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Response of the rotifer community to human-induced changes in the trophic state of a reservoir

Seong-Ki Kim
Seong-Ki Kim
, 
Jeong-Cheol Kim
Jeong-Cheol Kim
, 
Gea-Jae Joo
Gea-Jae Joo
 e 
Jong-Yun Choi
Jong-Yun Choi
   | 26 nov 2020
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Article Category: Research Article
Pubblicato online: 26 nov 2020
Pagine: 329 - 344
Ricevuto: 29 apr 2020
Accettato: 23 giu 2020
DOI: https://doi.org/10.1515/ohs-2020-0029
© 2020 Faculty of Oceanography and Geography, University of Gdańsk, Poland
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1

Map of the study sites. Location of the study sites in southeastern South Korea are indicated by a solid square (■) in the inset map of the Korean Peninsula. The main map shows the Unmun Reservoir and two tributary streams (Unmun and Sinwon). The sampling points are indicated by open circles (○).
Map of the study sites. Location of the study sites in southeastern South Korea are indicated by a solid square (■) in the inset map of the Korean Peninsula. The main map shows the Unmun Reservoir and two tributary streams (Unmun and Sinwon). The sampling points are indicated by open circles (○).

Figure 2

Basic structure of the self-organizing map (SOM)
Basic structure of the self-organizing map (SOM)

Figure 3

Time-series fluctuations in environmental factors and rotifer density at the study sites in the Unmun Reservoir in 2009–2015. (a) WT (°C), water temperature; (b) DO (mg l−1), dissolved oxygen; (c) pH, (d) conductivity (μS cm−1), (e) turbidity (NTU), (f ) T-N (mg l−1), total nitrogen; (g) T-P (μg l−1), total phosphorus; (h) chlorophyll a (μg l−1), and (i) rotifer density (ind. l−1)
Time-series fluctuations in environmental factors and rotifer density at the study sites in the Unmun Reservoir in 2009–2015. (a) WT (°C), water temperature; (b) DO (mg l−1), dissolved oxygen; (c) pH, (d) conductivity (μS cm−1), (e) turbidity (NTU), (f ) T-N (mg l−1), total nitrogen; (g) T-P (μg l−1), total phosphorus; (h) chlorophyll a (μg l−1), and (i) rotifer density (ind. l−1)

Figure 4

Clustering through data learning in the self-organizing map. (a) U-matrix, (b) hierarchical dendrogram, (c) clustering result
Clustering through data learning in the self-organizing map. (a) U-matrix, (b) hierarchical dendrogram, (c) clustering result

Figure 5

Environmental factors and rotifer density measured in the Unmun Reservoir. WT (°C) – water temperature; DO (mg l−1) – dissolved oxygen; T-N (mg l−1) – total nitrogen; T-P (μg l−1) – total phosphorus
Environmental factors and rotifer density measured in the Unmun Reservoir. WT (°C) – water temperature; DO (mg l−1) – dissolved oxygen; T-N (mg l−1) – total nitrogen; T-P (μg l−1) – total phosphorus

Figure 6

Interannual summer and autumn distribution of eight dominant rotifer species in the Unmun Reservoir. (a) Anuraeopsis fissa, (b) Ascomorpha ovalis, (c) Brachionus calyciflorus, (d) Keratella cochlearis, (e) Ploesoma hudsoni, (f ) Polyarthra spp., (g) Synchaeta oblonga, (h) Trichocerca gracilis. ●: summer, ○: autumn
Interannual summer and autumn distribution of eight dominant rotifer species in the Unmun Reservoir. (a) Anuraeopsis fissa, (b) Ascomorpha ovalis, (c) Brachionus calyciflorus, (d) Keratella cochlearis, (e) Ploesoma hudsoni, (f ) Polyarthra spp., (g) Synchaeta oblonga, (h) Trichocerca gracilis. ●: summer, ○: autumn

Figure 7

Interannual summer change of environmental factors in the Unmun and Sinwon streams. (a) DO (mg l−1) dissolved oxygen; (b) conductivity (μS cm−1); (c) turbidity (NTU); (d) T-N (mg l−1) total nitrogen; (e) T-P (μg l−1) total phosphorus; (f ) chlorophyll a (μg l−1)
Interannual summer change of environmental factors in the Unmun and Sinwon streams. (a) DO (mg l−1) dissolved oxygen; (b) conductivity (μS cm−1); (c) turbidity (NTU); (d) T-N (mg l−1) total nitrogen; (e) T-P (μg l−1) total phosphorus; (f ) chlorophyll a (μg l−1)

