Inter-colony isotopic niche dynamics and the effects of cumulative stressors on incubation phenology and behaviour in an Arctic seabird

• Main Author: Smith, Reyd Alexandra
• Format: Master Thesis
• Language: English
• Published: University of Windsor 2021
• Subjects: Arctic; Common Eider; ice algae; Phytoplankton; Sea ice; Somateria mollissima
• Online Access: https://scholar.uwindsor.ca/etd/8536; https://scholar.uwindsor.ca/context/etd/article/9541/viewcontent/uc.pdf

Human activity has resulted in global environmental shifts that are altering Arctic marine systems through rising air and ocean temperatures, and a dramatic reduction of sea ice. These changes influence food web dynamics through changes in primary producer abundance and distribution, such as ice algae and phytoplankton, as well as wildlife at higher trophic levels. Mercury is an endocrine-disrupting metal elevated in the environment due to human industrial activity. Mercury accumulation is influenced by prey choice, and therefore is affected by altered food web dynamics. Elevated mercury has been shown to impact incubation behaviour and decrease reproductive success in birds. Worse yet, this effect may be amplified by concurrent exposure to elevated air temperatures, however, these relationships have not been empirically researched to date. We first examined the impact of foraging behaviour on mercury exposure by examining the multidimensional isotopic niche of ten common eider (Somateria mollissima, Mitiq) colonies. Results suggest a wide degree of variation in their foraging strategies determined via stable isotope analysis, potentially impacted by changes in primary production, sea ice presence and migratory status. We then examined whether variation in the multiple stressors, mercury and environmental conditions, affected incubation phenology and behaviour. We found that exposure to higher temperatures during incubation, both individually and simultaneously with elevated mercury, predicted an increase in movement during incubation. Shorter incubation durations also occurred in birds exposed to high air temperatures, resulting in a decreased likelihood of nest success. For the first time, our results suggest that eider colonies across the Arctic have a wide degree of variation in their foraging strategies which influence mercury levels. Individuals with elevated mercury, when combined with elevated air temperatures, were shown to have potential implications on incubation behaviour. Thus, exploring multiple ...