There’s been a video making the rounds of social media, showing rafts of debris floating in the ocean, most of it plastic. I keep seeing it being shared along with laments about how we humans are a scourge on the face of the earth and we’re killing the ocean.
Only… that’s not completely accurate. While the impact of plastic debris is undeniable, the actual ramifications of that are still somewhat murky. For one thing, the oft-quoted cliché that nature abhors a vacuum is quite true. And therefore we can safely theorize that plastic is going to be incorporated into the ecosystem, which it is. Floating debris becomes a ‘plastic reef’ which supports microbial communities that don’t occur elsewhere in the seas. The tiniest of plastic bits can still carry a biofilm community of microbes.
It has been long believed that plastic is not biodegradable, but in recent years we’ve found that is simply not true. And it’s not only microbes that eat plastic – there are waxworms that munch away on it, although they are helped along by microbes in their gut that aid in digestion. (like our own gut microbiome!) This is a slow process, but it means that the scare-mongering about ‘plastics lasting forever!!!’ isn’t accurate and can be taken with a large grain of salt when evaluating the long-term impact of pollution on our oceans and world.
Scientists studying the mass of plastic in the ocean have been reporting, with undisguised surprise, that there isn’t as much of it in the ocean as there ought to be. How much less? About a hundred times less than was originally calculated. How much of that is due to biodegration through microbial means is still being studied, but that is certainly a factor. Even when not fully broken down, plastic particles less than a millimeter in size become so weighed down by their biofilms that they sink to the bottom of the ocean and become part of the substrate.
So do we need to worry about plastic in the oceans? Sure. I’m not suggesting you walk out on the pier and pitch your trash in. But on the other hand, we don’t need to worry that the seas of the world are going to become so choked with floating plastic as to make them unnavigable. I wonder if these plastic reefs don’t offer tiny organisms shelter from predators, much like, say, Sargasso mats do. There are drawbacks – the microbes carried by the plastic might be pathogenic – and benefits, like this patent for floating microbes on plastic beads to eat oil (yes, microbes eat that, too. Seriously. If it exists in the ecosystem, I can guarantee you something is going to eat it!).