Distribution Of Organic-walled Dinoflagellate Cysts Research Articles

Distribution of organic-walled dinoflagellate cysts in surface sediments of the southern Caribbean and the eastern tropical Pacific and its environmental implications

Little is known about the marine palynology of the neotropical oceans. Here, we present the first comprehensive study of organic-walled dinoflagellate cyst assemblages in 52 surface marine sediment samples from the southern Caribbean (SC) and the eastern tropical Pacific (ETP) and explain how these assemblages relate to sea-surface parameters. Multivariate analyses show that of the several environmental parameters considered, sea-surface salinity (SSS), phosphate concentrations, and nitrate concentrations best explain the relative abundances and the geographic distribution of dinoflagellate cysts in the studied area. Consistent with regional differences in marine productivity, dinoflagellate cyst concentrations were markedly different in the SC (1979 ± 1053 cysts/g) and the ETP (3105 ± 1956 cysts/g). Sediments of the SC are characterized by high relative abundances of the Spiniferites spp. group, cysts of Protoceratium reticulatum, and the presence of rare dinocyst taxa. The dinocyst assemblages from the ETP are characterized by higher relative and absolute abundances of Bitectatodinium spongium, Brigantedinium spp., and Echinidinium aculeatum. This pattern is explained by the more eutrophic nature of the ETP compared to the highly saline and oligotrophic SC. Average values of the Shannon Index (H′) from the ETP are higher compared to the SC, demonstrating that dinocysts respond to the greater climatic variability that characterizes the ETP. Brigantedinium spp. abundances are negatively correlated to H′ diversity supporting its dominant character within the dinocyst community. This work fills a gap in our knowledge on modern dinocyst distribution in neotropical oceans and provides a modern reference for interpreting down core dinocyst variations and paleocenographical reconstructions in the region.

Biogeography of dinoflagellate cysts in northwest Atlantic estuaries.

Few biogeographic studies of dinoflagellate cysts include the near‐shore estuarine environment. We determine the effect of estuary type, biogeography, and water quality on the spatial distribution of organic‐walled dinoflagellate cysts from the Northeast USA (Maine to Delaware) and Canada (Prince Edward Island). A total of 69 surface sediment samples were collected from 27 estuaries, from sites with surface salinities >20. Dinoflagellate cysts were examined microscopically and compared to environmental parameters using multivariate ordination techniques. The spatial distribution of cyst taxa reflects biogeographic provinces established by other marine organisms, with Cape Cod separating the northern Acadian Province from the southern Virginian Province. Species such as Lingulodinium machaerophorum and Polysphaeridinium zoharyi were found almost exclusively in the Virginian Province, while others such as Dubridinium spp. and Islandinium? cezare were more abundant in the Acadian Province. Tidal range, sea surface temperature (SST), and sea surface salinity (SSS) are statistically significant parameters influencing cyst assemblages. Samples from the same type of estuary cluster together in canonical correspondence analysis when the estuaries are within the same biogeographic province. The large geographic extent of this study, encompassing four main estuary types (riverine, lagoon, coastal embayment, and fjord), allowed us to determine that the type of estuary has an important influence on cyst assemblages. Due to greater seasonal variations in SSTs and SSSs in estuaries compared to the open ocean, cyst assemblages show distinct latitudinal trends. The estuarine context is important for understanding present‐day species distribution, the factors controlling them, and to better predict how they may change in the future.

Dinoflagellate cyst distribution in the oligotrophic environments of the Gulf of Aqaba and northern Red Sea

