What is the first thing that goes through our minds when we think about oxygen production in our planet? For most people, it surely is the color green – trees, forests, the Amazon rainforest, etc. The fact is, it is the wrong color and what should cross our minds is blue. The ocean produces between 50 and 70% of the oxygen that can be found in the atmosphere [1]. Not the ocean itself, of course, but some of the microorganisms that live in it: unicellular algae and cyanobacteria. These creatures, as plants do, are able to photosynthesize. 

These organisms are just a fraction of the whole biodiversity that can be found in Earth’s seawater. Most of the planet is water, it is called the “blue planet” after all. It is estimated that we only know about two-thirds of the whole marine biodiversity, which would be about 250 000 species. Ocean ecosystems and the living beings that inhabit them are incredibly relevant to sustaining Earth’s life balance [2]. This is why it’s vital to protect and conserve them [3].

Among the different objectives in the Kunming-Montreal declaration (COP15 from the Convention on Biological Diversity), one of them is to attain 30% of the protected ocean area by 2030 [5]. There are still 6 years left, but the current situation is quite distant from the objective: only about 8% of the seawater is protected – or “declared as such” –, as some areas do not even have a management plan. One of the main difficulties to deal with is international management, as these areas are unclaimed by countries. The High Seas Treaty, which had been under negotiations for 20 years, proposes certain tools to manage the marine protected areas (MPA) in these “no man’s waters”. 

But what do we have to protect marine biodiversity from? The main threats are overexploitation of fishing resources, water quality decrease, oil spills, habitat fragmentation, invasive species, algal blooms, and climate change [6].

According to the UN Food and Agriculture Organization (FAO), we have gone from 90% of fish populations being in a biologically sustainable status, to 64% by 2015 [7]. This overexploitation is actually the main threat to marine biodiversity. It is urgent to reduce the exploitation of fishing resources, focusing on large-scale fisheries and bottom-trawling. We should work on promoting small-scale traditional fishing which has lower impacts, as well as reducing our consumption.

Marine transport is also responsible for many impacts on seawater ecosystems. Consumption is disproportionate, especially in first-world countries. As an example, in the Mediterranean basin, lies about 1/3 of the global marine transport. Transport not only fragments habitats and has direct impacts on living beings wherever it passes through, it also represents one of the main introduction paths for invasive species. Keeping the actual consumption and production–level means keeping up with this amount of marine transport, and consequently keeping up with its impacts.