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Mercury (Hg) is a pervasive environmental contaminant that accumulates in the organs and tissues of seabirds at concentrations capable of causing acute or long-term adverse health effects. In the present study, Hg concentrations in Adelie penguin (Pygoscelis adeliae) egg membranes and chick feathers served as a proxy for Hg bioavailability in the marine environment surrounding the northern Antarctic Peninsula. Stable isotopes were measured in conjunction with Hg to infer information regarding feeding habits (δ15 N, diet/trophic level; δ13 C, foraging habitat). The Hg concentrations were low relative to toxicity benchmark values associated with adverse health effects in birds and ranged between 0.006 and 0.080 µg g-1 dry weight (n = 65) in egg membranes and 0.140 to 1.05 µg g-1 fresh weight (n = 38) in feathers. Egg membrane δ15 N signatures suggested that females from different breeding colonies had similar diets consisting of lower and higher trophic prey prior to arrival to breeding grounds. In contrast, δ15 N signatures in feathers indicated that chick diet varied by colony. The Hg concentrations demonstrated significant positive relationships with δ15 N, providing support for the hypothesis of Hg biomagnification up the food chain. The δ13 C signatures in both tissue types provided evidence of foraging habitat segregation among populations. The differences in Hg exposure and foraging ecology suggest that each colony has localized foraging behaviors by breeding adults that warrant additional investigation. Environ Toxicol Chem 2021;40:2791-2801. © 2021 SETAC.

In this study, total mercury (THg) was analyzed in archaeological human bone from 23 sites dating to between the Middle Neolithic and the Antiquity. A total of 370 individuals from individual or collective burials was sampled, mostly using cortical bone from the humerus. These individuals were recovered from over 50 different funerary structures ranging from tholoi, pits, caves, and hypogea. Although cinnabar (HgS) is a likely cause of mercury poisoning and toxicity for people exposed to this mineral from mining or use as a paint or pigment, not all sites investigated here had cinnabar associated with the burials or other excavated areas. We found unusual levels of THg in many of the sampled individuals that we assume were caused by exposure to cinnabar in life, and not by diagenetic processes or other exposures to mercury such as through diet, which would only cause negligible accumulation of THg in bone. Our data, based on the largest sampling ever undertaken on contamination of human bone through archaeological evidence, provide a baseline for additional research on cinnabar and its use in Prehistory. Moderate to high levels of THg in human bone are mainly associated with societies dating from the second half of the 4th to late 3rd millennia B.C. (Late Neolithic to Middle Chalcolithic) in southern Iberia. By the Late Chalcolithic and Early Bronze Age, the use of cinnabar decreased significantly and became minimal or absent. The use and abuse of cinnabar appears to have been pervasive throughout the above-mentioned period and particularly between c. 2900-2300 B.C. This occurred in connection with the high symbolic and probably sacred value of the substance, which was sought after, traded, and extensively used in a variety of rituals and social practices. info:eu-repo/semantics/publishedVersion

High performance liquid chromatography (HPLC) combined with mass spectrometry (MS) was used to analyse deposited pigments (including chlorophyll a, phaeophytin a, canthaxanthin, echinenone, zeaxanthin, scytonemin and mycosporine-like amino acids) from two sediment profiles of ponds in the Ross Sea area, East Antarctica. We explored the sources and characteristics of each pigment, reconstructed an 800-year record of ultraviolet radiation (UVR) and total incoming light intensity, and identified the possible factors that may have influenced historical UVR changes in this region. The results indicated at least four UVR peaks during the past 800 years, corresponding to c. AD 1950–2000, 1720–1790, 1560–1630 and 1350–1480, with the intensity from the most recent sediments being the highest. A comparison between the changes in UVR and total incoming light intensity showed similar patterns between AD 1720 and 1830, suggesting that factors controlling the UVR intensity in the Ross Sea area may be related to insolation fluctuation at that time. The two proxies are, however, weakly correlated during other periods. Historically, there is a relationship between the reconstructed UVR and solar activity, but this natural process may be strongly affected by multiple factors, including climate parameter change and anthropogenic activities during the modern times.

AIM: Our aim was to determine the age and dispersal history of Colorado pinon (Pinus edulis) in western Colorado during the early to late Holocene using radiocarbon‐dated needles and nutshells from packrat (Neotoma spp.) middens. LOCATION: The Uncompahgre Plateau (UP) comprises more than 600,000 ha of public and private lands in west‐central Colorado, USA. Elevations within UP range from 1400 to 3140 m and it is characterized by numerous deep canyons and flat‐topped mesas. The Upper Gunnison Basin (UGB) encompasses a 243,000‐ha area enclosed within the southern Rocky Mountains in south‐western Colorado, USA. It spans 2200–4300 m in elevation, with no outlet apart from the Black Canyon of the Gunnison lower than 2650 m. METHODS: Middens were sampled by breaking off small sections of solidified deposits located in caves and crevices that were then disaggregated in water with repeated rinsing to separate all the plant remains. Single conifer needles and nutshells from 28 middens were radiocarbon dated to determine the age and timing of dispersal into western Colorado. RESULTS: Thirty‐two midden samples were collected, of which 28 produced identifiable plant remains that were radiocarbon dated. Pinon needles and/or nutshells were identified and radiocarbon dated from 20 of these middens from seven localities in UP. The results indicated that pinon did not become established in UP until c. 6000 yr bp, which contrasts with the nearby UGB, where pinon charcoal has been identified from seven archaeological sites with dates ranging from 8000 to 3000 yr bp. MAIN CONCLUSIONS: Our data are consistent with a model of late Pleistocene/early Holocene pinon migration into the Colorado Plateau from Arizona and New Mexico before becoming established in western Colorado. The timing of the pinon migration into south‐central Colorado along the Rio Grande corridor from New Mexico remains uncertain. While pinon–juniper woodlands currently dominate the lower elevations of UP, pinon had disappeared from UGB by c. 3000 yr bp and remains absent there today except for a few isolated trees.

