Cyst Record Research Articles

Historical cyst record as evidence for the recent introduction of the dinoflagellate Gymnodinium catenatum in the north-eastern Atlantic

The geographical origin of the warm-temperate paralytic shellfish poison producer Gymnodinium catenatum Graham is still under debate. It was first reported in the north-eastern Atlantic in 1976, from the Galician rías (North-West Iberia). Since then, and until 1995, recurrent blooms were recorded, with north-south progression of the affected areas, eventually affecting the whole West and South Atlantic coasts of Iberia and the Moroccan coast. This study presents results obtained from cyst analyses of a 210Pb-dated box core and a 14C-dated piston core, collected off Iberia, covering the last 2 000 years. They indicate that G. catenatum is not endemic to the area but has been introduced around the beginning of the last century, coinciding with another major environmental change, possibly related to cultural eutrophication.

Dinoflagellate cysts as indicators of climatic and oceanographic changes during the past 40 kyr in the Santa Barbara Basin, southern California

The dinoflagellate cyst record from Ocean Drilling Program Hole 893A, Santa Barbara Basin, southern California, is examined at millennial‐scale resolution for the past ∼40 kyr. Changes in cyst abundance, composition of cyst assemblages, and their diversity reflect major shifts in climate and ocean circulation in the region over this time interval. Throughout the sequence, dinoflagellate cyst assemblages are dominated by heterotrophic dinoflagellates. Brigantedinium spp. and other upwelling‐related taxa such as Echinidinium and Protoperidinium americanum are abundant, indicating the continued influence of coastal upwelling on the basin during the late Quaternary. A significant increase in cyst accumulation rates is seen during the Holocene and, to a lesser extent, during shorter warming events such as Bolling/Allerod and Dansgaard‐Oeschger interstadials, implying enhanced marine productivity during these periods. Cyst diversity is high during the Holocene. An increase in abundance of cysts produced by autotrophic dinoflagellates in the late Holocene suggests enhanced input of warm, nutrient‐rich waters. In contrast, cyst assemblages from the Last Glacial Maximum exhibit a relatively low diversity and an increase in the cysts of heterotrophic dinoflagellates, in particular Selenopemphix nephroides. The presence of this taxon in association with Brigantedinium spp. implies substantial cooling of surface waters in the Santa Barbara Basin at that time.

Dinoflagellate cysts and hydrographical change in Gullmar Fjord, west coast of Sweden

This high-resolution study of the latest Holocene dinoflagellate cyst record from Gullmar Fjord, on the west coast of Sweden, provides evidence for the recognition of two major dinoflagellate communities within the fjord over the last 85 years. These communities may have their origins with the history of cultural eutrophication within the region, but are more likely to be associated with the wider phenomenon of the North Atlantic Oscillation and/or the complex hydrographical response of the fjord to various changing climatic environments between 1915 and 1999. The changing dinoflagellate cyst populations are compared in detail with the many hydrographical parameters available from this well studied fjord with its long instrumental records. Indeed the dinoflagellate cysts fail to demonstrate a convincing ongoing eutrophication record for the fjord but do show a major change in the cyst assemblages at about 1969/1970 at a time when the NAO was changing from a negative phase to the present-day positive phase. Gullmar Fjord is important in the history of dinoflagellate cyst studies, being the site of the 1954 study by Erdtman in which viable cysts, produced within the phytoplankton, were first documented within the water column.

Holocene shelf-sea seasonal stratification dynamics: a dinoflagellate cyst record from the Celtic Sea, NW European shelf

