Sea foam

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Sea foam is a bubbly layer that forms when seawater with dissolved organic matter is stirred by waves near the shore. The organic stuff, including proteins, lipids, and other compounds from algae and plankton, acts like soap and helps air bubbles stick together. As waves crash, air gets trapped in the water, bubbles rise to the surface, and they join to make foam that can cling to itself and spread with the wind.

Foam is a global phenomenon, but its amount and character change by location. It can travel inland on strong coastal winds and is sometimes affected by pollution from oil, detergents, pesticides, and other human activities. Sea foam forms in similar ways to sea spray, but it contains higher amounts of dissolved organic matter, which helps stabilize the bubbles.

What foam is made of varies, but it’s usually a mix of decayed plant and animal material, bacteria, plankton, and seaweed debris. In some places, it can be rich in proteins and fats. The exact mix changes with seasons and nearby ecosystems. Foam can also contain small amounts of pollen in some regions, altering its chemistry.

Foam can be unstable and last only seconds, or it can persist for hours or days if tiny particles (like minerals) or certain salts help stabilize the bubbles. Unfiltered seawater often helps foam last longer than filtered water.

Ecologically, sea foam can provide food for some marine organisms and act as a way to move nutrients around in the coastal environment. It can also transport algae and other organisms to new areas, and it can trap and host various microbes.

Despite being a natural feature, sea foam isn’t always harmless. It can pick up pollutants from the surface, including petroleum compounds, pesticides, metals, and PFAS, and these substances can affect the foam’s toxicity and how long it lasts. Harmful algal blooms can produce toxic foams that may irritate the airways or skin and can be dangerous for people and wildlife. Foams near oil and gas facilities or busy urban areas may contain more pollutants and microbes adapted to those conditions.

In short, sea foam is a natural mix of air, water, and organic material that forms when waves churn the ocean’s surface. It plays a role in coastal ecosystems, but it can also reflect nearby pollution and environmental stress.