Marine animals ingest microplastic particles and excrete them in their feces, posing a risk to the marine environment

Professor Schenker on a research dive. Credit: Dr. Tom Schlesinger.
A new study from Tel Aviv University reveals alarming findings about the spread of microplastic particles in marine food webs. In recent years, numerous studies have investigated the dangers of marine animals, and more specifically filter feeders, ingesting non-degradable microplastic particles.
In this study, the researchers sought to understand how biological filtration by filter-feeding organisms affects microplastics in the environment. This finding indicates that the particles are excreted in the faeces of marine animals and cannot be identified as plastic for the marine environment, but may be other organic matter suitable for consumption.
Furthermore, the presence of microplastics in feces affects fecal dispersal, leading to the accumulation of feces and plastic particles. This increases carbon and nitrogen levels on the ocean floor and can lead to algae blooms, with significant impacts on the balance of marine food webs.
The research was conducted by Drs. Eden Harrell, student in the Department of Zoology in the Wise School of Life Sciences, Professor Noah Schenker in the Department of Zoology and Steinhardt Museum of Natural History, and Professor Ines Zucker in the Department of Mechanical Engineering and the Porter School.Environmental and Earth Sciences are all taught at Tel Aviv University. Masu. The study was published in the journal Chemosphere.
Professor Schenker said: “About 10 years ago, when awareness of the problem of plastic pollution in the marine environment began to grow, many researchers focused on determining the location and size of microplastic particles. The focus of research has shifted to the impact and impact of microplastic particles.ā However, while much of the experimentation in this field is done using purchased clean plastic, plastic particles are exposed to a variety of influences and pollutants in the ocean.
“We need to understand whether and how plastic changes after passing through the digestive systems of marine organisms, and how this process affects the presence of plastic and its availability to other organisms. The purpose was to find out whether


The laboratory at Tel Aviv University where the experiment was conducted. Credit: Eden Harrell.
In the lab, the researchers created an experimental system that simulates seawater containing sea squirts, a marine animal that feeds by efficiently and indiscriminately filtering small particles from water. The researchers exposed sea squirts to two types of plastic particles. One is the widely used conventional polystyrene (PS), and the other is polylactic acid (PLA), which is commercially available as a biodegradable and environmentally friendly bioplastic.
Next, we investigated the effect of the sea squirt’s filtration process on the concentration and distribution of plastic particles in the water at four different times: at the time of exposure, and after 2 hours (when the sea squirt had filtered all available water and ingested the microplastic particles). I checked at intervals. , after 24 hours, and after 48 hours (after digestion and excretion of feces into the water).
The results showed that approximately 90% of the polystyrene particles were removed from the water after 2 hours of filtration, but after passing through the digestive system, all particles returned to the water after 48 hours. In contrast, the concentration of PLA particles in water decreased significantly and remained low for 48 h. The larger PLA particles could have broken down during digestion and returned to the water as small, undetectable nanosized particles.
In the second phase of the study, the researchers looked at what happened to microplastic particles that were filtered, digested, and excreted into the water column. To do so, they isolated microplastic particles from ascidian feces and analyzed them using Raman spectroscopy, a sophisticated instrument that determines the chemical composition of materials by scattering laser light.
“We found that our sensitive spectroscopic equipment was unable to identify the material as plastic at all, and instead identified the particles as another type of organic material,” Harrell said. “We found that microplastic particles are excreted from the ascidian’s digestive system, which is covered with a layer of feces.” And the marine environment may also recognize these particles as this organic material.
“Many marine animals eat feces, so it is quite possible that they recognize plastic with altered properties as food and ingest it. In this way, marine animals are also exposed to microplastics, and the marine food chain The fecal coating also exposes them to microplastics, which can act as a substrate for bacterial colonization, as well as heavy metals and residual organic substances (such as antibiotics) on the plastic particles. increase the adhesion and accumulation of pollutants such as ā


Researchers analyze secretions from marine animals. Credit: Eden Harrell
Professor Zucker added: “This phenomenon also affects bioplastics that are sold as ‘biodegradable’. “Plastic particles undergo various changes in the environment.” From weathering to digestive processes, they turn into contaminants and disease vectors within the food web, as investigated in this study. ā
In the third phase of the study, the researchers looked at the opposite effect: how microplastic particles affect feces, an organic material that plays an important role in marine ecology.
“We found that plastic changes important physical properties of feces,” Harrell said. “Normal feces sink very slowly through the water column, becoming food for many organisms along the way. In contrast, Fecal matter containing microplastic particles quickly sinks to the sea floor, making it an important source of nutrients from the water column.
“Additionally, faster subsidence rates reduced fecal dispersion, causing fecal and plastic particles to accumulate near where animals settled. This accumulation increased levels of carbon and nitrogen on the ocean floor. This represents another significant impact of microplastics on the balance of marine food webs, which can cause algae blooms. ā
The researchers said, “With this study, we have uncovered an important aspect of the influence of filter-feeding animals on the properties of microplastic particles in their environment and in marine food webs. The most worrying conclusion is that the microplastic problem is far more complex.” More than I originally thought.
“Plastic pollution in the marine environment has many unexpected aspects, and its complexity continues to grow. In some cases, neither we nor the environment can even recognize it as plastic. Time. As time passes, plastic continues to have a negative impact on more and more marine ecosystems. It is our duty to develop new technologies to reduce this dangerous phenomenon.”
Further information: Eden Harel et al, Impact of biological filtration by ascidians on microplastic composition in the water column, Chemosphere (2024). DOI: 10.1016/j.chemosphere.2024.143589
Provided by Tel Aviv University
Citation: Marine animals consume microplastic particles and excrete them in feces, posing risks to the marine environment (January 15, 2025) https://phys.org/news/2025-01- Retrieved January 15, 2025 from marine-animals-consume-microplast-particles.html
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