Abundance Of Dinoflagellate Cysts Research Articles

The utility of freshwater dinoflagellate cyst assemblages as a paleoecological proxy: An assessment from boreal lakes (northwest Ontario, Canada)

Aquatic palynomorphs have the potential to provide valuable insights into past environments but little has been done to assess the utility of freshwater dinoflagellate cysts as palaeoecological proxies of lacustrine environments. This study is the first to compare the distribution of freshwater dinoflagellate cysts found in surface sediments from 32 boreal lakes with varying physical and chemical characteristics. Cysts of Fusiperidinium wisconsinense, Parvodinium umbonatum, and Peridinium willei were nearly ubiquitous, but of the remaining cyst taxa, only Parvodinium inconspicuum, Peridinium limbatum, and Peridinium volzii were abundant but present in a smaller number of lakes. Assemblage composition broadly clustered into three groups: 1) an assemblage (primarily Peridinium spp.) associated with relatively shallow, mesotrophic lakes; 2) an assemblage dominated by F. wisconsinense in mesotrophic lakes with intermediate depth and relatively high pH and alkalinity; and 3) an assemblage dominated by P. umbonatum in deeper oligotrophic lakes. Moreover, changes in dinoflagellate cyst assemblage were assessed in a sediment core spanning the Holocene from nearby Gall Lake and interpreted alongside other previously published paleoecological proxies from this core. High abundances of many dinoflagellate cysts including P. limbatum, P. willei, F. wisconsinense, and P. inconspicuum were observed when lake production was high at a time when lake-levels were low and climate was more arid than today. This study suggests that dinoflagellate cysts in lacustrine sediments are, when abundant, promising both in modern and core samples, and the relationships between assemblages today and in the past can contribution additional information in understanding past ecological conditions.

A contribution to the knowledge of Cretaceous to Neogene Palynology in the Colombian Caribbean.

The palynological study of a composite section of 14 cores drilled from the Sinu-San Jacinto Basin in the Colombian Caribbean (NW South America) provides for the first time a Cenozoic palynostratigraphic zonation scheme for this region. In addition, the study of calcareous nannofossils and planktonic foraminifera allowed an independent calibration of the palynomorph assemblages to the international chronostratigraphic chart. The palynological results were compared with other studies for the northern part of South America and Colombia. Twelve Late Paleocene-Pliocene palynological zones are proposed for the Caribbean, some of which differ from those proposed for the Llanos and Llanos Foothills basins. A Paleocene palynological assemblage is reported for this part of the basin. Variations in the biostratigraphic ranges of some palynomorphs and new species with stratigraphic value are described. High diversity and abundance of dinoflagellate cysts in some stratigraphic intervals require more detailed study. Evidence of reworking in some stratigraphic intervals (e.g., Cretaceous and Oligocene in Miocene sediments), makes it necessary to be careful about the last appearance record of microfossils in exploration and geologic mapping.

Upper Cretaceous (Cenomanian) palynostratigraphy and palynofacies of the Shushan Basin, North Egypt

This study provides an updated quantitative analysis and prospective paleoenvironment reconstruction of the Tut oilfield, Shushan Basin, North Egypt to evaluate the hydrocarbon reservoirs in space and times for further development plans and modeling in the Tethyan region. Two sporomorph interval zones (Classopollis brasiliensis and Afropollis jardinus), and one total foraminiferal Range Zone (Thomasinella punica) are proposed. Three palynofacies assemblages are differentiated using cluster analysis of the different palynofacies parameters. The paleoenvironmental conditions during the Cenomanian were reconstructed. Palynofacies assemblage I of the Baharyia Formation suggests a marginally dysoxic-oxic basin environment with a common occurrence of ostracods and terrestrial organic matter, while palynofacies assemblage II reflects the high abundance of dinoflagellate cysts, suggesting a suboxic-anoxic middle neritic environment. Palynofacies assemblage III of the upper part of the Abu Roash G Member represents a relatively deep water inner-middle neritic environment. Three 3rd order significant sequences separated by two hiatus surfaces (Ce3 and Ce4) are described and correlated with the global eustatic sea-level. The hydrocarbon evaluation results show that the samples from the Abu Roash G Member contain oil-prone material of kerogen type II, while the samples of the Baharyia Formation are characterized by kerogen type III (gas-prone). Spore coloration analysis reveals that the samples from the studied units are too immature to produce gas or oil and are ineffective as sources of hydrocarbons.

