Biological, Earth and Environmental Sciences - Journal Articles
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Item Spatial and temporal variation in mortality from avian influenza in Greenland Barnacle Geese Branta leucopsis in their wintering grounds(Taylor & Francis, 2024-12-23) Percival, Steve; Bowler, John; Cabot, David; Duffield, Steve; Enright, Martin; How, James; Mitchell, Carl; Percival, Tracey; Sigfusson, ArnorCapsule: Avian influenza caused the loss of more than 20% of the Greenland Barnacle Goose population, but this impact varied between wintering areas and over time. Aims: The primary objective was to investigate the spatial and temporal mortality patterns due to avian influenza (H5N1) in wintering Greenland Barnacle Geese. Methods: We analysed a comprehensive dataset of marked individuals spanning six years, with observations from a network of observers across their wintering range. The study specifically compared the mortality rates of Greenland Barnacle Geese during the H5N1 outbreak years (2021/2022 and 2022/2023) with the three previous winters (2018/2019–2020/2021). Results: The study found significant spatial and temporal variation in mortality resulting from avian influenza outbreaks within the Greenland Barnacle Goose population on their wintering grounds in Scotland and Ireland. Some sites (Islay, Tiree and Sligo) experienced 30–56% reductions in survival rates, while others (Uist and Mayo) showed little or no impact. The timing of the main outbreaks also differed between sites. Excess deaths (in comparison with the previous baseline), estimated using mark-resighting data, indicated that mortality was considerably higher than suggested from direct field counts, reaching at least 20% of the global population in the peak outbreak winter (2022/2023). Conclusion: The results highlight the importance of spatial and temporal dynamics in avian influenza impacts. Disease dynamics should be integrated into population management models and used for setting appropriate thresholds for minimum population levels, to ensure resilience to disease outbreaks and long-term viability.Item Callixylon seamrogia sp. nov., a new species from the uppermost Famennian (Upper Devonian) of Ireland(Elsevier Ltd., 2024-12-12) Durieux, Thibault; Decombeix, Anne-Laure; Harper, Carla J.; Ramel, Merlin; Mays, Chris; Prestianni, Cyrille; Trinity College Dublin; Science Foundation Ireland; DECA; Institut national des sciences de l'Univers; Conseil National de la Recherche Scientifique; Irish Research Council; Ministère de l'Europe et des Affaires ÉtrangèresThe fossil record of the Devonian tree Archaeopteris/Callixylon is extensive worldwide, however, the underground parts of these plants remain scarcely known. To date, there are only three studies that provide detailed anatomical descriptions of their roots. This study describes new anatomically preserved roots and stems of Callixylon from uppermost Famennian (Upper Devonian) deposits of Sandeel Bay, County Wexford, Ireland. The wood is characterized by tracheids with the pitting pattern typical of Callixylon (i.e., radial pits forming groups separated by non-pitted areas), and the presence of numerous ray tracheids that are smaller than the parenchyma ray cells in tangential section and unevenly arranged inside the rays. The roots are characterized by a three-lobed actinostele with multiple exarch protoxylem strands, an unusual organization reported for the first time in Callixylon roots. The stems are eustelic, with a heterocellular pith composed of thin and some thick-walled cells. Based on their unique combination of characters, the specimens are assigned to a new species, Callixylon seamrogia, the first species of Callixylon reported from Ireland. Based on comparisons with previous architectural studies of Callixylon, the stems are hypothesized to correspond to main axes of the new species, one of them bearing an apically emitted non-persistent branch. These new specimens from Ireland provide new information on the rooting system of Archaeopteris/Callixylon and improve our understanding of the anatomical and systematic diversity within the genus.Item Overland flights of terns and consequent high exposure to polychlorinated biphenyls (PCBs) in Northwest France in the 1970s(BioOne, 2023-06-27) Nisbet, Ian C. T.; Cabot, David; Partridge, KarlSandwich (Thalasseus sandvicensis), Common (Sterna hirundo), and Roseate Terns (S. dougallii) made overland flights from a breeding site in Brittany (northwest France) to forage in a semi-enclosed basin (Rade de Brest) ∼30 km away in 1976 and 1978. The foraging area was contaminated with polychlorinated biphenyls (PCBs) and high levels of PCBs were detected in several tern eggs. Levels of PCBs in tern eggs were sufficiently high to have caused adverse effects on reproduction. PCBs should be considered as potential contributory causes of declines in tern populations in the 1960s–1970s, in addition to other known causes including predation and trapping in the winter quarters.Item Migratory herbivorous waterfowl track satellite-derived green wave index(Public Library of Science, 2014) Shariatinajafabadi, M.; Wang, T.; Skidmore, A. K.; Toxopeus, A. G.; Kölzsch, A.; Nolet, B. A.; Exo, K.