season, I demonstrated that adults birds flight >100km to reach the sea-ice and feed on specific sea-ice associated prey. According to these results, I therefore speculate that the predicted decrease in sea ice extent will have major effects on little auks, year-round.
Simultaneously, I used a new biomarker (IP25) to determine the degree of association of birds with sea-ice. This biomarker is indeed exclusively produced by sea-ice-associated diatoms and is then transmitted through the different trophic levels of the marine food-chain. It can thus be used to investigate whether, and to which extent, a predator depends on resources derived from the sea-ice environment. I used this new analytical technique for the first time on Arctic vertebrates. I am currently finalising the analysis of data in order to define (1) the importance of the sea-ice environment for Greenland populations of little auks, and (2) the role played by sea-ice for the reproduction and the survival of little auks breeding in East Greenland. This information will be crucial to model how the decrease of the sea-ice extent in the Arctic will affect little auks according to their breeding site and their distribution in the North Atlantic.
Finally, the fourth objective of this research project has been to investigate, through the analyses of time-series data collected over the last 8 years, how the winter survival of little auks is affected by climate change. Though this analysis is still in progress, I believe that it will provide important information towards the understanding of the impact of future climate change on seabird population trends, essential for the establishment of conservation and management strategies.
Simultaneously to these main objectives, I performed different collaborations and combined various methods to examine the winter ecology and distribution of other seabirds in the Arctic and the North Atlantic. I for instance highlighted contrasted migratory strategies adopted by two sympatrically breeding guillemot species in the Arctic, with important consequences for their energetics. By studying different populations of northern gannets in the North Atlantic, I also demonstrated for the first time in seabirds that in contrast with the general opinion that large pelagic birds have unlimited ranges beyond the breeding season, gannet post-breeding movements should not be attributed to dispersive migration or vagrancy, but instead follow an oriented chain migration pattern.
All the results obtained within this project are essential for the conservation of the Arctic avian biodiversity in the current context of climate change and habitat modification. They indeed provide information about the location of sensitive hotspots for the marine biodiversity in the North Atlantic that might require a particular attention and protection. They also provide a new knowledge of the role played by the environment for the distribution, breeding success and survival of seabirds. This knowledge will notably help to the establishment of stringent management plans aiming to protect the sensitive Arctic marine ecosystems, a requisite recently highlighted by several international initiatives as the Arctic Council and the International Maritime Organization.
The main objective of this project was to perform a comprehensive study of the potential consequences of ongoing and future climate change upon seabirds during their inter-breeding period, by focusing on little auks (Alle alle). The study of seabirds is indeed essential as they are the most threatened group of birds in the world and play a key role in Arctic marine food webs. Moreover, seabirds potentially function as powerful ecological indicators of marine food webs, and such bio-indicators are extremely valuable in remote areas such as the North Atlantic and the Arctic where detailed at-sea investigations of ecological processes are costly and challenging. In this context, the little auk represents an interesting model species because they are the most abundant seabird in the Arctic and North Atlantic and have a wide distribution ranging from Canadian to Russian coasts, enabling the study of populations in different environmental conditions.
In order to establish predictive studies allowing to understand how climate change will affect little auks, it is first essential to have a good knowledge of their ecological niche. This basic information was nonetheless missing. The first objective of this project was therefore to define the non-breeding distribution of little auks at an inter-population level and to understand the ecological determinant of these distribution patterns. To this end, I first used miniaturized electronic devices to track the non-breeding distribution of little auks from four major colonies distributed throughout the North Atlantic. I highlighted two key hotspots used by this species: one located in the Greenland Sea and essentially used as a moulting ground and one off Newfoundland used as a winter quarter. Crucially, by combining this information with oceanographic and zooplankton data, I modelled the wintering niche of little auks and showed how the environmental conditions drive their migratory strategy and their distribution in the North Atlantic. Birds indeed select wintering areas according to different environmental parameters presumably to optimize their energy balance, by maximizing the energy intake (little auks favour patches of high copepod abundance) while minimizing thermal stress and energy expenditures (birds are distributed in a narrow thermal niche where air temperatures are comprised between 0ºC and 5ºC), in order to promote high winter survival. These results greatly advance our knowledge on critical areas and habitat preference of little auks and our understanding of seabird responses to extreme environmental conditions. They also provide essential information for future predictive studies aiming at understanding how climate change might impact this species by affecting the different components of their ecological niche.
