Guillemot Eggs Research Articles

Legacy and emerging contaminants in common guillemot Uria aalge eggs in Ireland and Wales

Guillemot eggs from multiple Irish colonies and one Welsh colony were analysed for legacy pollutants such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and other organochlorine compounds (OCs), as well as metals. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) were measured in eggs to understand the influence of diet on contaminant levels detected. Wide-scope target and suspect screening techniques were used on a single guillemot egg, providing novel information on contaminants of emerging concern. Stable isotope ratio analysis showed that guillemots from Great Saltee Island and Lambay Island (Ireland's east coast) had a similar carbon source (δ13C) and fed at similar trophic levels (δ15N), pollutant levels were higher in eggs from Lambay Island near Dublin, Ireland's industrialised capital city. Guillemot eggs from Aughris Head (Atlantic west coast of Ireland), and Skomer Island (Wales) had differing isotopic niches to other colonies. Egg samples from Aughris Head had the lowest levels of pollutants in this study (with the exception of mercury) and amongst the lowest levels reported worldwide. In contrast, Skomer Island had the highest level of pollutants with higher concentrations of Σ16PCB, Σ6PBDE and HCB than Irish colonies, most likely a result of its proximity to historically industrial areas. Levels of PCBs, p,p’ –DDE and mercury in guillemot eggs have decreased over time according to this study, in concurrence with worldwide trends. Levels of pollutants in guillemot eggs, in this study, fall below existing thresholds for adverse effects in other species, with the exception of mercury.

Avian egg collections: museum collection bias driven by shape and size

Avian eggs exhibit substantial intra‐ and interspecific variation in shape, size and colour. Considerable efforts have been made to better understand the evolutionary drivers behind such variation, often using museum egg collections. Usually it is assumed that museum collections accurately represent the variation seen in natural populations, but this may not be the case if there is collection bias. Collection bias may lead to the over‐representation of certain egg traits in collections, due to the aesthetic (or other) preferences of collectors. The aim of this study is to begin to look for the occurrence of potential collection bias in museum egg collections by comparing three shape indices (pointedness/asymmetry, elongation and polar asymmetry) and egg volume between subsets of eggs in museum collections with those of recently sampled eggs in the field for three different bird species: common guillemot Uria aalge, razorbill Alca torda and northern fulmar Fulmarus glacialis. We found no evidence of collection bias in our sampled razorbill and northern fulmar museum collection eggs, but some evidence for a bias in sampled museum collection eggs of common guillemots. Since the guillemot's egg differs from most bird eggs in being pyriform, we suggest that collection bias by historic egg collectors may be more prevalent in species with extreme egg traits. Researchers using museum egg collections to examine questions relating to egg shape should be aware of collection bias risks and consider how to minimise the effect of these possible biases on accumulated datasets.

Wade'sBirds of Bempton Cliffsand his observations on Guillemot (Uria aalge) eggs

Edward Walter Wade (1864–1937), author of The Birds of Bempton Cliffs (1903, 1907), is almost unknown. He worked as a clerk for the family timber company in Hull and in his spare time visited Bempton Cliffs, where he climbed (routinely without a rope) to observe the seabirds and to collect eggs. He was an active member of the Hull Scientific and Field Naturalists' Club and became one of their Vice-Presidents and President. Between 1902 and 1920 he was a member of the British Ornithologists' Union. Wade's published comments on guillemots and their pyriform-shaped eggs, at Bempton, were unusually insightful, in part because his observations were made at close range (a consequence of his climbing ability), and partly because he thought carefully about what he saw. Wade was among the first to point out that the spinning-like-a-top explanation for the guillemot's pyriform egg shape was incorrect based on his own observations. An appendix lists Wade's 69 articles, mostly about birds in Yorkshire, published between 1901 and 1930.

