Illumina RNA sequencing to assmeble a transcriptome for the oyster Ostrea lurida and identify genes signficantly differentially expressed among three populations of oysters that differ in their tolerance of low salinity. Our new transcripmotme provides an important genomic resource for future work in this species of conservation concern. Genes differentially expressed between oyster populations provide insight into mechanisms underlying different low salinity tolerances. Overall design: Oysters from three populations (each with six repliicates) were exposed to control (34 parts per thousand) and low salinity (5 part per thousand) treatment (total n=36). A cDNA library was created for each sample and sequenced using the Illumina HiSeq 4000 platform. Twelve individual samples were multiplexed into one paired-end 150bp lane