Animals and ocean deoxygenation

A paper just published A 2021 Horizon Scan of Emerging Global Biological Conservation Issues (Sutherland et al 2020) identifies “Deoxygenation” impacts on Coral Reef Health and “Increases in Dissolved Iron Availability” as two of the top environmental issues on the horizon. These two are connected issues but the paper stops short of mentioning the significance of iron availability, animals and ocean deoxygenation as linked systems and the role wildlife plays in making the resulting environment habitable for humans. So I’m going to add the narrative here.

Ocean deoxygenation and iron

Iron is a key limiting nutrientA substance that contains the raw materials for life. At a chemical level, these are contained inside compounds that are absorbed into the body and essential energy-containing molecules are extracted, so that energy can be transformed into other chemical processes that use the energy for living. More in modern Earth’s oceans and as Sutherland et al (2020) point out, an outpouring of iron from polar meltwater is expected to trigger increased algal blooms and “increasing drawdown and sequestration of carbon” – reducing global warming.

Good news so far? Not quite.

Deoxygenation will also occur with this increase in algal growth at the poles. Elsewhere, a warmer climate is expected to increase algae growth, due to warmer more sunlit days. As algae die, the nutrientsEnergy and nutrients are the same thing. Plants capture energy from the Sun and store it in chemicals, via the process of photosynthesis. The excess greenery and waste that plants create, contain chemicals that animals can eat, in order to build their own bodies and reproduce. When a chemical is used this way, we call it a nutrient. As we More they release, combine with the ocean’s dissolved oxygen, making it unavailable to animals and wildlife dies.

This is also why trying to artificially tamper with iron in the oceans is a dangerous plan.

The threat without animals

The problem is, deoxygenation and loss of animals destabilises the fragile food chains that humans depend on. Even if an increase in marine plants removes more carbon, humans can’t live among a soup of algae and bacteria and we might get over-run by jellyfish. We need fish, birds, whales and sharks to survive. We’re animals of a similar size and nature and we live among them, in the structures that sits on top of the algal processes.

Think of Earth like software on a PC … at the base is MS-DOS. This basal operating system is like the sunlight that hits the Earth and all the physical continents and ocean. Microsoft Windows sits on top of MS-DOS. It’s like the plant layer, that translates the basic operations into functions that can be read by software. Then, to make life liveable, we need a suite (an “ecosystem”) of interacting software. This is run by the animals (including humans), much in the way you are currently running the computer or phone you’re using to read this. When we all operate altogether, we perform our daily tasks as part of a system, which has ‘biodiversity’ value throughout.

The way animals and ocean deoxygenation are regulated by iron

Animals help mix the ocean’s surface layers, cooling our atmosphere and delivering more oxygen into the system. Ironically, they also increase the amount of algae by introducing huge concentrations of iron into surface waters. These are the ways animals and ocean deoxygenation are linked.

Hang on a minute though, we just said more algae is bad for human habitation, didn’t we? As in everything ecosystemHow ecosystems function An ecosystem is a community of lifeforms that interact in such an optimal way that how ecosystems function best, is when all components (including humans and other animals) can persist and live alongside each other for the longest time possible. Ecosystems are fuelled by the energy created by plants (primary producers) that convert the Sun's heat energy More based, the system is non-linear.

It’s not the amount of algae that matters, it’s where and when it occurs. Iron from animals increases the diversity and abundance of algae over time but in such precise quantities, that it can’t pollute the ocean. They transfer(of nutrients) the thing that sets animals apart from plants, is that they can move. Some of the biggest migrations on Earth every day, are the movement of insects like caterpillars, from the stem of a plant to a leaf and back, before turning into butterflies and transferring the energy elsewhere. Large-scale migration of grazing animals and migratory songbirds moves More, amplifyAmplification (of nutrients and energy). Animals consume plants and other animals and in doing so, reintroduce important energy-containing nutrients back into the environment, at even higher concentrations and in patches. Amplification of energy is driven by migration and happens at every scale, from insects moving daily in and out of your vegetable patch, to African wildebeest herds and the seasonal More and concentrate nutrients in the right place and time, meaning a diversity of animals (and human fisheries, where relevant) also know where to find it. More animals might mean more algae, but it means a more stable carbon-oxygen balance, which is what humans and other animals need to survive.

The biodiversityWhat is the definition of biodiversity? When we ask, what is the definition of biodiversity? It depends on what we want to do with it. The term is widely and commonly misused, leading to significant misinterpretation of the importance of how animals function on Earth and why they matter a great deal, to human survival. Here I will try to More ‘hotspots’ we talk about, are regulated by animals, not algae. Deoxygenation is simply a redistribution of energy from places where it is useful for human survival (where animals put it), into places it is not useful e.g. abundant algal blooms. Under a “new normal”, we would see rampant algal growth across large areas of ocean in unpredictable ways, ways in which animals can’t function(Of an ecosystem). A subset of ecosystem processes and structures, where the ecosystem does something that provides an ecosystem service of value to people. More.

The take home message is that human beings exist inside the animal-led biodiversity processes, not the algae-led processes. All algae will do is absorb the same quantity of heat from the sun but in the absence of animals, there will be a failure to build the trophic systems that make Earth habitable. 

Spotlight

IUCN Ocean Deoxygenation