Daption Research Articles

Assessing the trophic ecology and migration on the exposure of cape petrels and Wilson's storm petrels from Antarctica to perfluoroalkylated substances, trace and major elements

Chemical pollution is a global concern as contaminants are transported and reach even the remote regions of Antarctica. Seabirds serve as important sentinels of pollution due to their high trophic position and wide distribution. This study examines the influence of migration and trophic ecology on the exposure of two Antarctic seabirds, Wilson's storm petrel (Oceanites oceanicus - Ooc), and Cape petrel (Daption capense - Dca), to chemical elements and perfluoroalkyl substances (PFAS). Our methodology involved assessing the concentration of these pollutants in feather samples obtained from carcasses, offering a practical means for monitoring contamination. Trace and major element concentrations were comparable in both species, suggesting that migratory patterns have a minimal impact on exposure levels. However, Ooc had higher concentration of PFAS compared to Dca (mean, ng g−1dry weight, PFOA: Ooc:0.710, Dca:0.170; PFTrDA: Ooc:0.550, Dca:0.360, and PFTeDA: Ooc:1.01, Dca:0.190), indicating that migration to the more polluted Northern Hemisphere significantly affects PFAS exposure. Furthermore, while no strong associations were found between either trace elements or PFAS and the three stable isotopes (δ13C, δ15N, and δ34S), a negative association was observed between PFUnDA and δ15N, hinting at potential biodilution. The research concludes that the migratory patterns of these seabird species affect their PFAS exposure, underscoring the critical need for further exploration and understanding of these relationships to better inform conservation strategies.

Rhinonyssus nenecoi sp. nov. (Mesostigmata: Rhinonyssidae); a new nasal mite from Daption capense (Procellariiformes: Procellariidae).

Parasitic nasal mites have been surveyed in a range of vertebrate hosts, but only two species of Rhinonyssidae have been described from procellariiform seabirds. We here describe Rhinonyssus nenecoi sp. nov., from Cape petrels, Daption capense (Procellariidae), collected in Rio Grande do Sul State, southern Brazil. The new species is morphologically most similar to R. procellaricus and R. pluvialis differing mainly by a strongly sclerotised podosomal shield with four pairs of setae, covering more than half of the idiosoma; a podosomal shield with a V-shaped posteromedial projection; an irregularly-shaped sternal shield; and a ventral opisthosoma with 3-4 pairs of setae.

Distribution and diet of cape petrels (Daption capense) attending fishing vessels off the Patagonian Continental Shelf during the non-breeding season in austral winter: insights from on-board censuses and stable isotope analysis

Distribution and diet of cape petrels (Daption capense) attending fishing vessels off the Patagonian Continental Shelf during the non-breeding season in austral winter: insights from on-board censuses and stable isotope analysis

H6N8 avian influenza virus in Antarctic seabirds demonstrates connectivity between South America and Antarctica.

Wild aquatic birds are the natural reservoirs of avian influenza viruses (AIVs). It is estimated that 100 million seabirds live in the Antarctic Peninsula and adjacent islands, regularly encountering migratory birds that use the islands to nest. Between 2010 and 2013, we collected samples from 865 seabirds in Elephant, King George and Livingston islands, around Antarctica Peninsula: chinstrap penguin (n = 143); gentoo penguin (n = 208); Adelie penguin (n = 46); brown skua (n = 90); Cape petrel (n = 115) and southern giant petrel (n = 263). Serum (n = 673) samples were analysed by competitive ELISA and swabs (n = 614) were tested by one step real-time RT-PCR for avian influenza virus (AIV). Sera from 30 chinstrap penguins, 76 brown skuas and a single Adelie penguin were seropositive for AIV. Thirteen swab samples were AIV positive by RT-PCR, and complete genome sequences of H6N8 AIVs isolated from brown skua and chinstrap penguin in 2011 were obtained. Phylogenetic analyses indicated that all gene segments of the H6N8 viruses were closely related to Argentinian and Chilean AIVs. The prevalence with which we identified evidence for AIVs infection in various Antarctic seabirds suggest viral circulation in Antarctic avifauna and interspecies viral transmission in the sub-Antarctic region.

