Entity

Time filter

Source Type

Chevy Chase, MD, United States

Clucas G.V.,University of Southampton | Dunn M.J.,British Antarctic Survey | Dyke G.,University of Southampton | Emslie S.D.,University of North Carolina at Wilmington | And 5 more authors.
Scientific Reports | Year: 2014

Climate change is a major threat to global biodiversity. Antarctic ecosystems are no exception. Investigating past species responses to climatic events can distinguish natural from anthropogenic impacts. Climate change produces 'winners', species that benefit from these events and 'losers', species that decline or become extinct. Using molecular techniques, we assess the demographic history and population structure of Pygoscelis penguins in the Scotia Arc related to climate warming after the Last Glacial Maximum (LGM). All three pygoscelid penguins responded positively to post-LGM warming by expanding from glacial refugia, with those breeding at higher latitudes expanding most. Northern (Pygoscelis papua papua) and Southern (Pygoscelis papua ellsworthii) gentoo sub-species likely diverged during the LGM. Comparing historical responses with the literature on current trends, we see Southern gentoo penguins are responding to current warming as they did during post-LGM warming, expanding their range southwards. Conversely, Adélie and chinstrap penguins are experiencing a 'reversal of fortunes' as they are now declining in the Antarctic Peninsula, the opposite of their response to post-LGM warming. This suggests current climate warming has decoupled historic population responses in the Antarctic Peninsula, favoring generalist gentoo penguins as climate change 'winners' while Adélie and chinstrap penguins have become climate change 'losers'. Source


Lynch H.J.,University of Maryland University College | Crosbie K.,International Association of Antarctica Tour Operators | Fagan W.F.,University of Maryland University College | Naveen R.,Oceanites Inc.
Antarctic Science | Year: 2010

Commercial, shipborne tourism along the Antarctic Peninsula grew exponentially between 1989-90 and 2007-08, raising concern about the impact such activity may have on the environment of the region. Previous analyses of Antarctic tourism have focused narrowly on patterns of visitation and potential impacts at terrestrial landing sites. Here, using 19 years of passenger landing statistics and five years of reconstructed ship itineraries, we explore patterns of tourism activities in the Antarctic Peninsula region using a spatially explicit network theory analysis of ship itineraries. We find that passenger landings and marine traffic are highly concentrated at a few specific locations and that growth in tourism activity occurred disproportionally rapidly at these sites relative to growth in visitation of the Peninsula as a whole. We conclude by discussing the pros and cons of spatially concentrated tourism activity and the associated implications for ecosystem management. © 2009 Antarctic Science Ltd. Source


Lynch H.J.,University of Maryland University College | Lynch H.J.,State University of New York at Stony Brook | Fagan W.F.,University of Maryland University College | Naveen R.,Oceanites Inc. | And 2 more authors.
Marine Ecology Progress Series | Year: 2012

Numerous studies link climate change with advancing breeding phenology in birds, but less frequently considered are the joint impacts on sympatrically breeding communities of birds. We used data on clutch initiation dates (CID) from 4 sites along the Western Antarctic Peninsula for 3 congeneric and sympatrically breeding penguin species (Adélie Pygoscelis adeliae, gentoo P. papua and chinstrap P. antarcticus) to understand what factors correlate with the phenology and synchrony of breeding and how these factors might change with the recent warming experienced in this region. We found that clutch initiation was most significantly correlated with October air temperatures such that all 3 species advanced clutch initiation to varying degrees in warmer years. Gentoo penguins were able to advance CID almost twice as much (3.2 d °C-1) as Adélie (1.7 d °C-1) and chinstrap penguins (1.8 d °C-1). Beyond the variation explained by mean October temperatures, there was an unexplained trend to earlier clutch initiation of 0.15 ± 0.05 d yr-1. Greater plasticity in gentoo breeding phenology compressed the mean interval between Adélie and gentoo breeding in warm years and this may increase competition for nesting space in mixed colonies. Our results suggest that differential responses in breeding phenology to changing temperatures represent an additional mechanism by which climate change may affect competitive interactions and, consequently, pygoscelid penguins on the Antarctic Peninsula. © Inter-Research 2012. Source


Lynch H.J.,State University of New York at Stony Brook | Naveen R.,Oceanites Inc. | Trathan P.N.,British Antarctic Survey | Fagan W.F.,University of Maryland University College
Ecology | Year: 2012

As important marine mesopredators and sensitive indicators of Antarctic ecosystem change, penguins have been a major focus of long-term biological research in the Antarctic. However, the vast majority of such studies have been constrained by logistics and relate mostly to the temporal dynamics of individual breeding populations from which regional trends have been inferred, often without regard for the complex spatial heterogeneity of population processes and the underlying environmental conditions. Integrating diverse census data from 70 breeding sites across 31 years in a robust, hierarchical analysis, we find that trends from intensely studied populations may poorly reflect regional dynamics and confuse interpretation of environmental drivers. Results from integrated analyses confirm that Pygoscelis adeliae (Adé lie Penguins) are decreasing at almost all locations on the Antarctic Peninsula. Results also resolve previously contradictory studies and unambiguously establish that P. antarctica (Chinstrap Penguins), thought to benefit from decreasing sea ice, are instead declining regionally. In contrast, another open-water species, P. papua (Gentoo Penguin), is increasing in abundance and expanding southward. These disparate population trends accord with recent mechanistic hypotheses of biological change in the Southern Ocean and highlight limitations of the influential but oversimplified "sea ice" hypothesis. Aggregating population data at the regional scale also allows us to quantify rates of regional population change in a way not previously possible. © 2012 by the Ecological Society of America. Source


Polito M.J.,University of North Carolina at Wilmington | Lynch H.J.,University of Maryland University College | Naveen R.,Oceanites Inc. | Emslie S.D.,University of North Carolina at Wilmington
Marine Ecology Progress Series | Year: 2011

While the foraging ecology of the Adélie penguin Pygoscelis adeliae and gentoo penguin P papua has been well studied, little is known on the distribution and diet of these species outside the breeding season In the present study we used stable carbon (δ13C) and nitrogen (d15N) isotope analyses of eggshells to examine the pre-breeding diets and foraging habitats of female Adélie and gentoo penguins from 23 breeding colonies along the eastern and western Antarctic Peninsula (AP), South Shetland Islands, and South Orkney Islands, in 2006 Adélie penguin eggshells from the eastern AP, South Shetland Islands, and South Orkney Islands shared similar isotopic signatures and were significantly lower in both δ13C and δ15N values than eggshells from birds breeding along the western AP This result suggests that Adélie penguin populations that are geographically separated during the breeding season by the Adélie 'gap,' a 400 km region in the western AP devoid of breeding Adélie penguins, also inhabit geographically distinct habitats during the late winter prior to the breeding season To a lesser degree, gentoo penguin eggshell isotope values also varied across breeding colonies, which likely reflects local scale variation in their near-shore foraging grounds Furthermore, unlike the breeding period when krill (primarily Euphausia superba) dominates penguin diets in these regions, our findings suggest that fish and/or other high trophic-level prey species comprise a significant portion (468 to 629%) of female Adélie and gentoo penguin diets prior to breeding © Inter-Research 2011. Source

Discover hidden collaborations