| 1. |
- Dimiza, Margarita D., et al.
(author)
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Coccolithophore Distribution in the Western Black Sea in the Summer of 2016
- 2023
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In: Diversity. - : MDPI. - 1424-2818. ; 15:12
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Journal article (peer-reviewed)abstract
- Coccolithophores are an important component of phytoplankton abundance and biomass in the brackish environments of the Black Sea. Here, the abundance, composition, and distribution of coccolithophores were investigated in water samples taken from the first 50 m at 18 stations in the western Black Sea during a coccolithophore bloom, in June 2016. The total cell abundances ranged from 2 to 763 x 104 coccospheres L-1; Emiliania huxleyi was the most dominant species, but also Syracosphaera spp. (S. dilatata and S. molischii), Acanthoica (A. acanthifera and A. quattrospina), and Algirosphaera robusta displayed remarkably high concentrations. The formation of the seasonal thermocline significantly affects the vertical distribution of coccolithophores. Emiliania huxleyi, Syracosphaera spp., and Acanthoica spp. were restricted to the upper part of the water column, whereas high abundances of Algirosphaera robusta occurred below the thermocline. Overall, our results show significant differences in the vertical (ANOSIM R = 0.50, p = 0.0001) and spatial (ANOSIM R = 0.18, p = 0.0006) distribution of coccolithophores. Higher abundances of E. huxleyi and Syracosphaera spp. were recorded in the northwestern inner shelf region when compared to the open-sea samples. The observed coccolithophore spatial distribution is suggested to be mostly associated with the influx of less saline river water with high nutrient concentrations.
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| 2. |
- Jordan, Richard W., et al.
(author)
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Observations on the morphological diversity and distribution of two siliceous nannoplankton genera, Hyalolithus and Petasaria
- 2015
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In: Micropaleontology. - 0026-2803 .- 1937-2795. ; 61:6, s. 439-455
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Journal article (peer-reviewed)abstract
- Scale-bearing siliceous nannoplankton are occasionally encountered in surface seawater samples, but are rarely identified or illustrated. In this study, the morphological diversity of the haptophyte Hyalolithus neolepis and the enigmatic Petasaria heterolepis are investigated in scanning and transmission electron microscopes using materials from around the world. Results show that H. neolepis scales exhibit variation in the width of the marginal hyaline area, but intermediate specimens make separation of the two morphologies difficult. Petasaria heterolepis scales also show differences, in the presence of tubercle rows in the hyaline area and degree of hyaline areal coverage, but separation into discrete varieties is difficult at present. However, specimens with scales bearing a protuberance are considered to be distinct enough to warrant the erection of a new species, Petasaria protuberans Jordan,Malinverno, Å upraha, Thomsen et Young sp. nov.
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| 3. |
- Malinverno, Elisa, et al.
(author)
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Silicoflagellates in the eastern mediterranean and Black Seas : Seasonality, distribution and sedimentary record
- 2019
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In: Deep-sea research. Part II, Topical studies in oceanography. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0967-0645 .- 1879-0100. ; 164, s. 122-134
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Journal article (peer-reviewed)abstract
- Silicoflagellate populations and fluxes were analyzed from water samples and sediment traps in several basins of the eastern Mediterranean and Black Sea, to show species distribution in response to ecological factors and compared with the Quaternary records of the region. In the eastern Mediterranean, Dictyocha stapedia was the most abundant species, represented by two varieties: var. stapedia, smaller and with an apex spine, that dominated in the pelagic settings, and var. aspinosa, larger and lacking an apex spine, that dominated in the north Adriatic Sea. Dictyocha aculeata was the second most abundant species, Octactis pulchra was seasonally dominant in the Adriatic Sea. Stephanocha speculum occurred sporadically in the Adriatic Sea with 6-sided normal-sized specimens, but was nearly absent from pelagic assemblages. In the Black Sea, assemblages and fluxes were characterized by larger 7-sided skeletons of D. speculum with apex spines and a lower abundance of O. pulchra.
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