Evaluation of Field Studies of UVB Radiation Effects on Antarctic Marine Primary Productivity

Abstract

Phytoplankton productivity can account for half the global production of organic carbon each year. Serious concerns exist that global thinning of atmospheric ozone (03) and associated enhancement of UV -B radiation, may impair phytoplankton primary productivity. Thus it is essential to quantify 03-related effects on primary production and elucidate regulating mechanisms underlying any impairment of phytoplankton biology by UV- B under natural conditions. Field studies conducted under the influence of the severe Antarctic 03 hole can provide the sensitivity required to quantify 03-dependent impacts on marine primary production. Given the further reduction in global stratospheric 03 expected to occur at all latitudes over the next century, the findings of these field studies may also be relevant outside polar regions. The objectives of the paper are: I) to provide an ecological framework in which to judge the findings of Antarctic field studies conducted to date; 2) to evaluate experimental designs, controls, and instrumentation suitable to address the 03 question of "whether 03-depletion, and associated enhancement of UV-B radiation, over Antarctica is reducing marine primary production in natural phytoplankton communities?"; 3) present relevant findings that may improve substantially our ability to predict changes in rates of carbon fixation within p.hytoplankton communities experiencing enhanced UV -B radiation. Findings are reported which indicate: I) that controversial results between studies can be resolved once spectral intercalibration of data is achieved; 2) that public use of both laboratory and field-based studies is fraught with misstatements and a clear lack of understanding as to what field questions can be answered with which data bases; 3) that significant 03-dependent UV -B inhibition of rates of primary production do occur in the Southern Ocean; 4) that successful modeling of the biological consequences requires a full spectral approach based on precise knowledge of the fluxes in UV-B, UV-A, and photosynthetically-available radiation.