Distribution Of Dinoflagellate Cysts Research Articles

Palaeoenvironmental change in the Early Cretaceous Silesian Basin of the Western Carpathians (NE Czech Republic) inferred from palynological data

A Berriasian–lowermost Cenomanian composite stratigraphic section of the Silesian Basin of the Outer Western Carpathians was studied palynologically with an emphasis on quantitative palynomorphs and dinoflagellate cyst distribution. The quantitative composition of the dinoflagellate cyst assemblages reflects a palaeoenvironmental change from inner neritic to outer neritic or oceanic conditions. This change is considered to reflect a relative rise in sea level (according to the 2nd order eustatic curve) and/or tectonic subsidence in the basin. In the lower part (Berriasian to Hauterivian), dinoflagellate cysts characterising a shallow-water environment with variable salinity dominate. The quantitative composition of the dinoflagellate cysts of the latest Hauterivian to early Aptian is characteristic of a deeper shelf environment. In the latest Aptian to Albian, there is already sedimentation in a basinal sedimentary environment (oceanic dinoflagellate cysts are present here as an autochthonous element), with the redeposition of material supplied from littoral to deeper shelf areas. For the composition of palynomorph assemblages, sporomorphs play a more important role in the period from the late Valanginian to the early Aptian. This role is proved by an increased supply of terrestrial material, and it corresponds to a higher amount of black claystones and sandstones.

Organic-walled dinoflagellate cyst distribution in the Gulf of Mexico

In order to document the distribution of organic-walled dinoflagellate cysts (dinocysts) and their relationship with sea-surface parameters (temperature, salinity, primary productivity), palynological analyses were performed on 44 surface sediment samples from the Gulf of Mexico (17°N to 29°N). Samples display low to moderate concentrations with values ranging from 78 to 3576 dinocysts·g − 1 dry weight sediment. Assemblages are dominated by either Brigantedinium spp. or Polysphaeridium zoharyi along with the phototrophic taxa Spiniferites spp. and Operculodinium spp. Redundancy analyses (RDA) identified the distance to the coast and/or water depth and annual temperature as being the most important factors that control cyst distribution in the Gulf of Mexico. The first two axes explain respectively 44.7% and 20% of the total variance. The inshore to offshore trend in cyst distribution emphasized by the RDA involves changes in associations of species with the presence of Impagidinium spp. in more oceanic assemblages and higher representation of P. zoharyi nearshore. This latter species, produced by the potentially toxic dinoflagellate Pyrodinium bahamense , reaches very high abundances notably on the west Florida shelf and in the Mexican lagoons. Additionally, Melitasphaeridium choanophorum , which was considered to have gone extinct by the end of the Pleistocene, appears as a modern component of marine sediment from the north and southwestern Gulf. Our results thus demonstrate a biostratigraphical range extending to the present, at least in the study area. This palynological investigation highlights the importance of the Gulf of Mexico as potential refuge for late Cenozoic species thought to be extinct. • Gulf of Mexico as potential refuge for late Cenozoic species thought to be extinct. • Melitasphaeridium choanophorum appears as a modern component of marine sediment. • The distance to the coast and/or water depth are the main parameters that control assemblages.

Palaeoenvironmental reconstruction and biostratigraphy with marine palynomorphs of the Plio–Pleistocene in Tjörnes, Northern Iceland

