A comprehensive assessment of mercury exposure in penguin populations throughout the Southern Hemisphere: Using trophic calculations to identify sources of population-level variation.

The wide geographic distribution of penguins (Order Sphenisciformes) throughout the Southern Hemisphere provided a unique opportunity to use a single taxonomic group as biomonitors of mercury among geographically distinct marine ecosystems. Mercury concentrations were compared among ten species of penguins representing 26 geographically distinct breeding populations. Mercury concentrations were relatively low (⩽2.00ppm) in feathers from 18/26 populations considered. Population-level differences in trophic level explained variation in mercury concentrations among Little, King, and Gentoo penguin populations. However, Southern Rockhopper and Magellanic penguins breeding on Staten Island, Tierra del Fuego, had the highest mercury concentrations relative to their conspecifics despite foraging at a lower trophic level. The concurrent use of stable isotope and mercury data allowed us to document penguin populations at the greatest risk of exposure to harmful concentrations of mercury as a result of foraging at a high trophic level or in geographic 'hot spots' of mercury availability.

Brasso RL ，Chiaradia A ，Polito MJ ，Raya Rey A ，Emslie SD ... -  《-》

Penguin eggshell membranes reflect homogeneity of mercury in the marine food web surrounding the Antarctic Peninsula.

Remote regions such as the Antarctic have become increasingly important for investigations into far-reaching anthropogenic impacts on the environment, most recently in regard to the global mercury cycle. Spatial patterns of mercury availability in four regions of the Antarctic Peninsula were investigated using three species of sympatrically breeding Pygoscelis penguins as biomonitors. Eggshells with intact membranes from Adélie, Gentoo, and Chinstrap penguins were collected at 24 breeding colonies in the South Orkney Islands, South Shetland Islands, eastern Antarctic Peninsula, and western Antarctic Peninsula during the 2006/2007 austral summer. In addition, we compared eggshell membrane mercury concentrations with eggshell stable isotope values (δ(15)N and δ(13)C) to determine if species-specific trophic or foraging habitat preferences influenced female mercury exposure prior to breeding. With few exceptions, mercury concentrations were found to be fairly homogeneous throughout the Antarctic Peninsula suggesting little spatial variation in the risk of exposure to dietary mercury in this food web. Mercury concentrations in Gentoo and Adélie penguins were similar while Chinstrap penguins tended to have higher eggshell membrane mercury concentrations than their congeners. However, inter and intra-specific differences in eggshell membrane mercury concentration were not related to eggshell δ(15)N or δ(13)C values, a likely result of all three species foraging at similar trophic positions. The lack of regional-scale differences in mercury availability in this marine ecosystem may be a reflection of generally uniform atmospheric deposition and upwelling of regionally homogeneous deep water rather than from geographically distinct point sources.

Brasso RL ，Polito MJ ，Lynch HJ ，Naveen R ，Emslie SD ... -  《-》

Temporal and interspecific variation in feather mercury in four penguin species from Macquarie Island, Australia.

We measured mercury (Hg) concentrations in feathers from four penguin species collected on Macquarie Island, Southern Ocean, to 1) establish baseline Hg concentrations; and 2) compare Hg from samples collected in 2002 ("modern") and from museum specimens collected between 1937 and 1976 ("historic"). Inter-specific differences in feather Hg reflected known differences in habitats and diversity of diets: benthic-foraging Gentoo penguins and Rockhopper penguins that foraged both inshore and offshore had significantly higher feather mercury than the more pelagic, specialist foraging King and Royal penguins. Hg significantly decreased between historic and modern samples in King and Royal penguins. This decrease could be due to changes in either diet, foodwebs, or atmospheric Hg input and sources in the Southern Hemisphere. Because Macquarie Island is home to 2.8 million marine animals, these data may indicate that other species that forage and breed in this region are also exposed to low Hg concentrations in this environment.

Gilmour ME ，Holmes ND ，Fleishman AB ，Kriwoken LK ... -  《-》

Influence of migration range and foraging ecology on mercury accumulation in Southern Ocean penguins.

In order to evaluate mercury (Hg) accumulation patterns in Southern Ocean penguins, we measured Hg concentrations and carbon (δ13C) and nitrogen (δ15N) stable isotope ratios in body feathers of adult Adélie (Pygoscelis adeliae), gentoo (Pygoscelis papua), and chinstrap (Pygoscelis antarctica) penguins living near Anvers Island, West Antarctic Peninsula (WAP) collected in the 2010/2011 austral summer. With these and data from Pygoscelis and other penguin genera (Eudyptes and Aptenodytes) throughout the Southern Ocean, we modelled Hg variation using δ13C and δ15N values. Mean concentrations of Hg in feathers of Adélie (0.09 ± 0.05 μg g-1) and gentoo (0.16 ± 0.08 μg g-1) penguins from Anvers Island were among the lowest ever reported for the Southern Ocean. However, Hg concentrations in chinstrap penguins (0.80 ± 0.20 μg g-1), which undertake relatively broad longitudinal winter migrations north of expanding sea ice, were significantly higher (P < 0.001) than those in gentoo or Adélie penguins. δ13C and δ15N values for feathers from all three Anvers Island populations were also the lowest among those previously reported for Southern Ocean penguins foraging within Antarctic and subantarctic waters. These observations, along with size distributions of WAP krill, suggest foraging during non-breeding seasons as a primary contributor to higher Hg accumulation in chinstraps relative to other sympatric Pygoscelis along the WAP. δ13C values for all Southern Ocean penguin populations, alone best explained feather Hg concentrations among possible generalized linear models (GLMs) for populations grouped by either breeding site (AICc = 36.9, wi = 0.0590) or Antarctic Frontal Zone (AICc = 36.9, wi = 0.0537). Although Hg feather concentrations can vary locally by species, there was an insignificant species-level effect (wi < 0.001) across the full latitudinal range examined. Therefore, feeding ecology at breeding locations, as tracked by δ13C, control Hg accumulation in penguin populations across the Southern Ocean.

Sontag PT ，Godfrey LV ，Fraser WR ，Hinke JT ，Reinfelder JR ... -  《-》

Assessing mercury contamination in Southern Hemisphere marine ecosystems: The role of penguins as effective bioindicators.

Gimeno M ，Rossell L ，Julià L ，Giménez J ，Sanpera C ，Coll M ，Bustamante P ，Ramírez F ... -  《-》