Cyclotella paleo-ocellata, a new centric diatom (Bacillariophyta) from Lake Kinneret (Israel)

Abstract

Large, subfossil populations of an unknown centric, planktonic diatom were observed in a lake sediment core from Lake Kinneret (Israel), which is here described as Cyclotella paleo-ocellata sp. nov. The new taxon, which belongs to the Cyclotella ocellata species complex, is described and separated from other similar taxa (e.g., Cyclotella ocellata, Cyclotella kuetzingiana, Cyclotella polymorpha, Cyclotella paraocellata) based on a combination of the following morphological characters: valve diameter, number of orbiculi depressi (circular depressions), number of striae/10 µm, stria length, number and position of rimoportulae and the number of central and marginal fultoportulae. Cyclotella paleo-ocellata can be distinguished mainly by two prominent characteristics: (1) the number and the arrangement of the orbiculi depressi (4-8) which increase with the valve diameter and (2) the marginal fultoportulae, situated on each, every second or third costa. Since Cyclotella paleo-ocellata is at present only known from the subfossil bottom sediments of Lake Kinneret, its ecological preferences are inferred simply from the associated diatom flora.

Opportunism or aquatic specialization? Evidence of freshwater fish exploitation at Ohalo II- A waterlogged Upper Paleolithic site

“…At present, the lake is mainly fed from the north by the Jordan River, which also drains the lake southwards. The lake is warm and monomictic, and its water level fluctuates up to 4 m depending on precipitation, evaporation, and water abstraction [ 33 ].…”

Reconciling diverse lacustrine and terrestrial system response to penultimate deglacial warming in southern Europe

“…C. ocellata has broad ecological preferences (in part because it is likely to represent a species complex), but in these systems, appears to indicate oligotrophic-mesotrophic conditions, particularly when accompanied by large, non-classic forms (Cvetkoska et al, 2014a). The large Ioannina morphotypes await taxonomic description, but show affinities with recently described Mediterranean taxa separated from the C. ocellata complex, comprising C. prespanensis Cvetkoska, Hamilton, Ognjanova-Rumenova and Levkov, C. paraocellata Cvetkoska (Cvetkoska et al, 2014b), and C. paleo-ocellata Vossel and Van de Vijver (Vossel et al, 2015).…”

Lake Kinneret (Israel): New insights into Holocene regional palaeoclimate variability based on high-resolution multi-proxy analysis

“…The application of a transfer function to reconstruct lake-water nutrient concentrations from the taxonomic composition of diatom communities was not appropriate. The dominant taxon Cyclotella ocellata has an extremely broad tolerance for nutrient availability (Cremer and Wagner, 2003; Fritz et al, 1993; Houk et al, 2010; Kiss et al, 1996; Schlegel and Scheffler, 1999; Van Dam et al, 1994) and another common taxon, Cyclotella paleo-ocellata , is newly described (Vossel et al, 2015) and without a modern analogue.…”

“…Total diatom concentration and the Ca/Ti-ratio remains low in spite of better diatom preservation, indicating reduced lacustrine productivity. As Cyclotella ocellata is known for its extremely broad tolerance for nutrient availability (Cremer and Wagner, 2003; Fritz et al, 1993; Houk et al, 2010; Kiss et al, 1996; Schlegel and Scheffler, 1999; Van Dam et al, 1994), the co-occurrence of Cyclotella ocellata with Cyclotella paleo-ocellata is interpreted in this record as an indicator of oligotrophic conditions in a deeper open-lake system (Vossel et al, 2015, and references therein). Notably, the peak in the S/Ti-ratio at the beginning of DAZ-4b (~8.6 cal.…”

“…DAZ-3 is characterized by the consistently high abundance of planktonic diatom taxa (> 80%) mainly belonging to the Cyclotella ocellata-complex (table 2), indicating stable, high lake levels and an oligo-mesotrophic state throughout this subzone (Vossel et al, 2015, and references therein). The marked transition to plankton dominance represents strong evidence for a rapid increase in lake level around 7,400 cal yrs BP, which is also observed in the diatom data from Lake Prespa, further north (Cvetkoska et al, 2014).…”