Deposits from the Tjörnes Peninsula in northern Iceland enable the assessment of past ocean currents and the influence of the nearby island. Most palaeoecological studies with dinoflagellate cysts from the northern and central Atlantic focus on oceanic or shelf settings and deal with outer neritic and oceanic species. Dinoflagellate cyst studies of marginal marine settings are scarce and represent only short time intervals. The Tjörnes section however accommodates 1200m of sediments that are mainly shallow marine. The sediments are attributed to the Lower Pliocene Tjörnes beds and the overlying Upper Pliocene to Pleistocene Breidavík Group. The dinoflagellate cysts and other marine palynomorphs from 68 samples from the Tjörnes beds and 20 samples from the Breidavík Group are studied. The deposits are divided into five dinoflagellate cyst assemblage zones (DAZ) and one barren interzone (BIZ). The changes in the assemblages proved to be independent of the changes in bathymetry of the sedimentary environment. Heterotrophic dinoflagellate cysts dominate in DAZ1. An abrupt impoverishment in species diversity is observed in DAZ2 when autotrophic species dominate the assemblage. Slightly preceding the entrance of Pacific molluscs in the area in unit 14 of the Serripes Zone, heterotrophic species (unit 12/13) re-enter the area in DAZ3. The marked decrease and return of the heterotrophic species does not relate to conditions of preservation, but may result from the loss of nutrients. The upper part of DAZ1 and the base of DAZ3 reflect major changes in the palaeoceanography and span a period during which the polar front may have moved temporarily from the area. The first event situated at the top of DAZ1 occurred in litholog unit 4 halfway the Tapes Zone between circa 5 and 4.8Ma. The second event at the top of litholog unit 12 around 4.5Ma has been linked to the shoaling of the Central American Seaway. Heterotrophic dinoflagellates disappear almost completely from the area during the deposition of the Pleistocene Breidavík Group (DAZ4-5). A transition from a heterotrophic dominated assemblage to an autotrophic dominated assemblage is observed in the Hörgi Formation (DAZ4a). An assemblage dominated by autotrophic cold water species, comparable to the present-day assemblage of the area north of Iceland, occurs from unit 10 in the Pleistocene Svarthamar Member on (DAZ5). This study underscores that the distribution of temperature sensitive dinoflagellate cysts is influenced by the availability of nutrients and changes in ocean currents.

Dinoflagellate cyst assemblages in recent sediments of Visakhapatnam harbour, east coast of India: Influence of environmental characteristics

The distribution and abundance of dinoflagellate cysts in recent sediments from Visakhapatnam harbour, east coast of India was investigated and compared with sediment characteristics and physico-chemical variables of the overlying water column. The cyst abundance varied from 11 to 1218cystsg–1dry sediment. Changes in the cyst assemblages from phototrophic to heterotrophic forms were observed from inner to outer harbour stations, and related to changes in environmental characteristics. Enhanced cyst production of potentially harmful dinoflagellate Protoceratium reticulatum was recorded in the inner harbour stations with higher nutrient concentrations. Protoperidinium cysts were the most diversified group, and were dominant in the outer harbour stations having improved water conditions and circulation. This study points out the potential use of dinoflagellate cyst populations in providing information on environmental conditions.

Distribution of dinoflagellate cysts in Hudson Bay surface sediments – implications for late Quaternary application

Distribution of dinoflagellate cysts in Hudson Bay surface sediments – implications for late Quaternary application

Atlas of modern dinoflagellate cyst distribution based on 2405 data points

Dinoflagellate cysts are useful for reconstructing upper water conditions. For adequate reconstructions detailed information is required about the relationship between modern day environmental conditions and the geographic distribution of cysts in sediments. This Atlas summarises the modern global distribution of 71 organic-walled dinoflagellate cyst species. The synthesis is based on the integration of literature sources together with data of 2405 globally distributed surface sediment samples that have been prepared with a comparable methodology and taxonomy. The distribution patterns of individual cyst species are being compared with environmental factors that are known to influence dinoflagellate growth, gamete production, encystment, excystment and preservation of their organic-walled cysts: surface water temperature, salinity, nitrate, phosphate, chlorophyll-a concentrations and bottom water oxygen concentrations. Graphs are provided for every species depicting the relationship between seasonal and annual variations of these parameters and the relative abundance of the species. Results have been compared with previously published records; an overview of the ecological significance as well as information about the seasonal production of each individual species is presented.The relationship between the cyst distribution and variation in the aforementioned environmental parameters was analysed by performing a canonical correspondence analysis. All tested variables showed a positive relationship on the 99% confidence level. Sea-surface temperature represents the parameter corresponding to the largest amount of variance within the dataset (40%) followed by nitrate, salinity, phosphate and bottom-water oxygen concentration, which correspond to 34%, 33%, 25% and 24% of the variance, respectively. Characterisations of selected environments as well as a discussion about how these factors could have influenced the final cyst yield in sediments are included.