The dispersal of dinoflagellate cyst caused by international ships under repair conditions: a potential invasion risk to the Yangtze River Estuary, China.

The foreign dinoflagellate cysts in ships' ballast water tank sediments (BWTS) can be viable for a long time under hostile storage conditions. It is crucial to understand the detailed mechanisms of harmful biological invasions in estuary ecosystems. To study the relationship between the abundance of dinoflagellate cysts and environmental factors, cyst assemblages were analyzed in 7 sediment samples, collected from one international commercial ship that arrived in Shanghai in August 2020. Twenty-three dinoflagellate cyst taxa were identified in 5 groups, including autotrophic (9) and heterotrophic (14) species. Distribution of dinoflagellate cysts in the different ballast water tanks is heterogeneous. Dinoflagellate cysts in BWTS of the repaired ship were dominated by Scrippsiella acuminata, Protoperidinium leonis, Protoperidinium oblongum, Lingulodinium polyedra, Alexandrium tamarense/A. catenella, Protoperidinium pentagonum, and Protoperidinium subinerme. The abundance of the dinoflagellate cysts in each tank ranged from 80.69 to 330.85 cysts g-1 DS (dry sediment). Multivariate statistical analyses revealed that the variation in cysts from different tanks had positive correlations with total nitrogen (TN), total phosphorus (TP), and pH and negative correlations with total organic carbon (TOC) except for sample TK5. For germination of dinoflagellate cysts in BWTS, 12 species were germinated in 40days and cysts of potentially toxic dinoflagellate species were more abundant than those of non-toxic species. Results show that potentially viable and harmful/toxic dinoflagellate cysts are present in BWTS of ships arriving in Shanghai, China. Consequently, knowledge obtained in this study can be valuable for further managing of potential biological invasion of the Yangtze River Estuary.

Recurring Patterns of Sea Level Changes within a Palynological-Based Sequence Stratigraphy Framework of the Middle Jurassic Organic Matter-Rich Khatatba Formation, Egypt

The Middle Jurassic was a time of marginal to shallow shelf settings dominated by organic matter-rich deposition in northern Egypt, southern Tethys. Paleoenvironmental and sequence stratigraphic reconstructions are of paramount significance for a better understanding of basin history and related reservoirs and source rock units. For this purpose, a detailed palynomorph and palynofacies analysis of the Middle Jurassic Khatatba Formation in the Dahab-Mireir Basin, north Western Desert, was conducted. A moderately to well-preserved, moderately diverse palynomorph assemblage of spores, pollen, and dinoflagellate cysts is identified. Marker dinoflagellate cysts, including Dichadogonyaulax sellwoodii, Escharisphaeridia pocokii, Gonyaulacysta adecta, Korystocysta gochtii, Pareodinia ceratophora, and Wanaea acollaris, defined a Bajocian to Callovian age. Palynofacies analysis of the Khatatba Formation revealed two assemblages, whereby PFA-1 is the most abundant in the study well and is comprised mainly of terrestrial phytoclasts deposited nearby fluvio-deltaic sources. The infrequently reported PFA-2 consists of moderate abundances of phytoclasts and AOM, deposited in an inner shelf environment. A more reliable paleoenvironmental interpretation was indicated based on three palynomorph assemblages. The spore-dominated assemblage indicated deposition in a deltaic environment, while the mixed palynomorph assemblage revealed fluvio-deltaic to marginal shallow marine conditions. The microplankton-dominated assemblage is represented by minor samples and reflects an offshore inner shelf condition. Furthermore, the Middle Jurassic relative sea level was reconstructed based on the quantitative variations in the terrestrial/marine (T:M) ratios and abundances of spores, pollen, and dinoflagellate cysts. This led to the subdivide of the Khatatba Formation into thirteen third-order transgressive-regressive sequences, which can be correlated with the global Jurassic short-term sea level changes. Active tectonics and accelerated drifting of the Eurasian Plate during the Middle Jurassic are suggested to control basin uplift/subsidence and, therefore, recurring patterns of relative sea level change.

