As a young Benonian growing up in the early 90s, I remember summer holidays on Boulders Beach building sandcastles with elaborate tide-based moats and desperately trying to coerce unwilling penguins to swim with me. Salty and sun kissed, lungs filled with fresh sea air. Little did I know that when I returned to the Highveld I was still breathing in that same sea air, well, the oxygenic component at least, the mine dump dust and Jacaranda pollen were simply added extras.

The global oceans are estimated to contribute an impressive 50-85% of the oxygen (O2) present in the earth’s atmosphere. It is often assumed the Amazon and other reputable rainforests are responsible for atmospheric O2, however rainforests only cover 2% of the earth’s total surface area; the oceans cover a remarkable 71%.

Phytoplankton, delicate and diverse, a floating force of nature. Image credit: Richard Kirby

Phytoplankton, delicate and diverse, a floating force of nature. Image credit: Richard Kirby

From the Blue Planet to greenhouse gases, the delicate balance between atmospheric components ultimately controls the earth’s temperature. Greenhouse gases, including carbon dioxide (CO2), methane and ozone, absorb and re-emit a wide range of energy (heat). Carbon dioxide is naturally present in the earth’s atmosphere as part of the global carbon cycle, however human activities are raising the concentrations to new heights. Carbon dioxide acts as the global thermostat and as levels rise so does the air temperature. This in turn speeds up evaporation and increases the amount of water vapour present in the atmosphere, compounding the warming effect.

It is apparent that our earth needs O2 production and excess CO2 removal. Luckily we have a nifty two-birds-one-stone solution, packaged into sophisticated single-celled organisms known as phytoplankton. The name ‘phytoplankton’ is Greek in origin, phyton and planktos describing the ‘plant wanderers’ that range from the intrepid open ocean explorers to the green stuff in the pool the Kreepy can’t reach.

Phytoplankton are self-contained marvels of evolution, using energy from the sun to produce sugar for survival.

Phytoplankton are self-contained marvels of evolution, using energy from the sun to produce sugar for survival.This complex process is known as photosynthesis, whereby phytoplankton draw CO2 out of the atmosphere to produce simple sugars, yielding O2 as a mere manufacturing byproduct. Not only do they regulate the gaseous composition of the earth’s atmosphere but they also form the basis of the marine food web. Phytoplankton are the primary source of food for zooplankton, including krill and jellyfish, which feed fish, penguins and whales, in turn providing food for seals, sharks, dolphins and marine birds such as the awe-inspiring albatross.

Phytoplankton, also known as microalgae, have a large and diverse family tree. They inhabit both marine and freshwater systems and exist in various shapes, sizes and colours. They are perhaps most recognised for their signature green tone, due to the presence of the photosynthetic pigment chlorophyll, which is essential for capturing light energy. Phytoplankton may however also appear slightly red or brown due to the presence of other species-specific pigments.

Emma Bone, PhD student at UCT and the CSIR, deep in the Southern Ocean on board the SA Agulhas.

Emma Bone, PhD student at UCT and the CSIR, deep in the Southern Ocean on board the SA Agulhas.

So, we have phytoplankton recycling CO2 and producing O2, why is global warming still such a hot topic? Unfortunately the oceans are finite and there is a limited amount of CO2 that can be removed from the atmosphere and exported to the depths. Global oceans at present take up an estimated one third of anthropogenic CO2, with the Southern Ocean responsible for half that amount. The Southern Ocean is world’s fourth largest ocean and lies just off the coast of Mzansi, situated south of the sub-tropical front (approximately 40°S), where it extends to and encompasses the icy continent of Antarctica. It is uncertain as to whether this important carbon sink can maintain its current uptake rate with the increasing pressure placed on it by man(un)kind. With oceans slowly becoming more acidic as a direct result of excess CO2, shell-forming organisms are unwittingly falling prey to the decreasing pH, with certain armoured phytoplankton working overtime to sequester CO2 or face death by dissolution. The silent battle wages on.

On my personal journey from the slimy ponds of the Bunny Park to the Phyaeocystis antarctica blooms of the Southern Ocean, I have gained an enormous appreciation for all things algae, for the tiny conductors that unknowingly orchestrate life on earth.

