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Operculodinium centrocarpum

Zonneveld, K.A.F. and Pospelova V. (2015). A determination key for modern dinoflagellate cysts. Palynology 39 (3), 387- 407.

 
dorsal view
single grain - reference collection Bremen
Sample xxxxx
photographs: Karin Zonneveld
cross section
 

Field characteristics

Operculodinium centrocarpum sensu Wall et Dale 1966

Field characteristics:
Chorate spherical cysts with radiating slender processes. Cyst wall is microgranular. The processes are simple, occasionally geminal with conical bases, slender shafts with capitate, acuminate or slightly furcated terminations. They may be aligned in the girdle region but are usually intratabular in position. Archeopyle is precingular (type P).

Dimensions: Cyst body diameter: 33 to 48 µm; length of processes: 7 to 14 µm.
Motile affinity: Protoceratium reticulatum (Claparède et Lachmann 1859) Bütschli 1885.
Cyst-theca relationship: Wall and Dale, 1967
Stratigraphic range: Eocene to Recent.

Comparison with other species:
This species can be recognised on its precigular archeopyle with the loss of one single plate and the morphology of the processes. The processes are hollow. They are of the same thickness from the basis to the distal ends. No stria or other ornamentation can be seen by light microscope on the processes. The form of the process-tips is acuminate with varying number and size of the branches. The branches can be so small that the spines look capitate. Also by this species often reduced spine lengths are observed. In that case the spines are not acuminate/capitate/geminate but are distally open without ornamentation. The cell wall is often finely granulated.

Geographic distribution

Geographic distribution based on :
Zonneveld et al., 2013. Atlas of modern dinoflagellate cyst distribution based on 2405 datapoints. Review of Palaeobotany and Palynology, v. 191, 1-197
Operculodinium centrocarpum can be regarded as a cosmopolitan species that can be observed in high relative abundances in all environments covered by this Atlas.
Distribution:
Operculodinium centrocarpum is observed in all studied environments from the polar to equatorial regions and coastal to open oceanic sites. Highest abundances (up to 91%) occur in the temperate to subpolar North Atlantic Ocean.

Environmental parameters:
SST: -2.1 - 29.8°C (spring - summer), SSS: 9.8 - 39.4 (summer - summer), [P]: 0.06 - 1.87 μmol/l, [N]:, 0.01 - 25.99 μmol/l, chlorophyll-a:, 0.001 - 21.8 ml/l, [O2]: between 0.01 - 8.2 ml/l.
Operculodinium centrocarpum can be abundant in sites where upper water temperatures are < 0°C throughout the year. High relative abundances can be observed in regions where salinities are reduced as result of meltwater input during the summer season or due to river discharge. This species is not restricted to regions with specific trophic conditions in the upper waters.

Comparison with other records:
Apart from the sites included in this atlas Operculodinium centrocarpum is recorded from the SW Indian margin, the White Sea, a fjord in northern Norway (North Atlantic Ocean), the South China Sea, Chinese coastal waters, the Peruvian upwelling area and the Gulf of Oman (Godhe et al., 2000; Marret and Zonneveld, 2003; Golovnina and Polyakova, 2004; Wang et al., 2004c; Novichkova and Polyakova, 2007; Rørvik et al., 2009 and references therein). In the Arctic O. centrocarpum occurs in areas that can be covered by sea ice for up to 12 months a year whereby a negative relationship exists between its relative abundance annual ice cover (de Vernal et al., 1998; Radi and de Vernal, 2008).
Sediment trap and seasonal distribution studies do not reveal a clear seasonal pattern in the cyst production, although in the Mediterranean Sea cyst production is restricted to the summer-early autumn seasons (June-October, Montresor et al., 1998). Furthermore it is observed in suspendet matter of the Marmara Sea in summer (Mudie pers. comm 2012). No seasonal trend or relationship with upper water characteristics could be documented in the upwelling areas off Somalia (Arabian Sea), off NW Africa and the Iberian peninsula, as well as in the North Pacific regions Omura Bay (Japan), central Strait of Georgia and Saanich Inlet (BC, Canada, Zonneveld and Brummer, 2000; Ribeiro and Amorim, 2008; Susek et al., 2005; Fujii and Matsuoka, 2006; Pospelova et al., 2010; Zonneveld et al., 2010; Price and Pospelova, 2011). In the British Columbia studies, O. centrocarpum is observed throughout the year and often forms the most abundant cyst species. This is in contrast to the other studies cited above, where it is only recorded sporadically in trap or surface sediments.