The latest is a new study published last week which looked at the impact of discarded disposable surgical masks on coastal ecosystems. Surprise surprise, what they found wasn't good.
If I'm reading the study right (it's getting late, I'm tired, and I'm generally pissed off with the world, so I may not be) the researchers collected discarded masks from beaches in Hong Kong and then took them back to their lab. They then studied how the masks broke down in seawater and took samples of that water. They used the water to grow copepods, an abundant group of zooplankton, and watched what happened.
They found that high levels (100 microplastics/mL) of microplastics from the masks caused the development time of the copepods to increase - they took longer to mature. The same high levels also caused them lengthen the space between broods and reduced their fecundity. At what they called "environmentally relevant" levels (10 microplastics/mL) these differences were fortunately absent. However, even at these lower levels the length of their poo increased significantly, though I'm unsure if there are any known environmental consequences to this (I wonder who got the job of measuring them).
The authors conclude,
[Microplastics released from [surgical masks] can be ingested, be egested, and accumulate in the intestine of marine copepods, causing an adverse effect on their fecundity. As one of the most abundant classes of zooplankton and primary consumers in the marine environment,30 copepods play a critical role in the bioaccumulation of contaminants in the marine environment.33 MPs can enter the body of higher marine organisms through bioaccumulation and biomagnification, resulting in potential harmful effects. In addition, the reduced fecundity of copepods will also lead to the reduction of food resources for higher marine organisms, thereby threatening the balance of the marine ecosystem.