JPR Advance Access originally published online on November 17, 2007
Journal of Plankton Research 2008 30(2):199-210; doi:10.1093/plankt/fbm090
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Effect of short-term exposure to UVA and UVB on potential phytoplankton production in UK coastal waters
Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, PL1 3DH, UK
* CORRESPONDING AUTHOR: i.joint{at}pml.ac.uk
Received on April 2, 2007; accepted on November 15, 2007
 |
Abstract |
|---|
The influence of vertical mixing on phytoplankton sensitivity to UV light has been assessed over an annual cycle. Photosynthesis rates of natural assemblages were compared in samples that were incubated at fixed position in a light gradient and with duplicate samples that simulated vertical mixing by movement in the same gradient with a periodicity of 4 h. This is the typical time-scale of vertical mixing in coastal waters in the English Channel. There were clear seasonal differences in the short-term response of phytoplankton to enhanced UVA+UVB. For most of the year, there was no detectable effect of UV on photosynthetic carbon fixation. But natural assemblages in late winter/early spring, when high UV light may sporadically occur at this latitude, were sensitive to UVA+UVB. In some samples, primary production was 40% of that measured in the absence of UV light. At the time of maximum sensitivity to UV, the phytoplankton assemblage was dominated by diatoms. Simulated vertical mixing resulted in more inhibition of photosynthesis by UVA+UVB light than when samples were at constant light with the same time-integrated irradiance. Transient increases in UVA+UVB due to ozone depletion, such as have been observed over Northern Europe, could have a serious impact on coastal phytoplankton production in late winter/early spring.
Communicating editor: K.J. Flynn