Published records of the Holocene evolution of seasonal stratification in the Celtic Sea (NW European shelf) have been based on benthic proxies, notably benthic foraminifera and associated stable isotopic data. We have investigated organic-walled dinoflagellate cyst assemblages from a well-dated Holocene sequence from the central Celtic Sea in order to assess the signal from this planktonic proxy and to reconstruct paired bottom-and surface-water conditions through time. This sequence has, on the basis of the benthic proxies, been interpreted previously as a record of the replacement of tidally mixed water by stratified water associated with tidal-front migration during the early Holocene. Interpretation of the dinocyst record has been facilitated by a parallel study of the distribution of cysts from Celtic Sea surface sediments and their relationship with seasonal water masses. The dinocyst stratigraphy indicates mixed-water conditions during the early Holocene consistent with reduced water depths (hence lowered sea level) over the core site. The first significant change in the dinocyst assemblages is recorded at around 6650 cal. years BP and indicates a transition from mixed-frontal conditions to seasonal stratification. This interpretation of frontal migration is consistent with changes in the benthic foraminiferal assemblages and associated stable isotopes at the same core depth. From 6650 to 3600cal. years BP, the significant occurrence of Bitectatodinium tepikiense accompanied by SpiniJferites elongatus is attributed to strong seasonality, with winter sea-surface temperatures possibly below 5C. Another transition at 3600cal. years BP is attributed to a reduction in seasonality generated by milder winter conditions linked to a stronger influence of the thermohaline circulation over the studied area. This transition is not recorded by the benthic proxies and is attributed to climate forcing rather than to any change in tidal dynamics. It is notable that many mires in western Britain record distinct wet shifts contemporary with this change.

Dinoflagellate cyst record of the Eocene-Oligocene boundary succession in flysch deposits at Leluchów, Carpathian Mountains, Poland

Abstract Organic-walled dinoflagellate cysts from Eocene-Oligocene transitional deposits have been studied in a section at Leluchów, Flysch Carpathians, Poland. The Eocene-Oligocene boundary, as based on dinoflagellate cyst distribution, is placed in the upper part of the Leluchów Marl Member. The main biostratigraphic events associated with this boundary interval are the highest occurrence of Areosphaeridium michoudii and Areosphaeridium diktyoplokum , and the lowest occurrence of Wetzeliella gochtii . Distinct changes in dinoflagellate cyst assemblages and palynofacies across the Eocene-Oligocene boundary at Leluchów imply a drop in relative sea-level within the Carpathian flysch basin that might correlate with a major eustatic fall during the earliest Oligocene. A drop in sea surface temperature is recognized prior to the Eocene-Oligocene boundary, and evidence is presented for an increase in nutrient level and decrease in salinity within the photic zone during the earliest Oligocene.

Dinoflagellate cyst record of the deep-sea Cretaceous-Tertiary boundary at Uzgruň, Carpathian Mountains, Czech Republic

Abstract The record of organic-walled dinoflagellate cysts in deep-sea facies across the Cretaceous-Tertiary boundary is poorly known. A detailed study of uppermost Maastrichtian-lowermost Danian Tethyan deep-sea flysch sediments deposited below the carbonate compensation depth at Uzgruň, in the Czech Republic, has yielded numerous and relatively well-preserved dinoflagellate cysts. Their distribution allows the Cretaceous-Tertiary boundary to be placed within a 73 cm interval, within which an iridium anomaly occurs. Assemblages show no major shifts within the boundary interval, but gradual changes were recorded that possibly relate to sea-level fluctuations and/or nutrient availability. High concentrations of peridinioids appear to indicate upwelling in this part of the Tethys near the Cretaceous-Tertiary boundary. The presence of thermophilic dinoflagellate cysts throughout the section points to a stable, warm-temperate to subtropical climate during the latest Maastrichtian and earliest Danian. Events, such as the Areoligera sp. acme, Manumiella seelandica acme and the Spinidinium sp. acme, known from other Cretaceous-Tertiary boundary sections around the world, were recognized within the studied material.

A high-resolution dinoflagellate cyst record from latest Holocene sediments in Koljö Fjord, Sweden

A high-resolution dinoflagellate cyst record is detailed for the very latest Holocene sediments preserved in a silled fjord from western Sweden. Koljö Fjord is characterised by brackish water conditions together with intermittent deep-water renewal and oxygen depletion. The data provide information derived from the phytoplankton populations living in the surface waters, including possible changes to the nutrient availability and salinity regimes using an actualistic ecological approach. The cyst record provides evidence that the dinoflagellate populations within the surface waters of the fjord over the last 155 years or so have fluctuated markedly. The dinoflagellate cyst record from Core KG1A demonstrates a 10-fold increase in both total cyst numbers and Lingulodinium polyedrum since c. 1938, and a shift from assemblages with high Pentapharsodinium dalei to those with high L. polyedrum and Protoceratium reticulatum from about 1980. These fluctuations are singly and/or collectively indicative of possible cultural changes within the fjord; the effects of the North Atlantic Oscillation on both deep-water renewal and seasonality; nutrient enhancement (eutrophication?); and increased water column stability.