Environmental factors and rotifer density in different clusters defined by SOM. Significant differences between clusters were based on one-way ANOVA. SD – standard deviation; F – F-value; p – probability value; WT (°C) – water temperature; DO (mg l−1) – dissolved oxygen; T-N (mg l−1) – total nitrogen; T-P (μg l−1) – total phosphorus

Factor Units Mean SD Cluster F p
1 2 3
WT °C 15.6 8.8 19.6 ± 5.9 19.3 ± 7.1 4.2 ± 2.1 52.3 < 0.01
DO mg l−1 107.8 17.2 94.6 ± 13.3 108.1 ± 10.7 124.0 ± 16.3 28.5 < 0.01
pH 8.19 0.6 8.04 ± 0.5 8.06 ± 0.5 8.60 ± 0.8 6.9 0.02
Conductivity μS cm−1 93.9 10.2 85.6 ± 6.9 100.3 ± 6.7 93.5 ± 10.6 25.9 < 0.01
Turbidity NTU 9.8 2.5 8.0 ± 2.1 11.2 ± 1.8 9.8 ± 2.6 16.6 < 0.01
T-N mg l−1 1.5 0.3 1.2 ± 0.3 1.6 ± 0.2 1.5 ± 0.3 19.9 < 0.01
T-P μg l−1 17.8 3.3 15.2 ± 1.8 20.2 ± 2.1 16.9 ± 3.5 33.4 < 0.01
Chlorophyll a 12.3 4.2 8.9 ± 3.0 14.7 ± 2.8 12.6 ± 4.3 22.4 < 0.01
Anuraeopsis fissa ind. l−1 32.9 36.9 12.0 ± 5.9 65.6 ± 34.5 3.6 ± 6.8 61.8 < 0.01
Ascomorpha ovalis 26.0 27.7 59.1 ± 21.4 13.8 ± 11.5 4.4 ± 8.6 96.7 < 0.01
Brachionus calyciflorus 29.6 32.8 10.4 ± 4.2 59.3 ± 29.8 3.6 ± 6.6 69.7 < 0.01
Keratella cochlearis 41.5 30.2 36.9 ± 10.7 65.3 ± 26.1 6.4 ± 7.7 66.0 < 0.01
Ploesoma hudsoni 16.8 23.4 47.6 ± 16.0 2.3 ± 3.3 1.9 ± 4.0 199.3 < 0.01
Polyarthra spp. 20.5 12.4 26.7 ± 8.3 25.8 ± 8.3 3.7 ± 5.4 65.3 < 0.01
Synchaeta oblonga 9.2 7.4 13.8 ± 6.1 10.8 ± 5.8 0.6 ± 1.8 39.5 < 0.01
Trichocerca gracilis 22.0 27.3 5.2 ± 6.9 46.8 ± 24.4 1.1 ± 2.8 68.5 < 0.01

Characteristics of each cluster based on the distribution patterns of input variables and the number of study sites in each cluster. WT (°C) – water temperature; DO (mg l−1) – dissolved oxygen; T-N (mg l−1) – total nitrogen; T-P (μg l−1) – total phosphorus

Cluster Variable Year Season Characteristics No.
Environment Rotifer
1 WT Ascomorpha ovalis, Ploesoma hudsoni, Polyarthra spp., Synchaeta oblonga 2009, 2010, 2011 spring, summer, autumn low nutrient concentration 27
2 WT, Conductivity, Turbidity, T-N, T-P, Chlorophyll a Anuraeopsis fissa, Brachionus calyciflorus, Keratella cochlearis, Polyarthra spp., Synchaeta oblonga, Trichocerca gracilis 2012, 2013, 2014, 2015 spring, summer, autumn eutrophication state, most rotifers are abundant 36
3 DO, pH, T-N - - winter low water temperature, low rotifer density 21

Land cover (m2) change of the Unmun and Sinwon streams. Res. – residential area; Com. – commercial area; Cul. – cultural/recreational area; Paddy – paddy area; Field – field

Unmun Stream Sinwon Stream
Res. Com. Cul. Paddy Field Res. Com. Cul. Paddy Field
2003 108 132 0 0 352 613 197 180 139 634 5082 0 329 444 326 708
2007 124 809 6066 0 362 887 186 557 167 932 6186 0 302 955 308 158
2013 195 124 10 734 4209 218 754 266 878 154 048 44 684 40 504 112 260 256 991
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1897-3191
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Inglese
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