Malacological insights into the marine ecology and changing climate of the late Pleistocene – early Holocene Queen Charlotte Islands archipelago, western Canada, and implications for early peoples

Abstract

The first intertidal species to colonize the Queen Charlotte Islands archipelago along the northeastern Pacific margin of Canada after the last glacial maximum (LGM) was Macoma nasuta at 13 210 ± 80 14C years BP. Prior to this time, molluscs were likely excluded where grounded ice extended from the 2 km thick Cordilleran ice sheet on mainland British Columbia. Low water temperatures, high sedimentation rates, high turbidity, dilution, and low primary productivity limited invertebrate colonization subsequent to the LGM, a period of rapid sea-level and climate change. As an adult, M. nasuta is a facultative deposit-suspension feeder that tolerates high turbidity and lowered salinity, and its pediveligers and early juveniles must also have been able to survive these conditions. Subsequently, in addition to M. nasuta, Macoma irus (inquinata), Saxidomus giganteus, Protothaca staminea, Protothaca tenerrima, Hiatella pholadis, Clinocardium nuttallii, and Mytilus trossulus constituted a typical intertidal bivalve assemblage. These findings are explained in terms of the physiology, feeding mechanisms, development, and sediment preferences of living molluscs. The disappearance of most bivalve species between ~11 000 and 10 000 14C years BP indicates the onset of a short interval of low sea-surface temperatures coincident with the Younger Dryas cooling event. Some cold-hardy species persisted, including Clinocardium californiense, Mya truncata, and Serripes groenlandicus. Bivalve species not previously reported as Pleistocene fossils were collected in sediments dating older than 10 000 14C years BP. They include Macoma incongrua, Musculus taylori, Mytilimeria nuttallii, and Tellina nuculoides. Fossil assemblages of intertidal molluscs are used to map ancient shorelines and indicate which species were available as a subsistence resource for early peoples from at least 13 210 ± 80 14C years BP. Intertidal food biomass densities may have reached present commercially harvested levels on southern Moresby Island by 8800 ± 70 14C years BP and on northern Graham Island by 8990 ± 50 14C years BP. When early peoples might have been migrating along the littoral zone, the molluscan productivity of the outer coast was much higher than it is at present.

Paleoceanography of the Gulf of Alaska during the past 15,000 years: Results from diatoms, silicoflagellates, and geochemistry

“…Sea ice and sea ice-related diatoms are more common in the YD interval (~30-40% of the diatom assemblages) than they are during the Bø-Al (~20-30%), suggesting cooler, more stratified conditions during the YD, similar to the records in core 85JC and elsewhere in the North Pacific. Cooler conditions off southeast Alaska during the YD are consistent with the results of Hetherington and Reid (2003) in the Queen Charlotte Islands and Mathewes et al (1993) and Patterson et al (1995) off British Columbia to the south.…”

Paleoceanography of the Gulf of Alaska during the past 15,000 years: Results from diatoms, silicoflagellates, and geochemistry

“…Sea ice and sea ice-related diatoms are more common in the YD interval (~30-40% of the diatom assemblages) than they are during the Bø-Al (~20-30%), suggesting cooler, more stratified conditions during the YD, similar to the records in core 85JC and elsewhere in the North Pacific. Cooler conditions off southeast Alaska during the YD are consistent with the results of Hetherington and Reid (2003) in the Queen Charlotte Islands and Mathewes et al (1993) and Patterson et al (1995) off British Columbia to the south.…”

Quantifying marine reservoir effect variability along the Northwest Coast of North America

“…In South-Central Alaska, the oldest dated specimens are at 13,230 ± 25 14 C yr BP / 13,670–14,790 cal yr BP (Pasch et al, 2010), in Southeast Alaska at 13,240 ± 60 14 C yr BP / 13,660–14,820 cal yr BP (J.F. Baichtal, unpublished data), and in British Columbia at 13,210 ± 80 14 C yr BP/ 13,600–14,790 cal yr BP (Hetherington and Reid, 2003). While we lack terrestrial samples from these slightly older contexts to produce paired-sample reservoir corrections, we note the overlap between the earliest food clams in Southeast Alaska (13,660–14,280 cal yr BP) and the last pagophilic Ring Seal remains from Shuká-Kaa Cave (13,970–15,700 cal yr BP, calibrated in Supplemental Table S8) as proxies for the elimination of substantial sea-ice in the region.…”

Variation in oxygen consumption among ‘living fossils’ (Mollusca: Polyplacophora)