Integrating palynological and geochemical data in a new approach to palaeoecological studies: Upper Cretaceous of the Banterwick Barn Chalk borehole, Berkshire, UK

The dinoflagellate cyst record from an Upper Cretaceous (uppermost Cenomanian–upper Coniacian) Chalk core, drilled at Banterwick Barn, Berkshire, is described and statistically correlated with elemental and stable isotope bulk sediment geochemical data from the same core. Seventy-two dinocyst species and subspecies are recorded, and stable carbon and oxygen isotopic (δ 13C, δ 18O) trends are documented. Lithostratigraphy and chemostratigraphic correlation of the δ 13C curve with an expanded section at Dover, Kent, are used to identify stratigraphically significant marls, and determine the positions of macrofossil zones and stage boundaries in the Banterwick Barn core. These data indicate that >30 m of chalk at Dover are represented by <2 m of Chalk Rock at Banterwick Barn, with much of the succession being absent due to erosion and non-deposition. First and last appearance datums (FAD, LAD), first and last common occurrences, and acmes of key Turonian–Coniacian dinocyst species are documented and compared with other records from the Anglo–Paris Basin. A new subspecies, Senoniasphaera rotundata alveolata is proposed, which has a FAD in the lower Turonian and last appears (LAD) in the lower Coniacian. Senoniasphaera rotundata rotundata [autonym, herein] has its FAD in the middle Turonian, first common occurrence in the uppermost Turonian, and LAD in the upper Coniacian. An extremely impoverished assemblage of dinocysts in the highest Cenomanian to lowest Turonian is considered to be largely a preservational artefact of intraclastic nodular and calcarenitic chalks, and is not related directly to the well-documented global oceanic anoxic event (OAE2) occurring at that time (∼93.5 Ma). A sharp increase in dinocyst abundance in the lower Turonian corresponds with a change in lithology to more marly chalks. A gradual decrease in the number of species is observed through the middle Turonian to upper Coniacian; δ 18O records show that this was associated with global climatic cooling. Cluster analysis of the dinocyst abundance record with geochemical data indicates four distinct species groups with characteristic geochemical associations, i.e. Groups 1–4. Groups 1 and 2 are associated with phases of increased siliciclastic supply; a positive correlation with higher δ 13C values differentiates the latter. Group 3 is independent of carbonate and detrital input, and Group 4 is associated with high carbonate flux and low detrital supply. These groupings suggest that cyst-forming dinoflagellates exhibited a range of ecological niches in the Late Cretaceous. Although the relationship between the encystment process and the geochemical associations is unclear, key environmental factors are likely to be sea-level and climate related, including water depth, turbidity, nutrient supply, sea-surface temperature, and environmental stability/predictability. Integrated geochemical and palynological studies have great potential for inter-regional correlation and palaeoenvironmental interpretation.

Dinoflagellate cyst records and human disturbance in two neighboring estuaries, New Bedford Harbor and Apponagansett Bay, Massachusetts (USA)

The dinoflagellate cyst records in sediments from New Bedford Harbor and Apponagansett Bay demonstrate sensitivity to environmental change caused by human activity in the watersheds over the last 500 years. Changes in the species richness, as well as absolute and relative abundance of dinoflagellate cyst taxa reflect recent periods of development around the estuaries. Cyst taxa sensitive to these changes include Dubridinium spp ., Polykrikos schwartzii, Lingulodinium machaerophorum, Operculodinium israelianum and Selenopemphix quanta. The greatest changes in the dinoflagellate cyst record occur during the 20th century, when New Bedford Harbor was exposed to both toxic pollution and heavy nutrient loading from point and non-point sources. Apponagansett Bay was not subject to industrial pollution and nutrient enrichment has been lower (from non-point sources). In Apponagansett Bay there is an increase in the dinoflagellate cyst species richness while species richness first increased, then declined in New Bedford Harbor. During the same period, the total dinoflagellate cyst concentration in New Bedford Harbor fluctuated over a wide range. The decline of species richness and the large fluctuations in the total cyst abundances signal the intensified anthropogenic disturbance in the watershed, notably a high degree of eutrophication and toxic pollution.

