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Spiny brown dinoflagellate cysts are commonly used as sea‐ice indicators in the Arctic, but their biological affinities are not well known. We present the first indication of hitherto temperate Protoperidinium tricingulatum in the Arctic based on single‐cell LSU rDNA sequencing from sediments of the Disko Bay‐Vaigat Sound, West Greenland. The morphological similarity of the sequenced cyst morphotype to the sea‐ice indicator Islandinium? cezare morphotype 1 is striking. The morphology of the isolated cysts, as well as those observed in the total cyst assemblage following standard palynological preparation, both resemble either I.? cezare morphotype 1 or P. tricingulatum, suggesting that the specimens may in fact be close morphological variants of the same species. In addition, nine LSU rDNA sequences were obtained from morphological variants assigned to Islandinium minutum s.l.: including both subspecies minutum and subspecies barbatum. The two subspecies could not be differentiated based on partial LSU rDNA sequencing. Overall, Arctic spiny brown dinoflagellate cyst species may be morphologically more diverse and taxonomically more complex than shown earlier and further genetic and morphological studies are needed. Importantly, the value of cysts as palaeoecological indicators depends on a sound understanding of their biological affinity and taxonomy. [ABSTRACT FROM AUTHOR]

The organic matter content of marine sediments is often used to infer past changes in ocean conditions. However, the organic carbon pool preserved in coastal sediments is a complex mixture derived from different sources and may not reflect in situ processes. In this study, we combine taxonomic identification of reworked palynomorphs with pyrolysis organic geochemistry and reflected‐light organic petrographic microscopy to investigate the provenance, composition and preservation of organic matter in a marine sediment core retrieved from the NE Greenland shelf. Our study reveals continuous yet variable input of land‐derived organic carbon to the marine environment throughout the late Younger Dryas–Holocene, with the highest input of inert carbon in the late Younger Dryas. Although the sediments contain some recent marine palynomorphs, there is no other evidence of fresh marine organic carbon. In contrast, our results indicate that these shelf sediments represent a significant sink of recycled organic carbon. The results of pyrolysis geochemistry revealed that ~90% of the total organic carbon in the sediments is inert. The organic petrography analyses revealed that >70–84% of the organic carbon in the sediment core is terrigenous. Reworked dinoflagellate cysts showed a continuous provenance of Cretaceous land‐derived material, most likely from the nearby Clavering Island. Our study points to the importance of constraining the organic matter origin, composition and preservation in marine sediments to achieve more accurate palaeoenvironmental reconstructions based on organic proxies. [ABSTRACT FROM AUTHOR]

Abstract We present a record of dinoflagellate cyst assemblage composition, abundance, and morphology from the central Baltic Sea, spanning the late 19th to the early 21st centuries. Environmental time-series were analyzed in relation to changes in community structure and diversity as inferred from the sediment record, and average summer sea surface salinity (SSS) was reconstructed based on the average process length of Protoceratium reticulatum resting cysts. The reconstructed summer SSS was compared to instrumental data for a critical evaluation of this approach. The most abundant species in this record were P. reticulatum and Biecheleria baltica , and on average ten taxa were identified per sample. The cyst record of B. baltica indicated that although this species has been present in the Gotland Basin at least since the 1880s, its concentrations have increased significantly since the 1980s, possibly linked to eutrophication. Variations in assemblage composition and P. reticulatum cyst morphology reflected patterns of major, instrumentally recorded hydrographic and environmental changes in the Baltic Sea during the past century. The variability in microfossil relative abundances was best explained by the average spring SSS as well as by the average NO 3 concentrations during spring and by the combined effects of average summer SSS and NAO variability. Reconstructed summer SSS and instrumental SSS showed notable differences, depending on the year and function applied for reconstruction. Although roughly reflecting the same patterns, the reconstructed values are offset when compared to instrumental measurements. We put forward suggestions for improvement of the process-length method and recommend using the reconstructed values as an indication of relative changes in past summer sea surface salinity, preferably as part of a multiproxy approach. Highlights • New dinoflagellate cyst record from the Gotland Basin spanning the late 19th century to the early 21st century. • Statistical analysis on the long-term influence of environmental parameters on phytoplankton species. • Average summer sea surface salinity reconstructions based on cyst process-lenght of Protoperidinium reticulatum. • Critical evaluation of the process-lenght method for salinity reconstructions and recommendations for improvement. [ABSTRACT FROM AUTHOR]