Distribution of dinoflagellate cysts and other aquatic palynomorphs in surface sediments from the Beagle Channel, Southern Argentina

Palynological analyses of 22 surface sediment samples from the Beagle Channel, Tierra del Fuego, Argentina, were performed in order to investigate the distribution of dinocyst assemblages and other aquatic palynomorphs and to explore their relationships with sea-surface conditions, which are regionally characterized by cold and low salinity conditions (4–9 °C and 27–33.5, respectively). Results show relatively low dinocyst concentrations (253 to 5568 cysts/g) and species diversity (19 taxa identified). The assemblages are mostly composed of Protoperidiniaceae and appear typical of a marginal marine environment with surface waters characterized by low to moderate salinity and high nutrient content due to river inputs. The assemblages are thus compatible with the occurrence of freshwater to brackish water taxa Botryococcus braunii , Botryococcus sp., Polyasterias sp., Halodinium sp., and Radiosperma corbiferum . The dinocyst assemblages are dominated by Brigantedinium spp., Echinidinium spp. and Selenopemphix quanta accompanied by cysts of Pentapharsodinium dalei , Islandinium minutum , Votadinium spinosum , Polykrikos kofoidii and Polykrikos schwartzii . The assemblages from the Beagle Channel show similarities with those of high latitude regions of the Northern Hemisphere. However, some taxa, which were exclusively reported from relatively warm environments in the Northern Hemisphere, occur in relatively high percentages in the Beagle Channel (e.g. Echinidinium delicatum and Votadinium spinosum ). The absence of Selenopemphix antarctica in the Beagle Channel is consistent with its known ecological affinities, since it characterizes environments marked by seasonal sea-ice cover. ► First record of dinocyst assemblages are from off the coast of southern South America. ► They are comparable with assemblages from the continental shelf of the Arctic Ocean. ► Include taxa previously reported from temperate to warm climatic domains. ► SST and SSS might not be the most determinant parameters in their distribution.

Species Diversity and Eco-geographical Distribution of Dinoflagellate Cysts in the Bohai Sea, China

Species Diversity and Eco-geographical Distribution of Dinoflagellate Cysts in the Bohai Sea, China

The impact of different pollution sources on modern dinoflagellate cysts in Sishili Bay, Yellow Sea, China

The spatial distribution of dinoflagellate cysts in the surface sediment of Sishili Bay, Yellow Sea, China, was studied, with the purpose of understanding the impact from nutrient enrichment and industrial pollution. Thirty-five dinoflagellate cyst taxa belonging to 15 genera and 3 unknown cysts were identified and quantified at 22 sampling sites. Autotrophic cysts (e.g., Spiniferites bentori var. truncata) and heterotrophic cysts (Brigantedinium sp.1 and Quinquecuspis concreta) dominated the sediment samples. The spatial distribution of cyst abundance showed a significant positive correlation with increased nutrients, but was negative to heavy metal pollution. The highest cyst abundance (with an average of 539 cysts g(-1) DW) occurred in Zone A, corresponding to nutrient enrichment caused by domestic sewage discharge. In contrast, the lowest cyst abundance (with an average of 131 cysts g-1 DW) occurred in Zone E. impacted heavily by the industrial pollution. The abundance of autotrophic cysts decreased dramatically in Zone E compared with heterotrophic cysts and showed a sensitivity to industrial pollution. How heavy metals affect physiological mechanisms in autotrophic and heterotrophic cysts differentially is in need of in-depth study. (C) 2011 Elsevier B.V. All rights reserved.

Deciphering the palaeoecology of Late Pliocene and Early Pleistocene dinoflagellate cysts

