international Polar Year science

摘要: ABSTRACT. The Ross Sea polynya is one of the most productive areas Southern Ocean; however, little known about how plankton there respond to inhibitory solar exposure, particularly during early-spring period enhanced UVB (290– 320 nm) due ozone depletion. Responses exposure phytoplankton and bacterial assemblages were studied aboard research ice breaker Nathaniel B. Palmer cruises NBP0409 NBP0508. Photosynthesis production (thymidine leucine incorporation) measured in situ incubations upper 10 m at three stations, which occupied before, during, after annual peak a bloom dominated by Phaeocystis antarctica. Near-surface was consistently inhibited down 5– 7 m, even when some surface present. Relative inhibition increased productivity decreased with increas-ing severity nutrient limitation as diagnosed using F v / , measure maximum photosynthetic quantum yield. high for both high-biomass postbloom but sensitivity thymidine uptake differed between stations. These results provide fi rst direct evidence that particular ultraviolet radiation, causes signifi cant productivity.