1.3.4.6 Summary of marine and freshwater biological systems

In marine and freshwater ecosystems, many observed changes in phenology and distribution have been associated with rising water temperatures, as well as changes in salinity, oxygen levels and circulation. While there is increasing evidence for climate change impacts on coral reefs, separating the impacts of climate-related stresses from other stresses (e.g., over-fishing and pollution) is difficult. Globally, freshwater ecosystems are showing changes in organism abundance and productivity, range expansions, and phenological shifts (including earlier fish migrations) that are linked to rising temperatures. Many of these climate-related impacts are now influencing the ways in which marine and freshwater ecosystems function.