Temporal and Spatial Dynamics of Archaeal Communities in Two Freshwater Lakes at Different Trophic Status

Abstract

In either eutrophic Dianchi Lake or mesotrophic Erhai Lake, the abundance, diversity, and structure of archaeaplankton communities in spring were different from those in summer. In summer, archaeaplankton abundance generally decreased in Dianchi Lake but increased in Erhai Lake, while archaeaplankton diversity increased in both lakes. These two lakes had distinct archaeaplankton community structure. Archaeaplankton abundance was influenced by organic content, while trophic status determined archaeaplankton diversity and structure. Moreover, in summer, lake sediment archaeal abundance considerably decreased. Sediment archaeal abundance showed a remarkable spatial change in spring but only a slight one in summer. The evident spatial change of sediment archaeal diversity occurred in both seasons. In Dianchi Lake, sediment archaeal community structure in summer was remarkably different from that in spring. Compared to Erhai Lake, Dianchi Lake had relatively high sediment archaeal abundance but low diversity. These two lakes differed remarkably in sediment archaeal community structure. Trophic status determined sediment archaeal abundance, diversity and structure. Archaeal diversity in sediment was much higher than that in water. Water and sediment habitats differed greatly in archaeal community structure. Euryarchaeota predominated in water column, but showed much lower proportion in sediment. Bathyarchaeota was an important component of sediment archaeal community.

Keywords: Bathyarchaeota; Euryarchaeota; freshwater lake; microbial community; planktonic; sediment; trophic status.

FIGURE 1

Abundance of archaeal 16S rRNA gene in spring and summer water samples (A) and sediment samples (B) from different sampling locations in Dianchi Lake and Erhai Lake. Different letters above the columns indicate the significant differences (P < 0.05).

FIGURE 2

Archaeal community operational taxonomic units (OTUs) (A), Chao1 richness estimator (B), Shannon index (C), and Simpson index (D).

FIGURE 3

Share OTUs among waters and sediments for pooled sequences. The Venn diagram was plotted using program R. DS and ES represent the sediments from Dianchi Lake and Erhai Lake, respectively, while DW and EW represent the waters from Dianchi Lake and Erhai Lake, respectively.

FIGURE 4

Unweighted pair group method with arithmetic mean (UPGMA) clustering of water and sediment samples from Dianchi Lake and Erhai Lake. Samples DWAp1, DWAp2, DWAp3, DWAp4, DWAp5, and DWAp6 represent the April water samples from sites D1–D6 in Dianchi Lake, respectively. Samples DWAu1, DWAu2, DWAu3, DWAu4, DWAu5, and DWAu6 represent the August water samples from sites D1–D6 in Dianchi Lake, respectively. Samples EWAp1, EWAp2, EWAp3, EWAp4, EWAp5, and EWAp6 represent the April water samples from sites E1–E6 in Erhai Lake, respectively. Samples EWAu1, EWAu2, EWAu3, EWAu4, EWAu5, and EWAu6 represent the August water samples from sites E1–E6 in Erhai Lake, respectively. Samples DSAp1, DSAp2, DSAp3, DSAp4, DSAp5, and DSAp6 represent the April sediment samples from sites D1–D6 in Dianchi Lake, respectively. Samples DSAu1, DSAu2, DSAu3, DSAu4, DSAu5, and DSAu6 represent the August sediment samples from sites D1–D6 in Dianchi Lake, respectively. Samples ESAp1, ESAp2, ESAp3, ESAp4, ESAp5, and ESAp6 represent the April sediment samples from sites E1–E6 in Erhai Lake, respectively. Samples ESAu1, ESAu2, ESAu3, ESAu4, ESAu5, and ESAu6 represent the August sediment samples from sites E1–E6 in Erhai Lake, respectively.

FIGURE 5

Comparison of the quantitative contribution of the sequences affiliated with different archaeal classes to the total number of sequences from a given lake water or sediment sample. The archaeal sequences that could not be affiliated with known phylum are included as “others”. Samples DWAp1, DWAp2, DWAp3, DWAp4, DWAp5, and DWAp6 represent the April water samples from sites D1–D6 in Dianchi Lake, respectively. Samples DWAu1, DWAu2, DWAu3, DWAu4, DWAu5, and DWAu6 represent the August water samples from sites D1–D6 in Dianchi Lake, respectively. Samples EWAp1, EWAp2, EWAp3, EWAp4, EWAp5, and EWAp6 represent the April water samples from sites E1–E6 in Erhai Lake, respectively. Samples EWAu1, EWAu2, EWAu3, EWAu4, EWAu5, and EWAu6 represent the August water samples from sites E1–E6 in Erhai Lake, respectively. Samples DSAp1, DSAp2, DSAp3, DSAp4, DSAp5, and DSAp6 represent the April sediment samples from sites D1–D6 in Dianchi Lake, respectively. Samples DSAu1, DSAu2, DSAu3, DSAu4, DSAu5, and DSAu6 represent the August sediment samples from sites D1–D6 in Dianchi Lake, respectively. Samples ESAp1, ESAp2, ESAp3, ESAp4, ESAp5, and ESAp6 represent the April sediment samples from sites E1–E6 in Erhai Lake, respectively. Samples ESAu1, ESAu2, ESAu3, ESAu4, ESAu5, and ESAu6 represent the August sediment samples from sites E1–E6 in Erhai Lake, respectively.

FIGURE 6

Redundancy analysis (RDA) ordination plot for the first two principal dimensions of the relationships between archaeaplankton OTU composition and lake water parameters. Green filled and open circles indicate the spring and summer water samples at sites D1–D6 in Dianchi Lake, respectively. Blue filled and open circles indicate the spring and summer water samples at sites E1–E6 in Erhai Lake, respectively.

FIGURE 7

Redundancy analysis ordination plot for the first two principal dimensions of the relationships between sediment archaeal OTU composition and sediment parameters. Green filled and open circles indicate the spring and summer sediment samples at sites D1–D6 in Dianchi Lake, respectively. Blue filled and open circles indicate the spring and summer sediment samples at sites E1–E6 in Erhai Lake, respectively.