Dinoflagellate cyst evidence for Quaternary palaeoceanographic change in the northern Scotia Sea, South Atlantic Ocean

A dinoflagellate cyst record has been examined from two cores recovered from the crest and margins of a sediment drift in water depths of 3500–4500 m in the northern Scotia Sea, South Atlantic Ocean. 46 dinoflagellate cyst analyses have been conducted, covering a time-span ranging from the Holocene down to MIS 6, representing about 160 ka. This provides a resolution of approximately 3500 years. The sediments are predominantly fine-grained contourites and diatom-rich hemipelagites, capped by sandy-silty contourites rich in the planktonic foraminifer Neogloboquadrina pachyderma. The cores can be subdivided into four dinoflagellate cyst units, supported by diatom and radiolarian biostratigraphy, biogenic barium geochemistry, oxygen isotopes and magnetic susceptibility curves. The youngest dinoflagellate cyst unit was found only in the core from the drift crest, and has been dated at between 4380 and 12 275 yr BP by radiocarbon dating. The unit is characterised by autotrophic dinoflagellate cysts with similarities to modern cysts from the region, although the assemblages display some marked internal variability that may suggest rather unstable Holocene oceanographic conditions. The next downhole unit was found in both cores and provided radiocarbon ages of 14 580 yr BP and 16 840 yr BP. Recovered cyst assemblages suggest deposition within or near to maximum sea ice limits, corresponding to a northward shift of the Antarctic Convergence during the Last Glacial Maximum within oxygen Marine Isotope Stage (MIS) 2. The final two units lack radiocarbon age control. The next downhole unit is characterised by heterotrophic dinoflagellate cysts such as round, brown Protoperidinium spp. and Selenopemphix antarctica, indicating deposition within maximum sea ice limits. This unit has a wide age range within MIS 5a–d including MIS 6. Toward the base of this unit the assemblage contains autotrophic dinoflagellate cysts such as Impagidium spp., Protoceratium reticulatum and Spiniferites spp., indicative of warmer, interglacial conditions, suggesting a retreat of the Antarctic Convergence and interpreted as MIS 5e, the last interglacial. MIS 3–4 are not resolved by the dinoflagellate cysts. The oldest unit recovered is marked by a return to heterotrophic dinoflagellate cysts with deposition in the presence of seasonal sea ice and open water, suggesting the Antarctic Convergence was now northward of the core site. The dinoflagellate cyst assemblages recovered from the cores illustrate the glacial–interglacial dynamism between two important biogeographical boundaries; the Antarctic Convergence to the north and the maximum sea ice limit toward the south.

A centennial scale organic-walled dinoflagellate cyst record of the last deglaciation in the South Adriatic Sea (Central Mediterranean)

A high-resolution study of sea surface temperature (SST) and primary productivity changes during the last deglaciation in the South Adriatic Sea is presented on the basis of organic-walled dinoflagellate cysts (dinocysts), compared with stable oxygen and carbon isotope records derived from Globigerina bulloides. Two more defined warming phases between 14.75 and 14.10 cal kyr BP (GI-1e) and between 13.85 and 13.25 cal kyr BP (GI-1c), and perhaps a mild one between 12.95 and 12.60 cal kyr BP (GI-1a), interrupted by two cold events between 14.10 and 13.85 cal kyr BP (GI-1d) and between 13.25 and 12.95 cal kyr BP (GI-1b) are highlighted. Weaker SST oscillations occurred within the relatively stable periods GS-2a (17.00–14.75 cal kyr BP), GS-1 (or Younger Dryas, 12.60–11.60 cal kyr BP) and Early Holocene. Several dinocyst proxies used to evaluate surface primary productivity suggest that the cold events GI-1d and GI-1b are associated with episodes of both enhanced primary productivity and, perhaps, improved organic matter preservation due to reduced deep water formation. Phases of more pronounced increased surface primary productivity without stagnation in bottom waters are recorded during GI-1c and early GS-1. Freshwater (Po River) discharge seems to be the cause of enhanced productivity during event GI-1c (at 13.4 cal kyr BP) and, probably, during GI-1d.