Analysis of the attempts to breed seabirds in uninhabited territories of the Haswell archipelago and Adams Island (East Antarctica)

Data on new breeding sites of seabirds in Antarctica allow a better understanding of spatial species distribution, correct population estimates, and the processes occurring in populations and ecosystems. The aim of the work is to compile and analyze knowledge about the spatial distribution of breeding seabird populations and attempts to breed in new, previously uninhabited territories. Ground-based observations and population counts were conducted at the Haswell archipelago (Queen Mary Land, Davis Sea) by several observers from 1912 to 2016. The total area studied was 12 km². An aerial census of penguins on Adams Island was conducted in 2011. Based on this census, it might be stated that 6 out of 9 breeding species of seabirds have made attempts to develop new breeding sites. Regular breeding of birds within the archipelago is established on 8 islands. Emperor Penguins (Aptenodytes forsteri), Snow Petrels (Pagodroma nivea) and South Polar Skuas (Stercorarius maccormicki) showed no change in spatial distribution. Adélie Penguins (Pygoscelis adeliae), Southern Fulmars (Fulmarus glacialoides), Cape Petrels (Daption capense) and mixed pairs of Brown Skua (Stercorarius antarcticus) × ​​South Polar Skua bred in new sites (6 islands and 1 nunatak). New likely breeding sites have been recorded for the Southern Fulmar, Cape Petrel and Wilson's Storm Petrel (Oceanites oceanicus). An unsuccessful breeding attempt in a previously uninhabited territory has been observed in the Antarctic Petrel (Thalassoica antarctica). New breeding sites for seabirds may result from the avoidance of predation by South Polar Skuas. Changes in local meteorological conditions could be a factor contributing to the breeding attempts by seabirds in the territories previously uninhabited by them. The increase in South Polar Skuas populations, invasion of Brown Skuas on the Haswell Islands, increased breeding attempts and occupation of new breeding sites by Adélie Penguins and tube-nosed seabirds in the early 21st century are evidence of changes in ecological conditions in the local ecosystem.

New and legacy persistent organic pollutants (POPs) in breeding seabirds from the East Antarctic

Persistent organic pollutants (POPs) are pervasive and a significant threat to the environment worldwide. Yet, reports of POP levels in Antarctic seabirds based on blood are scarce, resulting in significant geographical gaps. Blood concentrations offer a snapshot of contamination within live populations, and have been used widely for Arctic and Northern Hemisphere seabird species but less so in Antarctica. This paper presents levels of legacy POPs (polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs)) and novel brominated flame retardants (NBFRs) in the blood of five Antarctic seabird species breeding within Prydz Bay, East Antarctica. Legacy PCBs and OCPs were detected in all species sampled, with Adélie penguins showing comparatively high ∑PCB levels (61.1 ± 87.6 ng/g wet weight (ww)) compared to the four species of flying seabirds except the snow petrel (22.5 ± 15.5 ng/g ww), highlighting that legacy POPs are still present within Antarctic wildlife despite decades-long bans. Both PBDEs and NBFRs were detected in trace levels for all species and hexabromobenzene (HBB) was quantified in cape petrels (0.3 ± 0.2 ng/g ww) and snow petrels (0.2 ± 0.1 ng/g ww), comparable to concentrations found in Arctic seabirds. These results fill a significant data gap within the Antarctic region for POPs studies, representing a crucial step forward assessing the fate and impact of legacy POPs contamination in the Antarctic environment.

Demography of cape petrels in response to environmental changes

AbstractPredicting the responses of populations in changing environments is an important task for ecologists. Understanding the population dynamics of high‐latitude breeding species is critical given the particularly rapid environmental changes that occur in these regions. Using long‐term mark–resighting data acquired over 53‐years in Pointe Géologie, Terre Adélie, Antarctica, we estimated age‐specific demographic parameters and evaluated the effect of the environment on survival of a poorly known species, the cape petrel Daption capense. We then modeled the dynamics of this population using a life‐history model and performed prospective and retrospective analyses to estimate the sensitivity of the population growth rate to demographic parameters, and to quantify their relative contribution. Survival of cape petrel increased with age, being 0.610 (±0.193) for juveniles, 0.739 (±0.158) for individuals from 2 to 4, and 0.920 (±0.031) for older individuals. Minimum age at first reproduction was 3 years old, the age at which all birds were recruited was 14 years, and mean age at first reproduction was 9.05 (±2.06) years. Adult survival increased over time and was positively correlated with the southern annular mode (SAM). The stochastic population growth rate was estimated at 1.019, and adult survival over age 5 made the largest contribution to variance of the population growth rate. Sensitivity analyses revealed that population regulation was mainly driven by the SAM. Our results suggest that despite the decrease in breeding success, the population of cape petrels at Pointe Géologie increased due to the increase in immature and adult survival.

