Resumo

There is a consensus that climate change has the potential to alter marine ecosystems. However, researchers are still far from understanding the extent and consequences of possible interactions between climate change and anthropogenic pollution. Due to inherent complexity, the impact of factors such as ocean acidification, rising UV-B radiation and oil pills on earth´s biomes have mainly been studied independently, yet it is the extent of their synergistic effects what might truly compromise ecosystem functioning in a real case scenario. A possible way of studying potential interactions is to conduct experiments under controlled conditions. Here, we used a newly developed microcosm system (ELSS - experimental life support system) to simulate the independent and combined effects of ultraviolet radiation, low pH (7.95 ±0.07 control pH and 7.67±0.07 low pH) and oil contamination on microbes in estuarine sediment. The response of the active bacterial communities and the changes in volatile metabolite profile due to these treatments were thoroughly evaluated. The active bacterial community from each treatment was characterized by using a barcoded pyrosequencing approach of the bacterial 16S rRNA (cDNA) gene. The sediment volatile metabolite profile was determined by two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GC×GC-TOFMS). Preliminary results indicate that interactions between low pH and oil contamination modify both the sediment active bacterial communities and the volatile metabolite profile. Rising atmospheric CO2 concentrations will continue to lower oceanic pH. Although the mechanisms that underlie this interaction are not yet clear, our results indicate that in the future, coastal ecosystem responses to oil contamination might be substantially altered.