The fascination of underwater environments: the exploration of ecosystems

The fascination of underwater environments: the exploration of ecosystems

The Mediterranean is one of the areas of the planet with the largest underwater biodiversity: among fish, expanses of sand, rocky dens and coral formations, the Italian seabed offers scenarios of extraordinary beauty, capable of offering exciting views and encounters even during short dives dedicated to spearfishing.

The great variety of habitats and marine environments that characterizes Italian coastal waters is not secondary when it comes to diving for fishing: the ecosystem healthin fact, it is essential not only to ensure the presence of prey in the years to come, but also to protect the emotions that only an immersion in a sea rich in life can offer.

The underwater biodiversity of the Mediterranean

With its 17 thousand species, the Mediterranean it is one of the richest areas of the Earth in terms of biodiversity: with an extension that covers just 0,82% of the marine expanses, Mare Nostrum hosts approximately 7,5% of the world's species. And it's not just about fish: in the seas of the Italian coasts there are prairies, sandy expanses that teem with almost microscopic life, coral formations and ancient wrecks that become habitats for hundreds of animal and plant species.

The depths of the sea remain one of the most unfathomable mysteries on the planet, and our coasts are no exception. One of the largest projects of mapping of the Mediterranean Italian was started last May by researchers from theISPRA. Among the main purposes of the project, which is called MER, is the high definition mapping of the Posidonia oceanica and Cymodocea knotosa, fundamental for guaranteeing the health of the entire national marine ecosystem (the last mapping, scientists explain, dates back to 20-30 years ago).

When they say that divers have access to a world that remains secret to most humans, after all, they aren't lying: there is still much to discover on the underwater ecosystems of the Mediterranean, and diving remains one of the very few ways to come into contact with them wonders of marine habitats.

The state of health of marine habitats in Italy

Marine ecosystems are among the most sensitive of all: pollution, the increase in temperature, fishing pressure and human activities have a devastating impact on life in the Mediterranean. In some areas the concentration of microplastics is approaching 10 kg per square kilometre, while the rich Posidonia oceanica meadows are retreating and the thermocline seems to disappear.

Diver fishermen will have noticed that gorgonians are found at increasingly extreme depths, and that the expanses of Posidonia are becoming sparser every year. There shortage of fish in areas that were once teeming with life is a direct consequence of the degradation of these habitats, and the situation can only be reversed with new protection strategies and mitigation of the effects of climate change.

The good news is that the initiatives taken in recent years appear to have had some positive effects. According to the latest ISPRA report, in the Mediterranean corals have started to grow again, which have been identified in 160 sites in 8 Italian regions, e pollution has decreased: from 2015 to today, beached waste has halved, although there is still a lot to do to fall within the definition of "good environmental status".

In short, within this decade we will be called to do something a choice from which there will be no going back: implement important actions regarding environmental protection, or get used to the prospect of losing the extraordinary biodiversity of the Mediterranean forever.

Marine environments: 10 Mediterranean habitats

Waiting for a more precise mapping that allows us to better understand the Mediterranean habitat, scientists are already trying to classify the different marine ecosystems considered important for the health of Mare Nostrum.

In one 2010 study, for example, describe themselves 10 marine environments observed along the Salento peninsula, but it is also specified that their importance can be extended to the entire Mediterranean Sea:

• coastal lagoons: these are transition waters, among the most productive habitats on the planet;
• supralittoral: it is the area cyclically covered and uncovered by the tide which can host crustaceans but also algae bioconstructions which form habitats comparable to those of coral reefs in the tropics;
• sandy coasts and Posidonia oceanica meadows: Posidonia, which can grow on sandy or rocky layers, is the exclusive habitat of several species (including the Pinna nobilis, or fin mussel, the largest bivalve mollusc in the Mediterranean);
• pelagic environment;
• sea ​​caves: they are not only the refuge of hundreds of species of fish, but also allow the formation of bio-constructions similar to coral reefs (which it would be best to avoid touching);
• marine desert: in some areas where fishing pressure has been particularly intense, there is desertification of the seabed. Sea date fishing, for example, has left behind desert beds in various Italian regions, from Liguria to Sardinia;
• wall coral: Mediterranean coral grows on rocky walls and is made up of coral algae (and their calcareous skeletons) which completely cover the rock. This habitat is home to the most spectacular benthic species in the Mediterranean;
• platform reef: in Puglia and beyond, thecoralligen is formed from small aggregates of pebbles or shells found on the seabed or on flat rocks;
• sands: that sand on which it sits waiting for prey it may seem deserted, but in reality it is home to many species, including cnidarians, annelids, nematodes and crustaceans that live only among the grains of sand:
• deep coral formations: they are among the least explored habitats, and are well outside the reach of a scuba diver. These formations develop starting from 300 meters of depth, where photosynthesis does not occur: the bioconstructions, in fact, are the work of two species of madreporary corals (Lophelia pertusa and Madrepora oculata), put in serious danger by trawling practices which have degraded these very delicate deep-sea ecosystems.

The exploration of the underwater ecosystem in the Mediterranean

Diving in the Italian Mediterranean offers very different scenarios: there are areas where sharks and large cetaceans regularly transit and others very rich in anemones and gorgonians, and then impressive underwater mountains, underwater statues and wrecks populated by fish of all kinds.

Every ecosystem has its treasures to offer: in the sea of Cinque Terre you can get lost in burrows, but it is also possible to admire madrepores, damselfish and meet some seahorses, while the Secca della Colombara, a Ustica, offers the view expanses of sponges and corals among which you can glimpse moray eels, barracudas and groupers.

In the sea of Calabria, near the Strait of Messina, there is a majestic underwater mountain over twenty meters high that emerges from an ethereal expanse of white sand, and which is populated by an incredible variety of species, including spectacular Cerianthus and nudibranchs, among the most colorful creatures on the planet.

The exploration of the underwater ecosystem, whether for fishing or to admire and photograph sea creatures, should be animated by immeasurable respect for this extraordinary richness. Even if you don't know the marine habitats in detail, every dive can turn into a fleeting exploration of it mysterious beauty and hidden from the gaze of humans.