Rationale Physiological stress and starvation have been shown to affect δ(13)C and δ(15)N isotope values and, given that animals often die from starvation, the cause of death may be an important factor to consider in stable isotope analyses of opportunistically collected samples. Methods We addressed this issue by comparing tissue stable isotope values of living and deceased Adelie (Pygoscelis adeliae) and Chinstrap Penguin (P. antarctica) chicks collected from the same respective populations. Results No significant difference was found between living and deceased penguin chick feather, down, and toenail isotope values and both groups displayed similar isotopic trends between tissue types. In addition, similar relationships were observed between both species and across several seasons. Furthermore, sub-dermal adiposity and cause of death (starvation and/or predation) had no significant effect on the δ(13)C and δ(15)N values. Conclusions Our findings suggest that tissues from deceased penguins can be isotopically representative of tissues obtained from the living population, despite the cause of death, and support the use of opportunistic sampling in stable isotope analyses.

Most tropical booby species complete breeding foraging trips within daylight hours, thus avoiding nights at sea. Nazca Boobies Sula granti are unusual in this respect, frequently spending one or more nights away from the nest. We used GPS dataloggers, time-depth recorders, and changes in body weight to characterize foraging trips and to evaluate potential influences on the decisions of 64 adult Nazca Boobies to spend a night at sea, or to return to their chicks on Isla Espanola, Galapagos, in daylight hours. The tagged birds foraged east of Isla Espanola, undertaking both single-day (2‐15 h, 67% of trips) and overnight trips (28 h‐7.2 days, 33%), and executing 1‐19 foraging plunge-dives per single-day trip. Birds might forage longer if they are in nutritional stress when they depart, but body weight at departure was not correlated with trip length. Birds might be expected to return from longer trips with more prey for young, but they returned from single-day and overnight trips with similar body weights, consistent with previous indications that Nazca Boobies forage until accumulating a target value of prey weight. Birds with a lower dive frequency during the first 5 h of a trip were more likely to spend the night at sea, suggesting that they might choose to spend the night at sea if prey capture success was low. At night, birds almost never dived and spent most of their time resting on the water’s surface (11.8‐12.1 h, > 99% of the time between civil sunset and civil dawn). Thus, the night is an unproductive time spent among subsurface predators under low illumination. The birds’ webbed feet provided evidence of this risk: 24% of birds were missing > 25% of their foot tissue, probably due to attacks by predatory fish, and the amount of foot tissue lost increased with age, consistent with a cumulative risk across the lifespan. In contrast, other tropical boobies (Blue-footed Sula nebouxii and Brown Boobies Sula leucogaster), which do not spend the night on the water, showed no such damage. These results suggest that chick-rearing Nazca Boobies accept nocturnal predation risk on occasions of low prey encounter during a foraging trip’s first day.

Recently, Ballance et al. (2006) revived the hypothesis that cetaceans were a major force in the structuring of Southern Ocean food webs, and suggested that they are still playing a keystone role even as their loss continues (see also review in Mori and Butterworth 2006), a subject that we herein would like to emphasize. According to this hypothesis, following 60 yr of directed industrial whaling (Tonnessen and Johnsen 1982, Baker and Clapham 2002), the demise of the great whales (blue, Balaenoptera musculus intermedia; fin, B. physalus; and humpback, Megaptera novaeangliae) led to changes in populations and demographic parameters among penguins, seals, and minke whales (B. bonaerensis; see also Laws 1977, Bengtson and Laws 1985). These changes to populations of the great whales’ competitors came about upon release from trophic competition as a result of the "krill surplus" that ensued (i.e., of Antarctic krill, Euphausia superba; Bengtson and Laws 1985).

2,6-Dialkyl-5-methylene-1,3-dioxan-4-ones were prepared in good diastereomeric excess by treating pantolactone acrylate with a series of selected aldehydes in the Baylis-Hillman reaction. With benzaldehyde and trichloroacetaldehyde, non-cyclic products resulted. In the case of the latter aldehyde the α1-hydroxyalkyl acrylate 5b was isolated as a single diastereomer and its absolute configuration established by X-ray crystallography.

