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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, ciliates, copepods). 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 cysts m−2 day−1) compared to non-active upwelling intervals (29.0 × 103 cysts m−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 Nino 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.

Despite the fact that dinoflagellate cysts of the diverse genus Spiniferites are abundant in coastal and estuarine sediments worldwide, little is known about patterns of their seasonal or annual pr...

We present a high resolution sedimentary record of dinoflagellate cysts spanning the last ~ 900 years recovered from Effingham Inlet, a glacial fjord on the west coast of Vancouver Island, Canada. The combination of seasonal coastal upwelling supporting high levels of marine primary productivity in surface waters, together with restricted bottom water circulation in the silled fjord, fosters the preservation of laminated sediments in the inner basin of Effingham Inlet. Geochemical data are used to assess the sedimentary facies of the core, which is composed primarily of laminated units (50.2%) occasionally interrupted by “seismites” (39.5%) and homogenous units (10.2%). The chronology of the ~ 2 m-long core is based on varve counting and fifteen 14C dates, and is anchored by a seismite previously dated at AD 1946. The dinoflagellate cyst assemblages are diverse (total of 47 taxa), abundant (average concentrations of 102,900 cyst g− 1 of dry sediment), and characterized by a proportionally equal contribution of autotrophic and heterotrophic cyst taxa in most samples. Overall, cyst assemblages are characterized by Operculodinium centrocarpum (36.2%) accompanied by Brigantedinium spp. (18.0%) and Dubridinium spp. (6.6%). Multivariate analyses are used to extract the dominant patterns of variability in autotrophic and heterotrophic dinoflagellate cyst assemblages separately, and help in identifying the temperature and primary productivity gradients encoded in the cyst sedimentary record in this particular estuary. Specific intervals identified in the dinoflagellate cyst record are interpreted to represent the local expression of the “Medieval Climate Anomaly” (from the base of the record, ~ AD 1090 to 1230), the “Little Ice Age” (~ AD 1230 to late 19th century) and warming in the second half of the 20th century. The timing of these intervals are consistent with the regional paleoclimate and help constrain past climatic and oceanographic variability on the west coast of Vancouver Island. The origin of homogenous units in the sedimentary record of Effingham Inlet and paleoseismicity in the region are also discussed.

We present a continuous record of dinoflagellate cysts from a core of laminated sediments collected in the Santa Barbara Basin (SBB), off Southern California. The core spans the last ∼260 years and is analysed at biennial (two-year) resolution. Variations in dinoflagellate cyst assemblages are compared with 20th century historical changes, and are used to examine changes in primary productivity and species composition, which are bound to the variability in upwelling and sea-surface temperature (SST) in the region. Cysts produced by heterotrophic dinoflagellates dominate the assemblages. In particular, Brigantedinium spp. (on average 64.2% of the assemblages) are commonly associated with high levels of primary productivity, typically observed under active upwelling conditions, when nutrient supply is higher. Other heterotrophic taxa such as cysts of Protoperidinium americanum, Protoperidinium fukuyoi, Protoperidinium minutum and Archaeperidinium saanichi, all Echinidinium species, Quinquecuspis concreta and Selenopemphix undulata are more abundant in the early part of the record (∼1750s–1870s). These taxa are generally associated with high primary productivity and are observed predominantly during intervals marked by relatively variable conditions of SST, stratification and nutrient loading. The 20th century is marked by an increase in several species of autotrophic affinity, primarily Lingulodinium machaerophorum and Spiniferites ramosus. In recent surface sediments from the region, these species are more abundant in the Southern California Bight, and they are associated with conditions of relaxed upwelling in the SBB (typically observed during summer and fall), when SST is higher and nutrient supply is moderate. Their increasing concentrations since the early 20th century reflect warmer SST and possibly stronger stratification during the warmest season. Taken together, the changes in cyst assemblages provide further evidence that persistently warmer conditions in the SBB began affecting marine populations by the late 1920s. Decadal-scale variations in primary productivity are encoded in the heterotrophic dinoflagellate cyst record, with higher (lower) concentrations of heterotrophic taxa occurring during “cool” (“warm”) phases of the Pacific Decadal Oscillation (PDO) index. Wavelet analysis of heterotrophic taxa concentrations suggests a weaker influence of the PDO on biota of the region during the 19th century.

