Figures of dinoflagellate cysts (relative abundance, temperature, salinity and nutrients)

This Atlas summarises the global distribution of extant organic-walled dinoflagellate cysts in the form of 61 maps illustrated by the relative abundance of individual cyst taxa in recent marine sediments from the Atlantic Ocean and adjacent basins, the Antarctic region (South Atlantic, southwestern Pacific and southern Indian Ocean sections), the Arabian Sea and the northwestern Pacific. This synthesis is based on the integration of literature sources together with data from 835 marine surface sediments prepared on a comparable methodology and taxonomy. The relationships between distribution patterns of cyst species and the surface-water parameters (temperature, salinity, phosphate and nitrate concentrations) are documented with graphs depicting the relative abundance of species in relation to seasonal and annual values of the above mentioned parameters at the sample sites. Two ordination techniques (detrended correspondence analysis and canonical correspondence analysis) have been carried out to statistically illustrate the relationships between species distribution and sea-surface conditions. Results have been compared with previously published records and an overview of the ecological significance of each individual species is presented. Characterisations of selected environments as well as a discussion about how additional processes such as preservation and transport could have affected the present dataset are included.

Lower Cretaceous dinoflagellate cysts of Exmouth Plateau, Nortwest Australia

Cores from Leg 122, Sites 762 and 763, were sampled at intervals of one sample per 1.5-m section in the Lower Cretaceous sequences. More than 400 samples were studied, most of which contained dinoflagellate cysts, spores, pollen, and various types of palynoclasts. From the entire palynomorph assemblage mainly dinoflagellate cysts were studied to give a stratigraphic outline for the Lower Cretaceous. Stratigraphic units were interpreted in terms of zones in use for the Jurassic and Cretaceous of Australia. At both sites a condensed Valanginian to Aptian sequence and an expanded middle to late Berriasian sequence containing a rich microplankton assemblage were recovered. Sites 762 and 763 can be correlated with each other and with the wells Eendracht-1 and Vinck-1.

X-ray fluorescence data (calcium and iron), bulk organic d13C, and dinoflagellate cysts of ODP Hole 189-1172D

The 'Paleocene/Eocene Thermal Maximum' or PETM (~55 Ma) was associated with dramatic warming of the oceans and atmosphere, pronounced changes in ocean circulation and chemistry, and upheaval of the global carbon cycle. Many relatively complete PETM sequences have by now been reported from around the world, but most are from ancient low- to midlatitude sites. ODP Leg 189 in the Tasman Sea recovered sediments from this critical phase in Earth history at Sites 1171 and 1172, potentially representing the southernmost PETM successions ever encountered (at ~70° to 65° S paleolatitude). Downhole and core logging data, in combination with dinoflagellate cyst biostratigraphy, magneto-stratigraphy, and stable isotope geochemistry indicate that the sequences at both sites were deposited in a high accumulation-rate, organic rich, marginal marine setting. Furthermore, Site 1172 indeed contains a fairly complete P-E transition, whereas at Site 1171, only the lowermost Eocene is recovered. However, at Site 1172, the typical PETM-indicative acme of the dinocyst Apectodinium was not recorded. We conclude that unfortunately, the critical latest Paleocene and PETM intervals are missing at Site 1172. We relate the missing section to a sea level driven hiatus and/or condensed section and recovery problems. Nevertheless, our integrated records provide a first-ever portrait of the trend toward, and aftermath of, the PETM in a marginal marine, southern high-latitude setting.