Владислав Монченко — видатний зоолог та його внесок у розвиток зоологічних колекцій

The article is dedicated to the memory of the outstanding scientist-zoologist Vladyslav Ivanovich Monchenko. A brief outline of the main events of the scientist’s activity is given. V. I. Monchenko’s scientific achievements include 191 works published during his lifetime (among them 8 monographs and textbooks), almost 50 newly described taxa of copepod crustaceans and their parasites, and a unique collection of Copepoda. Fundamen-tal generalisations carried out by V. I. Monchenko are recognised by scientists far beyond Ukraine. Those in-clude the life cycles of copepods and the mechanisms of their regulation, as well as the analysis of the mor-phological evolution of this group, including experiments on the presence of cryptic species among cyclopods. His contribution to the biogeography of the Ponto–Caspian Basin are also important. The scientist’s contribu-tion to the development of the National Museum of Natural History (NMNH) NAS of Ukraine is shown. Among the valuable collection specimens transferred by V. Monchenko to the NMNH are various sponges, sea anemones, and ascidians from the Southern Ocean, sailfish and jellyfish from the Pacific Ocean, crustaceans (Brucerolis bromleyana) and corals from the coast of New Zealand. The collection also includes 39 specimens of exotic gastropod and bivalve molluscs, collected in various parts of the Indian and Atlantic oceans and in bodies of fresh water of oceanic islands, as well as a skeleton of a female Cape petrel (Daption capense). The fish exhibition includes a mounted Copper shark (Carcharhinus brachyurus) caught by a researcher in the Pa-cific Ocean off the coast of Japan, and a wet specimen of a pilot fish (Naucrates ductor) from the Pacific Ocean. Sixty specimens of 17 species of fish from the Pacific Ocean and the Black Sea are stored in the scien-tific collection of the NMNH. The scientist received high recognition for his research and contributions into the development of science and scientific schools, he was elected a corresponding member of the NAS of Ukraine (2000), an academician of the NAS of Ukraine (2003), became a laureate of the D. K. Zabolotny Prize (1975) and the State Prize of Ukraine in the Field of Science and Technology (2007), and received the honorary title ‘Honoured Worker of Science and Technology of Ukraine.’

Phenology-based adjustments improve population estimates of Antarctic breeding seabirds: the case of Cape petrels in East Antarctica.

To monitor and conserve a species, it is crucial to understand the size and distribution of populations. For seabirds, population surveys are usually conducted at peak breeding attendance. One of the largest populations of Cape petrels in East Antarctica is at the Vestfold Islands, where environmental and logistical constraints often prevent access to breeding sites at the optimal time for population surveys. In this study, we aim to quantify the contemporary and historical breeding population size of these Cape petrels by adjusting nest counts for variation in breeding phenology using photographs from remote cameras. We also compare spatial distribution between 1970s and 2017/2018. Our results show ground counts occurred outside peak breeding attendance, and adjusting for phenology changed the contemporary and historical population estimates. The Cape petrels showed local intra-island or adjacent-island changes in their distribution between the 1970s and 2017/2018 with no evidence of expanding or restricting their distribution or a significant change in their breeding population size. The results emphasize the importance of accounting for phenology in population counts, where populations are inaccessible at an optimal survey time. We discuss the applications of our research methodology for populations breeding in remote areas and as a baseline for assessing population change.

Population decline of the cape petrel (Daption capense) on King George Island, South Shetland Islands, Antarctica

The Antarctic and the surrounding Southern Ocean are currently subject to rapid environmental changes and increasing anthropogenic impacts. Seabird populations often reflect those changes and so act as indicators of environmental variability. Their population trends may provide information on a variety of environmental parameters on the scale of years or decades. We therefore provide long-term data on the cape petrel (Daption capense) population from a long-term monitoring program on Fildes Peninsula, South Shetland Islands, Maritime Antarctic, an area of considerable human activity. Our data, covering a period of 36 years, indicate some variability, but no clear trend in the number of breeding pairs between the breeding seasons 1985 and 2006. However, beginning in the 2008 season, the population decreased significantly and reached a minimum in the 2020 season. The mean annual decrease between 2008 and 2020 was 10.6%. We discuss possible causes of this strong negative population trend. Anthropogenic disturbance only affects a few breeding sites in the area and is therefore unable, on its own, to explain the consistent population decline at all the breeding sites studied. We think it more likely that reduced food availability was the main cause of the drastic decline in the cape petrel population.

