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- Title
Transport by ocean currents influences the sedimentary dinoflagellate cyst distributions: Implications for paleoceanographic reconstructions.
- Authors
Nooteboom, Peter; Bijl, Peter; van Sebille, Erik; von der Heydt, Anna; Dijkstra, Henk
- Abstract
Sedimentary dinoflagellate cysts (dinocysts) are a widely used tool for paleoceanographicreconstructions. As for all micropaleontological proxies, an often-used underlyingassumption in dinocyst-based reconstructions is that the sedimentary assemblages representlocal conditions of the overlying ocean surface water. However, any immobile particlesinking down the water column is subjected to horizontal and vertical transport by oceancurrents, and the sedimentary microplankton might be transported from a location withdifferent sea surface conditions. We model the transport of the dinocysts in a high-resolution (0.1˚ horizontally) globalmodel of the present-day ocean, and compare the local surface environment to theenvironment where the cysts formed and are transported from. We find that the assumption that sedimentary dinocysts represent overlying surfacewater conditions is not valid in many regions of the world. The significance of cysttransport depends on ocean current strength and direction (e.g. large transport near awestern boundary current), the aggregation probability which could increase thesinking speed, and the depth of a sediment sample. By using reasonable sinkingspeeds of dinocysts and aggregates, extreme biases of around ±16˚ C are found. Wealso identify regions where the particle transport creates an insignificant bias, e.g.in shallow seas and near the equator if cysts are related to the overlying surfacetemperature. Our model results provide a way to mechanistically and statistically explain theunexpected occurrences of some dinocyst species outside of their ’normal’ occurrence region,such as the northerly occurrence of the sea-ice-affiliated dinocyst Selenopemphix Antarcticain the Southern Ocean: all these northerly occurrences feature a ’cold tail’ in their modeledparticle origination regions. Exclusion of such outlier occurrences yield much betterconstrained ecological affinites for dinocyst species, which has implications fordinocyst-based quantitative and qualitative proxies for paleoceanographic conditions.
- Subjects
DINOFLAGELLATE cysts; OCEAN currents; SEAWATER; WATER; SEDIMENT sampling
- Publication
Geophysical Research Abstracts, 2019, Vol 21, p1
- ISSN
1029-7006
- Publication type
Article