In an attempt to document the palaeoecological affinities of individual extant and extinct dinoflagellate cysts, Late Pliocene and Early Pleistocene dinoflagellate cyst assemblages have been compared with geochemical data from the same samples. Mg/Ca ratios of Globigerina bulloides were measured to estimate the spring–summer sea-surface temperatures from four North Atlantic IODP/DSDP sites. Currently, our Pliocene–Pleistocene database contains 204 dinoflagellate cyst samples calibrated to geochemical data. This palaeo-database is compared with modern North Atlantic and global datasets. The focus lies in the quantitative relationship between Mg/Ca-based (i.e. spring–summer) sea-surface temperatures (SST Mg/Ca) and dinoflagellate cyst distributions. In general, extant species are shown to have comparable spring–summer SST ranges in the past (SST Mg/Ca) and today (SST from World Ocean Atlas 2005, Locarnini et al., 2006), demonstrating that our new approach is valid for inferring spring–summer SST ranges for extinct species. For example, Habibacysta tectata represents SST Mg/Ca values between 10 and 15 °C when it exceeds 30% of the assemblage, and Invertocysta lacrymosa exceeds 15% when SST Mg/Ca values are between 18.6 and 23.5 °C. However, comparing Pliocene and Pleistocene SST Mg/Ca values with present day summer values for the extant Impagidinium pallidum suggests a greater tolerance of higher temperatures in the past. This species occupies more than 5% of the assemblage at SST Mg/Ca values of 11.6–17.9 °C in the Pliocene and Pleistocene, whereas present day summer SSTs are around − 1.7 to 6.9 °C. This observation questions the value of Impagidinium pallidum as reliable indicator of cold waters in older deposits, and may explain its bipolar distribution.

Distribution of dinoflagellate cysts in recent sediments from Izmir Bay (Aegean Sea, Eastern Mediterranean)

Abstract To determine the species composition, abundance and horizontal distribution of dinoflagellate cysts in recent marine sediments, samples were collected at 13 stations in Izmir Bay, Aegean Sea. At least thirty-six dinoflagellate cyst types were identified, with the assemblages mainly dominated by Lingulodinium machaerophorum , Polykrikos kofoidii , Operculodinium centrocarpum , Gymnodinium cf. nolleri and Quinquecuspis concreta . Total cyst concentrations ranged from 41 to 3292 cystsg − 1 dry weight sediment. The majority of the cysts occurred in the inner and middle parts of the bay, where higher cyst concentrations were observed. According to the One Way Anova test, the difference between stations was significant statistically (p Gymnodinium cf. nolleri and Oblea acanthocysta . Alexandrium minutum and Alexandrium affine type cyst were observed at almost all stations although the cyst type of the Alexandrium catenella/tamarense complex was only found in the outer bay. These findings indicate potential seedbeds for initiation of future blooms and outbreaks of potentially toxic species in Izmir Bay.

Dinoflagellate Cysts in Surface Sediments from Southern Coast of Korea

To investigate the distributions of dinoflagellate cysts in relation to environmental conditions from southern coast of Korea, surface sediment samples collected from 11 stations in Gamak Bay, Yeoja Bay and the offshore area of Yeoja Bay were analyzed. Dinoflagellate cyst assemblages observed in the study area included many species commonly reported from other temperate regions. Among them, Polykrikos cysts were dominant, together with Brigantedinium spp. and Spiniferites spp. Based on cluster analysis, dinoflagellate cyst assemblages were divided into two main groups; group I, located in Yeoja Bay and group II, located in Gamak Bay and the offshore area of Yeoja Bay. Principal component analysis identified differences in salinity levels as the main environmental factors affecting the distributional characteristics of dinoflagellate cyst assemblages in the study area. Gamak Bay is a typical eutrophied area as result of extensive human activities around the bay, and heterotrophic cysts, including Polykrikos cysts, are remarkably abundant and likely to be a useful indicator for eutrophication in Gamak Bay.

Distribution patterns of recent organic-walled dinoflagellate cysts in relation to environmental parameters in the Mediterranean Sea