Mean body size decreases with increasing temperature in a variety of organisms. This size-temperature relationship has generally been tested through space but rarely through time. We analyzed the sedimentary archive of dinoflagellate cysts in a sediment record taken from the West Greenland shelf and show that mean cell size decreased at both intra- and interspecific scales in a period of relatively warm temperatures, compared with a period of relatively cold temperatures. We further show that intraspecific changes accounted for more than 70% of the change in community mean size, whereas shifts in species composition only accounted for about 30% of the observed change. Literature values on size ranges and midpoints for individual taxa were in several cases not representative for the measured sizes, although changes in community mean size, calculated from literature values, did capture the direction of change. While the results show that intraspecific variation is necessary to accurately estimate the magnitude of change in protist community mean size, it may be possible to investigate general patterns, that is relative size differences, using interspecific-level estimates. [ABSTRACT FROM AUTHOR]

We present the first multi-site study of dinoflagellate cyst records spanning ca. AD 1860-2000 from the west Iberian coast. Our aim was to reconstruct environmental changes in the Western Iberia Upwelling Ecosystem, one of the most biologically productive areas in the world, and an active fishery region. A major shift in cyst assemblages was recorded off the northwestern shelf sector between 1920 and 1950 towards autotrophic dominance, and consisted of a multi-fold increase in total cyst concentrations and cysts of Lingulodinium polyedrum, accompanied by an increase in Protoceratium reticulatum cysts. The observed changes pre-date the industrialization of agriculture in Portugal, and are concomitant with a shift in the North Atlantic Oscillation (NAO) towards negative indices (higher river input) and increasing sea-surface temperatures. The southernmost record, with reduced river- and human influence, showed only minor changes during the 20th century. Here, an increase in Protoperidinioid cysts after the 1980s is related to upwelling intensification. Our study indicates that the main changes recorded in the Western Iberian Upwelling system during the 20th century were driven by regional climate variability (warming, increased water stability and nutrient availability), possibly enhanced by anthropogenic nutrient input from the second half of the century. Our results highlight the complexity of the environmental drivers that may act upon dinoflagellate communities within the same region. The 20th-century environmental change in the Western Iberian Ecosystem has resulted in a shift towards marked autotrophic dominance of dinoflagellate cyst communities, and the northward expansion of species associated with Harmful Algal Blooms. [ABSTRACT FROM AUTHOR]

Protoperidinium species with two anterior intercalary plates were originally classified by Jörgensen in the subgenus Archaeperidinium and assigned to the sections Excentrica, Avellana and Archaeperidinium by Taylor, on the basis of the relative size of anterior intercalary plates and the extent of cingulum displacement. Phylogenetic relationships among these three sections have not been fully explored. Recently, Archaeperidinium was reinstated as a genus, but several species fitting the emended description have not been transferred formally as molecular data were not available. In the present study we examined the cyst-theca relationship of seven species with two anterior intercalary plates: four species assigned to Protoperidinium and three to Archaeperidinium, from the China Sea. Partial large subunit ribosomal DNA sequences were obtained from these seven species by single-cell polymerase chain reaction, and for the cyst of Protoperidinium stellatum from France. Two new species, Archaeperidinium bailongense and Protoperidinium fuzhouense, were described based on both theca and cyst morphology, and the cyst-theca relationships of A. constrictum and P. abei var. rotunda were established for the first time. Maximum-likelihood and Bayesian inference analyses revealed that P. fuzhouense was nested within the Protoperidinium sensu stricto clade despite having only six postcingular plates, and sections Excentrica, Avellana and the genus Archaeperidinium were all monophyletic. Our results suggest that the presence/absence of a sulcal fin and antapical horns and the displacement of the cingulum are the most stable characteristics of the motile stages within the respective clades. [ABSTRACT FROM AUTHOR]