Hexahydro-3a, 7a-dihydroxy-3,7,7-trimethyl-2-phenyl-4H-furo [3,2-c]pyran-4-one 6 has been obtained from the reaction between tetrahydro-4, 4-dimethyl-2-oxo-3-furanyl propanoate 4 , benzaldehyde and base. The product is the result of a modified benzilic acid rearrangement.

The acrylate ester of salicylaldehyde, in the presence of DABCO, affords a crystalline coumarin salt. Formation of this derivative confirms a vital intermediate in the mechanism of the reaction. Salicylaldehyde, suitably protected, reacts with methyl acrylate to afford a novel coumarin not unlike the vasodilator chromonar.

A new, high yielding route to substituted glutaric acid derivatives via an ester enolate Claisen rearrangement of allylic malonates is described.

Reaction of N,N-diethyl cinnamyl carbamate with TBDMSC1 yields the mono-silylated carbamate which, on treatment with butyllithium, reacts with various electrophiles to give the corresponding disubstituted carbamates.

An efficient synthesis of N -Acylimidazolidinones derived from α,β-unsaturated acid chlorides using DABCO as the base is described.

We studied the effect of age and previous breeding experience on the probability of successful reproduction in female northern elephant seals (Mirounga angustirostris). Reproductive data, collected over a 12—yr period, were analyzed by multiple logistic regression to describe the functional relationships among the variables. We also examined the relationships among age, experience, date of breeding, and reproductive success to determine if differences in timing explain age—specific productivity. Finally, we investigated the relationship among age, experience, and maternal behavior to determine if correlates of reproductive effort could be related to age— and experience—specific patterns of reproductive success. Reproductive success increased between the maternal ages of 3 and 7 yr and then levelled off, demonstrating an asymptotic relationship. However, the relationship between reproductive success and age, after statistically controlling for previous experience, showed instead that success increased linearly throughout an animal's lifetime. In contrast, after statistically controlling for age, reproductive success was related to experience in a parabolic fashion; success increased with experience for the first few breeding attempts, but declined later in an animal's reproductive lifetime. The effects of experience depended on age: among young animals experience was apparently beneficial, but among old animals greater experience was deleterious. These results suggest experience—related senescence. Timing of breeding was related to experience, rather than age, in a curvilinear fashion; arrival and parturition dates were later for inexperienced and very experienced females, and were earliest for moderately experienced animals. Young animals that gave birth later in the season experienced reduced reproductive success; we observed no such decline in older animals. Thus, among young females, arriving and giving birth earlier each year was adaptive. Aggressiveness and dominance increased with age and experience, but we were unable to separate the effects of age and experience. We contend that the experience—related drop in reproductive success reflects the cost of reproduction. Breeding at a young age and/or continuously appears to result in lower reproductive success later in life. Furthermore, curvature in age—specific reproductive success can be explained by experience—related senescence. This result has general applicability, suggesting that age—related senescence instead may be due to reproductive "burn—out". These results indicate that previous breeding experience and differences in individual quality do not explain the pattern of increasing reproductive success with age in northern elephant seals, and provide indirect support for the hypothesis that animals increase reproductive effort as they age to offset a concomitant decrease in residual reproductive value.

The association between the distribution of blue-footed boobies Sula nebouxii (BFB) and marine productivity around their breeding grounds is unclear. In Peru, they breed in a region seasonally influenced by the cold, nutrient rich Humboldt Current, and by warm, nutrient poor oceanic waters. The foraging range of BFB in Peru is unknown, although some evidence suggest that they may feed in warm offshore waters. During the austral winter 2002 and summer 2003, we tracked 26 BFBs breeding on Isla Lobos de Tierra, Peru (located approximately 15 km west of the mainland), during 59 feeding trips using small direction recorders to determine their marine habitat use. BFBs preferentially moved to the east of the island and foraged over the continental shelf in cold water masses where marine productivity and the abundance of the main prey, the Peruvian anchovy Engraulis ringens, are usually higher than in other areas. Overall, the median maximum foraging distance from the colony was 39 km (range 3� 109 km), with 90% of all trips located within 30 km from the mainland, and enclosed in an area of 13,113 km 2 . These results reveal that BFBs exploit the productive waters of the Peruvian Coastal Upwelling System, rather than open oceanic waters as previously suggested. BFBs travelled a greater distance, dispersed in a broader area, and visited more offshore waters during the winter 2002, than during the summer 2003, following the typical seasonal horizontal dispersion of the Peruvian anchovy.

The synthesis of two synthetic intermediates 1 and 2, from alkyl-3-hydroxy-2-methylene butanoate via transformations involving Claisen rearrangements, is described

Vinyl esters such as 2, in the presence of DABCO, undergo intial reaction with aldehydes, followed by nucleophilic attack on a second aldehyde molecule. Subsequent intramolecular transesterification affords the dioxanones 5 in high yields and high diastereomeric excesses.

Vinyl esters such as 2, in the presence of DABCO, undergo intial reaction with aldehydes, followed by nucleophilic attack on a second aldehyde molecule. Subsequent intramolecular transesterification affords the dioxanones 5 in high yields and high diastereomeric excesses.