Ultraviolet-B radiation effects on the structure and function of lower trophic levels of the marine planktonic food web.

摘要: Abstract The impact of UV-B radiation (UVBR; 280–320 nm) on lower levels a natural plankton assemblage (bacteria, phytoplankton and microzooplankton) from the St. Lawrence Estuary was studied during 9 days using several immersed outdoor mesocosms. Two exposure treatments were used in triplicate mesocosms: UVBR (N treatment, considered as control treatment) lamp-enhanced (H simulating 60% depletion ozone layer). A bloom developed after day 3, but no significant differences found between entire experiment for biomass (chlorophyll cell carbon) nor abundances flow cytometry optical microscopy three size classes (picoplankton, nanoplankton microplankton). In contrast, bacterial showed significantly higher values H attributed to decrease predation pressure due dramatic reduction ciliate (∼70–80%) tre...