Increase in penguin populations during the Little Ice Age in the Ross Sea, Antarctica

Penguins are an important seabird species in Antarctica and are sensitive to climate and environmental changes. Previous studies indicated that penguin populations increased when the climate became warmer and decreased when it became colder in the maritime Antarctic. Here we determined organic markers in a sediment profile collected at Cape Bird, Ross Island, high Antarctic, and reconstructed the history of Adélie penguin colonies at this location over the past 700 years. The region transformed from a seal to a penguin habitat when the Little Ice Age (LIA; 1500–1800 AD) began. Penguins then became the dominant species. Penguin populations were the highest during ca. 1490 to 1670 AD, a cold period, which is contrary to previous results in other regions much farther north. Different responses to climate change may occur at low latitudes and high latitudes in the Antarctic, even if for same species

winTEr SUrvivOrShiP anD SiTE fiDEliTy Of nElSOn'S, SalTMarSh, anD SEaSiDE SParrOwS in nOrTh CarOlina

Abstract. Three species of coastal sparrows (Ammodramus nelsoni, nelson's Sparrow; A. caudacutus, Saltmarsh Sparrow; and A. maritimus, Seaside Sparrow) reside in north Carolina salt marshes in winter during their nonbreeding periods. we analyzed the timing of migration, survivorship, and site fidelity of these species with mark-recapture data from five winters (2006)(2007)(2008)(2009)(2010). By determining the percentage of individuals captured more than once, we documented a shift from transient to settled individuals during and following migration and used linear regressions to test whether this shift was related to mean monthly minimum temperatures. we also used MarK and capture histories over five winters to estimate probabilities of apparent survival and capture. On the basis of recapture data, the three species' populations were composed largely of transient individuals from October until the sparrows settled for the winter by late november. Our recapture data indicate that when coastal sparrows settle for the winter or return to the region in a subsequent year, they do so with high site fidelity. we found that the percent of nelson's and Seaside sparrows captured more than once had a negative relationship with mean monthly minimum temperature. we estimated survival of nelson's, Saltmarsh, and Seaside sparrows at 0.673, 0.520, and 0.483, respectively. Our data indicate that survival of these coastal sparrows through the nonbreeding season is comparable to existing estimates for their breeding populations. Surveys in the nonbreeding season and management plans should take into account the likely presence of a large proportion of transient individuals during migration. Resumen. Tres especies de gorrión, Ammodramus nelsoni, A. caudacutus y A. maritimus, residen en el invierno en las marismas de Carolina del norte, durante sus periodos no reproductivos. analizamos el momento de migración, la supervivencia y la fidelidad de sitio de estas especies con datos de captura-recaptura provenientes de cinco inviernos (2006)(2007)(2008)(2009)(2010). Mediante la determinación del porcentaje de individuos capturados más de una vez, documentamos un cambio de individuos transitorios a individuos establecidos durante y luego de la migración. luego, usamos regresiones lineales para evaluar si este cambio estuvo relacionado con las temperaturas mínimas medias mensuales. También usamos MarK e historias de captura a lo largo de cinco inviernos para estimar las probabilidades de supervivencia aparente y de captura. Sobre la base de los datos de recaptura, las poblaciones de las tres especies estuvieron compuestas principalmente por individuos transitorios desde octubre hasta que los gorriones se establecieron para pasar el invierno a finales de noviembre. nuestros datos de recaptura indicaron que cuando los gorriones de las especies estudiadas se establecen para pasar el invierno o regresan a la región en un año subsecuente, lo hacen exhibiendo una alta fidelidad de sitio. Encontramos que el porcentaje de individuos de A. nelsoni y A. maritimus capturados más de una vez tuvieron una relación negativa con la temperatura mínima media mensual. Estimamos la supervivencia de los individuos de A. nelsoni, A. caudacutus y A. maritimus en 0.673, 0.520 y 0.483, respectivamente. nuestros datos indican que la supervivencia de estas especies a lo largo de la estación no reproductiva es comparable con los estimados existentes para sus poblaciones reproductivas. los muestreos en la estación no reproductiva y los planes de manejo deberían considerar la presencia probable de una gran proporción de individuos transitorios durante la migración

Stable isotope analysis of ancient and modern gentoo penguin egg membrane and the krill surplus hypothesis in Antarctica