Mucky guillemot eggs are definitely not self-cleaning

Common guillemots really do put all their eggs in one basket; or at least one egg. Jostled by their neighbours and perched high on rain-lashed cliff ledges, pairs of guillemot parents tend their precious individual egg directly on the rock. ‘Breeding at high density is the guillemots’ way of protecting their eggs and chicks from predators such as gulls and ravens, but it means that colonies become rather unhygienic’, says Duncan Jackson from the University of Sheffield, UK, describing how the eggs become smeared with the neighbours’ faeces, potentially smothering the developing embryos within. So when Timothy Birkhead, also from Sheffield, heard press reports that muck does not stick to self-cleaning guillemot eggs, he was sceptical. ‘After studying guillemots on Skomer Island, Wales, for 40 years I knew that their eggs were invariably covered in it’, says Birkhead.Determined to dispel the self-cleaning modern myth, Birkhead and Jamie Thompson obtained a licence giving them permission to abseil down to the bird's precarious cliff face breeding ledges to photograph the eggs and collect a few. Back in Sheffield, they carefully cleaned the fragile shells before cutting them into 1 cm2 portions and gluing a fragment across the top of a glass vial filled with carbon dioxide to measure how much gas diffuses through the shell. Next, they daubed filth that had been collected from the nesting site over the shell and re-measured the vial's carbon dioxide level. Sure enough, less gas was able to diffuse across the mucky shells.Wondering how many of the shell pores that allow gas into and out of the egg become clogged when covered in muck, Jackson retrieved the fragments and filmed them with X-rays to build a detailed view of the shell and its layer of dirt. After reconstructing both, it was apparent that the shells that had the most clogged pores tended to have the lowest gas permeability.But it was still unclear whether the shells were capable of repelling water to wash away dirt. To test the shell's self-cleaning powers, Jackson gently tilted portions of the egg and sprinkled vacuum cleaner dust over them before dripping on droplets of water to see if they rolled away and washed the dirt off. ‘If the eggshell's surface still contained debris suspended in water droplets after our simple trial then the shell could not be self-cleaning’, says Jackson. However, despite their impromptu drenching, each fragment remained awash with a puddle of dusty water. The eggs were not self-cleaning, in contrast to the famously self-cleaning cauliflower and broccoli leaves that Jackson tested, which were immaculate after the simulated rain.Having confirmed that the eggs are not self-cleaning, Birkhead and Nicola Hemmings suggested that Jackson test whether the waterproof outer layer of the shell – known as shell accessory material – may somehow prevent the essential pores from becoming blocked. Stripping the complex outer layer – including calcium carbonate, fats, sugars, proteins and pigment – from the surface of the egg, Jackson then daubed muck on the exposed shell and filmed the surface with X-rays. The stripped soiled egg was in much worse shape than the shell that retained its outer coating, with more than three times as many pores clogged with dirt. ‘It looks like shell accessory material limits the amount of debris that can enter and block pores, which means that gases can travel through the guillemot's eggshell even when the egg is dirty’, says Jackson, although it is not clear how the outer layer prevents blockages. But one thing is certain: press reports that guillemot eggs are self-cleaning were a little premature.

Rare red eggs of the Common Guillemot (Uria aalge): birds, biology and people at Bempton, Yorkshire, in the early 1900s

Huge numbers of Common Guillemot (Uria aalge) eggs were harvested by local men known as “climmers” (climbers) at Bempton Cliffs, Flamborough, Yorkshire, until 1954 when egg collecting became illegal. Guillemot eggs are more variable in colour and pattern than those of any other bird. Egg collectors (oologists) particularly favoured sets of unusually coloured eggs laid by the same bird. Red guillemots eggs were extremely rare and eagerly sought. An example of one such egg known as the “Bempton Belle” was found in the collection of J. W. Goodall (active between about 1896 and 1909), and was celebrated in a poem. What was probably another red egg, known as the “Metland Egg”, was collected each year at Bempton between 1912 and 1938. The current whereabouts of the Metland eggs is unknown. We estimate that females laying red eggs occur less than once in a thousand (or ten thousand). We also speculate about the factors responsible for red eggs and why such eggs are so rare.

Common guillemot (Uria aalge) eggs are not self-cleaning.

