The benthic diatom assemblages of the glacier Avusor Great Lake and Koçdüzü Great Lake were investigated in August 2019. A total of 71 diatom species belonging to 34 genera were determined in the samples, 49 species from Avusor Great Lake and 37 from Koçdüzü Great Lake. Only 15 diatom species were common to both lakes. Total floristic similarity between the neighbouring lakes was only 21.12%. Genera with the highest number of species were Eunotia (8), Gomphonema (6), Pinnularia (6), Navicula (5) and Aulacoseira (4). The diatom flora of both lakes was formed by cosmopolitan species with a large influence from species in alpine and subalpine area. A comparison of the diatom assemblages of the investigated lakes showed differences in both relative abundance and species present in the individual lakes. Bioindicative analysis showed that the water of Koçdüzü Great Lake is more alkaline and less saturated with organic substances than Avusor Great Lake. In both lakes, the communities are composed of species adapted to living in the benthos of fresh waters of moderate temperature well enriched with oxygen. In both lakes, the water quality was Class 2 with a saprobity index of S = 1.08 in Avusor Great Lake and 0.97 in Koçdüzü Great Lake, but their communities were composed of species with both oligotrophic and mesotrophic status. Statistical comparison of the species composition of studied lakes with other high mountain lakes and the lakes in northern Turkey revealed the role of altitude as the main factor in the formation of diatom floras.

The composition of charophyte taxa and their habitat preferences in water bodies of the Artabel Lakes Nature Park were investigated on 15 August 2013 and 13 August 2016. A total of 73 taxa belonging to Conjugatophyceae (Zygnematophyceae) and Klebsormidiophyceae were recorded. The genera Cosmarium (37), Staurastrum (10) and Closterium (7) were most abundant. The partly unexpected presence of certain desmid taxa, i.e., taxa characteristic of eutrophic water, was recorded. Filamentous charophytes were represented by three taxa. The Willis curve for the distribution of species to genera had a trend line of R2 = 0.9123. Bioindication, statistical methods and comparative floristic results show that water in all of the studied lakes was fresh, of low-conductivity, circum-neutral and with little organic pollution. Four groups of lakes were identified as a result of statistical comparison of their environmental and biological variables. Bioindication results can be used as references for future monitoring of the lakes in protection of the species found in the Artabel Lakes Nature Park and can also be included in the National Water Quality Standard System of Turkey.

Algae contain a large amount of biological active compounds functioning as antioxidant, antimicrobial and anti-tumour. In the present research, antioxidant activity of freshwater alga Microspora sp. (Chlorophyta) extract prepared in different solvents (methanol, acetonitrile, ethanol, acetone and ethyl acetate) was determined with three different methods; 2,2-diphenyl-1-picrylhydrazyl (DPPH•), Iron (III) Reduction / Antioxidant Power (FRAP) Assay and Copper (II) Reductive Antioxidant Activity (CUPRAC). The alga samples collected from the high mountain lake (2733 meters above sea level) localized in Gümüşhane province of Turkey. The algal extracts prepared in different solvents showed antioxidant activity. The values of DPPH• varied from 8.97% (in acetonitrile extract) to 31.15% (in methanol extract). As in the DPPH• method, the lowest and highest values in the FRAP method were measured based on μM TEAC (Trolox Equivalent Antioxidant Capacity) in methanol and acetonitrile extracts as 60.303 μM and 359.394 μM respectively. While the lowest value of CUPRAC test was determined in acetonitrile extract (0.041 μM TEAC ) as in the other tests, highest value was measured in ethanol extract (0.101 μM TEAC ) as different from the others. While the values of highest antioxidant activity in both DPPH• and FRAP methods was measured in the methanol solvent, it was determined in the ethanol solvent for CUPRAC. Keywords: Algae; Microspora sp.; Antioxidant; DPPH•; FRAP; CUPRAC DOI: 10.17350/HJSE19030000129 Full Text:

The benthic algal composition of Charophyta in the Avusor Great Lake and Koçdüzü Great Lake at the altitude of about 3,000 m a.s.l. was investigated on 21 August 2019. A total of 112 species, belonging to Zygnematophyceae, were identified. The genera Cosmarium (44), Staurastrum (16), Closterium (15), and Euastrum (13) were most abundant. The members of filamentous charophyta were represented by two species. Bioindicator species characterize water in both lakes as clear, Class 2 of water quality and the lakes ecosystem as mesotrophic. The partly unexpected presence of certain desmids taxa, i.e., species characteristic of eutrophic water, was recorded.

The benthic algal flora of Avusor Great Lake and Kocduzu Great Lake in Rize was investigated on 21 August 2019. A total of 37 desmid taxa belonging to the genera Actinotaenium (2), Closterium (6), Cosmarium (12), Euastrum (4), Micrasterias (3), Penium (1), Staurastrum (8) and Staurodesmus (1) were assessed as new records for Turkey. In this paper, the morphotaxonomy, ecology, and distribution of each species is discussed in detail.