Unveiling the seabird nesting history of Green Island, Witless Bay Ecological Reserve, NL using paleolimnology

Seabirds are powerful biovectors that transfer nutrients across ecosystem boundaries; from their marine foraging to their terrestrial breeding grounds. These nutrient inputs accumulate in freshwater systems and can be traced through sediment analysis, offering a long-term archive of colony presence and ecological impact. Reconstructing historical seabird populations is essential for understanding long-term ecological change and informing conservation strategies. This thesis reconstructs historical seabird dynamics on Green Island (47°14'17" N, 52°46'49" W), a globally significant yet understudied seabird colony within Newfoundland’s Witless Bay Ecological Reserve. Using a multi-proxy paleolimnological approach, including δ¹⁵N isotopes, diatoms, pollen, chlorophyll a, and metal(loid) concentrations, a dated 30 cm core (~170 years) extends population records beyond existing data (~1940 CE). Congruent changes in all proxies suggest sustained ornithogenic enrichment beginning in the late 1930s until present. However, δ¹⁵N peaks mid 20th century and may be linked to shifts in prey composition associated with ocean warming. Aerial imagery between 1969 and 2023 further captured a decline in surface vegetation driven by excess nutrient input from guano deposition. Distinguishing species-specific contributions to nutrient loading remains challenging, particularly mixed species colonies. This study explored avian papillomavirus (APV) as a potential molecular proxy by screening both sediments and contemporary oropharyngeal and cloacal swabs. Although APV was not detected in sediments, likely due to degradation or low abundance, viral DNA was recovered from both Atlantic puffins (Fratercula arctica) and, for the first time in this region, from common murres (Uria aalge). Minimal sequence divergence suggests a slowly evolving lineage and possible interspecies transmission. While further research is needed to evaluate its sedimentary potential, these findings underscore the promise of combining molecular and paleolimnological approaches to improve species-level resolution in historical reconstructions. By extending seabird population records beyond existing census data, this research provides new insights into past seabird dynamics and their relationship with environmental change.