We tend to relate oxygen with the air we breathebut the reality is that it is also an essential component of all the waters on the planet, from oceans to rivers and lakes. That is why the call just made by a team of scientists from the University of California San Diego is so important. In a recently published study, they show that the dissolved oxygen in all these waters is plummeting and that this could have disastrous consequences. For this reason, they point out that it would be advisable to establish aquatic oxygen as one of the factors that can become points of no return in the decline of our planet.
The pace is alarming. According to these scientiststhe rate at which aquatic oxygen levels are falling is very alarming. It is due to several reasons. For a start, may be a consequence of excess nutrients known as eutrophication. Fertilizers, for example, are very rich in nitrogen, which is one of the most important nutrients for algae growth. When these proliferate too much, they cloud the water and prevent sunlight from adequately reaching aquatic photosynthetic organisms. This is the first cause of the decrease in aquatic oxygen levels. On the other hand, when these algae die they fall to the bottom and are degraded by bacteria that consume a lot of oxygen. There we will have even less.
On the other hand, hot water dissolves less oxygen than cold water. And we already know how much the planet’s water is warming lately. Finally, changes in water movement and ventilationfor example by the construction of dams, can hinder the distribution of oxygen in the water.
The consequences. Decreased aquatic oxygen levels are detrimental for many reasons. To begin with, living beings that breathe directly in water can clearly suffer the consequences. This ranges from microscopic organisms to fish and the sharks. However, even marine mammals, which come to the surface to breathe, suffer the consequences of this deoxygenation, as their prey relocates and their habitats are damaged.
On the other hand, many chemical processes that help regulate the climate on Earth suffer the effects of aquatic deoxygenation. This is the case of the carbon cycle, for example.
The nine planetary limits. The planetary limits are nine scenarios with thresholds within which humanity can continue to develop without there being an imminent danger to the planet. Once they are exceeded, it is assumed that the point of no return The deterioration of the Earth is very close. These limits are established for climate change, biosphere integrity, land use change, freshwater use, biogeochemical fluxes, ocean acidification, stratospheric ozone layeratmospheric aerosol loading and new entities, formerly known as chemical pollution.
For each of these contexts, there is an established limit that should not be exceeded. However, according to the last review of their status, The threshold has already been crossed in seven of them.
Aquatic oxygen as the tenth planetary limit. The authors of the study just published point out that aquatic oxygen should also be considered a planetary limit. Their levels are declining dangerously and action must be taken on the matter as soon as possible, as they affect ecosystems and the climate very directly. If this “title” were given, perhaps we would be more aware of its evolution and we could take action on the matter in time. For now, it’s just a proposal. However, given what we have seen, it is something that should be taken very seriously. We talk about forests as the lungs of the planet, but we cannot forget the aquatic lung. After all, that is where life first emerged.
Images | Magnificent
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