Depending on how closely you follow Chemical Intuition, you may or may not remember our article from way back in June of 2015 entitled "Welcome to the Plastisphere." In that article, we talked about the Texas-sized mass of microplastics in the Pacific Ocean and the huge amounts of plastic accumulating in the world's waters. We discussed the possible ecological impacts caused by the presence of so much plastic in the ocean. One of the conclusions from this piece was that microplastics are a magnet for pollutants present in the ocean, and if organisms ingest these microplastics, toxicity can occur through the high dose of pollutants adsorbed to these tiny pieces of trash. However, one conclusion from this piece was that direct evidence for ecosystem impacts were lacking.
In today's "Relevant or not" post, we'd like to quickly highlight a few recent articles that lend serious credence to the theory that, yes, microplastics significantly and negatively impact ecosystem functioning.
First, a paper in the Proceedings of the National Academy of Sciences from Sussarellu and co-workers demonstrated that when oysters ingest microplastics during gametogenesis, the feeding and reproductive capacities of the oyster are negatively impacted. This leads to decreases in the oysters' individual fitness. This is problematic as oysters are incredibly important for the role they play in filtering water; oysters form reefs in the ocean, and they function to increase both the water quality and biodiversity.
A commentary on the above article by Galloway and Lewis noted a calculation performed using data from another research paper that "the average dietary portion of six oysters would contain around 50 plastic particles." Oysters are highly effective filter feeders and remove around 70% of the microplastics in the surrounding seawater. The result? Your fancy seafood dinner is full of plastic debris.
The plastics we pump into our environment travel full circle, ultimately returning to us, the consumers. We can't escape our wasteful ways.
A recent article in the journal Science also discovered negative impacts of microplastic ingestion on organismal fitness, this time in the European perch. In this paper, they show that exposure to relevant concentrations of microplastic polystyrene particles resulted in lower growth rates and altered feeding behaviors in the European perch larvae. Most worrisome, perhaps, was that ingestion of plastic impacted the ability of the fish to respond to natural chemical cues; the larvae exposed to microplastics did not respond to olfactory threat cues, meaning that many more died at the hands of their predators.
These papers are part of a growing body of scientific literature pointing to the very real and negative impacts microplastics in the ocean have on organismal fitness. The impacts on organism fitness impact ecosystem functioning. Combined with other human-driven environmental perturbations (including ocean acidification as a result of larger concentrations of dissolved carbon dioxide and rising water temperatures as a result of global climate change), we should be very worried about the collapse of marine ecosystems.
What are we to do? As individual consumers, we can do as much as we can to reduce our plastic consumption. But much more is needed. Galloway and Lewis closed their commentary with strong words we should listen to: "Given the impossibility of removing all microplastics contamination from the oceans, the impetus is on all of us--governments, scientists, and individuals--to reduce our utterly ridiculous levels of plastic consumption and waste before we induce permanent alterations to our fragile marine ecosystem."