A 10 400-Year-Old Bowhead Whale (<i>Balaena mysticetus</i>) Skull from Ellef Ringnes Island, Nunavut: Implications for Sea-Ice Conditions in High Arctic Canada at the End of the Last Glaciation

Abstract

ABStRACt. Variations in the distribution and radiocarbon ages of postglacial bowhead whale (Balaena mysticetus) remains throughout the Canadian Arctic Archipelago indicate that the range of this whale expanded and contracted several times during the Holocene. Since the annual bowhead migration reflects the preference of this species for an ice-edge habitat, fossil bowheads have been used to infer that significant variations in summer sea-ice extent occurred throughout the archipelago during the last 10.5 thousand years. Previous studies have demonstrated that climatic amelioration, concomitant with enhanced meltwater flux from the retreating Laurentide Ice Sheet, cleared sea ice from the inter-island channels of the central archipelago, enabling early Holocene bowhead whales to extend beyond the range of contemporary populations. A 10.4 ka BP bowhead whale skull was discovered on Ellef Ringnes Island in the northern Canadian Arctic Archipelago, 700 km north of its previously reported early Holocene range. Consequently, sea ice along the polar margin of the Canadian Arctic Archipelago is inferred to have been less extensive than previously recognized. Both biological evidence and glaciological evidence suggest that this reduction in sea-ice extent was the result of climate forcing, amplified by meltwater-driven outflows from the rapidly retreating marine-based sector of the Innuitian Ice Sheet. Following a reduction of these outflows at ~9 ka BP, sea-ice conditions worsened, despite ongoing climatic amelioration, preventing additional bowhead whale incursions until ~4 ka BP. key words: bowhead whale, sea ice, deglaciation, ocean currents, paleoclimate RÉSUMÉ. Des variations en matière de répartitions et d'âges déterminés par la méthode du carbone 14 relativement aux restes de baleines boréales (Balaena mysticetus) postglaciaires trouvés dans l'archipel arctique canadien laissent croire que le parcours de cette baleine s'est agrandi et s'est rétréci à maintes reprises pendant la période de l'Holocène. Puisque la migration annuelle de la baleine boréale tient compte de la préférence de cette espèce pour un habitat de lisières de glace, les fossiles de baleines boréales ont permis de déduire qu'il y a eu d'importantes variations en matière d'étendue de la glace de mer à la grandeur de l'archipel en été au cours des derniers 10,5 milliers d'années. Des études antérieures ont permis de démontrer que l'amélioration climatique, alliée au plus grand débit de l'eau de fusion provenant de la calotte glaciaire reculante des Laurentides, ont eu pour effet d'enlever la glace des canaux interinsulaires de l'archipel central, ce qui a permis aux baleines boréales de l'Holocène inférieur de se rendre au-delà du parcours des populations contemporaines. Le crâne d'une baleine boréale de 10,4 ka avant le présent qui a été découvert sur l'île Ellef Ringnes dans le nord de l'archipel arctique canadien se trouvait à 700 km au nord du parcours de l'Holocène inférieur signalé auparavant. Par conséquent, on en déduit que la glace de mer ...

北極海の古海洋研究：

“…An enlargement of the middle Eocene interval of this dataset is shown on the right. Spielhagen et al, 2004Polyak et al, 2007Yamamoto and Polyak, 2009;Stein et al, 2010a, b 4 CAPE Project Members, 2001Kaufman et al, 2004;Kaufman et al, 2016Funder et al, 2011 5500 11000 9000 Dyke et al, 1996;Atkinson, 2009Stranne et al, 2014 6000 3000 1000 Vare Bendtsen, 1994;Hasumi, 2002 De Boer andNof, 2004;Hu et al, 2015Keigwin and Cook 2007Dansgaard et al, 1993Böhm et al, 2014 30 IP 25 Belt et al, 2007;Müller, 2013 IP 25 , Vare et al, 2008 IP 25 PIP 25 Fig. 10; Müller et al, 2011 IP 25…”

Model–data comparison and data assimilation of mid-Holocene Arctic sea ice concentration

“…This is particularly the case in the Canadian Arctic Archipelago (CAA) with its complicated disposition of narrow straits, where proxy records display contrasted signals for nearby locations (e.g. Vare et al, 2009;Atkinson, 2009). Furthermore, the uncertainties related to the interpretation of proxies or to their dating can also explain some of the discrepancies Sundqvist et al, 2010).…”

“…On the one hand, the little amount of bowhead bones found indicates high sea ice coverage (Dyke et al, 1996;Atkinson, 2009), but, on the other hand, the analysis of IP 25 in several sediment cores suggests low spring sea ice occurrence in the MH compared to the whole Holocene period (Vare et al, 2009;Belt et al, 2010). This heterogeneity can, at least partly, be due to the numerous narrow straits being associated with different circulation patterns (e.g.…”