Ribeiro, S., Moros, M., Ellegaard, M. & Kuijpers, A. 2012 (January): Climate variability in West Greenland during the past 1500 years: evidence from a high-resolution marine palynological record from Disko Bay. Boreas, Vol. 41, pp. 68-83. 10.1111/j.1502-3885.2011.00216.x. ISSN 0300-9483. Here we document late-Holocene climate variability in West Greenland as inferred from a marine sediment record from the outer Disko Bay. Organic-walled dinoflagellate cysts and other palynomorphs were used to reconstruct environmental changes in the area through the last c. 1500 years at 30-40 years resolution. Sea ice cover and primary productivity were identified as the two main factors driving dinoflagellate cyst community changes through time. Our data provide evidence for an opposite climate trend in West Greenland relative to the NE Atlantic region from c. AD 500 to 1050. For the same period, sea-surface temperatures in Disko Bay are out-of-phase with Greenland ice-core reconstructed temperatures and marine proxy data from South and East Greenland. This is probably governed by an NAO-type pattern, which results in warmer sea-surface conditions with less extensive sea ice in the area for the later part of the Dark Ages cold period ( c. AD 500 to 750) and cooler conditions with extensive sea ice inferred for the first part of the Medieval Climate Anomaly (MCA) ( c. AD 750 to 1050). After c. AD 1050, the marine climate in Disko Bay becomes in-phase with trends described for the NE Atlantic, reflected in the warmer interval for the remainder of the MCA ( c. AD 1050-1250), followed by cooling towards the onset of the Little Ice Age at c. AD 1400. The inferred scenario of climate deterioration and extensive sea ice is concomitant with the collapse of the Norse Western Settlement in Greenland at c. AD 1350. [ABSTRACT FROM AUTHOR]

We report on the survival and germination of up to a century-old marine protist resting stages naturally preserved in sediments from Koljö Fjord on the west coast of Sweden. This work has focused on germination of dinoflagellate cysts, but diatom resting stages were also observed. We record the longest known survival of dormant dinoflagellate cells. We individually isolated more than 1200 cysts of the three most abundant dinoflagellate taxa: Pentapharsodinium dalei, Lingulodinium polyedrum and Scrippsiella spp. Germination success decreased with core depth, and all successful germinations took place within the first 2 wk of incubation. Pentapharsodinium dalei had the highest germination success rate, with a maximum of up to 80% in 28-yr-old sediment, and could successfully germinate from core sediments dated to 1920 ± 12. Scrippsiella spp. cysts with cell contents occurred down to c. 90-yr-old sediment and could germinate from down to ca. 40-yr-old sediments, with a maximum germination rate of 50-60% in recent sediments. Cysts of L. polyedrum germinated frequently down to 20 yr and rarely to c. 80 yr, with a maximum of 20-50% germination success in recent sediments. Cyst isolation under cooled conditions rather than at room temperature resulted in a significantly higher germination success in P. dalei, while no effect was observed for L. polyedrum. The time elapsed since slicing of the core affected survival of L. polyedrum cysts negatively, most likely due to the effect of oxygen. The long-term survival potential of benthic resting stages that we report here has important implications, as viable resting stages accumulated in bottom sediments can be transported back to the water column by, for example, bioturbation and human-mediated sediment dredging. Hence, the sediment may to a higher degree than previously considered play a role as seed bank. This is important in a changing climate and might have particularly severe impacts in the case of harmful species. [ABSTRACT FROM AUTHOR]

Round brown spiny cysts are common elements of Recent and Quaternary dinoflagellate cyst records and are often used to infer past climate conditions. Echinidinium and Islandinium, two cyst-based genera composed of round brown spiny cysts, are believed to have affinities within the Protoperidiniaceae. However, their biological counterparts are still virtually unknown. In this study, we examined the cyst-theca relationship of an Echinidinium-like cyst isolated from recent sediments of the Portuguese coast. The cysts (25-34 μm) had an intercalary theropylic archeopyle and numerous processes (4-9 μm) with tapered stems and minutely expanded tips. Germinated cells were identified as Protoperidinium minutum on the basis of theca morphology and tabulation. This taxon has a complicated taxonomic history and most likely represents a complex of species with very similar thecae but different cyst morphologies. To provide a first step in elucidating the phylogeny of P. minutum and its evolutionary relationship among the Protoperidiniaceae, we undertook the first molecular study of this taxon on the basis of small-subunit (SSU) and large-subunit (LSU) ribosomal (r)DNA genetic sequences obtained through single-cell polymerase chain reaction. On the basis of SSU rDNA analysis, P. minutum formed a clade together with the Diplopsaloideae, not grouping together with the other Protoperidinium species. LSU rDNA-based phylogenies indicate P. minutum as early divergent within the Protoperidiniaceae. The evolutionary significance of round brown spiny cysts produced by P. minutum-like species and diplopsalids is discussed. [ABSTRACT FROM AUTHOR]

