Multi-decadal trends in biomarkers in harp seal teeth from the North Atlantic reveal the influence of prey availability on seal trophic position.

Arctic food webs are being impacted by borealisation and environmental change. To quantify the impact of these multiple forcings, it is crucial to accurately determine the temporal change in key ecosystem metrics, such as trophic position of top predators. Here, we measured stable nitrogen isotopes (δ N) in amino acids in harp seal teeth from across the North Atlantic spanning a period of 60 years to robustly assess multi-decadal trends in harp seal trophic position, accounting for changes in δ N at the base of the food web.

Multi-decadal environmental change in the Barents Sea recorded by seal teeth.

Multiple environmental forcings, such as warming and changes in ocean circulation and nutrient supply, are affecting the base of Arctic marine ecosystems, with cascading effects on the entire food web through bottom-up control. Stable nitrogen isotopes (δ N) can be used to detect and unravel the impact of these forcings on this unique ecosystem, if the many processes that affect the δ N values are constrained. Combining unique 60-year records from compound specific δ N biomarkers on harp seal teeth alongside state-of-the-art ocean modelling, we observed a significant decline in the δ N values at the base of the Barents Sea food web from 1951 to 2012.

Evidence of Vent-Adaptation in Sponges Living at the Periphery of Hydrothermal Vent Environments: Ecological and Evolutionary Implications.

The peripheral areas of deep-sea hydrothermal vents are often inhabited by an assemblage of animals distinct to those living close to vent chimneys. For many such taxa, it is considered that peak abundances in the vent periphery relate to the availability of hard substrate as well as the increased concentrations of organic matter generated at vents, compared to background areas. However, the peripheries of vents are less well-studied than the assemblages of vent-endemic taxa, and the mechanisms through which peripheral fauna may benefit from vent environments are generally unknown.

Interactions between Environmental Contaminants and Gastrointestinal Parasites: Novel Insights from an Integrative Approach in a Marine Predator.

Environmental contaminants and parasites are ubiquitous stressors that can affect animal physiology and derive from similar dietary sources (co-exposure). To unravel their interactions in wildlife, it is thus essential to quantify their concurring drivers. Here, the relationship between blood contaminant residues (11 trace elements and 17 perfluoroalkyl substances) and nonlethally quantified gastrointestinal parasite loads was tested while accounting for intrinsic (sex, age, and mass) and extrinsic factors (trophic ecology inferred from stable isotope analyses and biologging) in European shags .

Resolving Blocked Antigen Phenomenon in Hemolytic Disease of the Fetus and Newborn Due to Anti-K.

High-titer antibodies are a cause of false-negative reactions in red blood cell antigen phenotyping, an event referred to as blocked antigen phenomenon (BAP). In hemolytic disease of the fetus and newborn, BAP complicates laboratory workups as fetal phenotype is helpful in confirming the responsible antibody. Acid elution techniques, techniques using ethylenediaminetetraacetic glycine acid, as well as those using chloroquine diphosphate have been used to resolve BAP; however, ethylenediaminetetraacetic glycine acid destroys K-antigen expression and chloroquine diphosphate is not always effective.