Seasonal variations in dinoflagellate cyst fluxes and assemblage composition were investigated for the first time on the west coast of the United States of America. We analyzed the palynological content of an ~ two year-long (May 1995 to March 1997) fortnightly sediment trap time series from the Santa Barbara Basin (SBB, off Southern California), a region characterized by seasonal upwelling and high levels of primary productivity. A total of 47 dinoflagellate cyst taxa were identified in the trap samples, with assemblages dominated by cysts produced by heterotrophic taxa. Multivariate analyses support that dinoflagellate cyst fluxes and assemblages are reliable indicators of primary productivity, and reflect sea surface temperature (SST) variations associated with upwelling in the SBB. In particular, Brigantedinium spp. are associated with active upwelling intervals (fluxes up to 127,430 cysts m − 2 day − 1 and up to 86.6% of the assemblage), when SST is lower, stratification is weaker and diatom production is maximal. Conversely, Lingulodinium machaerophorum indicates relaxed upwelling conditions (up to 9640 cysts m − 2 day − 1 and 29.9% of the assemblage) characterized by higher SST, stronger stratification and reduced primary productivity. Selenopemphix undulata is associated with colder SST in the region, whereas cyst type A abundances increase with higher SST. Thecae of potentially toxic dinoflagellates are also documented, such as Lingulodinium polyedrum and Prorocentrum micans , which are mainly recorded under conditions of higher SST and strong stratification, and Dinophysis spp. with higher fluxes between June and September of both 1995 and 1996.

Process length variation of cysts of the dinoflagellate Protoceratium reticulatum (Claparede et Lachmann) Butschli in surface sediments from the North Pacific was investigated. The average process ...

Late Holocene paleoceanography and climate variability of the Southeastern Beaufort Sea (Canadian Arctic) have been investigated on the basis of sedimentary cores collected over the Mackenzie Slope. Piston, trigger and box cores were sampled at station 803 in 2004 aboard the CCGS Amundsen at 218 m water depth. The chronology of the piston core is constrained by 4 AMS-14C dates, as the sedimentation rate in the box core is assessed from 210Pb data. We obtain a continuous composite sequence covering the last 4600 years, with a sedimentation rate of ~ 140 cm.kyr− 1. Transfer functions (modern analogue technique) based on dinoflagellate cyst (dinocyst) assemblages were used to reconstruct the evolution of sea-surface conditions over the time period covered by the cores. Palynological data reveal that dinocyst assemblages are dominated by Operculodinium centrocarpum sensu lato (mean of 43.3%) throughout the core, with the accompanying taxa Brigantedinium spp. (19.6%), Islandinium minutum (15.6%) and cysts of Pentapharsodinium dalei (13.7%). Four zones have been established on the basis of dinocyst relative abundances. Dinocyst assemblage zone 1 (D1), from 4600 to 2700 cal years BP, is dominated by O. centrocarpum (mean of 49.0%). In zone D2 (2700–1500 cal years BP), the relative abundances of O. centrocarpum decrease (34.4%) in favour of the opportunistic, heterotrophic taxa Brigantedinium spp. (28.8%) and cysts of Polykrikos sp. var. arctic/quadratus (2.8%). Dinocyst zone D3 (1500–30 cal years BP or 450–1920 AD) is characterised by the high relative abundance of the peridinioid taxa I. minutum (19.9%). The last zone (D4), spanning from 1920 to 2004 AD, is again dominated by O. centrocarpum (44.5%), and shows low relative abundances of Brigantedinium spp. and cf. Echinidinium karaense. Quantitative reconstructions of past sea-surface parameters (August sea-surface temperature: SST, August sea-surface salinity: SSS, and duration of sea-ice cover) indicate relatively stable conditions over the last 4.6 kyr, with episodic cooling events (SST of ~ 1.5 °C below the modern value of 6 °C) that took place between 700 and 1820 AD. We associate the last and the longest of these cooling events (1560–1820 AD) with the Little Ice Age. Reconstructed SSS shows decadal oscillations since 1920 AD that we tentatively associate with the accumulation of freshwater by the Beaufort Gyre and the subsequent Great Salinity Anomalies. Our data suggest that similar salinity anomalies could have occurred ca. 1860 and 1790 AD. Stable isotopic data show a slight increase in δ13C values (from ~−27.1‰ at the base to ~−25.8‰ at the top) over the last 4.6 kyr that we associate with the gradual increase in atmospheric CO2 concentration as recorded by Antarctic ice cores. Variations in the δ15N profile suggest variations in Pacific water influence from 4600 to ~ 1300 cal years BP, associated with centennial scale shifts of the Arctic Oscillation phases.