Response of benthos to stress factors in Holocene Arctic fjord settings: Maktak, Coronation, and North Pangnirtung Fjords, Baffin Island, Canada
Maktak, Coronation and North Pangnirtung Fjords are situated on Cumberland Peninsula, Baffin Island, Canada, having a common freshwater source from the Penny Ice Cap. Bottom photographs were examined to identify epifaunal trails and shallow endobenthic burrow openings exposed on the seafloor surface. These were compared to biogenic sedimentary structures revealed through x-radiograph images and direct observations of Lehigh gravity core samples. Intermediate- and deep-tier structures characterize the ichnofabrics of the glaciomarine sediments. Extensive bioturbation by the shallow-tier and epibenthic tracemakers, most notably ophiuroid echinoderms (brittlestars) and other organisms, has destroyed much of the primary sedimentary fabric (i.e. lamination) resulting in homogenous silty clay sediments. The dominant deep-tier structure consisting of an open, three-dimensional boxwork burrow system is the most pervasive biogenic structure observed within the core samples. Interestingly, although proximal–distal trends in benthic macrofaunal composition are evident in the bottom photographs, ichnofabrics remain relatively constant along the length of the fjords. Environmental factors influencing the biological community in these modern high latitude fjords differ from conditions described in Paleozoic and Cenozoic fjord environments. An increasing number of recent studies are expanding significantly on the fjord ichnology database, and provide the basis for the revision of the currently proposed fjord trace-fossil model, accommodating the complexity and diversity of fjord settings.