As a young Benonian growing up in the early 90s, I remember summer holidays on Boulders Beach building sandcastles with elaborate tide-based moats and desperately trying to coerce unwilling penguins to swim with me. Salty and sun kissed, lungs filled with fresh sea air. Little did I know that when I returned to the Highveld I was still breathing in that same sea air, well, the oxygenic component at least, the mine dump dust and Jacaranda pollen were simply added extras.

The global oceans are estimated to contribute an impressive 50-85% of the oxygen (O2) present in the earth’s atmosphere. It is often assumed the Amazon and other reputable rainforests are responsible for atmospheric O2, however rainforests only cover 2% of the earth’s total surface area; the oceans cover a remarkable 71%.

Phytoplankton, delicate and diverse, a floating force of nature. Image credit: Richard Kirby

Phytoplankton, delicate and diverse, a floating force of nature. Image credit: Richard Kirby

From the Blue Planet to greenhouse gases, the delicate balance between atmospheric components ultimately controls the earth’s temperature. Greenhouse gases, including carbon dioxide (CO2), methane and ozone, absorb and re-emit a wide range of energy (heat). Carbon dioxide is naturally present in the earth’s atmosphere as part of the global carbon cycle, however human activities are raising the concentrations to new heights. Carbon dioxide acts as the global thermostat and as levels rise so does the air temperature. This in turn speeds up evaporation and increases the amount of water vapour present in the atmosphere, compounding the warming effect.

It is apparent that our earth needs O2 production and excess CO2 removal. Luckily we have a nifty two-birds-one-stone solution, packaged into sophisticated single-celled organisms known as phytoplankton. The name ‘phytoplankton’ is Greek in origin, phyton and planktos describing the ‘plant wanderers’ that range from the intrepid open ocean explorers to the green stuff in the pool the Kreepy can’t reach.

Phytoplankton are self-contained marvels of evolution, using energy from the sun to produce sugar for survival.

Phytoplankton are self-contained marvels of evolution, using energy from the sun to produce sugar for survival.This complex process is known as photosynthesis, whereby phytoplankton draw CO2 out of the atmosphere to produce simple sugars, yielding O2 as a mere manufacturing byproduct. Not only do they regulate the gaseous composition of the earth’s atmosphere but they also form the basis of the marine food web. Phytoplankton are the primary source of food for zooplankton, including krill and jellyfish, which feed fish, penguins and whales, in turn providing food for seals, sharks, dolphins and marine birds such as the awe-inspiring albatross.

Phytoplankton, also known as microalgae, have a large and diverse family tree. They inhabit both marine and freshwater systems and exist in various shapes, sizes and colours. They are perhaps most recognised for their signature green tone, due to the presence of the photosynthetic pigment chlorophyll, which is essential for capturing light energy. Phytoplankton may however also appear slightly red or brown due to the presence of other species-specific pigments.

Emma Bone, PhD student at UCT and the CSIR, deep in the Southern Ocean on board the SA Agulhas.

Emma Bone, PhD student at UCT and the CSIR, deep in the Southern Ocean on board the SA Agulhas.

So, we have phytoplankton recycling CO2 and producing O2, why is global warming still such a hot topic? Unfortunately the oceans are finite and there is a limited amount of CO2 that can be removed from the atmosphere and exported to the depths. Global oceans at present take up an estimated one third of anthropogenic CO2, with the Southern Ocean responsible for half that amount. The Southern Ocean is world’s fourth largest ocean and lies just off the coast of Mzansi, situated south of the sub-tropical front (approximately 40°S), where it extends to and encompasses the icy continent of Antarctica. It is uncertain as to whether this important carbon sink can maintain its current uptake rate with the increasing pressure placed on it by man(un)kind. With oceans slowly becoming more acidic as a direct result of excess CO2, shell-forming organisms are unwittingly falling prey to the decreasing pH, with certain armoured phytoplankton working overtime to sequester CO2 or face death by dissolution. The silent battle wages on.

On my personal journey from the slimy ponds of the Bunny Park to the Phyaeocystis antarctica blooms of the Southern Ocean, I have gained an enormous appreciation for all things algae, for the tiny conductors that unknowingly orchestrate life on earth.

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