If the foam is white, our ocean’s alright!
Plettenberg Bay is currently experiencing a most interesting natural phenomenon that makes its beaches look as if someone has added a particularly effective brand of bubble bath to the seawater.
Large amounts of white, fluffy foam, observed on Robberg Peninsula and various beaches, are carried in from the sea on churning waves. But what is the cause, and should beachgoers be worried?
Fortunately, this is a completely natural process and most often the sign of a healthy ecosystem.
The ocean produces a constant supply of decaying organic matter – plant life, fish, seaweed excretions, algae, microscopic organisms and other proteins and fats – that sinks down to the ocean floor.
When strong tidal movements churn up the ocean floor, it creates tiny air bubbles that carry these minute organic substances to the shore.
Once the current reaches the shore, waves cause the air bubbles to pop to the surface, forming foam as the sticky mass crashes onto the shore.
The life cycle is completed when microscopic organisms, sea lice, and birds come to feast on the bounty that is hidden inside the foam.
When the foam is white, it is usually an indication that it is not harmful, but in some cases foam contains pollutants such as oil, fertilizers and toxins produced by algal blooms.
Harmful algae blooms deplete the oxygen content of water, causing large die-offs of marine life, and increasing the amount of organic waste that can contribute to greater amounts of sea foam.
In this case, the foam shows different colours ranging from slimy green to brown.
Fortunately, the foam we see on our beaches now is all part of a healthy, natural process and, in the short time that it is here, makes for wonderful and interesting photo opportunities.
Written by Chrissie Cloete.
• Chrissie Cloete is an Environmental Biologist and freelance nature conservation consultant – contact her on xc.cloete@gmail.com for additional information.