Experimental assessment of the effect of UVB radiation on plankton community metabolism along the Southeastern Pacific off Chile

摘要

The potential effects of UV on community metabolism (NCP, GPP and R) wereassessed along the Southeast Pacific off the Chilean coast during theHumbold-2009 cruise (54.80° S–23.85° S) on board R/VHespérides from 5 to 15 March 2009. Estimates of community metabolismwere performed at eight stations, including three stations on Patagonianfjords and five stations on the Humboldt Current System. The effect of UVBradiation on net community production (NCP) was evaluated at the stations inthe Humboldt Current system by comparing metabolic rates derived usingquartz bottles, largely transparent to UVB, and borosilicate glass, which isopaque to UVB and part of UVA, incubated under the ambient solar radiation.Autotrophic planktonic communities with variable NCP prevailed along thearea, with the highest NCP rates (7.1–11.1 mmol O2 m?3 d−1)observed in the Patagonian fjords and the northernmost station. All fiveexperiments showed significantly different NCP rates between communitiesincubated under the full ambient radiation and those incubated under reducedUVB. One of the experiments showed elevated NCP when the community wasexposed to the full solar radiation, while four experiments showed asignificantly lower NCP in the presence of UVB. These results suggest thatthe intense UVB radiation in this area, partly inhibits NCP in the SouthwestPacific off Chile.