To determine the relationship between the spatial dinoflagellate cyst distribution and oceanic environmental conditions, 34 surface sediments from the Eastern and Western Mediterranean Sea have been investigated for their dinoflagellate cyst content. Multivariate ordination analyses identified sea-surface temperature, chlorophyll-a , nitrate concentration, salinity, and bottom oxygen concentration as the main factors affecting dinoflagellate cyst distribution in the region. Based on the relative abundance data, two associations can be distinguished that can be linked with major oceanographic settings. (1) An offshore eastern Mediterranean regime where surface sediments are characterized by oligotrophic, warm, saline surface water, and high oxygen bottom water concentrations (Impagidinium species, Nematosphaeropsis labyrinthus, Pyxidinopsis reticulata and Operculodinium israelianum). Based on the absolute abundance, temperature is positively related to the cyst accumulation of Operculodinium israelianum. Temperature does not form a causal factor influencing the accumulation rate of the other species in this association. Impagidinium species and Nematosphaeropsis labyrinthus show a positive relationship between cyst accumulation and nitrate availability in the upper waters. (2) Species of association 2 have highest relative abundances in the Western Mediterranean Sea, Strait of Sicily/NW Ionian Sea, and/or the distal ends of the Po/Nile/Rhône River plumes. At these stations, surface waters are characterized by (relative to the other regime) higher productivity associated with lower sea-surface temperature, salinity, and lower bottom water oxygen concentrations (Selenopemphix nephroides, Echinidinium spp., Selenopemphix quanta, Quinquecuspis concreta, Brigantedinium spp. and Lingulodinium machaerophorum). Based on both the absolute and relative abundances, Selenopemphix nephroides is suggested to be a suitable indicator to trace changes in the trophic state of the upper waters. The distribution of Lingulodinium machaerophorum is related to the presence of river-influenced surface waters, notably the Nile River. We suggest that this species might form a suitable marker to trace past variations in river discharge, notably from the Nile.

Recent geographical distribution of organic-walled dinoflagellate cysts in the southeast Pacific (25–53°S) and their relation to the prevailing hydrographical conditions

Forty-eight surface sediment samples from the southeast (SE) Pacific (25–53°S) are investigated for the determination of the spatial distribution of organic-walled dinoflagellate cysts along the western South American continental margin. Fifty-five different taxa are recorded and reflect oceanic or coastal assemblages. The oceanic assemblages are characterised by low cyst concentrations and the dominance of autotrophs, while the coastal assemblages generally contain a higher number of cysts, which are mainly produced by heterotrophic species. Highest cyst concentrations are observed in the active upwelling system offshore Concepción (35–37°S). Brigantedinium spp., Echinidinium aculeatum, Echinidinium granulatum/delicatum and cysts of Protoperidinium americanum dominate assemblages related to upwelling. Echinidinium aculeatum appears to be the best indicator for the presence of all year round active upwelling cells. Other protoperidinioid cysts may also occur in high relative abundances in coastal regions outside active upwelling systems, if the availability of nutrients, co-responsible for the presence/absence of their main food sources such as diatoms and other protists, is sufficient. The importance of nutrient availability as a determining environmental variable influencing cyst signals on a regional scale (SE Pacific) is demonstrated through statistical analyses of the data. Because of the importance of nutrients, uncertainties about the outcomes of quantitative sea-surface temperature (SST) reconstructions (Modern Analogue Technique) based on dinoflagellate cysts may arise, since no interaction between different hydrographical variables is considered in this approach. The combination of the SE Pacific surface sample dataset with other published cyst data from the Southern Hemisphere resulted in a database which includes 350 samples: the ‘SH350 database’. This database is used to test the accuracy of the quantitative reconstructions by calculating and comparing the estimated versus observed values for each site. An attempt to perform quantitative SST reconstructions on the last 25 cal ka of site ODP1233 (41°S; 74°27′W) is made and again stresses the importance of other environmental variables such as nutrient availability in determining the dinoflagellate cyst assemblages.

Dinoflagellate cyst-based reconstructions of mid to late Holocene winter sea-surface temperature and productivity from an anoxic fjord in the NE Pacific Ocean

Published contemporary dinoflagellate distributional data from the NE Pacific margin and estuarine environments ( n = 136) were re-analyzed using Canonical Correspondence Analysis (CCA) and partial Canonical Correspondence Analysis (pCCA). These analyses illustrated the dominant controls of winter temperature and productivity on the distribution of dinoflagellate cysts in this region. Dinoflagellate cyst-based predictive models for winter temperature and productivity were developed from the contemporary distributional data using the modern analogue technique and applied to subfossil data from two mid to late Holocene (∼5500 calendar years before present–present) cores; TUL99B03 and TUL99B11, collected from Effingham Inlet, a 15 km long anoxic fjord located on the southwest coast of Vancouver Island that directly opens to the Pacific Ocean through Barkley Sound. Sedimentation within these basins largely comprises annually deposited laminated couplets, each made up of a winter deposited terrigenous layer and spring to fall deposited diatomaceous layer. The Effingham Inlet dinoflagellate cyst record provides evidence of a mid-Holocene gradual decline in winter SST, ending with the initiation of neoglacial advances in the region by ∼3500 cal BP. A reconstructed Late Holocene increase in winter SST was initiated by a weakening of the California Current, which would have resulted in a warmer central gyre and more El Niño-like conditions.

