Microplastics – How do They End Up in the Ocean
by Fahmi, AMD-B’s 2024 Divemaster Intern
Microplastic are tiny fragments of plastic, usually less than 5 millimeters in size, that originate from textiles, such as microfiber shedding, personal care products or cosmetics, paint, tires, and the fragmentation of larger plastics we use. Like the plastic we are familiar with, microplastics are not biodegradable. The problem now is that they are resilient and ubiquitous. Microplastics have been found in nearly every environment, including animal digestion, and even humans. Due to their tiny size, microplastics spread through things like rainfall, rivers, and direct waste dumping. These particles make their way into our oceans, spreading across marine environments and impacting ecosystems everywhere.
Why are Corals Found with Microplastics
As filter feeders, corals pull in tiny particles from the water, mistaking microplastics for food. Because of their size, microplastics closely resemble natural food sources for coral, making them easy to ingest. Studies have shown that some types of coral might even prefer these plastic particles. Unfortunately, this means microplastics get lodged in coral tissues, often staying there for a long time.
How do Researchers Study Microplastics in Coral
To investigate, scientists collect coral samples and apply special dyes to make any microplastic particles stand out. They also use methods like spectrometry and fluorescence microscopy to locate and identify plastics at the microscopic level, helping to determine how much plastic is really being taken in by coral. In some cases, researchers use a process called acid digestion, where a mild acid dissolves the calcium carbonate skeleton, leaving behind microplastic particles. This method, used by one of our team members, enables a clear analysis of embedded plastics without damaging them.
What Microplastics Mean for Coral and Marine Life
For corals, microplastics are a big concern. These particles can get trapped in coral tissues or on coral surfaces, affecting their health. When corals absorb microplastics, it can lead to physical damage, reduced feeding efficiency, and even increased vulnerability to diseases. Corals rely on tiny algae called zooxanthellae, which help them get energy through photosynthesis. Microplastics can block light, disturbing this process and possibly contributing to coral bleaching.
Marine life that depends on corals for shelter or food can also suffer. Fish, crustaceans, and other creatures might ingest microplastics, which can lead to internal injuries, malnutrition, or chemical contamination, affecting entire marine ecosystems.
