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Size-fractionated chlorophyll a and phycocyanin temporal variations in a highly eutrophic lake and its isolated karstic springs

Tsola S. L., Renta C., Macingo S. C., Karayanni H.

Oceanological and Hydrobiological Studies

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2018

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Vol. 47, No. 2

118--127

EN

Monthly variations of size-fractionated chlorophyll a and phycocyanin were studied in Lake Pamvotis between August 2016 and January 2017. Sampling was conducted at two sampling sites: in the main lake (Site 1: Lake) and in an adjacent man-made water ski lake with karstic springs (Site 2: Springs). Samples were fractionated into three size classes: 0.2–2 μm (pico), 2–20 μm (nano) and 20–180 μm (micro). According to chlorophyll a values, eutrophic to hypereutrophic conditions prevail at Site 1 and oligotrophic to mesotrophic conditions – at Site 2. Similarly, Site 1 was distinguished by higher concentration of phycocyanin compared to Site 2. Fractionated chlorophyll a showed monthly variations at Site 1 with alternations in the dominance between the two larger fractions. The maximum of the 0.2–2 μm fraction was observed in October but it contributed less to the total chlorophyll a content than nano- or microphytoplankton. Its contribution was higher at Site 2, reaching occasionally ~ 40% of the bulk chlorophyll a. However, nanophytoplankton was the fraction found to respond faster when disturbances occurred. At Site 1, phycocyanin correlated well with total chlorophyll a as well as with the micro- and nanophytoplankton fractions, indicating that cyanobacteria represent an important component of the large-sized phytoplankton in Lake Pamvotis.

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The bottom sediments of Lake Uzarzewskie – a phosphorus source or sink?

Kowalczewska-Madura K., Gołdyn R., Dondajewska R.

Oceanological and Hydrobiological Studies

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2010

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Vol. 39, No.3

81-91

EN

Phosphorus release from bottom sediments studied in two zones of Lake Uzarzewskie differing in depth and water oxygenation displayed seasonal and spatial variability. The experiments indicated that the lake receives considerable internal loading, especially from the deeper, anaerobic, rarely-mixed part of the lake. Meanwhile, the shallow zone situated in the 0-3 m depth range, could be a sink for phosphorus during spring and a source during other seasons of the year. The total loading of phosphorus from the bottom sediments was over 950 kg year^-1 P, and 83% of this amount originated from the deeper part of the lake. The mean release from this part was 24.89 mg m^-2 d^-1 P and the maximum in fall was 35.4 mg m^-2 d^-1 P.

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Subfossil remains of Camptocercus lilljeborgii(anomopoda, chydoridae)

Sarmaja-Korjonen K.

Studia Quaternaria

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2005

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Vol. 22

37-39

EN

Subfossil remains of Camptocercus lilljeborgii were abundant in the sediments of a core taken from a presently paludified shore of Lake Väike Juusa, southern Estonia. This made it possible to identify and describe the subfossil remains of the taxon, especially headshields and shells. The remains resemble those of Camptocercus rectirostris but differ in details that make the identification easy. The headshield is stouter and more arched and has no surface sculpture. It can also be distinguished from headshields of Camptocercus fennicus and Acroperus harpae by shape. The shell is characterized by parallel blurred lines and teeth on the posterior-ventral angle. The postabdomen is elongate and narrow and has more than 20 teeth on the dorsal margins.