Dinoflagellate cyst distribution in surface sediments along the south-western Mexican coast (14.76° N to 24.75°N)

Abstract In this study, we explore the relationship between the modern assemblages of organic-walled dinoflagellate cysts and sea-surface conditions (temperature, salinity, primary productivity) and water depth and distance to the coast. Statistical treatments were performed on 95 surface sediment samples from sites located along the south-western Mexican coast (14.76° N to 24.75°N). Redundancy analysis (RDA) illustrates that the principal parameters correlated with the regional cyst distribution are the distance to the coast and the productivity in the upper water column, which is closely related to upwelling intensity. Empirical observations coupled with RDA provide insight into the spatial coverage of some cyst taxa produced by dinoflagellate species potentially responsible for harmful algal blooms along the coast. They also allow the recognition of four zones of assemblages, which are linked to the upwelling intensity and the productivity and characterize La Paz Bay, the south-western Mexican margin (from 15.95° N to 23.11° N), the northern part of the Gulf of Tehuantepec and the southern part of the Gulf of Tehuantepec.

Lithological and palynological evidence of late Quaternary depositional environments in the subaqueous Yangtze delta, China

AMS 14C ages of post-glacial core sediments from the subaqueous Yangtze delta, along with sedimentary structures and distributions of grain size, pollen spores, and dinoflagellate cysts, show an estuarine depositional system from 13 to 8.4 cal ka BP and a deltaic system from 5.9 cal ka BP to the present. The estuarine system consists of intertidal to subtidal flat, estuarine, and estuarine-front facies, characterized by sand–mud couplets and a high sedimentation rate. The deltaic system includes nearshore shelf and prodelta mud featured by lower sedimentation rate, markedly fewer coastal wetland herbaceous pollens, and more dinoflagellate cysts. We explain the extremely high sedimentation rate during 9.2–8.4 cal ka BP at the study site as a result of rapid sea-level rise, high sediment load due to the unstable monsoonal climate, and subaqueous decrease of elevation from inner to outer estuary. A depositional hiatus occurred during 8.2–5.9 cal ka BP, the transition from estuarine to deltaic system, caused possibly by a shortage of sediment supply resulting from delta initiation in paleo-incised Yangtze valley and strong tidal or storm-related reworking in offshore areas. The subsequent development of deltaic system at the study site indicates accelerated progradation of Yangtze delta post-5.9 cal ka BP.

Organic-walled dinoflagellate cysts as indicators of oceanographic conditions and terrigenous input in the NW African upwelling region

In order to examine the spatial distribution of organic-walled dinoflagellate cysts (dinocysts) in recent sediments related to environmental conditions in the water column, thirty-two surface sediment samples from the NW African upwelling region (20–32°N) were investigated. Relative abundances of the dinocyst species show distinct regional differences allowing the separation of four hydrographic regimes. (1) In the area off Cape Ghir, which is characterized by most seasonal upwelling and river discharge, Lingulodinium machaerophorum strongly dominates the associations which are additionally characterized by cysts of Gymnodinium nolleri, cysts of Polykrikos kofoidii and cysts of Polykrikos schwartzii. (2) Off Cape Yubi, a region with increasing perennial upwelling, L. machaerophorum, Brigantedinium spp., species of the genus Impagidinium and cysts of Protoperidinium stellatum occur in highest relative abundances. (3) In coastal samples between Cape Ghir and Cape Yubi, Gymnodinium catenatum, species of the genus Impagidinium, Nematosphaeropsis labyrinthus, Operculodinium centrocarpum, cysts of P. stellatum and Selenopemphix nephroides determine the species composition. (4) Off Cape Blanc, where upwelling prevails perennially, and at offshore sites, heterotrophic dinocyst species show highest relative abundances. A Redundancy Analysis reveals fluvial mud, sea-surface temperature and the depth of the mixed layer in boreal spring (spring) as the most important parameters relating to the dinocyst species association. Dinocyst accumulation rates were calculated for a subset of samples using well-constrained sedimentation rates. Highest accumulation rates with up to almost 80,000 cysts cm − 2 ka − 1 were found off Cape Ghir and Cape Yubi reflecting their eutrophic upwelling filaments. A Redundancy Analysis gives evidence that primary productivity and the input of fluvial mud are mostly related to the dinocyst association. By means of accumulation rate data, quantitative cyst production of individual species can be considered independently from the rest of the association, allowing autecological interpretations. We show that a combined interpretation of relative abundances and accumulation rates of dinocysts can lead to a better understanding of the productivity conditions off NW Africa.

