Abstract
Uncovering the limiting factors for benthic algal distributions in lakes is of great importance to understanding of their role in global carbon cycling. However, limited is known about the benthic algal community distribution and how they are influenced by geographic distance and environmental variables in alpine lakes. Here, we investigated the benthic algal community compositions in the surface sediments of six lakes on the Qinghai-Tibetan Plateau (QTP), China (salinity ranging from 0.8 to 365.6 g/L; pairwise geographic distance among the studied lakes ranging 8–514 km) employing an integrated approach including Illumina-Miseq sequencing and environmental geochemistry. The results showed that the algal communities of the studied samples were mainly composed of orders of Bacillariales, Ceramiales, Naviculales, Oscillatoriales, Spirulinales, Synechococcales, and Vaucheriales. The benthic algal community compositions in these QTP lakes were significantly (p < 0.05) correlated with many environmental (e.g., dissolved inorganic and organic carbon, illumination intensity, total nitrogen and phosphorus, turbidity and water temperature) and spatial factors, and salinity did not show significant influence on the benthic algal community structures in the studied lakes. Furthermore, geographic distance showed strong, significant correlation (r = 0.578, p < 0.001) with the benthic algal community compositions among the studied lakes, suggesting that spatial factors may play important roles in influencing the benthic algal distribution. These results expand our current knowledge on the influencing factors for the distributions of benthic alga in alpine lakes.
Highlights
The littoral zone of lakes is one of the most productive ecosystems on Earth, and it plays significant roles in the functioning of lacustrine ecosystems (Howard-Williams and Lenton, 1975; Strayer and Likens, 1986; Stoffels et al, 2005)
It is expected that environmental variables significantly affected the distribution of the benthic algal community in the studied lakes, which was evidenced by the significant correlation between benthic algal community composition and water temperature, light intensity, turbidity, and nutrient-related variables (i.e., dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), total phosphorus (TP), total nitrogen (TN)) (Figure 4)
It is remarkable to observe a strong correlation between benthic algal community structures and geographic distance in the studied lakes (Table 2), and that the dissimilarities of benthic algal communities increased with increasing geographic distance among the studied lakes (Figure 5)
Summary
The littoral zone of lakes is one of the most productive ecosystems on Earth, and it plays significant roles in the functioning (e.g., carbon cycling) of lacustrine ecosystems (Howard-Williams and Lenton, 1975; Strayer and Likens, 1986; Stoffels et al, 2005) Such inshore habitat hosts diverse algal communities, which are important contributors for primary production in aquatic ecosystems (Nozaki, 2001; Nozaki et al, 2003; Mooij et al, 2005; Nõges et al, 2010). Geographic distance influence on the algal (e.g., diatom) distribution was reported in some freshwater aquatic ecosystems (e.g., river, wetlands, streams) (Astorga et al, 2012; Wetzel et al, 2012; Goldenberg Vilar et al, 2014), studies are limited on benthic algal community composition and distribution in saline lakes. Illumina-Miseq sequencing was employed to investigate the plastid 23S rRNA genes of the benthic algal community compositions in these lake sediments
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