Aquatic Sciences Meeting, Albuquerque 2001

SS21 Ultraviolet Radiation and the Aquatic Biota (Disciplinary Connections)

Date: Wednesday, February 14, 2001, Time: 11:15:00 AM

Location: Galisteo

Neale, P, J, Smithsonian Environmental Research Center, Edgewater, MD, USA, neale@serc.si.edu

BIOLOGICAL WEIGHTING FUNCTIONS FOR UV INHIBITION OF PHOTOSYNTHESIS: COMPARISONS BETWEEN ENVIRONMENTS

The impact of solar ultraviolet radiation on aquatic biota is strongly dependent on both the light environment (incident intensity, water transparency) and the sensitivity of organisms to UV. We have less understanding of how much, and why, sensitivity varies compared to the aquatic UV environment. The sensitivity of phytoplankton photosynthesis to inhibition by ultraviolet radiation, as represented by biological weighting functions, has been determined for both cultures and natural assemblages in a variety of environments (polar, temperate, marine, estuarine and freshwater). Sensitivity varies widely over this diverse group: weights span about two orders of magnitude and responses with time show a varying contribution of repair. However, several patterns emerge when comparisons are made over fixed exposure periods (to adjust for kinetic differences). Natural assemblages are generally much more sensitive than nutrient sufficient cultures, particularly in the UVA (320-400 nm), though resistant assemblages are sometimes encountered. Resource availability (energy/nutrients) appears to be an important determinant of the expression of cellular defenses against UV.

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Aquatic Sciences Meeting, Albuquerque 2001

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