Table S1 rbcl_all_tax_length_metadata.csv

All 4,206 assembled freshwater metagenomes in the IMG database, defined as those with the metadata tag “Ecosystem Type = Freshwater”, were delineated on February 23, 2023 and scanned for genes that had been assigned domain annotation pfam00016 by the IMG metagenome annotation pipeline. Gene nucleotide sequences were downloaded along with source genome metadata and estimated scaffold read depth metrics. Genes were classified using the constructed rbcL taxonomic classifier following import into qiime2-amplicon-2023.9 operated with a minimum confidence threshold of 0.7.