Sea level changes and sequence stratigraphy of the Lower-Middle Jurassic Quse and Sewa formations in the Qiangtang Basin, central Tibet: Geochemical and palynological perspectives

ABSTRACT Sequence stratigraphy is a commonly used approach to understand basin-fill history and the occurrence of conventional reservoir and/or probable source rocks. Reconstructing a sequence stratigraphic framework in carbonates, marls, and organic-rich mudstones is challenging due to environmental, petrophysical, and sedimentological variations that can be subtle, whereas seismic data may be lacking or of limited use. For this reason, incorporation between palynological analysis and chemostratigraphic profiles is becoming increasingly common to facilitate sequence stratigraphic reconstruction. This study investigates the Quse (lower Toarcian) and Sewa formations (upper Bajocian-Bathonian) in the Bilong Co section from the Qiangtang Basin of central Tibet. Eighty-three rock samples were analysed for their whole-rock inorganic geochemical composition, of which 25 rock samples were tested for palynological and palynofacies analyses. The palynological composition defined two associations for the study section. The lower part of the Bilong Co section consisted is dominated by a moderate to high abundance of opaque phytoclasts versus low to moderate amorphous organic matter (AOM) content with a high concentration of sphaeromorphs pollen grains, revealing deposition of this interval at times of low relative sea level in fluvio-deltaic settings. The middle to upper parts of the section comprised of significantly high AOM content versus low phytoclasts and high content of sphaeromorphs pollen grains, but with increasing the relative abundance of dinoflagellate cysts, indicating a phase of high sea level. Chemostratigraphic variations relevant to changes in relative sea level delineated the subdivision of the Quse and Sewa formations into two and three third-order transgressive-regressive sequences, respectively. The collision between the Lhasa and Qiangtang blocks during the Early-Middle Jurassic is suggested to control consequent subduction and sea level highstand, especially during deposition of the Sewa Formation. Geochemical proxies that relate to shelf carbonate production are calcium, strontium, whereas proxies that relate to siliciclastics include titanium, zirconium, manganese, aluminium, and silicon, other redox-sensitive proxy like uranium is also implemented. This indicates that chemostratigraphic proxies are a promising tool for the interpretation of sea level cyclicity in terms of systems tracts and bounding surfaces.

The abundance and species assemblages of dinoflagellate cysts at sediments in the three estuaries of the Southern part of South Sulawesi

Harmful algal blooms (HAB) are a phenomenon of drastically increasing phytoplankton populations, which can cause problems in aquatic ecosystems. Dinoflagellate cysts are a type of phytoplankton that are the main source of causing the HAB phenomenon; this occurs due to unfavorable environmental conditions. The Southern Estuary of South Sulawesi has high fishery resources and high primary productivity. The coastal areas around these waters are widely used for anthropogenic activities that trigger nutrient increases. There are no studies on HAB, especially the abundance and community structure of dinoflagellate cysts at this location. This study aims to identify the types, abundance, and species assemblages of dinoflagellate cysts in the three estuaries of southern South Sulawesi. Sampling was carried out at three locations, namely the Pappa River Estuary, the Kelara River Estuary, and the Calendu River Estuary, in January 2022. Each location consists of 4 stations, 3 sub-stations with 3 repetitions sampling for each substation. Results showed that there were 34 species of dinoflagellate cysts belonging to 6 families, namely Gonyaulacaceae, Gymnodiniaceae, Osteropsidaceae, Peridiniaceae, Polykrikaceae, and Protoperidiaceae. The highest abundance of dinoflagellate cysts was at the Calendu River estuary station III, accounting for 82 cysts g−1, while the lowest abundance of dinoflagellate cysts was found at Pappa River estuaries stations I and II, accounting for 8 cysts g−1. The level of diversity, uniformity, and richness of dinoflagellate cysts was not significantly different in the three study sites. The family Osteropsidaceae was the most common type of dinoflagellate cyst found in the three study sites. The Osteropsidaceae family is a type of dinoflagellate cyst that contains toxins, so it can be assumed that the three research sites have the potential for HAB.

