title: HS1_100
design: Approximately 0.6 g of each sediment sample was used for DNA extraction. In brief, sediment DNA was extracted and purified using the FastDNA Spin Kit (MP Biomedical, USA) according to the manufacturers instructions. For metabarcoding, the V4-V5 region of eukaryotic 18S rRNA genes was amplified using PCR primers 528F (5-GCGGTAATTCCAGCTCCAA-3) and 706R (5-AATCCRAGAATTTCACCTCT-3). To facilitate sample multiplexing, 6-bp barcodes were attached to the forward primers. PCR was conducted with an initial denaturation at 98 C for 1 min; 30 cycles of 98 C for 10 s, 50 C for 30 s, and 72 C for 30 s; followed by a final extension at 72 C for 5 min. PCR products were purified with a GeneJET Gel Extraction Kit (Thermo Scientific), and sequencing libraries were generated using the Illumina TruSeq DNA PCR-Free Library Preparation Kit (Illumina, USA). Sequencing was performed on an Illumina MiSeq PE331 platform (Novogene, China).