Birds are arguably the most evolutionarily successful extant vertebrate taxon, in part because of their ability to reproduce in virtually all terrestrial habitats. Common guillemots, Uria aalge, incubate their single egg in an unusual and harsh environment; on exposed cliff ledges, without a nest, and in close proximity to conspecifics. As a consequence, the surface of guillemot eggshells is frequently contaminated with faeces, dirt, water and other detritus, which may impede gas exchange or facilitate microbial infection of the developing embryo. Despite this, guillemot chicks survive incubation and hatch from eggs heavily covered with debris. To establish how guillemot eggs cope with external debris, we tested three hypotheses: (1) contamination by debris does not reduce gas exchange efficacy of the eggshell to a degree that may impede normal embryo development; (2) the guillemot eggshell surface is self-cleaning; (3) shell accessory material (SAM) prevents debris from blocking pores, allowing relatively unrestricted gas diffusion across the eggshell. We showed that natural debris reduces the conductance of gases across the guillemot eggshell by blocking gas exchange pores. Despite this problem, we found no evidence that guillemot eggshells are self-cleaning, but instead showed that the presence of SAM on the eggshell surface largely prevents pore blockages from occurring. Our results demonstrate that SAM is a crucial feature of the eggshell surface in a species with eggs that are frequently in contact with debris, acting to minimise pore blockages and thus ensure a sufficient rate of gas diffusion for embryo development.

The point of a Guillemot's egg

The adaptive significance of avian egg shape in birds is poorly understood. The pyriform (pear‐like) shape of the Common Guillemot's Uria aalge egg has long been considered to be an adaptation to prevent eggs rolling off the bare cliff ledges on which this species breeds. Rolling was thought to be prevented either by the egg spinning like a top, which is not the case, or by rolling in an arc, which it does but with little influence on whether the egg will fall from a ledge. We therefore sought alternative explanations for the pyriform shape of the Common Guillemot's egg. This species breeds in extremely dense colonies, which makes their eggs vulnerable to mechanical damage from conspecifics, and to contamination by debris such as faeces and soil. We present evidence consistent with both these possible explanations. First, the pyriform shape of Common Guillemot eggs means that a higher proportion of the eggshell lies in contact with the substrate and this may minimize the effect of impacts. Resistance to impacts may be further enhanced because their eggshells are especially thick where they are in contact with the substrate. Secondly, Common Guillemot eggs are often heavily contaminated with faecal material and other debris during incubation. Most contamination is on the pointed end of the egg where it is in contact with the substrate; the pyriform shape thus keeps the blunt end of the egg, which has the highest porosity, relatively free of contamination, which in turn may facilitate both gas exchange during incubation and the hatching process, because the chick emerges from the blunt end of the egg.

Egg shape in the Common Guillemot Uria aalge and Brunnich\u2019s Guillemot U. lomvia: not a rolling matter?

The adaptive significance of avian egg shape is poorly understood, and has been studied only in those species producing pyriform (pear-shaped, or pointed) eggs: waders and guillemots (murres) Uria spp., albeit to a limited extent. In the latter, it is widely believed that the pyriform shape has evolved to minimise their likelihood of rolling off a cliff ledge: the idea being that the more pointed the egg, the narrower the arc in which it rolls, and the less likely it is it will fall from a cliff ledge. Previous research also claimed that the rolling trajectory—the diameter of the arc they describe—of Common Guillemot U. aalge eggs is influenced not only by its shape but also by its mass, with heavier (i.e. larger) eggs describing a wider arc than lighter eggs. The finding that both shape and mass determined the rolling trajectory of Common Guillemot eggs (the shape–mass hypothesis) was used to explain the apparent anomaly that Brünnich’s Guillemot U. lomvia produce eggs that are less pointed, yet breed on narrower ledges than Common Guillemots. They are able to do this, it was suggested, because Brünnich’s Guillemot eggs are smaller and lighter in mass than those of Common Guillemots. However, since some populations of Brünnich’s Guillemots produce eggs that are as large or larger than those of some Common Guillemot populations, the shape–mass hypothesis predicts that that (1) larger (i.e. heavier) eggs of both guillemot species will be more pyriform (pointed) in shape, and (2) that eggs of the two species of same mass should be similarly pointed. We tested these predictions and found: (1) only a weak, positive association between egg volume and pointedness in both guillemot species (<3% of the variation in egg shape explained by egg volume), and (2) no evidence that eggs of the two species of similar mass were more similar in shape: regardless of their mass, Brunnich’s Guillemot eggs were less pointed than Common Guillemot eggs. Overall, our results call into question the long-held belief that protection from rolling is the main selective factor driving guillemot egg shape.