Mobility of trace metals and microbiological pollution from dredged sediments to the Gulf of Gabes, Tunisia.

Sediments are periodically dredged from the major ports in the Gulf of Gabes (GG) during maintenance operations. These sediments are dumped near the coats of Sfax and Gabes cities. In the present study, 6 trace metals (Cd, Cu, Cr, Ni, Pb, and Zn) concentrations were assessed in both sediments and column water taken from the different basins of Sfax port. This study is the first to focus on the microbial and microalgae contaminations of Sfax port sediments. The spatial distributions of trace metals in dredged sediments from the different basins of Sfax port show that the maximum concentrations of Cd (13.75µg/g), Cu (892.5µg/g), and Zn (1447µg/g) exceeded the Geode standard thresholds. The same elements, also detected in the water column, exceeded the toxicity thresholds for phytoplankton, shellfish, and algae (Cd 0.095µg/l, Cu 4.52µg/l, and Zn 37µg/l). The presence of coliforms, indicators of sewage pollution, as pathogenic germs (Pseudomonas), was shown through microbiological examinations of the sediments and water column. The microalgae enumeration showed the abundance of dinoflagellate cysts (stressed form) which attests to the presence of severe conditions in Sfax port. Different toxic species were identified as Prorocentrum lima and Alexandrium minutum. The same trace metal sources and abundance in Sfax port and GG sediments suggest the hypothesis of their transfer from their disposal sites in coastal areas to deeper depths in the GG and until Boughrara lagoon (BL). As trace metals, microalgae species were also transferred by hydrodynamic currents inside the GG where they found suitable conditions to their proliferation causing the seawater coloration phenomenon, eutrophication, and degradation of the aquatic system.

Assemblages of dinoflagellate resistance cysts and copepod eggs in superficial sediments at the upper Gulf of California

The diversity, abundance, and geographic distribution of dinoflagellate cysts in recent sediments serve as bioindicators to specific regions' environmental conditions and productivity. We present dinoflagellate cysts assemblages from 53 superficial sediment samples from the upper Gulf of California (uGC) obtained in July 2016 and February 2017. Forty-seven species were identified, of which twenty-seven are considered heterotrophic (Het) and twenty autotrophic (Aut). Ten species of this last group are potentially toxin producers (PTxS). The total concentration (Tot) of cysts in all the samples was 3481 cysts/g in 2016 and 4223 cysts/g in 2017. Aut represented 59%, Het 41%, while the PTxS represented ∼36.5% of the Tot cysts. The higher abundance of the Aut is likely to manifest the local high sea surface temperature and salinity. The increase in the Tot of cysts in the 2017 set was related to a Gymnodinium catenatum harmful algal bloom. Copepod eggs abundance was 7137 eggs/g in 2016 and 6555 eggs/g in 2017. The Aut Gymnodinium spp., Spiniferites spp., Operculodinium spp, and the Het Protoperidinium americanum, Quinquecuspis concreta, Selenopemphix nephroides, Brigantedinium spp., and Echinidinium spp., were typical in both seasons but differed on their concentrations between each season. The cysts distribution between both sampling periods reflects local currents and the sediment dynamics of the uGC, and the high species diversity in this area reflects the elevated primary productivity in this area.

Modern Dinoflagellate Cyst Abundance and Trace Metals as Biomonitoring Tools in a Tropical Bay in Brazil

