Dinoflagellate Cysts as Proxies for Holocene Environmental Change in Estuaries: Diversity, Abundance and Morphology

Ellegaard, Marianne; Dale, Barrie; Mertens, Kenneth Neil; Pospelova, Vera; Ribeiro, Sofia

doi:10.1007/978-94-024-0990-1_12

Cited by 18 publications

(18 citation statements)

References 101 publications

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“…However, in field studies, sexual reproduction often occurs at the termination of dinoflagellate blooms when nutrient concentrations are not limited (e.g. Matsuoka & Takeuchi, 1995;Olli & Anderson, 2002;Kremp et al, 2009;Bravo et al, 2010;Ellegaard et al, 2017;Figueroa et al, 2018). Our observation of maximal cyst production of organic-walled cysts during active upwelling when nutrients are being replenished from deeper water layers indicates that this is also the case in the upwelling off Cape Blanc.…”

Section: Cyst and Shell (Export) Productionmentioning

confidence: 60%

“…Of the organisms in this study, dinoflagellates are a diverse group of unicellular eukaryotes that constitute an important part of the upper marine planktonic biomass (e.g. Ellegaard et al, 2017). They occur both as primary producers and as heterotrophic or mixotrophic grazers on a wide variety of prey consisting of organic debris, bacteria, phytoplankton and other protists (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Export flux succession of dinoflagellate cysts and planktonic foraminifera in an active upwelling cell off Cape Blanc (NW Africa)

Zonneveld

Meilland

Donner

et al. 2021

European Journal of Phycology

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To better understand production, succession, excystment and transport of dinoflagellate cysts (dinocysts) and planktonic foraminifera in the upper water column, we investigated their fluxes during a 7-day survey in the active upwelling off Cape Blanc (NW Africa) in November 2018 with drifting traps at 100 m, 200 m and 400 m water depth. The survey covered a change from active upwelling to stratified conditions. Highest production of organic dinocysts and planktonic foraminifera was observed during active upwelling conditions and decreased drastically towards the end of the survey. Calcareous dinocysts appeared later during upwelling relaxation. Cytoplasm-bearing (full) dinocysts and foraminifera were produced in the water column above the traps (<100 m depth). Some of the empty dinocysts were resuspended, implying that sediments below the survey site contain both local and allochthonous cyst assemblages. This is the first demonstration that excystment in the upper water column is species-specific. Brigantedinium excysted in the upper water column before reaching deeper depths, whereas no upper water column excystment was observed for the other dinoflagellate species.Dinoflagellate and planktonic foraminifera associations showed a clear succession. During active upwelling, Echinidinium zonneveldiae, Brigantedinium spp., other peridinioids, Echinidinium spp., cysts of Pentapharsodinium dalei, 'other photosynthetic organic-walled dinocysts', Neogloboquadrina incompta and Globigerinella calida were collected. During upwelling relaxation, Lingulodinium machaerophorum was produced; and under stratified conditions Gymnodiniaceae cysts (G. microreticulatum, G. catenatum) and the foraminifera Globigerina bulloides and Orbulina universa were sampled. Apart from enhancing knowledge of these species, our observations allow more detailed reconstructions of upwelling history in the Cape Blanc region based on sedimentary archives using fossilized dinoflagellate and planktonic foraminifera assemblages.

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Section: Cyst and Shell (Export) Productionmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Export flux succession of dinoflagellate cysts and planktonic foraminifera in an active upwelling cell off Cape Blanc (NW Africa)

Zonneveld

Meilland

Donner

et al. 2021

European Journal of Phycology

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“…A relationship between cyst morphology and the genetics of the motile form cannot simply be assumed without availability of cyst-theca studies and genetic analyses . This is because environmental factors also have a significant effect on cyst formation (Ellegaard et al, 2017). It is also not satisfactory to assume that one variable may be entirely responsible for driving species diversity.…”

Section: Discussionmentioning

confidence: 99%

Where should we draw the lines between dinocyst “species”? Morphological continua in Black Sea dinocysts

