Plastic algae to repopulate the seas

La Spezia - Global warming not only increases the temperature of the oceans but also contributes to their acidification, compromising the efficiency of the calcium skeleton processes of many animals, such as corals and molluscs, and plants such as coral algae that play an essential role in providing vital homes to many organisms in the Mediterranean. As a way to ensure the viability of such habitat communities formed by these algae which are threatened by acidification, a research group at Enea of Santa Teresa, La Spezia, together with a group from the University of Portsmouth (both headed by Italian researchers, Federica Ragazzola in the UK, and Chiara Lombardi in La Spezia) is planning to place artificially built algae on the seabed which, although plastic, are made out of a biodegradable material. Clearly, these won’t photosynthesize like real algae, but they will form a substrate for other species, and that’s better than doing nothing.

With their fronds, the algae will transform a two-dimensional environment, the bare seabed, into a three-dimensional one, offering shelter to other living species. These type of endeavours are known as “environmental restoration”, and are aimed at restoring optimal conditions, to protect against further degradation. On land we’ve been doing it for some time now through reforestation, and the reintroduction of locally extinct animals, even worms! But this type of intervention in the sea is almost unique.

Attempts have been made to transplant Posidonia seagrass (with live, not plastic ones) into declining underwater meadows, but they’ve had mixed success. In the tropics the practice of forming “coral gardens” has become widespread; coral pieces that have fallen from coral colonies, are fixed to the seafloor and, given time, some take hold. Then they’re assembled to form small coral formations that, hopefully, grow. In this case, as well, plastics play no role. We’ve also built artificial barriers with various materials, with precisely the same function as the plastic algae: to provide a home for fauna and flora. And also to protect the coast from erosion. These artificial reefs however, do not mimic the structure of “real” organisms: they still need to be colonized. But this will not happen if acidification decreases calcium carbonate fixation. So here’s where plastic comes in. This project is not free of controversy. While we’re trying to take the plastic out of the oceans, here we are adding it in, in the name of helping nature. Is it really biodegradable? And what about the organisms that feed off the coral algae, couldn’t they get poisoned by that plastic? Researchers are also trying to answer these questions. These Italian researchers should be a source of pride. They work abroad and coordinate projects involving Italy. Of course, the prospect for the future that this research opens up is not rosy. Just consider a forest of plastic trees. The plastic leaves may fall, they’re biodegradable. But they do not photosynthesize, just like the plastic algae. Thus, an important ecosystemic function is lost, only the structure remains, without the main function, photosynthesis. Will this be the best we can expect for our seas in the future? I really hope not. But I’m glad that Federica Ragazzola and Chiara Lombardi are engaged along this path. But, before we give up on the loss of coral algae, we must try to do everything we can to save them. To lose them would mean severing an important limb in the workings of nature. We may be able to replace it with a nice plastic leg, but it will not be the same thing.