Freitas, A.S.; Aguiar, V.M.C., and Baptista Neto, J.A., 2021. Modern dinoflagellate cyst abundance and trace metals as biomonitoring tools in a tropical bay in Brazil. Journal of Coastal Research, 37(6), 1247–1259. Coconut Creek (Florida), ISSN 0749-0208. The spatial distribution of the dinoflagellate cyst assemblages in 11 surface sediment samples collected in Guanabara Bay embayments and associated trace metals revealed the applicability of dinocysts as bioindicators of environmental conditions in estuarine systems. The surface sediment samples presented coarse to fine granulometry. The dinoflagellate cyst analysis followed the standard methodology through the elimination of carbonates and silica. Trace metals were extracted by the evaluation of 1 g of sediment plus a mixture of HNO3 and HCl in a microwave digestion system. Dinoflagellate cyst assemblages were dominated by Operculodinium centrocarpum, Spiniferites spp., and Lingulodinium machaerophorum. Trace metals (Cu, Zn, Pb, Cr, and Ni) showed variations at the different sampling points. The values obtained were Cu (6.7–82.8 mg kg–1), Zn (29.5–355.4 mg kg–1), Pb (18.3–86.2 mg kg–1), Cr (5.1–196.2 mg kg–1), and Ni (19.6–286.0 mg kg–1). Several samples showed high pseudototal concentrations of trace metals, which were above the natural concentrations found in nature. Statistical analysis showed a strong correlation between dinocysts species and some trace metals. Lingulodinium machaerophorum showed a high correlation with 4/5 analysed trace metals and is a eutrophication-sensitive species. However, Brigantedinium sp. presented a positive correlation with all trace metals analysed. The high frequency of L. machaerophorum cysts in all analysed samples associated with several trace metals is indicative of environmental eutrophication. The high availability of trace metals in the surface sediments of Guanabara Bay may be related to the untreated industrial wastes that are dumped directly into the bay.

Pattern and germination rate of dinoflagellate cyst from three river estuaries (Jeneberang, Maros and Pangkep Estuary) of Makassar Strait

The research objective was to determine the rate and germination pattern of dinoflagellates from three estuaries (Jeneberang, Maros and Pangkep Estuary) of the Makassar Strait. The germination rate of dinoflagellate cysts from three estuaries of the Makassar Strait was studied at room temperature (28°C) and at light: dark conditions 12:12 hours. Sediment samples were taken from three estuaries and treated for isolation of dinoflagellate cysts. The isolated dinoflagellate cysts were then incubated on 12 wells plates using f/2 medium for 28 days. The parameters measured in this study were the rate and pattern of germination measured every third day. The results showed that the germination rate of dinoflagellate cysts from Jeneberang Estaury was higher than other estuaries (Maros and Pangkep Estuary) for all stations. However, there was no significant difference in the germination rate between stations for all estuaries, except for the germination rate of Pangkep Estuary, there was a significant difference between station I and station IV. The germination pattern during the incubation period for all estuaries varied, however the abundance of dinoflagellate cysts from the Jeneberang estuary tended to increase with the incubation period. In conclusion, dinoflagellate cysts from Jeneberang Estuary had a higher germination rate and showed increased abundance during the incubation period.

The distribution of dinoflagellate cyst assemblages in recent sediments of the Oualidia Lagoon, Morocco, with a focus on toxic species

Harmful algal blooms (HABs) are becoming widely distributed and more frequent, threatening socioecosystems and human health. We determined species composition, abundance and spatial distribution of dinoflagellate cysts in the upper sediment of the Oualidia Lagoon located on the Atlantic coast of Morocco. Sediment samples were collected in 2017 at 51 stations, and environmental parameters were measured together with microphytoplankton abundance. Sediment characteristics including water percentage, organic matter content and grain size were determined. Fourteen dinoflagellate cyst morphotypes were identified, with Lingulodinium polyedrum (50%) and Gonyaulax spinifera (22%) dominating the assemblages. Total cyst densities ranged from 0 to 293 cysts g−1 dry sediment. Cyst densities were positively correlated with water content and organic matter content and increased with decreasing sediment grain size. We revealed the presence of three neurotoxic dinoflagellate species: Alexandrium minutum, the Alexandrium tamarense species complex, and Gymnodinium catenatum. Numerous cysts had accumulated in the sediment, and, because they are likely responsible for the initiation of HABs in Oualidia Lagoon, they should be monitored.

