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Willeke Lecture Sheds Light on the Deoxygenation of Ocean Waters- and what we can do to Help

By: Lindsey Brown

The average person consumes 19 cubic feet of oxygen a day; multiply that by 7.7 billion people - that’s quite a bit of oxygen. As the human population grows, the amount of oxygen we consume continues to climb and places a stress on our largest oxygen resource- the oceans. Annually, oceans provide approximately 1.6 gigatons of oxygen for all inhabitants of Earth. However, due to increasing population size, rising temperatures and nutrient enrichment, the deoxygenation of our oceans is occurring rapidly. Dr. Denise Breitburg, a senior environmental specialist at the Smithsonian Environmental Research Center, spoke on Thurs, Feb.7 as a part of the Willeke Lecture Series, presented by Miami University’s Institute for the Environment and Sustainability. She spoke regarding the deoxygenation of our oceans, the effects on people and animal populations and some potential solutions we can all practice.Dr. Breitburg began her presentation revering the oceans as “source[s] of wonder and inspiration” and considers them to be the “lifeblood of Planet Earth.” She continued to describe, however, that in the last few decades the oceans have become “hot, sour and breathless” due to the deoxygenation and acidification of their waters. Breitburg explained that the primary reasons for these detrimental changes are the rapidly growing human population, warming temperatures, as well as the elevating amounts of nutrients entering the ocean.All humans need oxygen; so do all animals, plants and all other types of organisms. As these populations augment, especially humans, the demand for oxygen continues to grow, with no rise in supply. The human population has nearly tripled since the mid-20th century; with the exponential growth of human oxygen needs, the oceans cannot keep up.Breitburg also discussed the disastrous effects on warming temperatures of oceans’ water through climate change that lead to deoxygenation. She expounded that as temperatures climb–due to global warming and increasing greenhouse gas emissions– the metabolic rates of marine creatures increase as well, requiring more oxygen to maintain function. Warming temperatures decrease oxygen introduction and additionally lead to stratification and alterations of the ocean’s currents.  The third primary cause of deoxygenation is too many nutrients becoming involved in the oceans’ waters. These nutrients are from agricultural and sewage waste are entering oceans’ waters at astonishing levels. Eutrophication–the process of too many nutrients becoming introduced to water– leads to lower oxygen levels in the water. In this case, too much of a good thing really is harmful. Her research has shown that eutrophication levels are highly dense in coastal areas with large populations and minimal policies regulating dumping practices.All these factors combine to greatly reduce the amount of oxygen in the oceans available to humans and to organisms living in the ocean. Low oxygen amounts act as a stress to fish, as they are unable to achieve homeostasis without necessary oxygen amounts. The exacerbation of disease progression, due to the stress of little oxygen, leads to decline in and harm to fish populations. Additionally, oxygen affects food webs and diversity in all ecosystems; a decline in oxygen levels leads to alterations in energy flow in an ecosystem and disrupting its habitual patterns.  While marine species face troubles in the water, human communities who rely on aquaculture and fisheries as their livelihoods and food sources combat issues of their own. Fisheries must maintain a mobile and efficient strategy to stay ahead of the growing hypoxic regions in their hunting waters. Economies and food supplies are negatively impacted, and Breitburg believes these economic concerns only stand to grow in the next few decades, although food securities and economies are challenging to predict.These startling facts and daunting conclusions are great causes for concern, but Dr. Breitburg explained that there are solutions to these issues. She demonstrated the paramount method to reduce deoxygenation includes reducing greenhouse gas emissions, and she stressed that planning, regulating and having clear goals is critical. She concluded her presentation with a call to action for her audience, encouraging students to increase engagement with civil society and policymakers to help our struggling oceans. In her urging, she believes everyone can tackle the problem of deoxygenation in oceans together. While it may seem dismaying, the rescuing of our oceans is something we can all help to achieve, one step at a time.  

Photo by IES Wikeke Lecture Series.