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Biometrics of stranded white-beaked dolphins (Lagenorhynchus albirostris) in Danish waters
No full textWhite-beaked dolphins (Lagenorhynchus albirostris) are among the most common toothed whales in the North Sea, but still relatively little is known about their general biology and their biometrics. The white-beaked dolphins are known to breed in the outer Danish waters and have recently been documented as breeding in inner Danish waters too. Here we present the biometrics (stranding location (n=128), stranding month (n=129), sex (n=103), reproductive status (n=103), length (n=102), external body dimensions (n=90) and blubber thickness (n=57; 22 with complete data set)) for individuals stranded between 1979 and 2023. Organ size was measured in 12 individuals. Most white-beaked dolphins (85%) were stranded on the coastline of the outer Danish waters, and with January, May and June as the most common months for stranding. Males made up 41%, of which 73% were immature, while only 36% of the stranded females were immature. Apart from the curve measures around the genital slit, no differences in the relative lengths of external measurements were found between males and females. No seasonal, sexual or geographical differences were found in blubber thickness. The intestines had a median length of 20.5 meter (18.30-23.90 meters) from the duodenum to the pelvic part of the rectum. Measurements of beak to belly button, beak to dorsal fin and tail width were highly correlated (R2<65%, p<0.0001). These data contribute to increased knowledge of white-beaked dolphins' biometrical measures.White-beaked dolphins (Lagenorhynchus albirostris) are among the most common toothed whales in the North Sea, but there is still relatively little known about their general biology and their biometrics. The white-beaked dolphins are known to breed in the outer Danish waters and have recently been documented as breeding in inner Danish waters as well. Herein, we present the biometrics (stranding location, n = 128; stranding month, n = 129; sex, n = 103; reproductive status, n = 103; length, n = 102; external body dimensions, n = 90; and blubber thickness, n = 57; 22 with complete dataset) for individuals stranded between 1979 and 2023. Organ size was measured in 12 individuals. Most white-beaked dolphins (85%) stranded on the coastline of the outer Danish waters, with January, May, and June as the most common months for stranding. Males made up 41% of the dolphins in this study, of which 73% were immature, while only 36% of the stranded females were immature. Apart from the curve measures around the genital slit, no differences in the relative lengths of external measurements were found between males and females, nor were seasonal, sexual, or geographical differences found in blubber thickness. The intestines had a median length of 20.5 m (18.30 to 23.90 m) from the duodenum to the pelvic part of the rectum. Measurements of beak to belly button, beak to dorsal fin, and tail width were highly correlated (R2 < 65%, p < 0.0001). These data contribute to increased knowledge of white-beaked dolphins’ biometric measurements
Anti-icing properties of polar bear fur
Get PDFThe polar bear (Ursus maritimus) is the only Arctic land mammal that dives into water to hunt. Despite thermalinsulation provided by blubber and fur layers and low Arctic temperatures, their fur is typically observed to be freeof ice. This study investigates the anti-icingproperties of polar bear fur. Here, we show that polar bear fur exhibitslow ice adhesion strengths comparable to fluorocarbon-coatedfibers, with the low ice adhesion a consequence ofthe fur sebum (hair grease). Lipid analyses reveal the presence of cholesterol, diacylglycerols, anteisomethyl-branchedfatty acids, and the unexpected absence of squalene. Quantum chemical calculations predict low iceadsorption energies for identified lipids and high adsorption for squalene, suggesting that sebum composition isresponsible for the observed anti-icingproperties. Our work enhances understanding of polar bears and their interactionswith their environment and builds on Inuit knowledge of natural anti-icingmaterials.The polar bear (Ursus maritimus) is the only Arctic land mammal that dives into water to hunt. Despite thermal insulation provided by blubber and fur layers and low Arctic temperatures, their fur is typically observed to be free of ice. This study investigates the anti-icing properties of polar bear fur. Here, we show that polar bear fur exhibits low ice adhesion strengths comparable to fluorocarbon-coated fibers, with the low ice adhesion a consequence of the fur sebum (hair grease). Lipid analyses reveal the presence of cholesterol, diacylglycerols, anteisomethyl-branched fatty acids, and the unexpected absence of squalene. Quantum chemical calculations predict low ice adsorption energies for identified lipids and high adsorption for squalene, suggesting that sebum composition is responsible for the observed anti-icing properties. Our work enhances understanding of polar bears and their interactions with their environment and builds on Inuit knowledge of natural anti-icing materials
Rapid analysis of shipworm attack - a novel digital tool for assessing shipworm damage (RANDA)
Get PDFShipworm (Teredo navalis) poses a significant threat to wooden structures and archaeological artifacts in marine environments, leading to extensive biodeterioration. Quantifying shipworm damage remains challenging due to the limitations of traditional assessment methods, which are often invasive, time-consuming, and/or subjective. In this study, we introduce RANDA (Rapid Analysis Digital Tool), a software designed to assess shipworm damage severity through image-based analysis of entry holes on wood surfaces, with the potential for non-destructive application. Data from 232 T. navalis entry holes and tunnels revealed a strong correlation between entry hole size and tunnel volume, suggesting that surface analysis can approximate internal damage. When applied to eight test panels, RANDA degradation estimates differed by -0.69±1.05 % from weight loss analysis and by 2.74 ± 1.67 % from tunnel volume measurements obtained via CT imaging. For hole classification, the RANDA model achieved a precision of 80 % and a recall of 81 %. While currently validated under controlled conditions, this method offers a rapid and reliable alternative to conventional approaches and represents an important step toward a non-destructive in situ assessment tool.Shipworm (Teredo navalis) poses a significant threat to wooden structures and archaeological artifacts in marine environments, leading to extensive biodeterioration. Quantifying shipworm damage remains challenging due to the limitations of traditional assessment methods, which are often invasive, time-consuming, and/or subjective. In this study, we introduce RANDA (Rapid Analysis Digital Tool), a software designed to assess shipworm damage severity through image-based analysis of entry holes on wood surfaces, with the potential for non-destructive application. Data from 232 T. navalis entry holes and tunnels revealed a strong correlation between entry hole size and tunnel volume, suggesting that surface analysis can approximate internal damage. When applied to eight test panels, RANDA degradation estimates differed by -0.69±1.05 % from weight loss analysis and by 2.74 ± 1.67 % from tunnel volume measurements obtained via CT imaging. For hole classification, the RANDA model achieved a precision of 80 % and a recall of 81 %. While currently validated under controlled conditions, this method offers a rapid and reliable alternative to conventional approaches and represents an important step toward a non-destructive in situ assessment tool
Bone diagenesis in archaeological contexts – insights from caribou remains at Aasivissuit, West Greenland
No full textOrganizing Warriors in the 6th and 7th century AD:The Evidence of the Stray-finds in East Denmark
No full textLate Germanic Iron Age weapon burials from Bornholm, Denmark, have been used to suggest the presence of a Merovingian inspired organization of warriors including conscripts. This article compares these burials’ inventory, focusing on the first part of the Late Germanic Iron Age (AD 520-630), to the distribution of similar types of metal stray-finds. Mapping the stray-finds from Bornholm indicates the whereabouts of the warriors and it is discussed whether this can contribute to a plausible representation of warriors and a geographicallyrooted organization of warriors. This evidence is tested on equivalent stray-find material from Sjælland and adjacent islands where weapon burials are almost absent. The study shows a difference between the burial inventory and the stray-finds regarding relative numbers of specific object types, and it is clear that the standardized set of weapons originally assumed to picture the conscripted warrior cannot be found
