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EN
A river is a water ecosystem that plays an important role in the hydrological cycle and functions as a catchment area for the surrounding area. One of the organisms inhabiting river waters is plankton. The purpose of this study was to determine and analyze the structure of the plankton community in the waters of the Cijulang River and to study the relationship between plankton abundance, as well as some physical-chemical parameters of the water. The study was conducted in January, February, and March 2018 on the Cijulang River, at 5 (five) stations with a purposive sampling method. Accordingly, 17 genera were found, from 7 phytoplankton classes consisting of 6 Bacillariophyceae genera, 1 Clorophyceae genera, 2 Cyanophyceae genera, 3 Zygnematophyceae genera, 2 Desmidiaceae genera, 1 Synurophyceae genera, and 2 Fragillariophyceae genera. Also found were 10 genera from 5 classes of zooplankton consisting of 4 genera Maxillopoda, 2 genera Branchiopoda, 1 genera Gastropoda on veliger fase, 1 genera Ostracoda, and 2 genera Copepoda. The abundance of phytoplankton obtained ranges from 11-57 cells / L, while the zooplankton ranges from 8 – 40 ind/L. The diversity index (H ') = 1.397 - 2.275 and dominance index (D) = 0.022 - 0.294. Physical-chemical parameters of the waters, respectively, were 22 °C - 31 °C, light intensity 47.5 cm - 254 cm, salinity 0 ppt - 20 ppt, and dissolved oxygen 6.2 mg / L - 13.4 mg / L. Ammonia concentration 0.03 - 0.08 mg / L. All stations had a phosphate value of less than 0.16 mg / L and a silicate concentration of 0.01 - 0.0581 mg / L.
EN
Here we summarize the results from 10 cruises in the Chukchi Sea, in August, each year from 2011 to 2020. Samples for the qualitative analysis of the microzooplankton were obtained from stations located across the Chukchi Sea using a 20µm plankton net. Conditions encountered, in terms of sea ice coverage and chlorophyll concentrations, varied widely from year to year without any obvious relationship with the composition of the microzooplankton assemblage. Examining a total of 242 samples gathered, we found a total of 44 tintinnid species (morphologically distinct forms). Plotting cumulative number of tintinnid species encountered vs cumulative number of samplings gave a typical species accumulation curve showing no sign of saturation suggesting that continued sampling in the Chukchi Sea will likely yield increases in the tintinnid species catalogue. The tintinnid species found ranged widely in lorica opening diameters (LOD) from about 11 µm to 80 µm in diameter. However, the median size of the LOD of the tintinnid assemblages varied little from year to year ranging only from about 30 µm to 40 µm. Most of the forms encountered were found in samples from only 1 or 2 cruises. Very few forms were found every year throughout the 10 years of sampling. These were 5 species of tintinnids (Acanthostomella norvegica, Leprotintinnus pellucidus, Pytchocylis obtusa, Salpingella acuminata, Salpingella faurei) and the nasselarian radiolarian Amphimelissa setosa. Examples of the morphological variability observed among individuals of Acanthostomella norvegica and Pytchocylis obtusa within single samples are shown with some individuals easily confused with forms described as other species are shown. To our knowledge, our data are the most extensive data set on Chukchi Sea microplankton. We provide all of the data recorded, which may serve as a baseline from which to assess changes projected in Arctic Sea systems, in a supplementary data file.
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