Early Oligocene dinoflagellate cysts from the Upper Rhine Graben

Using principal component analysis and cyst diversity and equity trends, we can recognize four distinct dinoflagellate cyst (dinocyst) assemblages from four Rupelian (Early Oligocene) cores in the Mainz Embayment of the northern Rhine Graben (SW Germany). These assemblages are the Spiniferites ramosus (PC1), Thalassiphora pelagica (PC2), Homotryblium tenuispinosum (PC3), and Vozzhennikovia spinula (PC4) assemblages. The four cores provide an onshore-offshore transect in the Mainz Embayment. The H. tenuispinosum assemblage shows high factor loadings in proximal to intermediate cores, which is interpreted to reflect temporary high-salinity conditions. Mean dinocyst diversity and equity increase with distance from the Mid-Rupelian shoreline, indicating increasingly stable paleoenvironmental conditions towards the center of the Mainz Embayment. Within individual cores, changes in dinocyst assemblages through time are related to paleoenvironmental and paleoclimatological changes. The three proximal to intermediate cores show dominance of the H. tenuispinosum assemblage repeatedly alternating with high factor loadings of the T. pelagica assemblage. In both cases, dinocyst diversity and equity tend to be reduced. Highest factor loadings of the S. ramosus assemblage occur in intervals where neither of the above assemblages is dominant and tend to coincide with dinocyst diversity and equity maxima. We interpret this distribution pattern to denote different paleoceanographic conditions, reflecting drier and more humid phases in the Early Oligocene of Central Europe. During relatively dry periods, increased salinity conditions prevailed in proximal to intermediate settings of the Mainz Embayment, as reflected by the dominance of the H. tenuispinosum assemblage. During more humid periods, increased runoff led to higher nutrient availability and the formation of a pycnocline separating slightly less saline surface waters from higher saline deeper waters, thus impeding vertical circulation. These environmental conditions are documented in high loadings of the T. pelagica assemblage which is indicative of increased eutrophication and/or oxygen-depleted bottom waters. Transitions between drier and more humid periods, i.e. episodes of normal marine conditions, are characterized by high loadings predominantly of the S. ramosus assemblage as well as increased dinocyst diversity and equity values. We propose that the alternations between drier and more humid phases may be related to variations in the ocean-atmosphere moisture flux from the North Atlantic into Central Europe bearing a high-latitude climate signal.

Calcareous dinoflagellate cysts analysis of sediment cores from the Equatorial South Atlantic Ocean

An overview is presented of the current state of knowledge on paleo-ecological aspects of calcareous dinoflagellate resting cysts. Apart from literature-based information, a discussion of new results is also provided from Equatorial Atlantic surface plankton samples, surface sediment samples and Late Quaternary sediments from two gravity cores. With the aid of redundancy analysis statistics, variations in the calcareous cyst content of both cores are correlated to variations in total organic carbon (TOC). On a global scale, the calcareous cyst distribution in bottom sediments varies with latitude and inshore-offshore gradients. In the Equatorial Atlantic Ocean, enhanced calcareous cyst production can be observed in regions and time intervals with stratified, oligotrophic conditions in the upper water masses.

Calcareous dinoflagellate cysts in surface sediments from the Mediterranean Sea

The distribution of calcareous dinoflagellate cysts in surface sediments from the Mediterranean Sea was quantitatively analysed. The samples contain 11 cyst species and the vegetative coccoid Thoracosphaera heimii. Cyst abundance increases towards the deeper parts of the basins and is generally higher in the eastern Mediterranean Sea. Three major distribution characteristics exist: (1) different assemblages in oceanic and neritic regions, (2) little agreement with the associations of areas studied so far like the Atlantic Ocean, and (3) a unique oceanic assemblage in the eastern Mediterranean Sea. A gradual change in cyst assemblages from the western to the eastern Mediterranean Sea was observed and statistically compared with the main environmental gradients in the upper water column. Temperature, nitrate concentration and possibly salinity appear to be the most important factors controlling cyst production. Three groups containing cysts with similar environmental preferences can be distinguished: (1) an eastern Mediterranean group related to relatively high temperature and salinity but low nitrate concentration, (2) a group of more or less consistently abundant cosmopolitan species tolerating or even preferring relatively low temperature and salinity but high nitrate concentration, and (3) a group containing species that are possibly adapted to neritic environments and have probably been transported from coastal areas into the studied regions. In contrast to other calcareous plankton, calcareous dinoflagellate cysts correlate strongly with the main environmental gradients in the Mediterranean Sea, bearing a high potential for palaeoenvironmental reconstructions.

