The diatom stratigraphy and palaeoecology of lake Ohrid, Yugoslavia

Abstract

An 8.85 m core (No. 9) was taken from Lake Ohrid, Yugoslavia, in August 1973 at a depth of 210 m, approximately 6 km offshore of Gorica, Yugoslavia. The core was sampled at 10-cm intervals and analyzed for moisture, organic and CaCO 3 content, and diatoms. There is a slight but steady decrease of moisture with depth, probably due to sediment compaction. The organic content showed little variation throughout the core (~ = 2.73-+ 0.39% of total weight). The CaCO~ content from 885-110 cm depth also showed little change (~ = 2.32 ± 0.55% of total weight) but increased in the top meter of the core (100-0 cm, 2 = 11.03 ± 8.86% of total weight). Throughout the core there is an inverse relationship between organic and CaCO 3 content, particularly in the top meter. Extrapolation to the bottom of the core using linear regression based on ~4C-dating yields a date of ca. 30,000 years B.P. Results indicate that Lake Ohrid has remained an oligotrophic lake throughout the period represented by Core 9. Diatom analysis shows one persistent group of diatoms throughout the core. This group consists of Cyclotella fottii, C. hustedtii, and C. hustedtii vat.1 and is referred to as the Cyclotella complex. Between 885-650 cm (ca. 30,000-20,000 yr B.P.) there is a sharp increase in numbers and a slight increase in diversity of species. This may correspond with the beginning of the warmer, more humid middle Pleniglacial. Between 650-100 cm (ca. 20,000-10,000 yr B2.) the Cyclotella complex appears usually alone in small numbers. There are a few other scattered species in this section, mainly Opephora martyi and Fragilaria pinnata. This section of the core probably corresponds with the cold upper Pleniglacial of the Wiirm (Weichselian). Between 100-0 cm (ca. 10,000-0 yr B.P.) there is the largest increase in number and diversity of species, particularly above 60 cm. The Cyclotella complex, C. ocellata, Cyclotella sp.1, Stephanodiscus astraea var. intermedia fo.1 and Stephanodiscus sp.1 are dominant. This is the only section of the core in which Stephanodiscus species occur, and probably corresponds with the Holocene.

Complexity of diatom response to Lateglacial and Holocene climate and environmental change in ancient, deep and oligotrophic Lake Ohrid (Macedonia and Albania)

“…Sublacustrine springs are located mainly on the eastern shore of the lake, with one in the northwestern corner (Matter et al, 2010). An important source of karstic springs is the Lake Prespa underground outflow, which provides 21 % of total Lake Ohrid Map showing the location of Lake Ohrid (Macedonia and Albania) and the coring sites Co1262 (this study; Wagner et al, 2012;Lacey et al, 2015), Lz1120 (Wagner et al, 2009), Co1202 Reed et al, 2010;Cvetkoska et al, 2012), DEEP site Cvetkoska et al, 2015) and Core 9 (Roelofs and Kilham, 1983). Arrows indicate main river flows (C: Cerava River; K: Koselska River; S: Sateska River; D: Crni Drim River), and asterisks indicate major springs (N: Sveti Naum; T: Tushemisht; B: Biljana; V: Dobrá Voda).…”

“…Reed et al, 2010;Cvetkoska et al, 2012). Cyclotella minuscula (Jurilj) Cvetkoska is a new species identification (Cvetkoska et al, 2014a), which was previously identified as Discostella stelligera (Cleve & Grunow) Houk & Klee (Roelofs and Kilham, 1983;Wagner et al, 2009) or briefly combined with Cyclotella ocellata Pantocsek (Reed et al, 2010;Cvetkoska et al, 2012). Cyclotella ocellata morphotypes were split according to number of ocelli.…”

“…Diatom results are compared with sedimentological and geochemical data from the same core (Wagner et al, 2012;Lacey et al, 2015). We also compare core Co1262 diatom results with low-resolution diatom data from core Lz1120 (southeastern Lake Ohrid; Wagner et al, 2009), core Co1202 (northeastern Lake Ohrid; Reed et al, 2010;Cvetkoska et al, 2012), the DEEP site (central Lake Ohrid; Cvetkoska et al, 2015) and core 9 (north-central Lake Ohrid; Roelofs and Kilham, 1983) and with palynological data from the region (Wagner et al, 2009;Panagiotopoulos et al, 2013).…”

Two new fossil Cyclotella (Kützing) Brébisson species from Lake Ohrid, Macedonia/Albania

“…Most of the data for Lake Ohrid is related to its contemporary flora, but some reports include fossil diatoms (e.g. Roelofs & kilHam 1983;CveTkoska et al 2012CveTkoska et al , 2014. Roelofs & kilHam (1983) made the first observations on diatom assemblages in Core 9 from Lake Ohrid, where they identified several species of Cyclotella as dominant.…”

“…Roelofs & kilHam 1983;CveTkoska et al 2012CveTkoska et al , 2014. Roelofs & kilHam (1983) made the first observations on diatom assemblages in Core 9 from Lake Ohrid, where they identified several species of Cyclotella as dominant. CveTkoska et al (2012) observed two characteristic species complexes in core Co1202: C. fottii HusTedT and C. ocellata panToCsek.…”