Perfluoroalkyl Acids (PFAAs) and Selected Precursors in the Baltic Sea Environment: Do Precursors Play a Role in Food Web Accumulation of PFAAs?

The present study examined the presence of perfluoroalkyl acids (PFAAs) and selected precursors in the Baltic Sea abiotic environment and guillemot food web, and investigated the relative importance of precursors in food web accumulation of PFAAs. Sediment, water, zooplankton, herring, sprat, and guillemot eggs were analyzed for perfluoroalkane sulfonic acids (PFSAs; C4,6,8,10) and perfluoroalkyl carboxylic acids (PFCAs; C6-15) along with six perfluoro-octane sulfonic acid (PFOS) precursors and 11 polyfluoroalkyl phosphoric acid diesters (diPAPs). FOSA, FOSAA and its methyl and ethyl derivatives (Me- and EtFOSAA), and 6:2/6:2 diPAP were detected in sediment and water. While FOSA and the three FOSAAs were detected in all biota, a total of nine diPAPs were only detected in zooplankton. Concentrations of PFOS precursors and diPAPs exceeded PFOS and PFCA concentrations, respectively, in zooplankton, but not in fish and guillemot eggs. Although PFOS precursors were present at all trophic levels, they appear to play a minor role in food web accumulation of PFOS based on PFOS precursor/PFOS ratios and PFOS and FOSA isomer patterns. The PFCA pattern in fish could not be explained by the intake pattern based on PFCAs and analyzed precursors, that is, diPAPs. Exposure to additional precursors might therefore be a dominant exposure pathway compared to direct PFCA exposure for fish.

Temporal trends of mercury in eggs of five sympatrically breeding seabird species in the Canadian Arctic

We compared temporal trends of total mercury (Hg) in eggs of five seabird species breeding at Prince Leopold Island in the Canadian high Arctic. As changes in trophic position over time have the potential to influence contaminant temporal trends, Hg concentrations were adjusted for trophic position (measured as δ15N). Adjusted Hg concentrations in eggs of thick-billed murres (Uria lomvia) and northern fulmars (Fulmarus glacialis) increased from 1975 to the 1990s, followed by a plateauing of levels from the 1990s to 2014. Trends of adjusted Hg concentrations in eggs of murres, fulmars, black guillemots (Cepphus grylle) and black-legged kittiwakes (Rissa tridactyla) had negative slopes between 1993 and 2013. Adjusted Hg concentrations in glaucous gull (Larus hyperboreus) eggs decreased by 50% from 1993 to 2003 before starting to increase again. Glaucous gull eggs had the highest Hg concentrations followed by black guillemot eggs, and black-legged kittiwake eggs had the lowest concentrations consistently in the five years compared between 1993 and 2013. Based on published toxicological thresholds for Hg in eggs, there is little concern for adverse reproductive effects due to Hg exposure in these birds, although the levels in glaucous gull eggs warrant future scrutiny given the increase in Hg concentrations observed in recent years. There is evidence that the Hg trends observed reflect changing anthropogenic Hg emissions. It remains unclear, however, to what extent exposure to Hg on the overwintering grounds influences the Hg trends observed in the seabird eggs at Prince Leopold Island. Future research should focus on determining the extent to which Hg exposure on the breeding grounds versus the overwintering areas contribute to the trends observed in the eggs.

Differences between Lipids Extracted from Five Species Are Not Sufficient To Explain Biomagnification of Nonpolar Organic Chemicals

Lipids are the major sorptive phase for many organic chemicals that bioaccumulate in foodwebs. However, “lipids” are usually operationally defined by the extraction protocol. Large differences in sorptive capacities between species would violate assumptions implicit in widely used lipid-normalization procedures and invalidate generic bioaccumulation factors. We extracted lipids from five species from different trophic levels and domains and determined fractions of triglycerides, phospholipids, and cholesterol. We passively dosed the lipids with cyclic volatile methylsiloxanes and chlorobenzenes via headspace from spiked olive oil to determine their sorptive capacities. Lipids from seal blubber and pork bacon solely composed of triglycerides had capacities similar to that of olive oil; lipids from mussels, herring, and guillemot egg had quantifiable fractions of phospholipids and cholesterol and showed capacities reduced by factors of up to 2.3-fold. Generally, the sorptive capacities of the lipids were no...

