It's Snowing in the Ocean

Though the title of today's blog may seem funny, it is no joke; there is snow in the ocean, and quite a lot of it. However, marine snow is definitely not what you think. There are no ice crystals forming, marine organisms don't get days off from school, and marine snow doesn't form during a particular season. Instead, marine snow is a conglomeration of sediment particles, biological materials (including dead zooplankton, fecal matter), and other organic matter that falls from the euphotic zone (top 200 meters of the ocean) to the deep sea. Marine snow is an incredibly important source of organic matter for the deep sea, as the deep sea is home of many organisms that cannot generate their own carbon. As marine snow falls through the ocean, bacteria and other organisms feed on the nutrients that are released from the snow, and other organisms may be trapped in the snow and travel to the ocean floor.

Although marine snow is really a feature of the pelagic (open ocean) zones, this week I found some examples in my coastal samples. The examples, shown here (the cloudy masses to the left of, and above, the pink blob), are likely due to resuspension of sediment in the area and the pooling of dead organic matter, falling to the seafloor in St. Andrews Bay. Although the bay system is rather shallow, marine snow can still form and provide resources to benthic organisms (living organisms that are associated with the seafloor). Marine snow can be a challenge when it is captured in samples, because the size of the conglomeration (see the difference between the snow and the individual sediment grains) means that it obscures the nematodes that I am trying to count and pick out. Also, nematodes may get trapped in the marine snow once it reaches the benthos, and removing a nematode from the mass of material can be a laborious process.

And while marine snow doesn't mean a snow day for marine schools, nor does it mean that we need to bring out our ocean plows, marine snow does provide an invaluable source of nutrients and materials for important marine organisms.

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