In the deep ocean, marine snow is a continuous shower of mostly organic http://en.wikipedia.org/wiki/Detritus - detritus falling from the upper layers of the water column. Its origin lies in activities within the productive http://en.wikipedia.org/wiki/Photic_zone - photic zone . Consequently, the prevalence of marine snow changes with seasonal fluctuations in http://en.wikipedia.org/wiki/Photosynthesis - photosynthetic activity and ocean currents. Thus marine snow is heavier in spring, and the reproductive cycles of some deep-sea animals are synchronized to take advantage of this ^{http://en.wikipedia.org/wiki/Wikipedia:Citing_sources - http://en.wikipedia.org/wiki/Polymer - polymers exuded as waste products by http://en.wikipedia.org/wiki/Bacterium - bacteria and http://en.wikipedia.org/wiki/Phytoplankton - phytoplankton . These aggregates grow over time and may reach several centimetres in diameter, travelling for weeks before reaching the ocean floor.}

However, most organic components of marine snow are consumed by http://en.wikipedia.org/wiki/Microbe - microbes , http://en.wikipedia.org/wiki/Zooplankton - zooplankton and other filter-feeding animals within the first 1,000 metres of their journey. In this way marine snow may be considered the foundation of deep-sea http://en.wikipedia.org/wiki/Mesopelagic - mesopelagic and http://en.wikipedia.org/wiki/Benthic - benthic http://en.wikipedia.org/wiki/Ecosystem - ecosystems : As sunlight cannot reach them, deep-sea organisms rely heavily on marine snow as an energy source. The small percentage of material not consumed in shallower waters becomes incorporated into the muddy "ooze" blanketing the ocean floor, where it is further decomposed through biological activity.

Marine snow has begun to garner interest from http://en.wikipedia.org/wiki/Microbiology - microbiologists , owing to the microbial communities associated with it. Recent research indicates transported bacteria may exchange http://en.wikipedia.org/wiki/Gene - genes with what were previously thought to be isolated populations of bacteria inhabiting the breadth of the ocean floor. In such an immense area there may be as yet undiscovered species tolerant of high pressures and extreme cold, perhaps finding use in http://en.wikipedia.org/wiki/Bioengineering - bioengineering and http://en.wikipedia.org/wiki/Pharmacy - pharmacy .

Some scientists have suggested that marine snow could play a role decreasing the http://en.wikipedia.org/wiki/Atmosphere - atmospheric concentration of anthropogenic http://en.wikipedia.org/wiki/Carbon_dioxide - carbon dioxide (and mitigate the strength of the http://en.wikipedia.org/wiki/Greenhouse_effect - greenhouse effect ). By http://en.wikipedia.org/wiki/Iron_fertilization - fertilising certain http://en.wikipedia.org/wiki/HNLC - unproductive regions of the http://en.wikipedia.org/wiki/World_ocean - world ocean , the resulting phytoplankton blooms could, via sinking marine snow, transport extra carbon to the deep ocean. Because of the relatively long residence time of the ocean's http://en.wikipedia.org/wiki/Thermohaline_circulation - thermohaline circulation , carbon transported this way could remain out of contact with the atmosphere for more than 1000 years. Projected increases in ocean temperatures caused by http://en.wikipedia.org/wiki/Global_warming - global warming may result in a decrease in the production of marine snow via the enhanced http://en.wikipedia.org/wiki/Stratification_%28water%29 - stratification of the water column. Increasing stratification decreases the availability of phytoplankton nutrients such as http://en.wikipedia.org/wiki/Nitrate - nitrate , http://en.wikipedia.org/wiki/Phosphate - phosphate and http://en.wikipedia.org/wiki/Silicic_acid - silicic acid , and could lead to a decrease in primary production and, thus, marine snow.