-M.; Griffin, L.; Stahl, J.; Cabot, DavidMany migrating herbivores rely on plant biomass to fuel their life cycles and have adapted to following changes in plant quality through time. The green wave hypothesis predicts that herbivorous waterfowl will follow the wave of food availability and quality during their spring migration. However, testing this hypothesis is hampered by the large geographical range these birds cover. The satellite-derived normalized difference vegetation index (NDVI) time series is an ideal proxy indicator for the development of plant biomass and quality across a broad spatial area. A derived index, the green wave index (GWI), has been successfully used to link altitudinal and latitudinal migration of mammals to spatiotemporal variations in food quality and quantity. To date, this index has not been used to test the green wave hypothesis for individual avian herbivores. Here, we use the satellite-derived GWI to examine the green wave hypothesis with respect to GPS-tracked individual barnacle geese from three flyway populations (Russian n = 12, Svalbard n = 8, and Greenland n = 7). Data were collected over three years (2008-2010). Our results showed that the Russian and Svalbard barnacle geese followed the middle stage of the green wave (GWI 40-60%), while the Greenland geese followed an earlier stage (GWI 20-40%). Despite these differences among geese populations, the phase of vegetation greenness encountered by the GPStracked geese was close to the 50% GWI (i.e. the assumed date of peak nitrogen concentration), thereby implying that barnacle geese track high quality food during their spring migration. To our knowledge, this is the first time that the migration of individual avian herbivores has been successfully studied with respect to vegetation phenology using the satellite-derived GWI. Our results offer further support for the green wave hypothesis applying to long-distance migrants on a larger scale. © 2014 Shariatinajafabadi et al.Item Decadal increase in vessel interactions by a scavenging pelagic seabird across the North Atlantic(Cell Press, 2023) Darby, J. H.; Clairbaux, M.; Quinn, J. L.; Thompson, P.; Quinn, L.; Cabot, David; Strøm, H.; Thórarinsson, T. L.; Kempf, J.; Jessopp, M. J.; Horizon 2020; Irish Research Council; Norges Forskningsråd; ForsvaretFisheries waste is used by many seabirds as a supplementary source of food,1 but interacting with fishing vessels to obtain this resource puts birds at risk of entanglement in fishing gear and mortality.2 As a result, bycatch is one of the leading contributors to seabird decline worldwide,3 and this risk may increase over time as birds increasingly associate fishing vessels with food. Light-level geolocators mounted on seabirds can detect light emitted from vessels at night year-round.4 We used a 16-year time series of geolocator data from 296 northern fulmars (Fulmarus glacialis) breeding at temperate and arctic colonies to investigate trends of nocturnal vessel interactions in this scavenging pelagic seabird. Vessel attendance has progressively increased over the study period despite no corresponding increase in the number of vessels or availability of discards over the same time frame. Fulmars are highly mobile generalist surface feeders,5 so this may signal a reduction in available prey biomass in the upper water column, leading to increased reliance on anthropogenic food subsidies6 and increased risk of bycatch mortality in already threatened seabird populations. Individuals were consistent in the extent to which they interacted with vessels, as shown in other species,7 suggesting that population-level increases may be due to a higher proportion of fulmars following vessels rather than changes at an individual level. Higher encounter rates were correlated with lower time spent foraging and a geographically restricted overwintering distribution, suggesting an energetic advantage for these scavenging strategists compared with foraging for natural prey. © 2023 The Author(s)