Interactive effects of body mass changes and species-specific morphology on flight behavior of chick-rearing Antarctic fulmarine petrels under diurnal wind patterns.

For procellariiform seabirds, wind and morphology are crucial determinants of flight costs and flight speeds. During chick‐rearing, parental seabirds commute frequently to provision their chicks, and their body mass typically changes between outbound and return legs. In Antarctica, the characteristic diurnal katabatic winds, which blow stronger in the mornings, form a natural experimental setup to investigate flight behaviors of commuting seabirds in response to wind conditions. We GPS‐tracked three closely related species of sympatrically breeding Antarctic fulmarine petrels, which differ in wing loading and aspect ratio, and investigated their flight behavior in response to wind and changes in body mass. Such information is critical for understanding how species may respond to climate change. All three species reached higher ground speeds (i.e., the speed over ground) under stronger tailwinds, especially on return legs from foraging. Ground speeds decreased under stronger headwinds. Antarctic petrels (Thalassoica antarctica; intermediate body mass, highest wing loading, and aspect ratio) responded stronger to changes in wind speed and direction than cape petrels (Daption capense; lowest body mass, wing loading, and aspect ratio) or southern fulmars (Fulmarus glacialoides; highest body mass, intermediate wing loading, and aspect ratio). Birds did not adjust their flight direction in relation to wind direction nor the maximum distance from their nests when encountering headwinds on outbound commutes. However, birds appeared to adjust the timing of commutes to benefit from strong katabatic winds as tailwinds on outbound legs and avoid strong katabatic winds as headwinds on return legs. Despite these adaptations to the predictable diurnal wind conditions, birds frequently encountered unfavorably strong headwinds, possibly as a result of weather systems disrupting the katabatics. How the predicted decrease in Antarctic near‐coastal wind speeds over the remainder of the century will affect flight costs and breeding success and ultimately population trajectories remains to be seen.

A new petrel (Aves: Procellariidae) from the early Miocene of Patagonia (Argentina)

ABSTRACT A right carpometacarpus (MLP 10-XII-11-1) from the early Miocene Gaiman Formation was collected in the fossiliferous locality Bryn Gwyn (Chubut Province, Argentina). After extensive comparisons with extinct and extant species, and geometric morphometric analyses, we concluded that it belongs to Procellariidae. It is supported by the presence of sulcus tendineus restricted to the distal half, a small crest belonging to the m. ulnometacarpalis dorsalis scar, notch and tubercle on the ventral rim of trochlea carpalis, a wide fovea carpalis caudalis not proximally delimited, a rounded, shallow, and proximo-cranial fossa supratrochlearis, and pneumatic foramina within the small fovea carpalis caudalis. The geometric morphometric analyses show clear similarities with Procellariidae, and locate MLP-10-XII-11-1 close to Procellaria aequinoctialis, Daption capense and Pterodroma incerta in the dorsal configuration, and to P. incerta and Macronectes giganteus in the ventral one. Also, the dorsal configuration is more conservative within families than the ventral one. Although this carpometacarpus does not present any exclusive character, the combination of characters found in the new fossil is unique, suggesting that MLP 10-XII-11-1 might represent a new genus and species. However, the proposal of a new species must wait until more complete specimens are found.

Polymer types ingested by northern fulmars (Fulmarus glacialis) and southern hemisphere relatives

Although ingestion of plastic by tubenosed seabirds has been documented regularly, identification of the polymer composition of these plastics has rarely been described. Polymer assessment may assist in identifying sources and may indicate risks from additives occurring in specific types of polymers. Using known test materials, two identification methods Fourier transform infrared spectroscopy and near infrared spectroscopy (FTIR and NIR) were compared. Although both methods were found to be similarly suitable for identification of plastic polymers, a significant difference was observed in identification of natural materials. FTIR frequently misclassified natural materials as being a synthetic polymer. Within our results, an 80% match score threshold functioned best to distinguish between natural items and synthetics. Using NIR, the historical variability of plastics ingested by northern fulmars (Fulmarus glacialis) from the Dutch sector of the North Sea was analysed for three time periods since the 1980s. For the more recent decade, variability between fulmars from different regions in the northeast Atlantic was investigated. Regional variation was further explored by analysing plastics obtained from the stomachs of southern hemisphere relatives of the fulmar (southern fulmar, cape petrel, snow petrel) and Wilson’s storm petrel. Results show that proportional abundance of polymer types in these seabirds is closely related to the plastic categories that they ingest (e.g. pellets, foam, fragments). The uptake of different plastic categories and related polymer types most likely reflects spatial and temporal variations in availability rather than ingestion preferences of the birds.

