Comparison of fatty acid profiles of different strains of diatom Cyclotella meneghiniana Kützing from the salt lake Tahilt-Nuur (Mongolia)

Diatoms are a widespread group of microorganisms, many of which are able to accumulate significantamounts of long-chain and polyunsaturated fatty acids. 5 strains of Cyclotella meneghiniana were isolated during the studyof diatom flora in the salt lakes of Mongolia. The taxonomic status was confirmed by morphological and molecular genetic studies, and the features of the fatty acid composition were also established. We found that Cyclotella meneghinianastrains are producers of long-chain polyunsaturated omega-3 fatty acids and are of interest for further biotechnologicalapplications.

Phytoplankton succession in the anthropogenic and climate ecological transformation of freshwater ecosystems

The study is focused on the influence of mechanisms of anthropogenic activity and climate changes of different types and levels on the autotrophic link of freshwater ecosystems. The studies of the river, lake, water reservoir and quarry phytoplankton in the territory of the Ukrainian Polissia were carried out during 2005–2019 according to the standard methods. At the same time, we determined water hydrophysical and hydrochemical characteristics. Exactly 812 algal species represented by 877 infraspecific taxa were identified, including 75 new ones for the Ukrainian Polissia, with a significant share of thermophiles and halophiles. The dominance of Chlorophyta, Bacillariophyta, Euglenozoa and Cyanobacteria was observed in all types of water bodies. With the increase in the nutrient content in the composition of dominant complexes of river ecosystems, the role of centric diatoms Cyclotella meneghiniana, C. stelligera, Stephanodiscus hantzschii increased. The vegetation intensity of Aphanizomenon flos-aquae increased in the water courses with partially regulated flow, while vegetation of Chrysococcus rufescens, Pseudokephyrion pillidium, Kephyrion ovum intensified in rivers with increased colour of water. Water reservoirs are dominated by representatives of Bacillariophyta, Cyanobacteria, Euglenozoa, Miozoa, mostly by Aphanizomenon flos-aquae and Peridinium cinctum. The lowest number of dominant species was identified in the lakes, and belonged to the genera Trachelomonas, Peridinium, Chlamydomonas, Crucigeniella, Cyclotella, Aulacoseira. The dominant species in quarries were Cyclotella meneghiniana, Chlamydomonas monadina, Ch. globosa, Coelastrum microporum, Gomphosphaeria aponina, Trachelomonas volvocina and Microcystis aeruginosa. The obtained data can be used to predict scenarios of changes in the autotrophic link under the influence of natural and anthropogenic factors, to develop methods for monitoring and managing ecosystems at different levels of anthropogenic transformation necessary to ensure an appropriate level of their functions and ecological services.

Estimation of effective dilution rate to inhibit cyanobacterial blooms based on a novel competitive growth model -Case study in Lake Tega, Japan

Although water transfer as a functional method to improve water quality and control cyanobacterial blooms in lakes has been used for several decades, there was few studies examining effective dilution rate depending on various water qualities in lakes. It would be due to the scarcity of water transfer execution in fields. Therefore, in order to clarify the optimum dilution rate to suppress cyanobacterial blooms, the competitive growth model based on the Droop model and the Lotka-Volterra model developed for eutrophic conditions was used. First, to verify the wide applicability of the simulation model, a competitive culture experiment between Microcystis sp. and Cyclotella meneghiniana under limited phosphorus and sufficient nitrogen concentration was conducted, then the cell densities of the two species were predicted by using the simulation model. Results of the competitive experiment revealed that there was no significant discrepancy in the growth of Microcystis sp. cell among different dilution groups (p＞0.05), while that of Cyclotella meneghiniana had significant discrepancy between groups (p＜0.05), and the accuracy of the simulation model under limited phosphorus concentration was verified. Based on these results, an exact effective dilution rate for the inhibition of Microcystis blooms in Lake Tega, Japan, was suggested by this novel simulation model. When the dilution rate reaches 13.3%, the Microcystis blooms will hard to occur. The predicted data were also compared with the actual data collected over years in Lake Tega, and its effectiveness has been confirmed.

Characteristics of Diatom Assemblages in Surface Sediments of the new Yongding River and Haihe River Estuaries, Tianjin

Diatom analysis was conducted on the surface sediments from the estuaries of the new Yongding River and Haihe River in Tianjin. The results showed that the main diatom assemblages in the new Yongding River was Navicula marina-Auliscus caelatus-Coscinodiscus hirosakiensis-Coscinodiscusoculus-iridis and Auliscus caelatus- Coscinodiscusoculus-iridis-Cyclotella meneghiniana-Cyclotella stylorum in the Haihe River. There was saprophilous taxa, Cyclotella meneghiniana, in both estuaries indicating that the two estuaries were polluted to a certain degree.

DISTRIBUSI DAN KEMELIMPAHAN PLANKTON DI WET DUNE SLACKS GUMUK PASIR PARANGTRITIS, BANTUL, DIY.

Komunitas plankton memiliki peran penting pada proses rantai makanan, siklus nutrien dan proses suksesi awal wet dune slacks. Kawasan wet dune slacks merupakan cekungan yang berada di antara punggung gumuk dan kondisi permukaan air tanah sangat bervariasi tergantung musim. Habitat unik yang telah dilindungi di benua Eropa ini justru belum banyak dipelajari di Indonesia. Tujuan penelitian ini adalah untuk mempelajari distribusi dan kemelimpahan plankton di wet dune slacks serta faktor fisiko-kimia yang paling mempengaruhi distribusi dan kemelimpahannya. Pencuplikan sampel dilakukan pada bulan Februari 2018 di Gumuk Pasir Parangtritis, Bantul, Daerah Istimewa Yogyakarta. Sampel air dicuplik menggunakan ember sebanyak 10 liter dengan 3 ulangan pada 5 wet dune slacks yang berbeda. Sampel air kemudian disaring menggunakan plankton-net ukuran 120 mesh serta diukur parameter fisiko-kimianya. Hasil dari pengamatan sampel plankton menunjukkan terdapat 37 spesies diatom pennate, 1 spesies diatom sentrik, 23 spesies alga unisel, 28 spesies alga koloni, 18 spesies alga filamen, 3 spesies dinoflagellata, 6 spesies protozoa berklorofil, 22 spesies rotifera, 6 spesies cladocera, 11 spesies ostracoda, 5 spesies copepoda, dan 5 spesies protozoa. Spesies plankton yang berhasil mengsuksesi kawasan wet dune slacks merupakan spesies yang memiliki strategi bertahan di habitat kekeringan dengan berubah ke fase istirahat, cyst, spora, dan resting eggs. Spesies fitoplankton yang mendominasi adalah Cyclotella meneghiniana sedangkan untuk zooplankton adalah Chlamydotheca flexilis dan Alona rectangula. Parameter fisiko-kimia kecepatan angin, C-organik, alkalinitas, sulfat, temperatur air, temperatur udara, intensitas cahaya,fosfat, pH dan oksigen terlarut menjadi faktor yang paling mempengaruhi distribusi dan kemelimpahan fitoplankton. Sedangkan untuk faktor fisiko-kimia yang paling mempengaruhi distribusi dan kemelimpahan zooplankton adalah kadar oksigen terlarut, CO2 terlarut, pH, temperatur air, temperatur udara, jeluk, jeluk Secchi, kecepatan angin, intensitas cahaya, C-organik, sulfat, fosfat.