“…In marine ecology, morphologically similar, co-occurring groups of species such as chitons may often be reported within single functional or taxonomic units without further detail (Steneck & Watling, 1982; Ortiz & Wolff, 2002; Bishop, 2003; Hetherington & Reid, 2003). The predicted impacts of environmental change, such as changes in physical conditions, may be presumed to have equal influence on species grouped together within these guilds.…”

Paleoceanography of the Gulf of Alaska during the past 15,000 years: Results from diatoms, silicoflagellates, and geochemistry

“…Sea ice and sea ice-related diatoms are more common in the YD interval (~30-40% of the diatom assemblages) than they are during the Bø-Al (~20-30%), suggesting cooler, more stratified conditions during the YD, similar to the records in core 85JC and elsewhere in the North Pacific. Cooler conditions off southeast Alaska during the YD are consistent with the results of Hetherington and Reid (2003) in the Queen Charlotte Islands and Mathewes et al (1993) and Patterson et al (1995) off British Columbia to the south.…”

Quantifying marine reservoir effect variability along the Northwest Coast of North America

“…In South-Central Alaska, the oldest dated specimens are at 13,230 ± 25 14 C yr BP / 13,670–14,790 cal yr BP (Pasch et al, 2010), in Southeast Alaska at 13,240 ± 60 14 C yr BP / 13,660–14,820 cal yr BP (J.F. Baichtal, unpublished data), and in British Columbia at 13,210 ± 80 14 C yr BP/ 13,600–14,790 cal yr BP (Hetherington and Reid, 2003). While we lack terrestrial samples from these slightly older contexts to produce paired-sample reservoir corrections, we note the overlap between the earliest food clams in Southeast Alaska (13,660–14,280 cal yr BP) and the last pagophilic Ring Seal remains from Shuká-Kaa Cave (13,970–15,700 cal yr BP, calibrated in Supplemental Table S8) as proxies for the elimination of substantial sea-ice in the region.…”

Variation in oxygen consumption among ‘living fossils’ (Mollusca: Polyplacophora)

“…In marine ecology, morphologically similar, co-occurring groups of species such as chitons may often be reported within single functional or taxonomic units without further detail (Steneck & Watling, 1982; Ortiz & Wolff, 2002; Bishop, 2003; Hetherington & Reid, 2003). The predicted impacts of environmental change, such as changes in physical conditions, may be presumed to have equal influence on species grouped together within these guilds.…”

Paleoceanography of the Gulf of Alaska during the past 15,000 years: Results from diatoms, silicoflagellates, and geochemistry

“…Sea ice and sea ice-related diatoms are more common in the YD interval (~30-40% of the diatom assemblages) than they are during the Bø-Al (~20-30%), suggesting cooler, more stratified conditions during the YD, similar to the records in core 85JC and elsewhere in the North Pacific. Cooler conditions off southeast Alaska during the YD are consistent with the results of Hetherington and Reid (2003) in the Queen Charlotte Islands and Mathewes et al (1993) and Patterson et al (1995) off British Columbia to the south.…”

Quantifying marine reservoir effect variability along the Northwest Coast of North America

“…In South-Central Alaska, the oldest dated specimens are at 13,230 ± 25 14 C yr BP / 13,670–14,790 cal yr BP (Pasch et al, 2010), in Southeast Alaska at 13,240 ± 60 14 C yr BP / 13,660–14,820 cal yr BP (J.F. Baichtal, unpublished data), and in British Columbia at 13,210 ± 80 14 C yr BP/ 13,600–14,790 cal yr BP (Hetherington and Reid, 2003). While we lack terrestrial samples from these slightly older contexts to produce paired-sample reservoir corrections, we note the overlap between the earliest food clams in Southeast Alaska (13,660–14,280 cal yr BP) and the last pagophilic Ring Seal remains from Shuká-Kaa Cave (13,970–15,700 cal yr BP, calibrated in Supplemental Table S8) as proxies for the elimination of substantial sea-ice in the region.…”

Variation in oxygen consumption among ‘living fossils’ (Mollusca: Polyplacophora)

“…In marine ecology, morphologically similar, co-occurring groups of species such as chitons may often be reported within single functional or taxonomic units without further detail (Steneck & Watling, 1982; Ortiz & Wolff, 2002; Bishop, 2003; Hetherington & Reid, 2003). The predicted impacts of environmental change, such as changes in physical conditions, may be presumed to have equal influence on species grouped together within these guilds.…”