Abstract Oligotrophic environmental systems form a major part of the marine aquatic environments on earth. Compared to mesotrophic and eutrophic environments extremely little information is available about the relationship between the distribution of organic-walled dinoflagellate cysts and physical and biological gradients in the upper water column. Here we present the first comprehensive study of the modern geographic distribution of organic-walled dinoflagellate cysts in the oligotrophic environments of the northern Red Sea and Gulf of Aqaba. We show that sediments of both regions have characteristic dinoflagellate cyst associations consisting of both heterotrophic and phototrophic species of which the latter, including both autotrophic and mixotrophic species, form the major part of the associations in both regions. The upper water environment of the Gulf of Aqaba is characterized by slightly enhanced nutrient concentrations compared to the Red Sea, due to water column mixing in winter. Its phytoplankton composition is dominated by pico- and ultra-plankton and a slight higher amount of eukaryotes compared to northern Red Sea. Its sedimentary cyst associations are characterized by higher relative and absolute abundances of the species Brigantedinium spp., Votadinium calvum, Echinidinium spp., Lingulodinium machaerophorum, Spiniferites spp., Spiniferites bentorii, Spiniferites membranaceus and Spiniferites mirabilis. Sediments of the northern Red Sea are characterized by high relative abundances of Impagidinium aculeatum, Impagidinium sphaericum, Operculodinium israelianum, Operculodinium longispinigerum, Operculodinium centrocarpum, cysts of Pentapharsodinium dalei, and Selenopemphix nephroides. A positive relationship between the distribution of the heterotrophic species Brigantedinium spp., Echinidinium spp. and V. calvum with the occurrence of other eukaryotic groups such as e.g. diatoms is documented. The distribution of S. nephroides cannot be related to the presence of diatom occurrences and it is suggested that the distribution of food sources other than diatoms affects its distribution. We document a positive relationship between the sedimentary distribution of the phototrophic dinoflagellate species L. machaerophorum and Spiniferites species and the abundance of the cyanobacteria Synechococcus in the water column. Since Synechococcus is known to be a potential prey of Lingulodinium polyedrum and members of the Gonyaulax spinifera complex (the motile forms producing these cysts) we suggest a possible cyst distribution–prey relationship of mixotrophic dinoflagellates.

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.

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.

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.

Distribution of organic-walled dinoflagellate cysts in shelf surface sediments of the Benguela upwelling system in relationship to environmental conditions

To obtain insight in the relationship between the spatial distribution of organic-walled dinoflagellate cysts (dinocysts) and local environmental conditions, fifty-eight surface sediment samples from the coastal shelf off SW Africa were investigated on their dinocyst content with special focus on the two main river systems and the active upwelling that characterise this region. To avoid possible overprint by species-selective preservation, samples have been selected mainly from shelf sites where high sedimentation rates and/or low bottom water oxygen concentrations prevail. Multivariate ordination analyses have been carried out to investigate the relationship between the distribution patterns of individual species to environmental parameters of the upper water column and sediment transport processes. The main oceanographical variables at the surface (temperature, salinity, nutrients chlorophyll- a) in the region show onshore–offshore gradients. This pattern is reflected in the dinocyst associations with high relative abundances of heterotrophic dinocyst species in neritic regions characterised by high chlorophyll- aand low salinity conditions in surface waters. Phototrophic dinocyst species, notably Operculodinium centrocarpum, dominate in the more oceanic area. Differences in the distribution of phototrophic dinocyst species can be related to sea surface salinity and sea surface temperature gradients and to a lesser extent to chlorophyll- a concentrations. Apart from longitudinal gradients the dinocyst distribution clearly reflects regional environmental features. Six groups of species can be distinguished, characteristic for (1) coastal regions (cysts of Polykrikos kofoidii and Selenopemphix quanta), (2) the vicinity of active upwelling ( Brigantedinium spp., Echinidinium aculeatum, Echinidinium spp. and Echinidinium transparantum), (3) river mouths ( Lejeunecysta oliva, cysts of Protoperidinium americanum, Selenopemphix nephroides and Votadinium calvum), (4) slope and open ocean sediments ( Dalella chathamense, Impagidinium patulum and Operculodinium centrocarpum, (5) the southern Benguela region (south of 24°S) ( Spiniferites ramosus) and (6) the northern Benguela region (north of 24°S) ( Nematosphaeropsis labyrinthus and Pyxidinopsis reticulata). No indication of overprint of the palaeo-ecological signal by lateral transport of allochthonous species could be observed.

