A new study shows that the semi-abyssal segment of the ocean, between 200 and 1000 meters deep, is populated in a way that we never imagined.
He is about to end up run over, his mother saves him
How many fish are there in the sea? Many, many. There are galore. Data in hand, the Oceans, ladies and gentlemen, are actually chock-full of fish. Swordfish, squid and cuttlefish are the most numerous inhabitants.
From one study published Nature Communications and made by Xabier Irigoyen, researcher of the Spanish Foundation AZTI-Tecnalia and the University of Saudi Arabia Kaust, it turns out that the semi-abyssal segment of the ocean, between 200 and 1000 meters deep, appears to be populated in a way that we never imagined, almost bordering on overcrowding. In fact, many species, including cuttlefish and squid, do not seem to intend to stop growing in number, thus contributing to abundantly populating the sea.
And so, although we cannot properly jump for joy because, in any case, the progressive drying up of the seas and oceans continues and, alas, it does not slow down, the oceans are much richer and more inhabited than expected.
A systematic review - According to the analysis, the semi-abyssal belt (the so-called zona mesopelagica) it is ten times more populated than previously thought. The researchers carried out a monitoring of the oceans through acoustic measurements, covering 32 thousand nautical miles. The shipment is part of the project Malaspina 2010 Circumnavigation Expedition, coordinated by Carlos Duarte of the Spanish National Research Council (Csic).
According to the results gathered from the circumnavigation, the total quantity of semi-abyssal fish would have increased from 1.000 million tons to 10 thousand million tons. Professor Carlos Duarte says that this expedition "provided a unique opportunity to evaluate the quantity of these fish which, although so numerous, constitute a great unknown in the open sea, given that, for many species, there are gaps in the knowledge of their biology and ecology and of the their adaptation. Until now - observes Duarte - we have only had the data provided by trawling ".
Xabier Irigoyen declares: “The fact that the biomass of mesopelagic fish is at least 10 times greater than previously thought, has significant implications for understanding the carbon flux in the sea ”.
These fish species rise to the upper layers of the ocean at night to feed and go down during the day so as not to be seen by predators. This up and down leads to an acceleration of the transport of organic matter in the ocean, which removes CO2 from the atmosphere, because instead of slowly sinking it is carried 500 and 700 meters deep and released with feces.
According to the researchers, in short, the excretion of material from the surface could partly explain the microbial respiration recorded in the deep layers of the ocean. THE mesopelagic fish they would then act as a link between plankton and large predators and would play a key role in reducing oxygen from the depths of the open sea.
Germana Carillo
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