Temporal and spatial trends of PCBs, DDTs, HCHs, and HCB in Swedish marine biota 1969-2012.

In the 1960s, the Baltic Sea was severely polluted by organic contaminants such as PCBs, HCHs, HCB, and DDTs. Elevated concentrations caused severe adverse effects in Baltic biota. Since then, these substances have been monitored temporally and spatially in Baltic biota, primarily in herring (Clupea harengus) and in guillemot (Uria aalge) egg, but also in cod (Gadus morhua), perch (Perca fluviatilis), eelpout (Zoarces viviparous), and blue mussel (Mytilus edulis). These chemicals were banned in Sweden in the late 1970s/early 1980s. Since the start of monitoring, overall significant decreases of about 70–90 % have been observed. However, concentrations are still higher in the Baltic Sea than in, for example, the North Sea. CB-118 and DDE exceed the suggested target concentrations (24 µg kg−1 lipid weight and 5 µg kg−1 wet weight, respectively) at certain sites in some of the monitored species, showing that concentrations may still be too high to protect the most sensitive organisms.Electronic supplementary materialThe online version of this article (doi:10.1007/s13280-015-0673-5) contains supplementary material, which is available to authorized users.

Toxaphene in the aquatic environment of Greenland

The octa- and nonachlorinated bornanes (toxaphene) CHBs 26, 40, 41, 44, 50 and 62 were analysed in Arctic char (Salvelinus alpinus), shorthorn sculpin (Myoxocephalus scorpius), ringed seal (Pusa hispida) and black guillemot eggs (Cepphus grylle) from Greenland. Despite their high trophic level, ringed seals had the lowest concentrations of these species, with a Σ6Toxaphene median concentration of 13–20ng/g lipid weight (lw), suggesting metabolisation. The congener composition also suggests transformation of nona- to octachlorinated congeners. Black guillemot eggs had the highest concentrations (Σ6Toxaphene median concentration of 971ng/g lw). Although concentrations were higher in East than in West Greenland differences were smaller than for other persistent organic pollutants. In a circumpolar context, toxaphene had the highest concentrations in the Canadian Arctic. Time trend analyses showed significant decreases for black guillemot eggs and juvenile ringed seals, with annual rates of −5 to −7% for Σ6Toxaphene. The decreases were generally steepest for CHBs 40, 41 and 44.

Comparing temporal trends of organochlorines in guillemot eggs and Baltic herring: Advantages and disadvantage for selecting sentinel species for environmental monitoring

Within Europe, the Marine Strategy Framework Directive (MSFD) is aimed at addressing the chemical status and quality of the marine environment. One of the main goals is to achieve Good Environmental Status (GES) in the marine environment. Environmental monitoring of biota e.g., Baltic herring and guillemot eggs, is conducted annually in Sweden to follow temporal changes in environmental contaminants. To determine the suitability of guillemot eggs as a sentinel species for investigating GES, we compared temporal trends of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in these two species from single sampling sites within Sweden.Lipid content from guillemot eggs was consistently high and stable (yearly mean for >40 years, ∼12%) compared to that of herring (yearly mean for >20 years, ∼3%). A significant decreasing trend of ΣPCDD/F in TEQ WHO1998 was observed in guillemot eggs, but no trend was seen in herring. CB118 significantly decreased in both species, but in the last 10 years this decrease was not significant in herring. A number of advantages, such as high lipid content in the egg and a low coefficient of variation make guillemot suitable as a sentinel species. The advantages and disadvantages of using either guillemot eggs or Baltic herring are compared.

Correction: Boldness Predicts Social Status in Zebrafish (Danio rerio)

There are two incorrect citations in section 4.1. Statistical Analysis. The first sentence of the second paragraph should have cited reference 32 instead of 33. Additionally, in the second to last sentence of the second paragraph, reference 34 should have cited the following work: Lundstedt-Enkel, K., Asplund, L., Nylund, K., Bignert, A., Tysklind, M., Olsson, M. and Orberg, J. (2006). Multivariate data analysis of organochlorines and brominated flame retardants in Baltic Sea guillemot (Uria aalge) egg and muscle. Chemosphere 65, 1591-1599.