Qualitative and Quantitative Study of Dinoflagellate Cysts in Surface Sediments of the Nador Lagoon (North-East Morocco)

The qualitative and quantitative study of dinoflagellates (cysts and vegetative forms) was carried out on samples of surface sediment and water of the Nador lagoon (North-East Morocco), collected during winter in February 2019. Therefore, it was necessary to undertake a qualitative and quantitative study on dinoflagellate cysts and vegetative forms in parallel with the aim of specifying the factors that control the concentration of cysts in the sediments, as well as their specific diversities and blooms. Notably, dinoflagellates are of undeniable ecological interest and are considered as sentinel species of the quantity of water because they respond quickly to environmental changes due to their very fast life cycle. Moreover, their cysts, due to their extreme resistance and abundance in sediments, constitute an extremely important tool in the evaluation of current environments. Results showed that the total abundances of dinoflagellate cysts vary between a concentration of 720 cysts/g dry sediments (DS) and 7215 cysts/g DS. This work was mainly conducted to study the abiotic parameters of the Nador lagoon that control the concentration of cysts in the sediments and address their specific diversity and the dominance of one group over the other.

Dinoflagellate cysts in surface sediments at Van Phong Bay, Khanh Hoa Province, Vietnam: distribution, abundance and potentially harmful algal blooms

Studies on dinoflagellate cysts provide important knowledge on the ecology of dinoflagellates and harmful algal blooms (HABs). In this study, distribution and abundance of dinoflagellate cysts in surface sediments from 17 stations at Van Phong Bay were analyzed. There were 55 different types of cysts representing 3 orders and 18 genera, and 8 unidentified cyst types recorded. Peridiniales was the most diverse order with 29 cyst types, including 20 Protoperidinium cyst types. There were 10 cyst types of 7 potential toxic dinoflagellate species and 4 of bloom forming species found, indicating a potential risk of harmful algal blooms in Van Phong Bay. Number of cyst types and density ranged from 12 to 31 types and from 115 to 3,760 per gram of dry weight sediment, respectively. Cysts of Leonella granifera were dominant at stations in the mouth of the Bay, while Scrippsiella trochoidea cysts dominated at all stations. Shannon diversity index (H') was low, varying from 1.192.72. There were two distinct cyst assemblages identified with 40% Bray-Curtis similarity, assemblage I with 2 stations (VP09 and VP10), and assemblage II with the other stations.

Eutrophication Driven by Aquaculture Fish Farms Controls Phytoplankton and Dinoflagellate Cyst Abundance in the Southern Coastal Waters of Korea

We examined the dynamics of dinoflagellate cyst and phytoplankton assemblages in eutrophic coastal waters of Korea, adjacent to fish and shellfish farms. Water temperature showed seasonality, whereas salinity and pH remained relatively consistent. Dissolved inorganic nutrient levels were higher in September and at the inner stations, where aquaculture fish farms are located than those in May and at the outer stations. Canonical correspondence analysis and artificial neural network analysis revealed multiple environmental factors that affect the distribution of phytoplankton and dinoflagellate cysts. Diatoms dominated in the phytoplankton assemblages, while the protoperidinioid group dominated in the dinoflagellate cyst assemblages. Cyst abundance was higher at the outer stations than at the inner stations due to transport by fast currents, and phytoplankton abundance was positively correlated with cyst abundance. An increase in diatom abundance led to an increase in heterotrophic/mixotrophic cyst abundance, indicating that excessive uneaten food and urinary waste from the fish farms caused eutrophication in the study region and fast growth of diatoms, thereby contributing to the growth of heterotrophic/mixotrophic dinoflagellates and consequently, high abundance of heterotrophic/mixotrophic dinoflagellate cysts.