Abundance and distribution of vernal bloom dinoflagellate cysts in the Gulf of Finland and Gulf of Riga (the Baltic Sea)

In the northern Baltic Sea, brackish water dinoflagellates Peridiniella catenata, Woloszynskia spp. and Scrippsiella hangoei form a major part of the spring bloom biomass, comparable to, or even exceeding the biomass of diatoms. The life cycle of these dinoflagellates involves a relatively short period of vegetative growth in early spring (2–3 months), followed by encystment during the first part of May, and a resting period in the form of benthic cysts. The bloom intensity of the Woloszynskia/Scrippsiella complex in the Baltic Sea is spatially variable, with peak abundances in the central and eastern Gulf of Finland, while the species are rare in the Gulf of Riga. During a field survey in late May 2004, we investigated the abundance and distribution of benthic cysts of P. catenata and Woloszynskia spp. in surface (5 cm) sediments around the Estonian coast. The broad distribution patterns of benthic cysts reflected the overall knowledge of basin-wide planktonic phase distribution of the species. On a finer scale, sediment properties (percent of clay, organic matter content) demarked the accumulation regions of the cysts. Woloszynskia cyst abundances in the surface 5 cm sediment were up to 3.2×106 cysts cm−2 and Peridiniella cyst abundances were approximately an order of magnitude less, up to 0.3×106 cysts cm−2.

A dynamic climate and ecosystem state during the Paleocene-Eocene Thermal Maximum: inferences from dinoflagellate cyst assemblages on the New Jersey Shelf

Abstract. Late Paleocene and Early Eocene climates and ecosystems underwent significant change during several transient global warming phases, associated with rapidly increasing atmospheric carbon concentrations, of which the Paleocene-Eocene Thermal Maximum (PETM; ~55.5 Ma) is best studied. While biotic response to the PETM as a whole (~170 kyrs) has been relatively well documented, variations during the PETM have been neglected. Here we present organic dinoflagellate cyst (dinocyst) distribution patterns across two stratigraphically expanded PETM sections from the New Jersey Shelf, Bass River and Wilson Lake. Many previously studied sites show a uniform abundance of the thermophilic and presumably heterotrophic taxon Apectodinium that spans the entire carbon isotope excursion (CIE) of the PETM. In contrast, the New Jersey sections show large variations in abundances of many taxa during the PETM, including the new species Florentinia reichartii that we formally propose. We infer paleoecological preferences of taxa that show temporal abundance peaks, both qualitative and absolute quantitative, from empirical as well as statistical information, i.e., principle (PCA) and canonical correspondence analyses (CCA). In the CCAs, we combine the dinocyst data with previously published environmental proxy data from these locations, such as TEX86 paleothermometry, magnetic susceptibility and sedimentary size fraction. The combined information supports previous inferences that sea level rose during the PETM, but also indicates a (regional) increase in fresh-water runoff that started ~10 kyr after the onset of the CIE, and perhaps precession-paced cycles in sea surface productivity. The highly variable dinocyst assemblages of the PETM contrast with rather stable Upper Paleocene assemblages, which suggests that carbon input caused a dynamic climate state, at least regionally.