Marine snow plays an important role in carbon storage and nutrient recycling in our oceans, but our impacts are starting to alter this natural phenomenon in a big way.
Every day large amounts of waste materials generated by natural processes fall through the water column in
Marine snow plays an important role in carbon storage and nutrient recycling in our oceans, but our impacts are starting to alter this natural phenomenon in a big way.
Every day large amounts of waste materials generated by natural processes fall through the water column in our oceans and settle on the seafloor. This is known as marine snow and, unlike the cold icy variety we experience, it is significantly more abundant, diverse and ecologically important. It provides food to the creatures of the deep and traps carbon absorbed by the oceans deep underwater. However this incredible natural process is starting to show signs of being impacted by our actions right as we start to need it the most. So what really makes up marine snow? And why is it so vital to marine life and us?
What is marine snow?
Marine snow is the general term given to particles of waste that fall through the water column towards the seafloor. There are two main types of marine snow, organic waste and inorganic waste. The majority of it is organic and consists of things like dead plankton, fish scales, decaying flesh and faeces, collectively known as detritus. The smaller inorganic component of marine snow consists of sand, soot and other dusts. The particles or ‘snowflakes’ of marine snow are usually around half a millimetre in size, but as they slowly reach the deep ocean they clump together and accumulate extra waste and can reach up to 10cm in size. This can take days and even weeks as the snowflakes slowly fall through the dense seawater, often appearing to barely move at all.
Settling on the seafloor
After days and weeks of falling into the deep the majority of marine snow will actually never make it to the bottom of the ocean (only around 3% reaches the seafloor) as it is instead consumed and recycled by marine creatures. However the snow that does not get re-used does end up settling on the seafloor like dead leaves falling to the forest floor. In coastal waters and on shallow continental shelves this layer of waste will quickly be utilized by crustaceans, molluscs and other bottom dwellers. However in the deep ocean open it joins a thick layer of debris commonly referred to as ‘ooze’. In some parts of the ocean this ooze can be hundreds of metres thick and is millions of years old.
Although marine snow occurs 24 hours a day throughout the entirety of our oceans it does not show consistent patterns of ‘snowfall’ throughout the year. Like real snow this is a result of changes in seasons, but rather than falling hardest in the winter, marine snow peaks in the spring. This is because in the oceans spring provides the ideal conditions for phytoplankton blooms. 