Dinoflagellate cyst assemblages in surface sediment from Jakarta Bay

Dinoflagellate cysts play an essential role in the initiation, recurrence and geographical expansion of harmful algal blooms (HABs). The horizontal distribution and abundance of dinoflagellate cysts in marine sediments provide essential information in giving early warnings of the presence of toxic species and possible continuing recurrence of HABs in a given area. This research carried out in the waters of Jakarta Bay. Sediment samples collected from thirteen sampling stations using TFO gravity corer 2.1 cm diameter from sediment thickness 0-4 cm. The results showed that resting cysts belong to Gonyaulax, Alexandrium, Scrippsiella, Protoperidinium, Gymnodinium, Gyrodinium. Two of them, namely Gymnodinium sp and Alexandrium sp, known as toxic species. Cysts in the sediment thickness 0-4 cm mainly dominated by the group of Gonyaulax (Gonyaulacoid). Cyst abundance in the sediment depth-layer 0-2 cm is higher than in depth-layer 2-4 cm. The number of dino-cysts in sediment layer 0-2 cm ranged from 2.984 – 22.298 cysts cm−3 while in the layer 2-4 cm the amount varies from 1.063 – 8.132 cysts cm−3 of wet sediment. The result revealed that dino-cyst abundance is higher in the deposit collected from locations near to the coast. The assemblages of dinoflagellate resting cysts seemed to have a relation with some hydrological parameters.

Species Assemblages and Distribution of Dinoflagellate Cysts from three Estuaries Sediment’s of Makassar Strait, Eastern Indonesia

Makassar Strait encompasses high fisheries resources and high biodiversity and primary productivity. Algae blooms often occur in these areas, but there is a lack of studies that have been carried out on HABs in these locations specifically determining the collection and abundance of dinocyst. The study aimed to determine species assemblages of dinoflagellate cysts from three estuaries of Makassar Strait. Sampling was conducted at three locations, i.e., Jeneberang, Maros and Pangkep Estuaries during July 2020. Each location of sampling consisted of 4 stations and 3 substations as a sampling replication. Variables that were measured in this study were dinoflagellate cysts abundance species assemblages and distribution. Results showed that there was no clear group of dinoflagellate cysts assemblages between locations, however dinoflagellate cyst assemblages from Jeneberang Estuary was significantly grouped. We recorded 48 dinoflagellate cysts species that belonged to 5 families, namely Goniodomaceae, Gonyaulacaceae, Gymnodiniacea, Peridiniaceae and Protoperidiniaceae. The dominant species of dinoflagellate cysts from Jeneberang Estuary was Scrippsiella crystallina, meanwhile the dominant dinoflagellate cyst from Maros and Pangkep Estuary was Gonyaulax verior and Pentapharsodinium tyrrhenicum, respectively. Scrippsiella trifida was a dinoflagellate cysts species was contributed to the dissimilarity of cyst assemblages between locations. We also found potential five toxic dinoflagellate cyst species. In conclusion, the dinoflagellate cysts species composition, diversity, species richness and cyst abundance was not significant difference between stations of all locations. The abundance of dinoflagellate cysts was significantly correlated by sediment grain size. All sampling sites has a potentially occurred of HABs due to the five potential cysts toxic and harmful species discovered.

Pollen-spore assemblages of the Navarro Group (Maastrichtian) of Texas, USA: biostratigraphical and palaeoecological significance

Diverse assemblages of spore–pollen floras are present in all formations in the Navarro Group (Maastrichtian) in outcrops of the Austin Section and the subsurface Frio Section. The stratigraphic ranges and relative abundance of spore, pollen, dinoflagellate cysts and acritarchs were used to establish four biozones (A, B, C and D). Biozone A corresponds to the undifferentiated Neylandville Marl–Nacatoch Sand Formation; Biozone B corresponds to the Corsicana Marl Formation; Biozone C corresponds to the lower half of the Kemp Clay Formation; and Biozone D corresponds to the upper half of the Kemp Clay Formation. Biozonal boundaries do not always correspond to formation boundaries. Biozones A, B, C and D of the Austin section are correlated with the subsurface Frio section. The zonal boundaries based on spore–pollen distribution in the Austin and the Frio sections correlate well with the timelines established in these two sections based on dinoflagellate cysts and acritarchs. All Navarro Group formations except the Olmos were deposited in marine environments ranging from intertidal to outer shelf. Olmos Formation sediments were deposited in a range of coastal terrestrial environments with occasional minor influences of the sea. Three transgressive phases (T1, T2 and T3) separated by four regressive phases (R1, R2, R3 and R4) are recognized. During the Maastrichtian the floral composition in Texas changed from predominantly pteridophytic and bryophytic in the early Maastrichtian to predominantly angiospermous flora in the middle and late Maastrichtian. Tropical to subtropical climates prevailed in Texas throughout the Maastrichtian but highland regions such as Llano Uplift and nearby Marathon and Arbuckle Mountains were cooler regions with a temperate to sub–temperate climate. The upper part of the Navarro Group records a gradual cooling trend suggested by the dominance of temperate angiosperm pollen taxa.