On the response of calcareous dinoflagellates to oligotrophy and stratification of the upper water column in the equatorial Atlantic Ocean

Large numbers of calcareous dinoflagellate cysts and the vegetative calcareous coccoid species Thoracosphaera heimii are generally found in sediments underlying oligotrophic and/or stratified (sub)surface water environments. It is difficult to distinguish between the relative importance of these two environmental parameters on calcareous cyst and T. heimii distribution as they usually covary, but this information is essential if we want to apply cysts properly in the reconstruction of palaeoenvironments and past surface water hydrography. In the multi-proxy core GeoB 1523-1 from the Ceará Rise region in the western equatorial Atlantic Ocean (covering the past 155 ka), periods of greatest oligotrophy are not synchronous with periods of greatest stratification (Rühlemann et al., Mar. Geol. 135 (1996) 127–152; Mulitza et al., Geology 25 (1997) 335–338; Mulitza et al., Earth Planet. Sci. Lett. 155 (1998) 237–249), giving us the unique opportunity to differentiate between the effects of both parameters on cyst accumulation. The calcareous cyst record of the core reflects prominent increases in accumulation rate of nearly all observed species only during the nutrient-enriched but more stratified isotopic (sub)stages 5.5, 5.3, 5.1 and 1. In this respect, the distribution trends in the core are more similar to those of the eastern equatorial upwelling region (GeoB 1105-4) than they are to those of the oligotrophic north-eastern Brazilian continental slope (GeoB 2204-2), even though temporal changes in bioproductivity are principally in antiphase between the eastern and western equatorial regions. We conclude that stratification of the upper water column and the presence of a well-developed thermocline are probably the more important factors controlling cyst distribution in the equatorial Atlantic, whereas the state of oligotrophy secondarily influences cyst production within a well-stratified environment.

Late Quaternary dinoflagellate cyst stratigraphy at the Eurasian continental margin, Arctic Ocean: indications for Atlantic water inflow in the past 150,000 years

Four sediment cores located at the Eurasian continental margin underlying the Atlantic layer have been studied for their dinoflagellate cyst content. Concentrations of distinct dinoflagellate cyst taxa display fluctuations in the late Quaternary, which are linked to changes in the inflow of relatively warm Atlantic surface and near-surface waters, resulting in increased local production of cysts in certain time intervals. Based on the assumption that marked changes in strength of inflow occurred synchronously at the Eurasian continental margin, concentration maxima can be used to correlate sediment cores. A dinoflagellate cyst record from the northern Barents Sea continental margin has been related to the stable oxygen isotope and paleomagnetic records to provide direct chronological information. The combination of these methods permits definition of stratigraphic sections equivalent to oxygen isotope stages in carbonate-poor sequences from the Eurasian continental margin. Previous age models of sediment cores are revised, based on dinoflagellate cyst abundance peaks and species distribution, but a firm chronostratigraphy of sedimentary sequences at the eastern Laptev Sea continental margin cannot be established because of the weak signal at the sites furthest from Fram Strait. In the past 150,000 years, the influence of Atlantic (sub-) surface waters generally decreased from west to east along the Eurasian continental margin, in particular during the glacials. Pronounced concentration maxima of cosmopolitan and temperate–subpolar dinoflagellate cysts indicate the inflow of Atlantic waters and seasonally increased production of cysts in the Holocene and Eemian. The Holocene is well-marked at the entire Eurasian continental margin but it is more difficult to assess the extent of (sub-) surface water inflow during the Eemian, which may have only reached the western Laptev Sea continental margin.