Trace elements in feathers of Cape Petrel (Daption capense) from Antarctica

The Cape petrel (Daption capense) has circumpolar distribution and potential to be used as sentinels of trace elements levels in the Antarctic environment. This study measured trace elements in carcass feathers (n = 30) of this yet under-studied Procellariiform species, in King George Island, Antarctica. This non-invasive sampling method was useful for quantifying mercury (Hg), cadmium (Cd), selenium (Se), and to perform the sex identification of birds. There were no significant differences between males and females for Hg (mean ± SD, 973 ± 930 ng g−1; 977 ± 570 ng g−1) and Se (3919 ± 637 ng g−1; 3782 ± 799 ng g−1), levels but males had significantly lower Cd levels than females (101 ± 76 ng g−1; 293 ± 251 ng g−1), respectively. Hg concentration in D. capense is lower than other Procellariiformes which indicate interspecific variations that may be related to their proximity to pollution sources. The reason for males having significantly lower Cd levels than females is unknown. This opportunistic and non-invasive sampling strategy can be useful in the environmental monitoring of the trace elements in polar environments.

High inter- and intraspecific niche overlap among three sympatrically breeding, closely related seabird species: Generalist foraging as an adaptation to a highly variable environment?

Ecological niche theory predicts sympatric species to show segregation in their spatio-temporal habitat utilization or diet as a strategy to avoid competition. Similarly, within species individuals may specialize on specific dietary resources or foraging habitats. Such individual specialization seems to occur particularly in environments with predictable resource distribution and limited environmental variability. Still, little is known about how seasonal environmental variability affects segregation of resources within species and between closely related sympatric species. The aim of the study was to investigate the foraging behaviour of three closely related and sympatrically breeding fulmarine petrels (Antarctic petrels Thalassoica antarctica, cape petrels Daption capense and southern fulmars Fulmarus glacialoides) in a seasonally highly variable environment (Prydz Bay, Antarctica) with the aim of assessing inter- and intraspecific overlap in utilized habitat, timing of foraging and diet and to identify foraging habitat preferences. We used GPS loggers with wet/dry sensors to assess spatial habitat utilization over the entire breeding season. Trophic overlap was investigated using stable isotope analysis based on blood, feathers and egg membranes. Foraging locations were identified using wet/dry data recorded by the GPS loggers and expectation-maximization binary clustering. Foraging habitat preferences were modelled using generalized additive models and model cross-validation. During incubation and chick-rearing, the utilization distribution of all three species overlapped significantly and species also overlapped in the timing of foraging during the day-partly during incubation and completely during chick-rearing. Isotopic centroids showed no significant segregation between at least two species for feathers and egg membranes, and among all species during incubation (reflected by blood). Within species, there was no individual specialization in foraging sites or environmental space. Furthermore, no single environmental covariate predicted foraging activity along trip trajectories. Instead, best-explanatory environmental covariates varied within and between individuals even across short temporal scales, reflecting a highly generalist behaviour of birds. Our results may be explained by optimal foraging theory. In the highly productive but spatio-temporally variable Antarctic environment, being a generalist may be key to finding mobile prey-even though this increases the potential for competition within and among sympatric species.

Pelagic seabirds as biomonitors of persistent organic pollutants in the Southwestern Atlantic.

Persistent Organic Pollutants (POPs) are accumulated through time and can exert different effect on ecosystems. POPs and Chlorpyrifos, a current use pesticide, were assessed in body feathers of males and females of Black-browed albatross (Thalassarche melanophris, BBA) and Cape petrels (Daption capense, CAP) during their non-breeding seasons at the Patagonian Shelf, Argentina. Chlorpyrifos showed the highest values among all pollutants in both species (49.56-84.88 ng g-1), resulting from current agricultural practices. The pattern OCPs > PCBs > PBDEs was observed in both species, and CAP showed higher concentrations than BBA probably as a consequence of higher lipid mobilization and pollutants availability during dispersion. Non-significant differences between sexes about POPs levels were found; however a slight tendency was observed, females>males in CAP, and males>females in BBA. More attention and further studies are needed to understand seabirds' physiology and its relationship with the pollutants distribution in their tissues and considering breeding season.