Abstract: A biometrical analysis of the dinoflagellate cyst Lingulodinium machaerophorum [Deflandre, G., Cookson, I.C., 1955. Fossil microplankton from Australia late Mesozoic and Tertiary sediments. Australian journal of Marine and Freshwater Research 6: 242–313.] Wall, 1967 in 144 globally distributed surface sediment samples revealed that the average process length is related to summer salinity and temperature at a water depth of 30 m by the equation (salinity/temperature) = (0.078⁎average process length+0.534) with R 2 =0.69. This relationship can be used to reconstruct palaeosalinities, albeit with caution. The particular ecological window can be associated with known distributions of the corresponding motile stage Lingulodinium polyedrum (Stein) Dodge, 1989. Confocal laser microscopy showed that the average process length is positively related to the average distance between process bases (R 2 =0.78), and negatively related to the number of processes (R 2 =0.65). These results document the existence of two end members in cyst formation: one with many short, densely distributed processes and one with a few, long, widely spaced processes, which can be respectively related to low and high salinity/temperature ratios. Obstruction during formation of the cysts causes anomalous distributions of the processes. From a biological perspective, processes function to facilitate sinking of the cysts through clustering. [Copyright &y& Elsevier]

Abstract: Temporal changes in the community structure of recent dinoflagellate cyst assemblages of Lisbon Bay (Iberian upwelling system) were investigated between 2000 and 2005. The assemblages were diverse and characterized by high inter-annual variability, rather than a clear seasonal pattern. In order to identify the main environmental drivers of community changes, several regional (river runoff, rainfall, upwelling, radiation, daylength) and in situ (sea surface temperature, salinity, bottom and surface chlorophyll a concentration) environmental parameters were tested. Multivariate statistical analysis allowed the identification of water stability as the main environmental gradient influencing the community composition, with river runoff in the preceding rain season and upwelling being the two drivers of stratification and turbulence, respectively. Both these processes can be described as nutrient enrichment processes, but the cyst signal indicates that the two mechanisms select for different functional groups. The main upwelling cyst signal is characterised by the dominance of heterotrophic species (Protoperidinioid species) and presence of the autotrophic chain-forming Gymnodinium catenatum, while the river runoff cyst signal is characterised by dominance of autotrophs forming calcareous cysts, mainly Scrippsiella spp. Lingulodinium polyedrum is suggested to be indicative of upwelling conditions in the region but reflecting an ecological niche different from the more classical heterotrophic assemblage and G. catenatum. Our results reinforce the applicability of dinoflagellate cysts as environmental tracers in the warm-temperate region of the NE Atlantic, and contribute to the development of palaeoenvironmental cyst-based signals. [Copyright &y& Elsevier]