Anpassungen der Eier und des Brutverhaltens von Trottellummen (Uria aalge aalgePont.) an das Brüten auf Felssimsen*

A comparative, descriptive and experimental investigation on Guillemots and Razorbills on Vedoy (63° 30′ N 12° E) was undertaken to discover how an egg characteristic (shape) together with behavioural characteristics enable Guillemots to incubate their egg on the bare surface of a cliff-ledge where it is in danger of falling off. Laboratory ad field experiments with several hundred eggs showed that the pear-shape evidently protects an egg that is rolling away from the nesting-site from falling off: Though Guillemot eggs do not stay on the ledges better than Razorbill eggs, they would — due to their higher weight — be in greater danger of falling off if they had the shape typical of a Razorbill egg. Observations on incubating Guillemots and Rezorbills plus an field experiment showed that Guillemots are distinguished by several behavioural characteristics by which they very strongly reduce the risk of an egg rolling away at all.

Assessment of emerging and traditional halogenated contaminants in Guillemot ( Uria aalge) egg from North-Western Europe and the Baltic Sea

Persistent organic pollutants (POPs) are readily detected in biological samples at remote sites in the Arctic and sub-Arctic due to long-range transport from source areas. The aim of this study was to investigate the presence of POPs, polybrominated contaminants and their metabolites in guillemot ( Uria aalge) eggs from Iceland, the Faroe Islands, Norway and Sweden to assess spatial trends of these compounds in the Arctic and sub-Arctic areas of Europe. Egg samples were extracted, and cleaned for chemical analysis. Concentrations of PCBs, 4,4′-DDE and β-HCH were an order of magnitude higher in eggs from the Baltic Proper compared to eggs from the North Atlantic. Concentrations of HCB were of the same magnitude at all sites, ranging from 160 to 520 ng/g fat. Concentration of BCPS was 100 times higher in eggs from the Baltic compared to eggs from the North Atlantic and seems therefore to be special regional problem. Concentrations of PBDEs were lower in eggs from the North Atlantic compared to eggs from the Baltic Proper but the difference was not as large as for PCBs and 4,4′-DDE. HBCDD showed the same spatial trend as PCBs, where the concentrations in eggs from the Baltic Proper were an order of magnitude higher than in eggs from the North Atlantic. OH-PCB and MeSO 2-PCB metabolites of PCBs, showed the same trend as the parent compounds while spatial trends of MeSO 2-DDE and OH-PBDEs, metabolites of 4,4′-DDE and PBDEs, respectively, differed from the trend of the parent compounds. This may be due to two factors; firstly, the limited ability of birds to metabolise DDT, and secondly, to natural production of OH-PBDE, respectively. Guillemot is suggested as a monitoring species for circumpolar monitoring.

Spatial trends of polyfluorinated compounds in guillemot (Uria aalge) eggs from North-Western Europe

Polyfluorinated alkyl compounds (PFCs) are a group of chemicals of growing concern that have been detected in biological and abiotic samples worldwide. This study reports the concentrations of a suite of PFCs: perfluorooctyl sulfonate (PFOS), perfluorooctyl sulfonamide (PFOSA) and perfluorinated carboxylic acids (PFCAs) in guillemot (Uria aalge) eggs, collected in North-Western Europe, from Iceland, the Faroe Islands, Sweden and two locations in Norway. The highest concentrations of PFOS were found in samples from Sweden (mean 400ngg−1 wet weight (w.w.)), which were almost five times higher than concentrations found in Norwegian samples (mean 85ngg−1w.w. from both sample sites). The concentrations found in Icelandic and Faroe samples were lowest (mean 16 and 15ngg−1w.w., respectively). Only Swedish samples differed significantly from the other locations. In general, PFCAs show a different spatial trend than PFOS. Perfluorooctanoic acid (PFOA) was not detected in any sample and perfluorononanoic acid (PFNA) was only detected in samples from Sweden. The most abundant PFCA was perfluoroundecanoic acid (PFUA) with highest concentrations in samples from Sweden (mean 82ngg−1w.w.), samples from the Faroe Islands had the second highest concentration (mean 57ngg−1w.w.) and samples from Iceland and Norway had concentrations ranging between 18 and 30ngg−1w.w. The original hypothesis was based on the idea that PFC concentrations are the highest close to more densely populated and industrialized areas and lower levels in remote areas. However, the geographic pattern is more complicated than predicted and varies among different PFCs.