FIRST BREEDING RECORD OF PINTADO PETREL DAPTION CAPENSIS AT MARION ISLAND

Pintado or Cape Petrels Daption capense have a circumpolar distribution and have been recorded breeding at 23 localities in the Southern Ocean. They have been recorded as vagrants to Marion Island since 1951. Oosthuizen et al. (2009) regarded them as occurring too frequently for the species to be regarded as a vagrant, but was never thought to be breeding there. This is the first record of the species breeding at the PEIs and brings the number of seabird species, including the Lesser Sheathbill, reported breeding there to 31.

Complete mitogenome of the Cape petrel Daption capense from Barton Peninsula, King George Island, Antarctica

The Cape petrel Daption capense, a seabird, is observed throughout the southern hemisphere including the Antarctic region. Herein, we report the complete mitogenome of Cape petrel with the GenBank accession number MH924023 to elucidate the genetic characteristics of this genus. The mitogenome is 17,312 bp long and comprises 13 protein-coding genes (PCGs), two rRNA genes, and 22 tRNA genes. The overall base composition of the 13 PCGs is as follows: A (31.1%), C (30.3%), T (25.4%), and G (13.2%), with a GC content of 43.5%. The results provide useful information for further genetic studies in Procellariiformes.

Seabird hotspots on icebergs in the Amundsen Sea, Antarctica

Our long-term study on the quantitative at-sea distribution of the upper trophic levels—seabirds and marine mammals—in polar ecosystems aims at quantifying the factors influencing their distribution as well as detecting possible spatial and temporal evolutions, with special attention to hydrography and to global climate changes. During the PS75 (ANT-XXVI/3) expedition of icebreaking RV Polarstern in February–March 2010, 6660 seabirds belonging to 11 identified species were recorded in the Amundsen Sea Embayment and Pine Island Bay during 760 half-hour transect counts. The most numerous species were by far Antarctic petrel Thalassoica antarctica, Adelie penguin Pygoscelis adeliae and snow petrel Pagodroma nivea representing together more than 80% of the total for the whole expedition (n = 5475). Substantial seabird hotspots were concentrated on three icebergs, representing 44% of all observations: 85% of the Antarctic petrels and 40% of the snow petrels. Moreover, 35 Cape petrels Daption capense capense were noted in the immediate surrounding of another iceberg (33% of the total). The highest overall counts were tallied on two icebergs: 250 Antarctic petrels and 500 snow petrels on the first one, and 1000 Antarctic petrels on the second. These hotspots seem to be typical for autumn situations and thus probably reflect the existence of pre-migratory gatherings following the breeding season. The consequences of these high local concentrations and thus the heterogeneity and non-normal distribution of the data are discussed, calculating mean values, standard deviation and density have very questionable value.

Influence of Delipidation on Hg Analyses in Biological Tissues: A Case Study for an Antarctic Ecosystem

The use of low-polarity organic solvents is widespread in cleanup/extraction processes in order to carry compounds of interest, remove interferences and separate phases, among other uses. A large number of studies have used delipidation to remove excess of lipids to analyse carbon stable isotopes in biological tissues for trophic and behavioural ecology investigations. In this context, the primary aim of this study is to assess the influence of one delipidation process on the results of total mercury (Hg) analyses and the possible use of delipidated samples from previous analyses, such as for stable isotopes, in Hg level determination. Samples of vegetation (angiosperm, lichens and mosses), invertebrates (krill and limpets), fish (marbled and black rockcod), bird liver and eggs (Antarctic, Gentoo and Adelie penguins, kelp gull, Antarctic tern, cape petrel and giant southern petrel) and pinniped tissues (Weddell seal, crabeater seal, southern elephant seal and Antarctic fur seal) were analysed for Hg before and after delipidation by cyclohexane. The difference between the two measurements ranged individually from −63 to 136% (in the moss Sanionia uncinata) and the averages ranged from −60 to 66% (in pinniped tissues). The proportion of organic Hg, which presents considerable lipophilicity, but also high affinity for sulfhydryl groups in proteins, might be responsible for such variability. Given the limitations of our study, we think it is safe to say that delipidated samples could not be used to infer total Hg values in non-delipidated ones.