Marine snow is a captivating ocean phenomenon that continuously drifts through the water column, resembling a silent, underwater blizzard. This gentle descent of organic and inorganic particles forms a consistent, yet often unseen, snowfall in the ocean’s depths. It represents a fundamental process linking the productive surface waters with the vast, dark regions below, shaping marine life in profound ways.
What is Marine Snow?
Marine snow refers to the continuous shower of mostly organic detritus that falls from the upper layers of the ocean to the deep sea. It appears as fluffy, white, or translucent particles suspended in the water, reminiscent of snowflakes slowly descending. This material is found throughout the water column, originating from the sunlit surface zones and gradually settling towards the ocean floor. The term “marine snow” was coined by explorer William Beebe, who observed this phenomenon from his bathysphere. These aggregates are a natural form of marine waste, encompassing a wide range of biological and non-biological components.
The Diverse Components of Marine Snow
The composition of marine snow is highly varied, primarily consisting of organic matter from the ocean’s productive surface layers. It includes dead or dying microscopic plants (phytoplankton) and animals (zooplankton), their remains, and shed tissues. Fecal pellets from various marine organisms are also a significant component, contributing to these sinking particles. Beyond these biological elements, marine snow incorporates inorganic materials such as sand, soot, and dust particles. Microscopic debris, including fragments of shells from certain phytoplankton like diatoms and coccolithophores, as well as clay minerals, also contribute.
The mixture of these components can vary based on geographic location, water depth, and the productivity of the surrounding ocean waters. For instance, areas with abundant phytoplankton blooms produce more organic components. Mucus excreted by zooplankton, such as salps and appendicularians, binds these materials together. This complex blend of organic and inorganic matter creates a rich, particulate aggregate.
How Marine Snow Forms
Marine snow forms through a process of aggregation, where smaller particles clump together to create larger aggregates. This process often begins with the death or grazing of phytoplankton in the sunlit surface waters. Microorganisms and other tiny particles, which are initially too small to sink effectively, begin to adhere to one another. Sticky substances play a role in binding these smaller pieces.
These binding agents include transparent exopolymer particles (TEPs), which are sugary mucus-like substances exuded by bacteria and phytoplankton. As these particles coalesce, they form larger, denser “snowflakes” that can range from a few millimeters to several centimeters in diameter. The increased size and density allow these aggregates to overcome the water’s buoyancy and begin their descent. The journey to the deep ocean can take weeks, with the aggregates continuously collecting more debris as they fall.
The Role of Marine Snow in Ocean Ecosystems
Marine snow serves as a primary food source for a wide array of deep-sea organisms. In the vast, dark regions of the ocean where sunlight cannot penetrate, photosynthesis is impossible, leaving organisms reliant on external food sources. Marine snow delivers nutrients and energy from the productive surface waters to these light-deprived ecosystems, sustaining creatures ranging from microscopic bacteria and zooplankton to larger invertebrates and fish. Many deep-sea animals are specialized filter feeders, adapted to capture these drifting particles.
Beyond providing sustenance, marine snow plays a role in the ocean’s biological carbon pump. This process involves the transport of carbon from the atmosphere and surface waters to the deep ocean. As marine snow, rich in organic carbon, sinks, it sequesters carbon in the deep sea, removing it from the atmosphere for potentially hundreds to thousands of years. This mechanism helps regulate Earth’s climate by storing carbon away from the atmosphere. The small percentage of marine snow not consumed during its descent eventually settles on the ocean floor, becoming part of the muddy sediment and contributing to long-term carbon storage.