Reconstructing early Holocene warmth in outer Isfjorden, Svalbard using stable isotope analysis on the ocean quahog, Arctica islandica

• Main Author: Christman, Emma Isabelle
• Format: Text
• Language: unknown
• Published: SCARAB 2022
• Subjects: Arctica islandica; Early Holocene; stable isotope; bioproxy; Arctic; Svalbard; Isfjord*; Isfjorden; Ocean quahog; Sea ice
• Online Access: https://scarab.bates.edu/honorstheses/394; https://scarab.bates.edu/cgi/viewcontent.cgi?article=1437&context=honorstheses

As the Arctic enters a regime of rapid warming in the 21st century, looking into Earth’s past may provide information on what can be expected in a rapidly warming arctic. This project combines two modes of bulk stable isotope technology, (nitrogen and oxygen) to gain a unique perspective on the life history of the bivalve Arctica islandica during shell growth and formation of the periostracum. The relevance of this work lies in both the novelty of combining these two sampling and analysis techniques on ~10,000 year old samples as well as the opportunity to further study these snapshots of early Holocene marine climate as analogs for anthropogenic warming. This research provides an investigation of water temperatures substantiated by a body of marine paleoclimate research in the region and accepted by the inclusion of ????15N analysis on sub-fossil Arctica islandica. The investigation of ????15N in periostracum of sub fossil Arctica islandica revealed a potential water mass origin signal that points towards the presence of Atlantic water in the fjords of Svalbard during the early Holocene. Temperature reconstructions showed seasonality in the early Holocene was greater than modern, ranging from 6 - 10°C in the seven sampled shells. Lowest temperatures portray a winter setting that might have supported sea ice in the fjords, with many of the temperature minimums reconstructed below 0°C. Temperature maximums ranged from 6 – 8°C in the Boggebekken clams. Although there is no evidence that Arctica islandica lives in Svalbard’s fjords in modern day, that could change in the coming decades as the fjords approach water temperatures comparable to the early Holocene.