Total organic carbon and pyrolysis analysis of the Lower Cretaceous in Compton Bay and Atherfield, Isle of Wight (England)

The Wessex Basin (United Kingdom) includes hundreds of meters of Lower Cretaceous clays, silts, and sands deposited in a wide range of depositional environments. Studies have investigated these depositional systems from the organic matter (OM) perspective. However, questions remain concerning the composition, source, and the overall depositional constraints on the distribution of sedimentary OM in this area. Elemental (carbonate % and total organic carbon - TOC) and pyrolysis analyses were conducted on representative lithofacies of the Lower Cretaceous from the Wessex Basin at the Compton Bay and Atherfield sections, Isle of Wight. The highest TOC contents were determined in the upper part of the Ferruginous Sands and Sandrock formations. These elevated TOC intervals are associated with predominantly estuarine deposition. Except for one sample from the Vectis Formation, Hydrogen Index (HI) in all studied units is low and indicates Type IV kerogen assemblages, interpreted to be linked with strongly variable climates (with pronounced dry periods) and significant water table fluctuations in the source area and during transport. The one sample with a Type II-III kerogen assemblage from the lagoonal Vectis Formation supports previous studies which suggested that OM in the Vectis Formation varied vertically as a function of fluvial sediment and terrestrial organic matter input to the lagoonal environment with changes in salinity, sediment resuspension, and turbulence as a result controlling the abundance of dinoflagellate cysts.

Changes in foraminiferal assemblages and environmental conditions during the T-OAE (Early Jurassic) in the northern Lusitanian Basin, Portugal

The foraminiferal assemblages and other microfossils from the Rabaçal area (Maria Pares section) in the Lusitanian Basin (Portugal) provide new insights regarding the Toarcian Oceanic Anoxic Event (T-OAE). Complementary analysis of the δ13C, total organic carbon (TOC) and geochemical redox and palaeoproductivity proxies reflect environmental changes that affected the microfossil assemblages. Detailed analyses of foraminiferal assemblages (their diversity, abundance, morphogroups and lifestyle) and geochemistry led us to discern phases of the biotic crisis and subsequent stages of recovery. Environmental instability, which began in the lattermost part of the Polymorphum Zone, is marked by a lesser abundance of foraminifera and ostracods, increased opportunist foraminifera, fluctuations in TOC values and the enrichment factor of phosphorous (PEF), as well as the onset of a negative carbon isotopic excursion (CIE). The peak phase of the biotic crisis corresponds with the lowest values for foraminiferal diversity and abundance (including a barren sample for benthic microfossils). The abundance and diversity of echinoderms, brachiopods, dinoflagellate cysts and calcareous nannofossils dropped sharply during the peak phase. This biotic crisis also entails extinction of the Order Metacopina and a local disappearance of echinoderms and brachiopods. Anoxic conditions at sea bottom did not develop, given the almost continuous record of foraminifera and trace fossils, yet oxygen-depleted conditions occurred. The lower part of the Levisoni Zone contains thin nodular limestones corresponding to a tempestitic–turbiditic facies. In this context, the re-oxygenation of bottom waters was favoured, as indicated by the presence of Thalassinoides and the low values of TOC and redox-sensitive elements (Mo, Ni and U). The survival phase in the wake of the biotic crisis is characterized by greater diversity and abundance of foraminifera and echinoderms (holothuroids and ophiuroids). The lowest δ13C values are recorded during this phase, with a dominance of opportunist (Eoguttulina) and facultative opportunist (Paralingulina tenera) foraminifera. Finally, recovery after the biotic crisis is evidenced by high values for specialists and potentially deep infaunal foraminifera, indicating oxic conditions in the sediment.