Late Quaternary sea‐surface conditions at DSDP Hole 594 in the southwest Pacific Ocean based on dinoflagellate cyst assemblages

AbstractInvestigation of organic‐walled dinoflagellate cyst distribution in 118 surface sediments from the Southern Ocean documents the relatively high diversity of cyst taxa (46 species) and distinct cyst assemblages in relation to surface water masses and temperature gradient. The Antarctic Water is characterised by the dominance of Selenopemphix antarctica accompanied by Brigantedinium spp. and Impagidinium pallidum. The Subantarctic Water association consists mainly of Nematosphaeropsis labyrinthus, Impagidinium paradoxum and Impagidinium sphaericum, whereas the Subtropical Water association is dominated by Operculodinium centrocarpum and Spiniferites membranaceus.Multivariate analyses (non‐metric multidimensional scaling) demonstrate the relationships with sea‐surface conditions and enable the application of the best analogue method on the Southern Ocean dinoflagellate cyst data base for reconstructing past sea‐surface conditions. The dinoflagellate cyst record from DSDP 594 (45°31.41'S, 174°56.88'E; 1204 m, southern margin of the Chatham Rise) shows important fluctuations in species composition from glacial to interglacial over the last 140 000 yr. Reconstruction of winter and summer SSTs reveals much lower temperature than present by 6 to 10 °C during marine oxygen isotope stages 6, 4 and 2, and higher temperature by 2–3 °C during substage 5e. Copyright © 2001 John Wiley &amp; Sons, Ltd.

Paleo-oxygenation in Tertiary epeiric seas: evidence from dinoflagellate cysts

The dinoflagellate cyst record from an epeiric setting in the Oligocene of Southwest Germany exhibits major changes associated with variations in paleo-oxygenation inferred from benthic foraminifera. Dinoflagellate cyst diversity and equitability strongly decline in the case of extreme oxygen depletion. The relative abundance of the dinoflagellate cyst Thalassiphora pelagica inversely correlates with the availability of benthic oxygen. The T. pelagica spectrum consists of different morphotypes which are considered to represent different stages within the cystal part of the T. pelagica life cycle following the concept of Benedek and Gocht. The distribution of these morphotypes is also linked to oxygen availability. Horizons with highest T. pelagica abundances are characterized by the occurrence of T. pelagica specimens representing an early stage in cyst formation. A model is proposed that uses T. pelagica as a proxy to assess oxygenation both at the sediment surface and in the water column. The occurrence of T. pelagica specimens representing an early stage in cyst formation is interpreted to reflect the extension of oxygen-depletion upwards into the water column. Because T. pelagica is an easily recognized, globally distributed element of Paleogene and Early Neogene dinoflagellate cyst assemblages, the application of this model may be of importance in the reconstruction of paleo-oxygenation in epeiric settings from these times. Its sensitivity to changes in benthic oxygenation can be as high as (if not higher than) that of the approach based on foraminifera. Moreover, it is applicable to decalcified sediments.

Global dinoflagellate event associated with the late Paleocene thermal maximum

The late Paleocene thermal maximum, or LPTM (ca. 55 Ma), represents a geologically brief time interval (∼220 k.y.) characterized by profound global warming and associated environmental change. The LPTM is marked by a prominent negative carbon isotope excursion (CIE) interpreted to reflect a massive and abrupt input of 12 C-enriched carbon to the ocean-atmosphere reservoir, possibly as a result of catastrophic gas-hydrate release, on time scales equivalent to present-day rates of anthropogenic carbon input. The LPTM corresponds to important changes in the global distribution of biota, including mass extinction of marine benthic organisms. The dinoflagellate cyst record indicates that surface- dwelling marine plankton in marginal seas also underwent significant perturbations during the LPTM. We report on the dramatic response of representatives of the genus Apectodinium from two upper Paleocene–lower Eocene sections in the Southern (New Zealand) and Northern (Austria) Hemispheres, where the dinoflagellate records are directly correlated with the CIE, benthic foraminifera extinction event, and calcareous nannofossil zonation. The results indicate that the inception of Apectodinium -dominated assemblages appears to be synchronous on a global scale, and that the event is precisely coincident with the beginning of the LPTM. Apectodinium markedly declined in abundance near the end of the LPTM. This Apectodinium event may be associated with (1) exceptionally high global sea-surface temperatures and/or (2) a significant increase in marginal-marine surface-water productivity. Such a globally synchronous acme of dinoflagellate cysts is unprecedented within the dinoflagellate cyst fossil record.

