COS 267-5 - Tracking population dynamics of the Northern gannet (Morus bassannus) nesting colony in Cape St Mary’s Ecological Reserve, Newfoundland, within a ~140-year sedimentary record

Thursday, August 18, 2022

4:30 PM – 4:45 PM EDT

Location: 513A

Presenting Author(s)

JB

Johanna-Lisa Bosch

Memorial University of Newfoundland - St Johns, NL
St Johns, Canada

Coauthor(s)

I�

Inmaculada Álvarez-Manzaneda

Queen's University, Ontario, Canada
Js

John smol

Queen's University, Canada
NM

Neal Michelutti

Queen's University, Canada
GR

Greg Robertson

Environment and Climate Change Canada, Canada
AL

Andrew Lang

Memorial University of Newfoundland
St Johns, Newfoundland and Labrador, Canada
KH

Kathryn Hargan

Memorial University of Newfoundland, Canada

Background/Question/Methods

Seabirds play a large role in the transfer of marine-derived nutrients from their feeding grounds back to their nesting colonies and can be linked to biological and chemical shifts in nearby ponds, which can be tracked in their sediment profiles. While many bacterial and fungal species are preserved within sediments, little is known about the impacts ornithogenic nutrients have on sediment microbiomes. Thus, our objectives are to: (1) compare the bacterial taxa found within seabird fecal samples to those in pond sediments to identify indicator species for reconstructing seabird population trends; and (2) compare the presence of indicator taxa to more commonly applied proxies in paleolimnology. Our study site, located in Cape St. Mary’s Ecological Reserve (Newfoundland, Canada) contains approximately 64,000 nesting seabirds, primarily northern gannet (Morus bassannus), but also black-legged kittiwake (Rissa tridactyla) and common murre (Uria aalge). As a first step to meeting our objectives, we infer historical changes in the size of the nesting colony using sedimentary chlorophyll a, diatom assemblages, stable-nitrogen isotopes, and metal(loid)s in the dated cores collected from an “impact” pond 240 m away from the nesting site, and a “reference” site, not receiving nutrients, 2.56 km away from the colony.

Results/Conclusions

According to our current results, the sediment impacted by seabird nutrients showed a shift in the dominant diatom species at ~1964, and a rapid increase of chlorophyll-a throughout the 1960s. These changes may be due to a shift from more acidic (pH ≈ 6) to alkaline pH in the water. We also performed metagenomic and ribosomal gene amplicon sequencing on DNA isolated from both sediment samples and fecal samples of gannets to conduct a comparative analysis of microbial abundance between sample types. Overall, our goal is to extend current knowledge concerning long-term seabird population shifts within Cape St. Mary’s Ecological Reserve and extend the suite of proxies available to reconstruct seabird populations to include metagenomic techniques.