Survey of Plankton Diatoms in Nanren Lake

Study Extent

Nanren Lake is located in the Nanren Mountain Ecological Protection Area in northeastern Kenting National Park on the east coast of the Hengchun Peninsula. The geographic position is 22°50’N and 120°50’E. The altitude of the nearby Nanren Mountain to the west of Nanren Lake is 479 m, categorized as low-altitude highland. The Central Water Body of Nanren Lake was originally paddy fields and wetlands. Local residents moved away because of the hardship of making a living there. In 1982, the only outlet of the water body, Hongtu Stream, became clogged, and water stagnated to form the current Nanren Lake. According to a survey conducted in 1990, the area of the lake at that time was 22.54 ha

Sampling

Plankton diatoms collection was performed on January 18, 2018. The sampling sites were the Ancient Nanren Lake (St1), west side of the main lake (St2), and east side of the main lake (St3), as illustrated in Fig. 1. From each site, 500 mL of lake water was collected and transported to the laboratory for observation and species identification.

Method steps

1. All the diatom fluids were first concentrated in a centrifugal machine for 10 minutes at 3,500 rpm; the fresh diatoms were then observed using a differential interference contrast microscope. Subsequently, acid washing was conducted using concentrated sulfuric acid, after which observation and identification processes were performed using an electron microscope.

1. Aulacoseira granulata
   rank: species
2. Brachysira vitrea
   rank: species
3. Burliganiella siolii
   rank: species
4. Cyclotella atomus
   rank: species
5. Cymbella novazeelandiana
   rank: species
6. Diploneis oblongella
   rank: species
7. Discostella stelligera
   rank: species
8. Encyonema gracile
   rank: species
9. Eunotia camelus
   rank: species
10. Eunotia rabenhorstii var. monodon
    rank: species
11. Eunotia subarcuatoides
    rank: species
12. Eunotia yberai
    rank: species
13. Frustulia rhomboides
    rank: species
14. Geissleria decussis
    rank: species
15. Gomphonema archaevibrio
    rank: species
16. Gyrosigma scalproides
    rank: species
17. Luticola goeppertiana
    rank: species
18. Navicula leptostriata
    rank: species
19. Navicula sp.
    rank: species
20. Nitzschia alpina
    rank: species
21. Nitzschia nana
    rank: species
22. Nitzschia palea
    rank: species
23. Nitzschia subacicularis
    rank: species
24. Pinnularia brauniana
    rank: species
25. Pinnularia subgibba
    rank: species
26. Sellaphora pupula
    rank: species
27. Stauroneis anceps
    rank: species
28. Stenopterobia curvula
    rank: species
29. Surirella sp.
    rank: species

Located in the Nanren Mountain Ecological Protection Area in the northeastern part of Kenting National Park, Nanren Lake comprises three permanent lakes: the Central Water Body, Independent Nanren Lake, and Yilan Lake (or Ancient Nanren Lake). The natural freshwater lake is formed of rainwater and spring water and is the largest static ecological water system in Nanren Lake.