Once this information acquired, the second objective was to predict how future climate change will impact the winter distribution of little auks by affecting their energetics and their ecological niche (prey availability and air temperature). This second part of the project is currently under process and I am now using the bioenergetics model Niche Mapper to model the most profitable places for wintering little auks throughout the North Atlantic under different environmental conditions. This will allow to predict future winter distribution of little auks under environmental changes.
Beyond the change of prey distribution and air temperature, Arctic species are facing a drastic and rapid decline of the sea-ice extent. However, sea-ice can represent an essential habitat for many Arctic species, including seabirds, and understanding the consequences of this change on the avian biodiversity is essential. The third objective of this project was therefore to estimate indirect impacts of climate change on little auks through sea-ice retreat. By the use of the biotelemetry, I first demonstrated the importance of the sea-ice for the little auk populations during both the breeding and the non-breeding seasons. During the non-breeding season, I showed that the distribution of birds breeding in Svalbard overlapped closely with the location of the ice edge, particularly in the Greenland Sea, the Barents Sea and the southwest Davis Strait. During the breeding season, I demonstrated that adults birds flight >100km to reach the sea-ice and feed on specific sea-ice associated prey. According to these results, I therefore speculate that the predicted decrease in sea ice extent will have major effects on little auks, year-round.
Simultaneously, I used a new biomarker (IP25) to determine the degree of association of birds with sea-ice. This biomarker is indeed exclusively produced by sea-ice-associated diatoms and is then transmitted through the different trophic levels of the marine food-chain. It can thus be used to investigate whether, and to which extent, a predator depends on resources derived from the sea-ice environment. I used this new analytical technique for the first time on Arctic vertebrates. I am currently finalising the analysis of data in order to define (1) the importance of the sea-ice environment for Greenland populations of little auks, and (2) the role played by sea-ice for the reproduction and the survival of little auks breeding in East Greenland. This information will be crucial to model how the decrease of the sea-ice extent in the Arctic will affect little auks according to their breeding site and their distribution in the North Atlantic.
Finally, the fourth objective of this research project has been to investigate, through the analyses of time-series data collected over the last 8 years, how the winter survival of little auks is affected by climate change. Though this analysis is still in progress, I believe that it will provide important information towards the understanding of the impact of future climate change on seabird population trends, essential for the establishment of conservation and management strategies.
Simultaneously to these main objectives, I performed different collaborations and combined various methods to examine the winter ecology and distribution of other seabirds in the Arctic and the North Atlantic. I for instance highlighted contrasted migratory strategies adopted by two sympatrically breeding guillemot species in the Arctic, with important consequences for their energetics. By studying different populations of northern gannets in the North Atlantic, I also demonstrated for the first time in seabirds that in contrast with the general opinion that large pelagic birds have unlimited ranges beyond the breeding season, gannet post-breeding movements should not be attributed to dispersive migration or vagrancy, but instead follow an oriented chain migration pattern.
All the results obtained within this project are essential for the conservation of the Arctic avian biodiversity in the current context of climate change and habitat modification. They indeed provide information about the location of sensitive hotspots for the marine biodiversity in the North Atlantic that might require a particular attention and protection. They also provide a new knowledge of the role played by the environment for the distribution, breeding success and survival of seabirds. This knowledge will notably help to the establishment of stringent management plans aiming to protect the sensitive Arctic marine ecosystems, a requisite recently highlighted by several international initiatives as the Arctic Council and the International Maritime Organization.