Abstract: The 'krill surplus' hypothesis in Antarctica posits that the historic depletion of krill-eating whales and seals in the 18-20th centuries provided a surplus of krill in the Southern Ocean that benefited penguins. A previous study which examined stable isotopes in ancient and modern tissues of Adélie penguin (Pygoscelis adeliae) provides support for this hypothesis. Specifically, a significant decrease in d 13 C and d 15 N values occurred in modern versus ancient tissues from an apparent dietary shift from fish to krill associated with the purported krill surplus. Here, we present new data on gentoo penguin (Pygoscelis papua) tissues from active and abandoned colonies at three locations in the Antarctic Peninsula. We found an overall, but weak, decrease in modern versus fossil d 15 N and d 13 C values of gentoo penguin egg membrane with considerable variation across three breeding sites. Dietary mixing models suggest that shifts between fish and krill in gentoo penguins were likely not as strong as those previously observed in Adélie penguins. This weaker signal probably results from the greater reliance on fish in their diets, past and present, though we cannot rule out declines in primary productivity or other ecosystem shifts which also could account for declines in d 13 C and d 15 N values

Integrating Stomach Content and Stable Isotope Analyses to Quantify the Diets of Pygoscelid Penguins

Stomach content analysis (SCA) and more recently stable isotope analysis (SIA) integrated with isotopic mixing models have become common methods for dietary studies and provide insight into the foraging ecology of seabirds. However, both methods have drawbacks and biases that may result in difficulties in quantifying inter-annual and species-specific differences in diets. We used these two methods to simultaneously quantify the chick-rearing diet of Chinstrap (Pygoscelis antarctica) and Gentoo (P. papua) penguins and highlight methods of integrating SCA data to increase accuracy of diet composition estimates using SIA. SCA biomass estimates were highly variable and underestimated the importance of soft-bodied prey such as fish. Two-source, isotopic mixing model predictions were less variable and identified inter-annual and species-specific differences in the relative amounts of fish and krill in penguin diets not readily apparent using SCA. In contrast, multi-source isotopic mixing models had difficulty estimating the dietary contribution of fish species occupying similar trophic levels without refinement using SCA-derived otolith data. Overall, our ability to track inter-annual and species-specific differences in penguin diets using SIA was enhanced by integrating SCA data to isotopic mixing modes in three ways: 1) selecting appropriate prey sources, 2) weighting combinations of isotopically similar prey in two-source mixing models and 3) refining predicted contributions of isotopically similar prey in multi-source models

Chronic mercury exposure in Late Neolithic/Chalcolithic populations in Portugal from the cultural use of cinnabar

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155748/1/Emslie_et_al_2015_Chronic_mercury.pd

Sources of organic matter and paleo-environmental implications inferred from carbon isotope compositions of lacustrine sediments at Inexpressible Island, Ross Sea, Antarctica

The carbon isotopic composition of organic matter (δ13Corg) was determined in two sediment cores (IIL1 and IIL9) recovered from Inexpressible Island, Ross Sea, Antarctica, and analyzed to identify the sources of that organic matter. The δ13Corg values of sediments of IIL9 were found to vary between −14.6‰ and −11.6‰, with a mean of −13.4‰ (n=48). These values were significantly higher than those of IIL1 sediments which varied between −23.2‰ and −20.4‰, with a mean of −21.8‰ (n=55). The variation in δ13Corg values in these two sediment cores indicate different sources of organic matter. The relatively high δ13Corg values in IIL9 are in accordance with a source from algae, while the low δ13Corg values in IIL1 evince significant influence from penguin guano with algae as the secondary source. Compared with the reference data from other high-latitude lake sediments and plants, the δ13Corg values in IIL9 were extremely high, a result likely related to intense competition for CO2 assimilation among algal species during the growing season in this relatively shallow pond. These results indicate that sedimentary δ13Corg is a reliable proxy for paleo-primary productivity in ponds at Inexpressible Island

Chronic mercury exposure in Late Neolithic/Chalcolithic populations in Portugal from the cultural use of cinnabar

Cinnabar is a natural mercury sulfide (HgS) mineral of volcanic or hydrothermal origin that is found worldwide. It has been mined prehistorically and historically in China, Japan, Europe, and the Americas to extract metallic mercury (Hg 0 ) for use in metallurgy, as a medicinal, a preservative, and as a red pigment for body paint and ceramics. Processing cinnabar via combustion releases Hg 0 vapor that can be toxic if inhaled. Mercury from cinnabar can also be absorbed through the gut and skin, where it can accumulate in organs and bone. Here, we report moderate to high levels of total mercury (THg) in human bone from three Late Neolithic/Chalcolithic (5400-4100 B.P.) sites in southern Portugal that were likely caused by cultural use of cinnabar. We use light stable isotope and Hg stable isotope tracking to test three hypotheses on the origin of mercury in this prehistoric human bone. We traced Hg in two individuals to cinnabar deposits near Almadén, Spain, and conclude that use of this mineral likely caused mild to severe mercury poisoning in the prehistoric population. Our methods have applications to bioarchaeological investigations worldwide, and for tracking trade routes and mobility of prehistoric populations where cinnabar use is documented