Benthic foraminifer and ostracod assemblages in the Beaufort Sea continental shelf over the last millennia: Evidence of unprecedented changes in the last two centuries

• Main Authors: Falardeau, Jade, de Vernal, Anne, Seidenkrantz, Marit-Solveig, Fritz, Michael
• Format: Conference Object
• Language: unknown
• Published: 2021
• Subjects: Nivea; Yukon; Arctic; Beaufort Sea; Herschel; Inuvialuit; Sea ice
• Online Access: https://epic.awi.de/id/eprint/54145/; https://epic.awi.de/id/eprint/54145/1/Abstract_congresso_PALEOARC_2021_def.pdf; https://hdl.handle.net/10013/epic.035b3b21-a3ca-4e86-830f-10487a45879b; https://hdl.handle.net/

The Inuvialuit ancestors, the Thule People, first occupied the northwestern American coasts about 1,000 years ago (Alunik et al., 2003). Today, the harvest of marine resources in the nearshore areas is still of great importance for local communities in terms of subsistence and cultural practices (Usher, 2002). In this context, we undertook a research project with the complementary aims to (1) reconstruct environmental variations in marine waters from the Beaufort Sea continental shelf over the last millennia and (2) disentangle the effects of the recent anthropogenic forcing. To meet these objectives, we used micropaleontological records, mostly based on benthic foraminifers and ostracods, from sediment core PG2303-2/3 retrieved at 43 meters depth in the Herschel Basin, off northern Yukon. The Herschel Basin allowed for continuous accumulation of sediment at a mean rate of 0.3 cm/yr (Pfalz, 2017). The benthic foraminifer concentrations range between 15 and 135 foraminifers/g, with raw counts (>100 specimen) allowing for population analyses. Elphidium clavatum and Cassidulina reniforme dominate the assemblage throughout the record. However, an occurrence peak of Triloculina trihedra at ~1300 CE and an increase of Haynesina nivea, Eoeponidella pulchella, Stainforthia feylingi and Textularia earlandi during the last two centuries mark the record. Ostracods record concentrations ranging between 0 and 9 ostracods/g. The ostracod assemblages are dominated by the euhaline taxa Cytheropteron spp. and Cytheropteron suzdalskyi. Paracyprideis spp., which can tolerate a wide range of salinities, is also abundant, particularly in the ~1800- 1900 CE interval. From these results, we suggest that the last two centuries were marked by important changes in the benthic fauna biodiversity on the Beaufort Sea shelf, with no equivalent since the occupation of the land by the Inuvialuit and their ancestors. Ultimately, this recent change indicates important variations in water mass properties, possibly linked to increase melting of land ice and sea ice in response to Human activities.