UV RADIATION AND THE AQUATIC ENVIRONMENT 



RAYMOND C. SMITH 



Center for Remote Sensing and Environmental Optics 



University of California 



Santa Barbara, CA 93105 



ABSTRACT: The work of numerous investigators provides conclusive evidence that 

 exposure to Middle Ultraviolet (MUV) Radiation decreases algal productivity. 

 Indeed, there is convincing evidence that MUV radiation, at present levels 

 incident at the surface of the ocean, has an influence on phytoplankton as 

 currently measured by fixed bottle 14-C productivity incubations. These results 

 suggest, but cannot prove, that ozone reduction may be harmful to phytoplankton 

 populations in Antarctic waters. The ozone reduction over Antarctic waters 

 during the Austral spring is now so large that it may be possible to carry out a 

 definite experiment and provide a direct quantitative assessment of enhanced MUV 

 on Antarctic phytoplankton populations. Data on motion of the ozone hole show 

 that there is substantial motion of the position of the hole relative to 

 geographical locations. The strong gradient in ozone, which characterizes the 

 ozone hole, causes a corresponding strong gradient in MUV; i.e., a "front" of 

 MUV. This front, analogous to oceanographic fronts, provides the opportunity to 

 carry out experiments on either side of the front and to compare the influence of 

 change in MUV stress in mature phytoplankton populations. 



REFERENCES: 



Baker, K.S. and R.C. Smith, 1982. Spectral irradiance penetration in natural 

 waters. In, The Role of Solar Ultraviolet Radiation in Marine Ecosystems (J. 

 Calkins, ed.). Plenum Press, New York, pp. 233-246. 



Baker, K.S., R.C. Smith, and A.E.S. Green, 1980. Middle ultraviolet radiation 

 reaching the ocean surface. Photochem. Photobiol. 32(3): 367-374. 



Baker, K.S., R.C. Smith and A.E.S. Green, 1982. Middle ultraviolet irradiance at 

 the ocean surface: measurements and models. In, The Role of Solar Ultraviolet 

 Radiation in Marine Ecosystems (J. Calkins, ed.). Plenum Press, New York, pp. 

 79-91. 



Kubitschek, H.E., K.S. Baker and M.J. Peak, 1986. Enhancement of mutagenesis and 

 human skin cancer rates resulting from increased fluences of solar ultraviolet 

 radiation. Photochem. Photobiol. 43: 443-447. 



Smith, R.C, 1974. Structure of solar radiation in the upper layers of the sea. 

 In, Optical Aspects of Oceanography, Chapter 5 (J.G. Jerlov, ed.). Academic 

 Press, New York, pp. 95-119. 



Smith, R.C. and K.S. Baker, 1979. Penetration of UV-B and biologically effective 

 dose-rates in natural waters. Photochem. Photobiol. 29: 311-323. 