QSBMR—Quantitative structure biomagnification relationships: physicochemical and structural descriptors important for the biomagnification of organochlorines and brominated flame retardants

AbstractThe aim of this project is to establish models to predict the biomagnification of contaminants present in Baltic Sea biota. In this paper a quantitative model that we term QSBMR—Quantitative Structure Biomagnification Relationships is presented. This model describes the relationship between the biomagnification factors (BMFs) for several organochlorines (OCs) and brominated flame retardants (BFRs), for example, polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs) and hexabromocyclododecane (HBCD), and their descriptors, for example, physico‐chemical properties and structural descriptors.The concentrations of contaminants in herring (Clupea harengus) muscle and guillemot (Uria aalge) egg from the Baltic Sea were used. The BMFs were calculated with the randomly sampled ratios (RSR) method that denotes the BMFs with a measure of the variation. In order to describe the physico‐chemical properties and chemical structures, approximately 100 descriptors for the contaminants were generated: (a), by using the software (TSAR); (b) finding log Kow values from the literature, and (c) creating binary fingerprint variables that described the position of the chlorine and bromine for the respective PCB and PBDE molecules. Partial least squares (PLS) regression was used to model the relationship between the contaminants' BMF and the descriptors and the resulting QSBMR revealed that more than 20 descriptors in combination were important for the biomagnification of OCs and BFRs between herring and guillemot.The model including all contaminants (R2X = 0.73, R2Y = 0.87 and Q2 = 0.63, three components) explained approximately as much of the variation as the model with the PCBs alone (R2X = 0.83, R2Y = 0.87 and Q2 = 0.58, two components). The model with the BFRs alone (R2X = 0.68, R2Y = 0.88 and Q2 = 0.41, two components) had a slightly lower Q2 than the model including all contaminants.For validation, a training set of seven contaminants was selected by multivariate design (MVD) and a model was established. This model was then used to predict the BMFs of the test set (seven contaminants not included in the model). The resulting R2 for the regression Observed BMF versus Predicted BMF was high (0.65). The good models showed that descriptors important for the biomagnification of OCs and BFRs had been used. These types of models will be useful for in silico predictions of the biomagnification of new, not yet investigated, compounds as an aid in risk assessments. Copyright © 2007 John Wiley &amp; Sons, Ltd.

Multivariate data analysis of organochlorines and brominated flame retardants in Baltic Sea guillemot ( Uria aalge) egg and muscle

Concentrations of organochlorines (OCs) and brominated flame-retardants (BFRs) were determined in guillemot ( Uria aalge) eggs from the island of Stora Karlsö in the Baltic Sea where 10 eggs/year were collected in the years 2000, 2001 and 2002. The dominating contaminant in egg was p, p′-dichlorodiphenyldichloroethylene ( p, p′-DDE) with a geometric mean (GM) concentration of 18 200 ng/g lipid weight (lw). The GM concentration in egg of hexabromocyclododecane (HBCD) of 140 ng/g lw, was significantly higher than that of polybrominated diphenyl ether (∑PBDE) of 77 ng/g lw. For the evaluation of the data multivariate data analysis techniques namely principal components analysis (PCA), partial least squares regression (PLS), soft independent modelling of class analogy (SIMCA classification), and PLS discriminant analysis (PLS-DA), were used. We investigated whether the eggs’ biological characteristics co-varied with egg concentrations of OCs and BFRs, and found e.g., significant negative correlations between egg weight and concentrations of HCB and p, p′-DDE. A PLS model with analyzed BFRs as the Y matrix and OCs as the X matrix could, with varying accuracy, calculate the concentrations of BFRs in the individual egg from their concentrations of OCs (e.g., R 2 Y of 0.89 for BDE47, and of 0.50 for HBCD). Lastly, we compared the contaminant concentrations in the eggs to those in previously analyzed pectoral muscles from adult guillemots from Stora Karlsö, from the year 2000. A PLS-DA model, showed that some of the contaminants (e.g., HBCD and CB28) had significantly higher concentrations in egg than in muscle, although 7 of the 14 contaminants showed no difference in concentrations between the two matrices.