Abundance of organic-walled dinoflagellate cysts and geochemical analysis of sediment core GeoB5546-2

NW African climate shows orbital and millenial-scale variations, which are tightly connected to changes in marine productivity. We present an organic-walled dinoflagellate cyst (dinocyst) record from a sediment core off Cape Yubi at about 27°N in the Canary Basin covering the time period from 47 to 3ka before present (BP). The dinocyst record reflects differences in upwelling intensity and seasonality as well as the influence of fluvial input. Sea-level changes play an important role for the upwelling pattern and productivity signals at the core site. Within the studied time interval, four main phases were distinguished. (1) From 45 to 24ka BP, when sea-level was mostly about 75m lower than today, high relative abundances of cysts of heterotrophic taxa point to enhanced upwelling activity, especially during Heinrich Events, while relatively low dinocyst accumulation rates indicate that filament activity at the core location was strongly reduced. (2) At sea-level lowstand during the LGM to H1, dinocyst accumulation rates suggest that local filament formation was even more inhibited. (3) From the early Holocene to about 8ka BP, extraordinary high accumulation rates of most dinocyst species, especially of Lingulodinium machaerophorum, suggest that nutrient supply via fluvial input increased and rising sea-level promoted filament formation. At the same time, the upwelling season prolongated. (4) A relative increase in cysts of photoautotrophic taxa from about 8ka BP on indicates more stratified conditions while fluvial input decreased. Our study shows that productivity records can be very sensitive to regional features. From the dinocyst data we infer that marine surface productivity off Cape Yubi during glacial times was within the scale of modern times but extremely enhanced during deglaciation.

Accumulation rates of dinoflagellate cysts at trap sites CB2, CB3, CB4, and CB9 off Cape Blanc

A 5-year sediment trap survey in the upwelling area off Cape Blanc (NW Africa) provides information on the seasonal and annual resting cyst production of dinoflagellates, their sinking characteristics and preservation potential. Strong annual variation in cyst production characterizes the region. Cyst production of generally all investigated species, including Alexandrium pseudogonyaulax (Biecheler) T. Horig. ex T. Kita et Fukuyo (cyst genus Impagidinium) and Gonyaulax spinifera (Clap. et J. Lachm.) Diesing (cyst genus Nematosphaeropsis) was enhanced with increasing upper water nutrient and trace-element concentrations. Cyst production of Lingulodinium polyedrum (F. Stein) J. D. Dodge was the highest at the transition between upwelling and upwelling-relaxation. Cyst production of Protoperidinium americanum (Gran et Braarud) Balech, Protoperidinium monospinum (Paulsen) K. A. F. Zonn. et B. Dale, and Protoperidinium stellatum (D. Wall) Balech, and heterotrophic dinoflagellates forming Brigantedinium spp. and Echinidinium aculeatum Zonn., increased most pronouncedly during upwelling episodes. Production of Protoperidinium conicum (Gran) Balech and Protoperidinium pentagonum (Gran) Balech cysts and total diatom valves were related, providing evidence of a predator-prey relationship. The export cyst-flux of E. aculeatum, P. americanum, P. monospinum, and P. stellatum was strongly linked to the flux of total diatom valves and CaCO3, whereas the export production of Echinidinium granulatum Zonn. and Protoperidinium subinerme (Paulsen) A. R. Loebl. correlated with total organic carbon, suggesting potential consumption of diatoms, prymnesiophytes, and organic matter, respectively. Sinking velocities were at least 274 m · d**-1, which is in range of the diatom- and coccolith-based phytoplankton aggregates and "slower" fecal pellets. Species-selective degradation did not occur in the water column, but on the ocean floor.