Oceans and their adjacent seas cover more than two-thirds of the surface of the Earth and provide for trillions of dollars of ecosystem services (fishery, coastal protection, dioxide absorption, leisure, culture, aestheticism…). This invaluable asset provides 17% of animal protein and it even exceeds 50% for some populated countries such as Bangladesh, Cambodia, the Gambia, Ghana, Indonesia, Sierra Leone, Sri Lanka and some Small Island Developing States (SIDS). But it faces three huge threats: (i) temperature rise, (ii) overfishing, and (iii) plastic pollution
In its AR5 report, IPCC emphasizes the fact that oceans absorbed 93% of the additional energy generated by greenhouse gas since 1970 and the consequences for marine ecosystems are disastrous. The list provided in the SR 1.5 report is chilling: increased tropical cyclone intensity with amplified impacts due to sea level rise, ocean acidification and its impact on organisms with shells and skeletons and the rest of the food chain, deoxygenation, endangered seagrass and mangroves, diminution of maritime capacity to capture CO2 (about 30% of human emissions). Some regions, such as deltas and estuaries, are particularly at risk.
In the meantime, worldwide overfishing is leading to a diminution of available stocks. The FAO considers that about 30% of fishes are overfished and in a biologically unsustainable situation. In response to demand, aquaculture has skyrocketed since 1990 and represents 45% of total fish production in 2016. This type of production generates concerns about epidemics and then, the abusive use of antibiotics which might spread out of farms.
Finally, while available fish quantity is declining, the quality is also alarming, even in the deepest places of the ocean. A recent study published by the Royal Society showed that 72% of Lysianassoidea amphipod extracted from six deep ocean trenches from around the Pacific Rim, at depths ranging from 7000 m to 10 890 m, contained plastic microparticles. This confirms that no more places in the world are plastic free, which is perhaps not a surprise given the annual production of 322 million tons of plastic.
If life comes from water, could death also come from there?