Postglacial succession and palaeoecology of Late Quaternary macrofaunal assemblages from the central Canadian Arctic Archipelago

Temporal and spatial variations of the species composition of Late Quaternary macrofossil assemblages in the vicinity of Prince of Wales Island, central Canadian Arctic are examined in this study. A total of 2247 specimens representing 15 taxa (9 bivalves, 6 gastropods) were recovered at 32 sites. The dominant species are the bivalves Hiatella arctica, Mya truncata and Astarte borealis that together represent 91% of the total macrofossils represented in the collections. Taphonomic analysis (i.e. ratio of opposite valves; size range; shell abrasion and overgrowth; resistance to breakage) and comparison of the species composition of Holocene macrofaunal assemblages with modern counterparts and their habitats indicate that the subfossil faunas most commonly represent para-autochthonous assemblages which inhabited glaciomarine or nearshore marine environments. As observed previously by other authors, changes in faunal composition through time from survivor or pioneer groups (Hiatella arctica, Mya truncata, Portlandia arctica, Macoma calcarea) to more diverse faunas (e.g. Astarte borealis, Clinocardium ciliatum, Serripes groenlandicus) are noted. The succession of faunas in the study area is interpreted as the result of oceanographic changes after deglaciation due to increased summer insolation and warming of surface waters in the early Holocene.