Climate change will include a decrease in seawater salinity in the Baltic Sea. We quantified the effects of the projected future desalination on survival of the early life stage of the littoral herbivore Idotea balthica. We collected egg-bearing Idotea from three range-margin Baltic Sea populations, we exposed half of each brood to either current (6‰) or future salinity (3.5‰). We genotyped a subsample of each brood to analyse patterns of allelic change and to identify genomic regions targeted by selection. The survival was overall reduced by hyposalinity and broods varied in response to hyposalinity implying genetic variation in tolerance, with a stronger decrease in genetic diversity in future salinity. Finally, we identified proteins with crucial roles in basic cellular functions. This study indicates that projected future northern Baltic Sea hyposalinity will not just hamper I. balthica survival, but its selective pressure may also affect genetic diversity and cell physiology.

气候变化将包括波罗的海的海水盐度降低。我们量化了预计的未来海水淡化对沿海食草动物Idotea balthica早期生存期的影响。我们收集了鸡蛋轴承Idotea我们从三个边际波罗的海种群中，将每个亲鱼的一半暴露于当前（6‰）或未来的盐度（3.5‰）。我们对每个育雏的子样本进行了基因分型，以分析等位基因变化的模式并确定通过选择靶向的基因组区域。低盐度使总体生存期降低，而低盐度对亲代的影响则不同，这意味着耐受性的遗传变异，而未来盐度的遗传多样性则有更大的降低。最后，我们鉴定了在基本细胞功能中起关键作用的蛋白质。这项研究表明，预计未来的北波罗的海低盐度不仅会影响巴氏衣原体的存活，而且其选择压力还可能影响遗传多样性和细胞生理。