Biggest threat is on it's way - some weird creatures eat, excrete, and transform microplastics into much harmful substances.

New reasearch has revealed alarming insights into how microplastic particles are transformed within marine ecosystems and exhibiting naive challenges to the health of the ocean’s food web. 

The study is telling how filter-feeding marine organisms modifies the behavior and composition of microplastics, creating unforeseen risks for marine environments.

Earlier studies elaborated the danger of marine animals ingesting micro plastics, while further researches is digging deep to explore how these microplastic pollution particles change after passing through the digestive systems of filter feeders. 

How filter feeders transform microplastics

Using a controlled laboratory experiment, the researchers simulated seawater environments containing ascidians and introduced two types of microplastic particles.

These particles included polystyrene (PS), a common conventional plastic, and polylactic acid (PLA), a biodegradable bioplastic marketed as environmentally friendly. The team monitored the filtration, digestion, and excretion processes over 48 hours.

The results showed stark differences between the two types of plastic. Ascidians removed 90% of polystyrene particles from the water within two hours, but these particles were reintroduced to the water after 48 hours following digestion.

Polylactic acid particles, on the other hand, decreased significantly in concentration and remained at low levels. Larger PLA particles appeared to break down during digestion – likely returning to the water as smaller, undetectable nanoparticles.

These findings reveal that while some microplastics persist in their original form, others may fragment into smaller particles, potentially amplifying their environmental impact.

Plastic disguised as organic matter

To understand the changes microplastics undergo during digestion, the team used Raman spectroscopy to analyze particles excreted by the ascidians. 

The analysis revealed a surprising transformation: the plastic particles were no longer identifiable as plastics. Instead, they appeared to be organic matter due to a fecal coating acquired in the digestive system.

Thr findings revealed that microplastic particles are excreted from the ascidian’s digestive system coated with a fecal layer, and it is likely that the marine environment also identifies these particles as this organic material.

This transformation increases the likelihood of these particles being ingested by other marine animals that feed on feces, further embedding microplastics into the food web. 

The fecal coating also facilitates bacterial colonization and the adhesion of pollutants like heavy metals and residual organic compounds, such as antibiotics, making these particles even more hazardous.

Plastic particles undergo many transformations in the environment, from weathering to digestive processes, turning them into carriers of pollutants and diseases within the food web.

Impacts of microplastics on feces

In addition to examining how filter feeders transform microplastics, the study explored how these particles affect the physical properties of feces – a vital nutrient source for many marine organisms. Feces containing microplastics displayed significant changes in behavior.

Rapid sinking

Unlike normal feces, which sink slowly and provide sustenance to organisms along their descent, feces containing microplastics sank rapidly to the seafloor. This deprives marine organisms in the water column of a crucial food source.

Localized accumulation

The faster sinking caused feces and microplastics to accumulate on the seafloor near the filter feeders, instead of dispersing evenly.

This buildup can lead to increased carbon and nitrogen levels, fostering algal blooms that disrupt marine ecosystems.

“This accumulation can increase carbon and nitrogen levels on the seafloor and trigger algal blooms, representing another critical impact of microplastics on the balance of the marine food web,”.

Complexity of microplastic pollution 

The study highlights the complexity of microplastic pollution, showing that the problem goes far beyond the particles themselves.

Their transformation through biological processes and environmental exposure creates unexpected and far-reaching consequences.

The most alarming conclusion is that the microplastic problem is far more complex than initially thought,” said the researchers. 

“Plastic pollution in the marine environment has many unexpected dimensions, and its complexities continue to grow. Sometimes, neither we nor the environment can even recognize it as plastic.”

The findings emphasize the urgent need for better technologies and strategies to mitigate the spread and impact of microplastics.

This research provides a crucial step toward understanding the hidden dimensions of microplastic pollution and calls for global action to protect marine life and the delicate ecosystems that sustain it.