Davide DB

Text and images: Davide De Benedictis - Claudio Valerio Cover photo: Marco Bartolomucci If we told you how long we've been diving, you'd immediately know how old we are. We'd just tell you that we've been diving for a long time and that our passion for the sea has always been a part of us. We've spent most of our time in the Mediterranean, and by diving year-round, we've seen the gradual changes in the sea we love the most. A while back, we observed some novice divers during our decompression stop and wondered what it was like for them exploring the seafloor. Are they aware of the changes they're witnessing, or are they unwitting victims of shifting baseline syndrome? Unfortunately, this is what we've been observing for years in the Mediterranean during the summer: a carpet of mucilage in the first few meters of depth. The video text is based on Greta Thunberg's famous speech at the Youth4Climate event in Milan in 2021. This speech, with its great impact and appealing style, has been used in lots of different contexts. However, to my knowledge, it hasn't been used in relation to the marine world. When we were editing the images, we thought of the old saying "Once it was all countryside here", which makes you think about the past in a nostalgic way. But even the most overused clichés have a grain of truth. To paraphrase the cliché, we could say that "Once it was all sargassum and Cystoseira here". These seaweeds, which are common in the Mediterranean, were an important part of the marine ecosystem. There were large groups of Sargassum and Cystoseira, which alternated with Posidonia oceanica bushes and seafloors covered with calcareous algae (maerl). Some of the algae were the size of a fist. The bottoms were also decorated with white gorgonians, which are typical of these shallow waters. Today, although these species are still present, many of them are difficult to observe and suffer from a thick layer of mucilage covering them. This is now so common during the summer months that only those with long diving experience, or observing the seabed in winter, can tell the difference. When we showed these images to a non-diving audience, even though we had a marine biologist explain them, they were still pretty skeptical until we showed them exactly the same places filmed in winter and spring before temperature rises. Then they finally understood what we were talking about: These two short videos show how challenging it is to communicate the changes taking place in the oceans. The warming waters and human activities are affecting underwater ecosystems just as much as they are affecting land ecosystems. But underwater, the problem is even more pronounced. There's a lack of historical data, which makes it tough to grasp how marine environments are changing (again, it's the shifting baseline syndrome). Plus, our direct experience of the underwater world is limited. Everyone can see the effects of fires in the Amazon rainforest on the news or watch the urban landscape change from the car window. But what's going on underwater? This is why it's so important to communicate the importance of marine ecosystem conservation in a clear and urgent way. This is the challenge we're up against. Given the lack of inspiration in our recreational diving, we've been wondering if there's somewhere where these changes haven't happened yet. It's probably the so-called "mesophotic zone or twilight zone", which is the bathymetric range in the Mediterranean from fifty to one hundred and twenty meters deep. As depth increases in this zone, plant life gradually makes way for animal life due to the decreasing levels of light. Recently, this zone has become really important for studying how climate and human activities are affecting our oceans. It's a completely undiscovered world that could be home to species that could be valuable resources for addressing problems related to global warming and overfishing in the surface marine zone. The trailer on our Underwater Italy channel gives you a sneak peek of the mesophotic seafloor of the Mediterranean. A while back, whenever we talked about our passion for deep diving, the response was always the same: "Why go to the trouble of going deep when there's so much to see here on the surface?" And then, of course, there was the inevitable warning about the dangers of deep diving. How could they be blamed for that? Back then, going beyond the limits of recreational diving was all about deep air and not much else. As it turns out, today in the Mediterranean, we can only observe intact ecosystems through deep diving, and the tools of technical diving allow us to do so in reasonable safety. However, even in these environments, things are changing. For years, we've been seeing signs of suffering in marine animal forests, even in the shallowest parts of the "mesophotic zone". This shows that the effects of climate change are constantly evolving. Here's an example of what's happening to some of the seabed in the Tuscan archipelago, between 50 and 70 meters deep. It seems that the damage is not only proportional to depth, but probably also depends on other factors such as currents and the morphology of the seabed. To get a full understanding of this phenomenon, further scientific studies will be needed. As divers, our role is simply to observe. It's crucial that we keep an eye on these changes in marine ecosystems and keep documentation up to date. Every observation and piece of research helps us to understand our underwater environment better. It's essential that we pay attention and put in the effort to adapt our conservation strategies so that we can meet the challenges that climate change poses. It's an ongoing process, but it's vital to preserve the wonders of the sea for future generations.