Changes in dinoflagellate cyst forming species composition, abundance and morphology along the surface salinity gradient in the Baltic Sea, Kattegat and Skagerrak were investigated and compared with detailed surface salinity data. A strong positive correlation was found between species diversity and surface salinity ( R 2 = 0.94; n = 7) in the Baltic Sea–Kattegat–Skagerrak system. The most pronounced decrease in dinoflagellate cyst diversity occurred between Kattegat and the Arkona basin, where the surface salinity also steeply declined. Overall, the total cyst abundance decreased along the salinity gradient. However, in the Gotland and particularly in the Northern Central basin cyst concentrations were elevated compared to the surrounding basins and the cyst community was dominated by heterotrophic cyst-producing dinoflagellate species. Possible factors behind this observation are discussed, with increased nutrient supply as the most likely primary cause. In addition, surface salinity was also confirmed to influence process length development of Operculodinium centrocarpum ( R 2 = 0.86; n = 145), which was the most abundant species in this study. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we describe a new species, Archaeperidinium saanichi sp. nov. within the Archaeperidinium minutum Jörgensen 1912 species complex. We examined the morphological variation of the cyst and motile stage by incubation experiments from sediment samples collected in coastal British Columbia (Canada), and compared it to closely related species. The theca of A. saanichi is differentiated from related species by overall size, the asymmetry of the intercalary plates and the right-sulcal plate (S.d.) not touching the cingulum. We provide a key to differentiate all closely related species. A. saanichi can be readily distinguished from A. minutum by a distinctively large cyst with a broad 2a type archeopyle and regularly spaced processes with relatively broad bases and aculeate process tips. Molecular phylogenetic analyses of large and small subunit (LSU and SSU) rDNA sequences demonstrated a close affinity of this species to A. minutum; however, the relatively high level of sequence conservation in dinoflagellate rDNA sequences made these particular markers inadequate for distinguishing one species from the other. Sediment-trap data suggest that A. saanichi has a preference for cooler temperatures and lowered salinities. [Copyright &y& Elsevier]

Abstract: Absolute abundances (concentrations) of dinoflagellate cysts are often determined through the addition of Lycopodium clavatum marker-grains as a spike to a sample before palynological processing. An inter-laboratory calibration exercise was set up in order to test the comparability of results obtained in different laboratories, each using its own preparation method. Each of the 23 laboratories received the same amount of homogenized splits of four Quaternary sediment samples. The samples originate from different localities and consisted of a variety of lithologies. Dinoflagellate cysts were extracted and counted, and relative and absolute abundances were calculated. The relative abundances proved to be fairly reproducible, notwithstanding a need for taxonomic calibration. By contrast, excessive loss of Lycopodium spores during sample preparation resulted in non-reproducibility of absolute abundances. Use of oxidation, KOH, warm acids, acetolysis, mesh sizes larger than 15 µm and long ultrasonication (>1 min) must be avoided to determine reproducible absolute abundances. The results of this work therefore indicate that the dinoflagellate cyst worker should make a choice between using the proposed standard method which circumvents critical steps, adding Lycopodium tablets at the end of the preparation and using an alternative method. [Copyright &y& Elsevier]

The accelerating sea-ice, ice sheet and glacial melt associated with climate warming have resulted in important changes in the Arctic region over the past decades. In northern Baffin Bay, the formation of the North Open Water (NOW) polynya, which is intrinsically linked to regional sea-ice conditions and ocean circulation, has become more variable in recent years. To understand how climate-driven changes affect sea-surface conditions in the polynya, we analyzed dinoflagellate cyst assemblages from a sediment core record that covers the past ca. 3800 years, and developed an index based on the locations of modern analogues from a large regional reference dataset. Our results suggest a prolonged open-water season characterized by higher summer sea-surface salinity and temperature between ca. 3800 to 2500 years BP, followed by gradual cooling, freshening and increased sea-ice influence from 2500 to 1500 years BP, and continued sea-surface cooling with a shorter open-water season from 1500 to 156 years BP. The modern warming translates into a rapid turnover in the composition of dinoflagellate cyst assemblages during the last 50 years of our record, unprecedented for at least the past 3800 years studied here. For the uppermost part of our core (ca. 2009 to 2015 CE), the dinoflagellate cyst assemblages suggest increased stratification and sea-surface freshening resulting from increased glacial runoff and Arctic sea-ice export into the NOW region. Arctic climate projections indicate accelerated sea-ice thinning and ice sheet melt in the future, pointing to a shorter polynya season and increased polar inflows leading to fundamental changes within the NOW polynya into future years. • Long-term subdecadal to multidecadal record of summer sea-surface conditions using dinoflagellate cysts in the North Water Polynya. • Development of an index based on the locations of modern assemblage analogues to assess changes to polynya dynamics. • Sea-surface cooling and freshening from ca. 2200 years to 156 years BP. • Late Holocene record shows no comparable analogue to the last ca. 50 years. [ABSTRACT FROM AUTHOR]