Publication Date:
2024-03-01
Description:
The Lena Delta in Northern Siberia is one of the largest river deltas in the world. During peak discharge, after the ice melt in spring, it delivers between 60-8000 m**3/s of water and sediment into the Arctic Ocean. The Lena Delta and the Laptev Sea coast also constitute a continuous permafrost region. Ongoing climate change, which is particularly pronounced in the Arctic, is leading to increased rates of permafrost thaw. This has already profoundly altered the discharge rates of the Lena River. But the chemistry of the river waters which are discharged into the coastal Laptev Sea have also been hypothesized to undergo considerable compositional changes, e.g. by increasing concentrations of inorganic nutrients such as dissolved organic carbon (DOC) and methane. These physical and chemical changes will also affect the composition of the phytoplankton communities. However, before potential consequences of climate change for coastal arctic phytoplankton communities can be judged, the inherent status of the diversity and food web interactions within the delta have to be established. In 2010, as part of the AWI Lena Delta programme, the phyto- and microzooplankton community in three river channels of the delta (Trofimov, Bykov and Olenek) as well as four coastal transects were investigated to capture the typical river phytoplankton communities and the transitional zone of brackish/marine conditions. Most CTD profiles from 23 coastal stations showed very strong stratification. The only exception to this was a small, shallow and mixed area running from the outflow of Bykov channel in a northerly direction parallel to the shore. Of the five stations in this area, three had a salinity of close to zero. Two further stations had salinities of around 2 and 5 throughout the water column. In the remaining transects, on the other hand, salinities varied between 5 and 30 with depth. Phytoplankton counts from the outflow from the Lena were dominated by diatoms (Aulacoseira species) cyanobacteria (Aphanizomenon, Pseudanabaena) and chlorophytes. In contrast, in the stratified stations the plankton was mostly dominated by dinoflagellates, ciliates and nanoflagellates, with only an insignificant diatom component from the genera Chaetoceros and Thalassiosira (brackish as opposed to freshwater species). Ciliate abundance was significantly coupled with the abundance of total flagellates. A pronounced partitioning in the phytoplankton community was also discernible with depth, with a different community composition and abundance above and below the thermocline in the stratified sites. This work is a first analysis of the phytoplankton community structure in the region where Lena River discharge enters the Laptev Sea.
Keywords:
Acanthoceras; Actinastrum cf. hantzschii; Amphidinium cf. crassus; Amphidinium cf. extensum; Anabaena, coiled, irregular; Anabaena, coiled, regular; Anabaena straight; Aphanizomenon spp.; Aphanocapsa spp.; Asterionella formosa; Aulacoseira; Aulacoseira cells, other; Aulacoseira granulata; Aulacoseira granulata var. angustissima; AWI_Coast; AWI Arctic Land Expedition; Bacteria, star-shaped; Bosmina spp.; Ceratium cf. hirundinella; cf. Cyclotella; cf. Trichocerca spp.; Chaetoceros spp.; Chlorophyte; Chlorophyte indeterminata; Ciliates; Ciliates, other; Closterium spp.; Coastal Ecology @ AWI; Coelastrum spp.; Copepoda, adult; Coscinodiscus; Cosmarium spp.; Crucigenia fenestrata; Crucigenia spp.; Cryptophytes; Crysophytes; CTD/Rosette; CTD-RO; Cuspidothrix issatchenkoi; Cyanobacteria; Cyanophyte filaments, other; Cyanophyte filaments, undifferentiated; Cyanophytes; Date/Time of event; DEPTH, water; Desmodesmus spp.; Diatoma spp.; Diatoms, pennales; Dictyosphaerium; Didinium gargantua; Dinobryon cf. cylindricum; Dinobryon spp.; Dinoflagellates, other; Dinoflagellate sp.; Dinophysis acuminata; Ebria tripartita; Elakatothrix spp.; Elevation of event; Euglenid indeterminata; Event label; Flagellates; Flagellates, green; Fragilaria; Fragilaria cf. crotonensis; Fragilaria spp.; Gomphonema; Gymnodinium; Gyrodinium spp.; Heterocapsa-like; Katodinium spp.; Keratella spp.; Koliella/Ankistrodesmus/Monoraphidium; Lagerheimia spp.; Laptev Sea; Latitude of event; Lena2010; Longitude of event; Lyngbya spp.; Melosira cf. varians; Melosira spp.; Meridion spp.; Monoraphidium, curved; Monoraphidium colony; Monoraphidium contortum; Myrionecta spp.; Nauplii; Nitzschia; Oocystis spp.; Pediastrum boryanum; Pediastrum boryanum var. longicorne; Pediastrum duplex; Pediastrum duplex var. gracillimum; Pediastrum spp.; Pediastrum tetras; Peridiniales; Peridiniella catenata; Phytoplankton, cell, other, indeterminata; Phytoplankton, cell cf. Actinastrum, indeterminata; Picocyanophytes; Plagiogrammopsis; Planktothrix spp.; Protoperidinium; Protoperidinium pellucidum; Protoperidinium spp.; Pseudoanabaena spp.; Quantitative phytoplankton method (Utermöhl, 1958); Rotifers, other; RU-Land_2010_Lena; Sample code/label; Sample volume; Scenedesmus; Scenedesmus cf. acuminatus; Scenesesmus cf. ornatus; Selenastrum spp.; Skeletonema spp.; Spondylosium spp.; Staurastrum spp.; Stephanodiscus spp.; Suctoria; Surirella; Synedra spp.; Synedra ulna; T1-10-01; T1-10-02; T1-10-03; T1-10-04; T1-10-05; T1-10-06; T1-10-07; T2-10-01; T2-10-02; T2-10-03; T2-10-04; T2-10-05; T3-10-01; T3-10-02; T3-10-03; T3-10-04; T3-10-05; T4-10-01; T4-10-02; T4-10-03; T4-10-04; T4-10-05; T5-10-01; T5-10-02; T5-10-03; T6-10-01; T6-10-02; T6-10-03; T8-10-01; T8-10-02; T8-10-03; Tabellaria spp.; Tetraedron spp.; Thalassiosira spp.; Tintinnid; Trachelomonas; Trachelomonas cf. hispida; Unidentified chain
Type:
Dataset
Format:
text/tab-separated-values, 8844 data points
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