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Diatom Studies

Tsegmed Bokhchuluun

Research objectives and activities

  • To examine and describe the diversity of diatom taxa in the tributary streams.
  • To define the most important indicator taxa of water quality and environmental conditions in the area
  • To analyze the ecology of aquatic habitats using diatoms.
  • To examine relationships between changes in land use and response of diatoms of eastern shore streams of Lake Hövsgöl
  • To set up a part of the basic data to establish information for the diatoms of Mongolia, important for past climate change reconstruction and climate modeling

Initial Results

We have identified 213 species belonging to 53 genera in the study region. Eighty four species grow only on plants and 53 species grow only on stones. Seventy six species are found in both habitats. The dominant species are defined based on the relative abundance of each location. For example: Achnanthes minutissima (40.85%) dominated in Turag, Cocconeis placentula (25%) the dominant in Borsog, Gomphonema olivaceum (22%) in Noyon, Gomphonema minutum (94%) in Shagnuul, Synedra ulna 60% in Dalbay and Fragilaria capucina (13.09%) in Sevsuul.>

Average Relative Abundunce

Figure 1 diatom cluster analysis

Figure 1: Cluster Analysis of Average Relative Abundance by River (NYN=Noyon, SHL=Shugnuul, BRG=Borsog, SVL=Sevsuul, DLB=Dalbay, TRG = Turag)

Fig.1 shows cluster analysis for using by all noted species average relative abundance in each valley in June 2003. Zone 1 was completed by the Borsog, Noyon and Shugnuul river’s species composition. Sevsuul and Dalbay river’s community were found zone 2. The Turag river had zone 3 by unique community.

Species composition

Figure 2 Cluster analysis of species composition

Figure 2: Cluster Analysis of Species Composition by River (NYN=Noyon, SHL=Shugnuul, BRG=Borsog, SVL=Sevsuul, DLB=Dalbay, TRG = Turag)

In June, species composition in Turag and Shugnuul river’s was found in same cluster zone, that different from species composition in other rivers (Figure 2). Borsog and Dalbay river are connected in cluster zone 1. The species composition of the Sevsuul river presented single outlier on the cluster tree and it shows that there is a different community structure from the others.

Turag, Shagnuul and Noyon (these valleys have heavy livestock grazing). These rivers were similar, based on species composition in June, the most suitable season for diatom growth. Indicator species of polluted water according to Van Dam’s indices (Van Dam, 1994) were dominants in these rivers. We conclude that these rivers are polluted due to the impact of livestock grazing.

Sevsuul River forms one group by itself, based on results of species composition, cluster analysis. In addition, 60 species are distributed only in the Sevsuul River, and are indicators of fresh and fresh brackish and brackish water. So we believe that Sevsuul River is beginning to be polluted.

As a result of cluster analysis on species relative abundance, Turag River is significantly different from the other rivers. In this river, human and livestock impact indicator species are dominant (Lange-Bertalot, 1999) and it is the poorest in species richness. So we believe that Turag River is a polluted river.

Diatom species richness and water temperature are directly correlated, p <0.01, r2= 0.5. It suggests that species richness increases as average temperature rises up to a certain limit. Species richness is also correlated with dissolved magnesium (p<0.005; r2= 0.59), and water hardness (p<0.004, r2=0.508).

The rivers are evaluated by water quality. Here, Turag River has brackish water, Sevsuul River has fresh brackish water and Borsog, and Dalbay Rivers have fresh water according for diatom species’ composition.

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