Effects of Global Change, Including UV and UV Screening Compounds

Primary productivity of phytoplankton and macroalgae depends on a number of external factors such as temperature, light availability and nutrients. It is affected by climate change which causes alterations in a number of parameters. Temperature increases result is changes in habitat selection and species composition and has a large impact on polar ecosystems by generating melt water which also affects species composition. Increasing solar UV radiation is a major stress factor for prokaryotic and eukaryotic phytoplankton. This is intensified by rising temperatures which result in higher stratification and a shallower mixing layer where the organisms are exposed to excessive visible and UV radiation. Phytoplankton and macroalgae counter this challenge by producing UV absorbing substances such as mycosporine-like amino acids and scytonemin-like, vertical migration and mat formation. Shoaling of the upper mixing layer also limits the accessibility to nutrients from deeper water layers. Increasing CO2 concentrations result in ocean acidification which affects productivity and calcification in animals, macroalgae and calcified phytoplankton.