Publication Date:
2024-02-02
Description:
In contrast to the wide range of studies carried out in temperate and high-latitude oceanic regions, only a few studies have focused on recent and Holocene organic-walled dinoflagellate cyst assemblages from the tropics. This information is, however, essential for fully understanding the ability of species to adapt to different oceanographic regimes, and ultimately their potential application to local and regional palaeoenvironmental and palaeoceanographic reconstructions. Surface sediment samples of the western equatorial Atlantic Ocean north of Brazil, an area greatly influenced by Amazon River discharge waters, were therefore analysed in detail for their organic-walled dinoflagellate cyst content. A diverse association of 43 taxa was identified, and large differences in cyst distribution were observed. The cyst thanatocoenosis in bottom sediments reflects the seasonal advection of Amazon River discharge water through the Guyana Current and the North Equatorial Countercurrent well into the North Atlantic. To establish potential links between cyst distribution and the environmental conditions of the upper water column, distribution patterns were compared with mean temperature, salinity, density and stratification gradients within the upper water column (0–100 m) over different times of the year, using correspondence analysis and canonical correspondence analysis. The analyses show that differences in these parameters only play a subordinate role in determining species distribution. Instead, nutrient availability, or related factors, dominates the distribution pattern. The only possible indicators of slightly reduced salinities are Trinovantedinium applanatum and Lingulodinium machaerophorum. Four assemblage groups of cyst taxa with similar environmental affinities related to specific water masses/currents can be distinguished and have potential for palaeoenvironmental reconstruction.
Keywords:
Amazon Fan; Amazon Shelf/Fan; Atlantic Caribbean Margin; Bitectatodinium spongium; Brazil Basin; Brigantedinium; Brigantedinium cariacoense; Ceara Rise; Continental slope off Brazil; Counting, dinoflagellate cysts; Dalella chathamensis; DEPTH, sediment/rock; Dinoflagellate cyst indeterminata; Diplopelta symmetrica; Echinidinium aculeatum; Echinidinium delicatum; Echinidinium granulatum; Echinidinium spp.; Echinidinium transparantum; Elevation of event; Equatorial Atlantic; Event label; GeoB; GeoB3809-1; GeoB3810-2; GeoB3812-2; GeoB3822-1; GeoB3825-1; GeoB3826-2; GeoB3827-1; GeoB3906-9; GeoB3908-11; GeoB3909-1; GeoB3910-3; GeoB3911-1; GeoB3912-2; GeoB3913-2; GeoB3914-3; GeoB3916-1; GeoB3918-1; GeoB3925-2; GeoB3935-1; GeoB3936-2; GeoB3937-1; GeoB3938-2; GeoB3939-1; GeoB4306-1; GeoB4311-1; GeoB4319-11; GeoB4401-3; GeoB4404-2; GeoB4408-3; GeoB4412-3; GeoB4417-5; GeoB4418-2; GeoB4423-3; GeoB4424-2; Geosciences, University of Bremen; Guayana continental slope; Impagidinium aculeatum; Impagidinium pallidum; Impagidinium paradoxum; Impagidinium patulum; Impagidinium plicatum; Impagidinium sp.; Impagidinium sphaericum; Impagidinium strialatum; Impagidinium variaseptum; Impagidinium velorum; Latitude of event; Lejeunecysta oliva; Lejeunecysta sabrina; Lingulodinium machaerophorum long; Lingulodinium machaerophorum short; Longitude of event; M34/3; M34/4; M38/1; M38/2; Melitasphaeridium; Meteor (1986); Midatlantic Ridge; Mid Atlantic Ridge; MUC; MultiCorer; Multispinula quanta; Nematosphaeropsis labyrinthus; Nematosphaeropsis lemniscata; Northeast Brasilian Margin; Northern Brasil Basin; Operculodinium; Operculodinium israelianum long; Operculodinium israelianum short; Pentapharsodinium dalei; Pixidinopsis reticulata; Polyspaeridium zoharyi; Protoceratium reticulatum long; Protoceratium reticulatum short; Protoperidinium americanum; Protoperidinium compressum; Protoperidinium nudum; Quenquecuspis concretum; Sample mass; see reference(s); Selenopemphix alticinctum; Slide volume; Spiniferites; Spiniferites bentori; Spiniferites bulloideus; Spiniferites delicatus; Spiniferites hyperacanthus; Spiniferites membranaceus; Spiniferites mirabilis; Spiniferites pachydermus; Spiniferites ramosus; Trinovantedinium capitatum; Tuberculodinium vancampoae; Vema Channel; Votadinium calvum; Votadinium spinosum
Type:
Dataset
Format:
text/tab-separated-values, 1938 data points
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