Babalola, L.O., Patterson, R.T., Prokoph, A. 2013. Foraminiferal evidence of a late Holocene westward shift of the Aleutian Low. Journal of Foraminiferal Research. v. 43 (2), p. 127-142.
The late Holocene distribution of agglutinated foraminifera and freshwater thecamoebians were documented within a 12.26 m piston core (VEC02A04) deposited between ~4560 – ~1090 calendar years before present (cal yr BP), collected from glacier-carved Frederick Sound, Seymour-Belize Inlet Complex, British Columbia. The sedimentary record archived in this core was characterized by unevenly distributed massive and laminated intervals interrupted by occasional slumps and turbidites. The faunal assemblages within the core was characterized by low diversity-low abundance agglutinated foraminiferal faunas (Shannon Diversity Index (SDI ≤1.36) ) with occasional allochthonous freshwater thecamoebians. The predominance of low-oxygen tolerant agglutinated foraminiferal taxa and absence of calcareous fauna indicate that oxygen was the main environmental stressor. Abundant organic matter in the core sediments provides additional evidence of low oxygen conditions that excluded most organisms that might have utilized this rich food resource.
A moderate upcore increase in the abundance of glaciomarine indicator species (e.g. Spiroplectammina biformis, Recurvoides turbinatus, Portatrochammina bipolaris and Cribrostomoides jeffreysii after 3125cal yr BP (above 7.19 m) indicates a subtle shift to progressively cooler bottom water conditions. The presence of varying proportions of thecamoebians through this upper core interval was likely related to increased spring snowmelt or early summer precipitation, which would have resulted in increased terrestrial erosion (e.g. reworking of marsh sediments into the fjord). Development of relatively cooler/drier climate conditions in the SBIC during the late Holocene corresponds to the Neoglacial advances in the NE Pacific, which is directly linked to a weakened and/or westward shift in Center of Action of the Aleutian Low.