Living Waters: Emphasising the need to protect life's breath on this planet

A fisheye view of the Great Barrier Reef Marine Park, Australia
The earliest known photosynthesising marine fossil we have record of goes back 3.5 billion years. The ocean was producing oxygen for billions of years before that. Early in our planet’s history, the atmosphere had almost no oxygen. Oxygen generated as a byproduct by photosynthesising microbes eventually built up in the atmosphere, drastically changing our planet’s environment and the history of life in the process.

A kelp forest flanks a sea lion in the Pacific Ocean off San Benito Island, Mexico
Land plants evolved from green marine algae, so we owe the ocean for all of the oxygen that comes from them as well. These submerged algae raised their heads above water once the atmospheric oxygen levels were high enough for the ozone layer to form, protecting them from lethal levels of UV radiation that pervaded the planet. Only one-third of the Earth’s oxygen comes from the green cover on land.

A NASA satellite image shows heat radiating from the Pacific
Oxygen is critical to the health of oceans. Their warming has caused a decline in phytoplankton levels by 40 percent since 1950. Ocean currents circulate cold water from depths, pushing nutrients to warmer surfaces, where planktons live, who feed on these nutrients and sunlight to grow.  Warmer water disrupts the action of ocean currents, starving planktons of nutrients, thus decreasing their ability to produce oxygen and absorb carbon dioxide, a process extremely important to the Earth’s carbon cycle.

A layer of toxic foam from sewage and industrial waste on Yamuna river in New Delhi, India
There are serious consequences to humans discharging nitrogen and phosphorus into our waterways through sewage, agriculture and industrial activity. The rise in the level of these nutrients in the water causes phytoplankton to multiply rapidly and create what’s known as an algal blooms. These toxic blooms cause zones of low oxygen in the water—often called dead zones— that can hurt the growth, reproduction and survival of fish and other animals. They can alter food webs in our estuaries and coastal oceans.

Smoke billows from a large steel plant in Inner Mongolia, China
Oceans are becoming more acidic as a result of absorbing excess carbon dioxide gas released in the atmosphere by human activity. Fossil fuel emissions and deforestation are the two major sources for carbon pollution. The rapid destruction of warm water coral reefs is evidence that ocean acidification will affect marine life. Reef ecosystems have served as ‘cradles of evolution’ throughout Earth’s biological history. More marine species have originated in reef ecosystems than in any other.

Scores of dead fish surface on the banks of the Guanabara Bay in Rio de Janeiro, Brazil
As the planet’s polluted atmosphere traps more heat, the oceans get warmer. Last year saw new highs of ocean temperature in the top 700 m and 2,000 m of water. Fish species known to hunt at depths are repeatedly floating to surface view today. The reason: Warm temperatures have knocked oxygen out of waters at great depths, making it difficult for the predators to breathe—let alone hunt—in deep waters. Insufficient oxygen in water reduces growth, increases disease, alters migratory behaviour and increases mortality of marine animals.

A fish farm in Maoer Lake, Jiangsu Province of China
The percent of seafood supplied by the aquaculture industry has risen from a mere 7 percent in 1974 to over 52 percent of all seafood consumed today. Dense aquaculture contributes to deoxygenation. Not only do densely kept animals use oxygen as they respire, but microbial decomposition of excess fish food and fish faeces also consumes oxygen. When this increased respiration and insufficient water flow occur at the same time in aquaculture pens, oxygen concentrations decline, leading to fish kills, a frequent occurrence in fish farms throughout East and Southeast Asia.

Garbage floats in the Ganga river along the ghats of Varanasi, India
A toxic soup of marine debris that gets swept into sewers, storm drains and waterways and eventually out to sea via rivers, has turned our oceans into floating garbage patches. Eight of the 10 ten rivers that carry 90 percent of the plastic that ends up in the ocean are found to be in Asia. What these rivers had in common: A vast population living along the banks, with a lack of incentive and infrastructure to recycle plastic waste. The Indus and the Ganga, carry the second and sixth highest amounts of plastic debris to the ocean.