Ocean salinity significantly affects marine biodiversity by influencing the distribution and abundance of marine species. Fluctuations in salinity can create stress for certain organisms, particularly aquatic plants and animals that have specific salinity tolerances. Areas of higher salinity, like estuaries, may be less hospitable for some freshwater species, while others, like saltwater fish, thrive. Changes in salinity due to climate change or human activity can alter food webs, affecting predator-prey interactions and species resilience. Ultimately, understanding salinity's impact is crucial for the conservation of marine ecosystems.