Stable Isotope Biogeochemistry of Seabird Guano Fertilization: Results from Growth Chamber Studies with Maize (Zea Mays)

Stable isotope analysis is being utilized with increasing regularity to examine a wide range of issues (diet, habitat use, migration) in ecology, geology, archaeology, and related disciplines. A crucial component to these studies is a thorough understanding of the range and causes of baseline isotopic variation, which is relatively poorly understood for nitrogen (δ(15)N). Animal excrement is known to impact plant δ(15)N values, but the effects of seabird guano have not been systematically studied from an agricultural or horticultural standpoint.This paper presents isotopic (δ(13)C and δ(15)N) and vital data for maize (Zea mays) fertilized with Peruvian seabird guano under controlled conditions. The level of (15)N enrichment in fertilized plants is very large, with δ(15)N values ranging between 25.5 and 44.7‰ depending on the tissue and amount of fertilizer applied; comparatively, control plant δ(15)N values ranged between -0.3 and 5.7‰. Intraplant and temporal variability in δ(15)N values were large, particularly for the guano-fertilized plants, which can be attributed to changes in the availability of guano-derived N over time, and the reliance of stored vs. absorbed N. Plant δ(13)C values were not significantly impacted by guano fertilization. High concentrations of seabird guano inhibited maize germination and maize growth. Moreover, high levels of seabird guano greatly impacted the N metabolism of the plants, resulting in significantly higher tissue N content, particularly in the stalk.The results presented in this study demonstrate the very large impact of seabird guano on maize δ(15)N values. The use of seabird guano as a fertilizer can thus be traced using stable isotope analysis in food chemistry applications (certification of organic inputs). Furthermore, the fertilization of maize with seabird guano creates an isotopic signature very similar to a high-trophic level marine resource, which must be considered when interpreting isotopic data from archaeological material

Are great tits (Parus major) inhabiting the vicinity of a pulp mill healthy? Impacts on physiology and breeding performance

The evaluation of pollution effects on wildlife provides biologically meaningful information concerning environmental quality and possible impacts on populations and can be used as an early warning of environmental change. We aimed to assess the potential effects of exposure to atmospheric pollution from pulp mill emissions on the morphology, physiology, and reproductive performance of the great tit (Parus major). Great tits from a population inhabiting the vicinity of a pulp mill had significantly higher feather mercury levels and were physiologically distinct from other birds not under the direct influence of the pollution source. This distinction, due to significantly higher levels of red blood cell-glutathione peroxidase antioxidant activity, in birds from the vicinity of the pulp mill, was observed both in autumn and winter and was repeatable between years. No detectable effects were observed on breeding performance or nestling morphology and physiology. The effects of pollution in this study seem to be related to increased levels of oxidative stress.publishe