Hoyle

Sala-Pérez

Sangiorgi

2019

J. Micropalaeontol.

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Abstract. The morphology of dinoflagellate cysts (dinocysts) is related not only to the genetics of the motile dinoflagellate from which it derives, but is also dependent on a range of environmental factors including salinity, temperature and nutrient status. Although this knowledge improves our understanding of the drivers behind dinocyst morphological variations, it makes the taxonomy governing their description somewhat complex. In basins such as the Black Sea, where environmental change can be extreme and occurs on relatively short (millennial) timescales, taxonomy becomes particularly challenging. Morphological continua can be observed between described forms, displaying a large range of intermediate phenotypes that do not necessarily correspond to any genetic difference. As these morphological nuances may preserve information about palaeoenvironments, it is important to find a systematic method of characterising morphotypes. Here, we show a dinocyst matrix within which dinocysts are described according to their similarity to (or difference from) described forms based on key descriptive parameters. In the example set out here, cyst shape and degree of process and/or ectophragm development are taken as two key parameters in Pyxidinopsis psilata and Spiniferites cruciformis, and can allow the description of intermediate forms even though the definitions do not overlap. We review some frequently occurring morphotypes and propose that using matrices to show the gradual variation between endmember forms is the most pragmatic approach until cyst–theca studies and genetic sequencing can be used to demonstrate relationships between genotypes and morphotypes. As prior studies propose salinity to be a primary driver of intraspecific variability, the endmembers presented may represent salinity extremes within an overall brackish environment. Although we cannot assign each morphotype to a value or a range of an environmental parameter (e.g. salinity) as the different morphotypes can occur in the same sample, using this matrix allows preservation of information about morphological variability without creating taxonomic categories that are likely to require alteration if genetic evidence becomes available.

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“…Given their capacity to fossilize, dinoflagellate cyst records from sediment cores are broadly used as a proxy to infer past environmental conditions (see Ellegaard et al, 2017 for a review). Stratigraphic cyst records, and more recently ancient DNA (De Schepper et al, 2019), represent a very valuable tool to study past biodiversity and reconstruct past marine ecosystems.…”

Section: Introductionmentioning

confidence: 99%

“…However, interpretations of the cyst record can be biased by several factors related to the variable representation of the planktonic populations in the sediments. Importantly, post-depositional processes such as sediment reworking, horizontal transport and selective degradation of cysts (e.g., Zonneveld and Brummer, 2000;Zonneveld et al, 2018) can complicate the interpretation of the environmental signals (Ellegaard et al, 2017). Moreover, when inferring palaeoenvironmental data from cyst records we must consider that (1) not all dinoflagellate species produce resting cysts -i.e., they will not be represented in the cyst records -and (2) cyst productivity rates can vary between species -meaning some species can be over-or underrepresented in the sediment cyst record.…”

Section: Introductionmentioning

confidence: 99%

Environmental Factors Affecting Spatial Dinoflagellate Cyst Distribution in Surface Sediments Off Aveiro-Figueira da Foz (Atlantic Iberian Margin)

et al. 2021

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Resting cysts of planktonic dinoflagellates, once produced, sink to the seabed where they can remain viable for a long time. These cysts have important ecological roles, such as acting as the inoculum for the development of planktonic populations. Moreover, dinoflagellate cyst records from depth sediment cores are broadly used as a proxy to infer past environmental conditions. In this study, the main objective was to obtain information on the relationships between the spatial distribution of modern dinoflagellate cysts and present-day hydrography in the NW Iberian shelf. Cyst assemblages were analyzed in 51 surface sediment samples with varying grain sizes, collected at different water depths, following nine transects perpendicular to the coast, between Aveiro and Figueira da Foz (Atlantic Iberian margin). Multivariate statistical analyses revealed marked land-sea and latitudinal gradients in the distribution of cysts, and helped investigate how environmental factors [water depth, grain size, sea-surface temperature (SST), sea-surface salinity (SSS), bottom temperature (BTT) and surface chlorophyll-a concentration (CHL)] influence modern dinoflagellate cyst composition and abundances. Three main ecological signals were identified in the modern dinoflagellate cyst assemblages: (1) the heterotroph signal as the main upwelling signal; (2) the dominance of P. reticulatum and L. polyedra signal, indicative of warm stratified conditions, possibly reflecting transitional environments between more active inshore upwelling and warmer offshore waters; and (3) the G. catenatum signal for the presence of mid-shelf upwelling fronts. The almost absence of viable cysts of the toxic and potentially toxic species G. catenatum L. polyedra and P. reticulatum suggests that in the study area, for these species, there is no build-up of significant cyst beds and thus planktonic populations must depend on other seeding processes. These results are the first detailed modern distribution of dinoflagellate cysts in the NW Iberian Atlantic margin (off Portugal), and show a good correspondence with hydrographic features of summer upwelling season in the study area, meaning that they are reflecting water column characteristics and therefore may be used as supporting evidence for the interpretation of stratigraphic cyst records and reconstruction of past marine ecosystems in W Iberia.

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Dinoflagellate Cysts as Proxies for Holocene Environmental Change in Estuaries: Diversity, Abundance and Morphology

Cited by 18 publications

References 101 publications

Export flux succession of dinoflagellate cysts and planktonic foraminifera in an active upwelling cell off Cape Blanc (NW Africa)

Export flux succession of dinoflagellate cysts and planktonic foraminifera in an active upwelling cell off Cape Blanc (NW Africa)

Where should we draw the lines between dinocyst “species”? Morphological continua in Black Sea dinocysts

Environmental Factors Affecting Spatial Dinoflagellate Cyst Distribution in Surface Sediments Off Aveiro-Figueira da Foz (Atlantic Iberian Margin)

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