Comparison of the Holocene and Eemian palaeoenvironments in the South Icelandic Basin: dinoflagellate cysts as proxies for the North Atlantic surface circulation

A precise assessment of the hydrological changes in the northern Atlantic Ocean throughout the last climatic cycle stands as one of the key priorities for understanding the mechanisms of global climate change. A high resolution micropalaeontological study of a sediment core (MD95-2015) retrieved from the South Icelandic Basin, allows us to infer patterns of North Atlantic surface hydrological changes during the present (Holocene) and the ultimate (Marine Isotopic Stage 5) Interglacial periods. The downcore distribution of organic-walled dinoflagellate cysts (dinocysts) is used, in conjunction with additional proxies (sediment magnetic susceptibility, CaCO 3, stables isotopes and planktic foraminifer assemblages) to identify climatic instabilities of various amplitudes. These events are mostly characterised by prominent changes in relative abundance of the dinocysts Spiniferites mirabilis and Operculodinium centrocarpum, whose maximum values are thought to trace sea-surface temperature peaks at the core site. Two hypsithermal periods are identified on this basis, between 126 and 120 kyr BP and from 9.2 to 5.7 cal kyr BP (∼8–5 14C kyr BP), respectively. Some discrepancies between the micropalaeontological tracers used are discussed here in the light of their qualitative and quantitative (transfer functions) ecological interpretation.

Distribution of organic-walled dinoflagellate cysts in surface sediments of the Southern Ocean (eastern Atlantic sector) between the Subtropical Front and the Weddell Gyre

Thirty-two surface sediment samples from the Southern Ocean (eastern Atlantic sector), between the Subtropical Front and the Weddell Gyre, were investigated to provide information on the distribution of modern organic-walled dinoflagellate cysts in relation to the oceanic fronts of the Antarctic Circumpolar Current (ACC). A clearly distinguishable distribution pattern was observed in relation to the water masses and fronts of the ACC. The dinoflagellate cysts of species characteristic of open oceanic environments, such as Impagidinium species, are highly abundant around the Subtropical Front, whereas south of this front, cosmopolitan species such as Nematosphaeropsis labyrinthus and the cysts of Protoceratium reticulatum characterise the transition from subtropical to subantarctic surface waters. The subantarctic surface waters are dominated by the cysts of heterotrophic dinoflagellates, such as Protoperidinium spp. and Selenopemphix antarctica. The cysts of Protoperidinium spp. form the dominant part of the assemblages around the Antarctic Polar Front, whereas S. antarctica concentrations increase further to the south. The presence of S. antarctica in sediments of the Maud Rise, a region of seasonal sea-ice cover, reflects its tolerance for low temperatures and sea-ice cover. A previously undescribed species, Cryodinium meridianum gen. nov. sp. nov., has a restricted distribution pattern between the Antarctic Polar Front and the ACC–Weddell Gyre Boundary.

The stratigraphic distribution of organic-walled dinoflagellate cysts in the Cretaceous and Tertiary

All information concerning the stratigraphic distribution of organic-walled dinoflagellate cysts in the Cretaceous and Tertiary sediments of the world, published prior to 1974, has been critically assessed. Stratigraphically reliable records are presented in tabular form; stratigraphical subdivision to stage or formation is incorporated wherever possible. Records of doubtful authenticity are commented on and questions of stratigraphic and taxonomic interest are discussed in the text. A new family, Family Florentiniaceae nov. fam., is erected, and the following new taxonomic combinations are proposed: Astrocysta ampla (Harland, 1973) nov. comb.; Cooksoniella larjakense (Vozzhennikova, 1967) nov. comb.; ? Florentinia truncigera (Deflandre, 1937b) nov. comb.; Phthanoperidinium pannonium (Lentin and Williams, 1973) nov. comb.; Spiniferites scabrosus (Clarke and Verdier, 1967) nov. comb. and Veryhachium hermesinoides (O. Wetzel, 1940) nov. comb., the latter being now considered to be an acritarch. The rejection is proposed of the following species, which were nomenclaturally superfluous when published: Astrocysta koslowskii (Górka 1963) Davey, 1970; Gonyaulacysta fragosa Brideaux, 1971; Hystrichosphaeridium brideauxi Lentin and Williams, 1973; Oligosphaeridium diastema Singh, 1971 and Pseudoceratium regium Singh, 1971. Reasons are given for the rejection of the following generic reallocations: Hystrichodinium voigti (Alberti, 1961) Corradini, 1973 and Tenua anaphrissa (Sarjeant, 1966c) Benedek, 1972. Rhombodinium Gocht, 1955 is considered to be best treated as a subgenus of Wetzeliella Eisenack, 1938 emend. Williams and Downie, 1966b as originally proposed by Alberti, 1961.