Climate change is threatening the world’s marine ecosystems in myriad ways, due to rising temperatures, ocean acidification, and sea-level rise. Another often-overlooked effect is that warmer temperatures and changing weather patterns can alter the transmission of many marine parasites and infectious diseases. Such diseases don’t just impact their host populations, as cascading effects can disrupt entire ocean food webs. Krti Tallam at Stanford University studies the evolution of marine parasites and diseases, along with the broader implications for marine ecology. In a recent review paper, Tallam focuses on critically important ecosystems within intertidal zones.