Land-sea correlation by means of terrestrial and marine palynomorphs from the equatorial East Atlantic: phasing of SE trade winds and the oceanic productivity

Sporomorphs and dinoflagellate cysts from site GIK16867 in the northern Angola Basin record the vegetation history of the West African forest during the last 700 ka in relation to changes in salinity and productivity of the eastern Gulf of Guinea. During most cool and cold periods, the Afromontane forest, rather than the open grass-rich dry forest, expanded to lower altitudes partly replacing the lowland rain forest of the borderlands east of the Gulf of Guinea. Except in Stage 3, when oceanic productivity was high during a period of decreased atmospheric circulation, high oceanic productivity is correlated to strong winds. The response of marine productivity in the course of a climatic cycle, however, is earlier than that of wind vigour and makes wind-stress-induced oceanic upwelling in the area less likely. Monsoon variation is well illustrated by the pollen record of increased lowland rain forest that is paired to the dinoflagellate cyst record of decreased salinity forced by increased precipitation and run-off.

A Holocene dinoflagellate cyst record from offshore north-east England

SUMMARY Dinoflagellate cyst analysis of a British Geological Survey vibrocore from offshore north-eastern England has revealed a detailed record of Holocene marine conditions for the western North Sea area. Constrained by radiocarbon dating, the almost complete record reveals an initial warming trend followed by changing environmental conditions that can be best explained in terms of the various influences of Scottish or English Coastal Waters as previously defined. The increasing influence of North Atlantic water is present, as is some lowering of seawater salinity at the site during the interpreted Subatlantic with the possible increased run-off from the rivers Tyne, Wear and Tees. This study shows that dinoflagellate cyst analysis is proving to be a useful tool in the high resolution environmental elucidation of offshore marine Holocene sequences.

Chemostratigraphic reconstruction of biofacies: Molecular evidence linking cyst-forming dinoflagellates with pre-Triassic ancestors

New data from numerous detailed mass-spectrometric studies have detected triaromatic dinosteroids in Precambrian to Cenozoic rock samples. Triaromatic dinosteroids are organic geochemicals derived from dinosterols, compounds known in modern organisms to be the nearly exclusive widely occurring products of dinoflagellates. We observed the ubiquitous occurrence of these dinosteroids in 49 Late Triassic through Cretaceous marine source rocks and the absence of them in 13 Permian-Carboniferous source rocks synergistic with the dinoflagellate cyst record. However, finding dinosteroids in lower Paleozoic and Precambrian strata presents challenging results for molecular paleontologists, evolutionary biologists, palynologists, and especially for those concerned with the food web at various times of biological crisis. Other than the few species known as parasites and symbionts, many other dinoflagellate species are important as primary producers. The presence of Precambrian to Devonian triaromatic dinosteroids gives chemostratigraphic evidence of dinoflagellates (or other organisms with similar chemosynthetic capabilities) in rocks significantly older than the oldest undisputed dinoflagellate fossils (dinoflagellate cysts from the Middle Triassic, ∼ 240 Ma), and older than the putative Silurian ∼ 420 Ma) dinocyst, Arpylorus antiquus (Calandra) Sargent, from Tunisia. This systematic chemostratigraphic approach can shed light not only on lineages of dinoflagellates and their precursors, but potentially on many other lineages, especially bacteria, algae, plants, and possibly some metazoans.

Dinoflagellate cyst biostratigraphy of the last 2.3 Ma from the Rockall Plateau, northeast Atlantic Ocean

The organic-walled dinoflagellate cyst record for Hole 552A of Leg 81 of the Deep Sea Drilling Project is extended to 2.3 Ma. Peaks of dinoflagellate cyst recovery are noted for isotope stages 19, 23, 25 and two unnumbered stages in Cores 7 and 8. Impagidinium cysts are persistently present throughout and especially prominent in the older sediments of Cores 7 and 8 where they are the characteristic component of the oxygen-light units. Younger dinoflagellate cyst assemblages from isotope stages 19, 23 and 25 characteristically contain Nematosphaeropsis labyrinthus (Ostenfeld) Reid, Operculodinium centrocarpum (Deflandre &amp; Cookson) Wall and Spiniferites spp., and are comparable to those recovered from sediments deposited over the last 0.7 Ma. This correlation of dinoflagellate cysts with the oxygen isotope stratigraphy over the last 2.3 Ma may provide a reference section for the eastern North Atlantic Ocean on the western flank of the Rockall Plateau.