Last week (18th to 21st March 2013), a symposium about microbial ecology and biogeochemistry of oxygen-deficient marine waters was held in Santa Cruz, Chile supported by the Agouron Institute and the Gordon and Betty Moore Foundation.
Low oxygen conditions are increasing worldwide in coastal areas as a result of human activities. Change in land use patterns, deforestation, intensive use of inorganic fertilizers in agriculture, discharge of industrial and municipal wastewaters have all contributed to increased nutrient inputs to rivers and coastal systems. As a consequence of these increased nutrient inputs algal blooms have increased in frequency and duration, including harmful algae, and leading to low oxygen in bottom waters when are decomposed by bacteria.
Besides human-induced low oxygen in coastal systems, there are also areas of the open ocean that have low oxygen conditions at mid-depth naturally. These open ocean areas are known as oxygen minimum zones (OMZ).
Low oxygen is a particularly severe disturbance in marine systems because it causes death of organisms and catastrophic changes in ecosystems.
“As oxygen levels decline, energy is increasingly diverted away from higher trophic levels into anaerobic microbial pathways, leading to significant chemical changes in the environment, such as the loss of fixed nitrogen and the production of greenhouse gases.” – as pointed out by the steering committee, composed by Osvaldo Ulloa, Ricardo Letelier, Phyllis Lam, Steven Hallam, Bess Ward, Dave Karl, and Wajih Naqvi.
During the meeting we discussed similarities and differences in the physical, biogeochemical and energy flux properties of different oxygen minimum zones; comparing and contrasting microbial ecology and biogeochemistry of different low-oxygen systems. We also considered global assessments and predictions based on model outputs. Another important output of the meeting was to identify collaboration opportunities, including research proposals, such as a possible SCOR Working Group proposal on the microbial biogeochemistry of low-oxygen systems, and cross-training opportunities among research groups. Other collaboration opportunities are to participate in a Special issue about low-oxygen systems and in a EOS/ASLO Bulletin article.
The last day of the meeting was devoted to designing research projects and new experiments to address pressing questions in low-oxygen systems at different scales: laboratory, microcosm, or mesocosm and field experiments or global international field efforts. In addition, to identify current technological and methodological needs and develop an action plan and to articulate questions that require comparing different low-oxygen systems.
During the meeting, I presented a poster about “thresholds of hypoxia for marine biodiversity and its environmental modulation”. This poster summarized some of the work made during my PhD with Carlos M. Duarte.
Daniel J. Conley presented a poster about the HYPER project that established a sound scientific basis for nutrient management in the Baltic Sea to reduce hypoxia and re-establish desired ecosystem services.
It was a very fruitful meeting and I feel honoured to have been part of it. I would like to thank the steering committee and the Agouron Institute and the Gordon and Betty Moore Foundation for giving me the opportunity to participate.
Articles used to make the poster:
Vaquer-Sunyer, R., and Duarte, C. M. 2008. Thresholds of hypoxia for marine biodiversity. PNAS 105(40): 15452-15457. DOI: 10.1073/pnas.0803833105
Vaquer-Sunyer, R., and Duarte, C. M. 2010. Sulfide exposure accelerates hypoxia-driven mortality. Limnol. Oceanogr. 55(3): 1075-1082 DOI: 10.4319/lo.2010.55.3.1075
Vaquer-Sunyer, R., and Duarte, C. M. 2011. Temperature effects on oxygen thresholds for hypoxia in marine benthic organisms. Global Change Biol 17: 1788-1797. DOI: 10.1111/j.1365-2486.2010.02343.x
Steckbauer , A., Duarte, C.M., Carstensen, J., Vaquer-Sunyer, R. and Conley, D.J. 2011. Ecosystem impacts of hypoxia: thresholds of hypoxia and pathways to recovery. Environ Res Let 6(2): 025003. DOI: 10.1088/1748-9326/6/2/025003