|Title||Dinoflagellate cyst production in the Cariaco Basin: a 12.5 year-long sediment trap study|
|Author||Bringué, M; Pospelova, V; Tappa, E J; Thunell, R C|
|Source||Progress in Oceanography vol. 171, 2018 p. 175-211, https://doi.org/10.1016/j.pocean.2018.12.007|
|Alt Series||Natural Resources Canada, Contribution Series 20180277|
|Media||paper; digital; on-line|
|File format||pdf (Adobe® Reader®); xlsx (Microsoft® Excel®)|
|Area||Caribbean Sea; Venezuela|
|Lat/Long WENS|| -66.2500 -64.0000 11.2500 10.0000|
|Subjects||marine geology; surficial geology/geomorphology; sedimentology; geochemistry; marine organisms; taxonomy; marine sediments; depositional environment; sedimentation; oceanography; water circulation
patterns; sea water geochemistry; Cariaco Basin; Dinoflagellates; phytoplankton; microzooplankton; 1997-98 El Niño; microbiology; upwelling|
|Illustrations||location maps; geoscientific sketch maps; tables; time series; pie charts; graphs; photomicrographs; bar graphs|
|Program||Western Arctic Sverdrup Basin, GEM2: Geo-mapping for Energy and Minerals|
|Released||2018 12 13|
|Abstract||Seasonal and interannual variability in dinoflagellate cyst production were assessed using a 12.5 year-long sediment trap time series from the Cariaco Basin (southern Caribbean Sea). This study
constitutes the longest such time series published to date, providing robust patterns of variability for individual dinoflagellate cyst taxa as well as for major phytoplanktonic and (micro-)zooplanktonic groups at the site. Cyst production is
interpreted in the context of physico-chemical properties measured in situ at the mooring site (primarily reflecting seasonal upwelling), and considering potential interactions with other major components of the pelagic food web (e.g., diatoms,
The time series consists in>300 sediment trap samples, each representing ?14 days of sedimentation, collected at the CARIACO station between Nov. 8, 1996 and May 19, 2009. Mass fluxes of biogenic silica, calcium carbonate and
organic carbon reflect dominantly the timing and strength of wind-driven, seasonal upwelling that brings colder, nutrient-rich waters to the surface, fostering primary productivity and the export of biogenous materials to the depths. On seasonal time
scales, dinoflagellate cyst production is closely coupled with upwelling strength, with higher cyst fluxes consistently observed under active upwelling conditions (average of 50.5×103 cystsm?2 day?1) compared to non-active upwelling intervals
(29.0×103 cystsm?2 day?1). Year-to-year variability is characterized by a large increase in cyst production observed over the last ?4 years of the time series (2006-2009) and minimum cyst fluxes recorded in the years 1998 and 1999, following the
strong 1997/98 El Niño event.
Dinoflagellate cyst assemblages are dominated by Brigantedinium spp. (59.1%), accompanied by Echinidinium delicatum (10.8%), Bitectatodinium spongium (8.4%), Spiny brown type A (2.9%) and Echinidinium spp. (2.4%).
Cyst produced by both autotrophic and heterotrophic dinoflagellates generally respond positively to upwelling in the basin. Most cyst taxa are associated with active upwelling conditions (e.g., Bitectatodinium spongium, Brigantedinium spp.,
Echinidinium delicatum, Quinquecuspis concreta, Selenopemphix quanta, Spiny brown type C), with some showing higher fluxes under active but weak upwelling conditions (e.g., Echinidinium granulatum, Echinidinium spp., cyst of P. fukuyoi, Spiny brown
type A). Other cyst taxa tend to show higher abundances at the onset of upwelling conditions (e.g., Echinidinium aculeatum, cyst of Protoperidinium stellatum) or following active upwelling intervals (e.g., Lejeunecysta marieae, Selenopemphix
nephroides). The detailed response of each dinoflagellate cyst taxon to environmental variability is presented in the form of an atlas, providing photomicrographs and detailing overall monthly production, contribution to the total trap assemblage as
well as cyst production over the 12.5 years of the time series.
|Summary||(Plain Language Summary, not published)|
This study documents dinoflagellate cyst production in the Cariaco Basin (off Venezuela) in the longest sediment trap time series published to date.
Dinoflagellates are a diverse group of aquatic protists composed of species that thrive under specific conditions, and their resting cysts, typically found in the sediments, are used as paleo-environmental indicators. The goal of this study is to
calibrate the environmental signals encoded by each dinoflagellate species by better constraining their specific ecology, for instance in terms of temperature tolerance and preferred food sources. Detailed production patterns for each species over
12.5 years are identified, and each species¿ response to changes in environmental conditions (e.g., upwelling phases, El Niño events) are discussed. This constitutes a robust reference dataset to be used as a basis for the interpretation of fossil
assemblages recovered from Quaternary and older sediments worldwide.