How and Why ?
June 8 is World Oceans Day. Since Rio Summit in 1992, we celebrate the beauty and fragility of this ecosystem. In the 19th century, Charles Baudelaire, a French famous poet, had already understood the proximity between man and oceans.
« Free man, you will always cherish the sea!
Sea is your mirror; you contemplate your soul »
Between overheating, acidification, eutrophication, pollution, seaweed… It is a very gloomy reflection of human soul that oceans send us.
In fact, we dump 8 million tons of plastic into the seas and oceans every year. That’s the equivalent of a garbage truck being dumped into the oceans every minute. 450 years is the time needed for a PET bottle to degrade. This is an alarming statement and a serious threat to aquatic life. Today, 693 marine species are directly threatened by plastic pollution (ocean.campus.fr). Yes, the debris is a bait for the fauna which confuses it with its usual preys. It is the well-known example of turtles that confuse bags with jellyfish, but piscivorous birds are also strongly impacted! Scientists even estimate that 90% of seabirds have plastic in their stomachs! And this only concerns macros plastics…
Microparticles (less than 5 millimeters) are even more abundant and just as dangerous. They are indeed present in all oceans (5 Gyres study) and could have consequences for our health! After ingestion of this waste by the oceanic fauna (plankton, fish…). These micro plastics accumulate in all marine organisms which then end up in our plates. They have been discovered in 114 aquatic species. These particles tend to absorb pollutants from the surface of the sea and accumulate in the species we eat. Do microplastics have an impact on human health when we consume sea products? This is a hypothesis that remains to be confirmed. They could act as endocrine disruptors, interfering with the normal production of genetic material necessary for reproduction. This could cause problems during the formation of fetuses. They are also suspected of being responsible for causing some cancers.
Human beings are responsible for oceans’ health. Overfishing is a source of significant biodiversity loss for marine environments. This is the case of the nassau grouper (Epinephelus striatus) in the Caribbean, which has seen its populations come close to extinction. Only very strict regulations have made it possible to save the species. If fishing is more and more regulated for species that we can find in our fish shops (tuna, salmon, grouper …). This is not the case for other species. Farmed fish also induces important impacts on the ecosystems: diet of farmed fish is mainly issued from fish meal which are overexploited (a well known example is the Peruvian anchovy). We should not forget that fishing is also responsible for the involuntary capture of some species. These are the by-catches, no more and no less than 300’000 small whales and dolphins, 250’000 loggerhead turtles (endangered species) and leatherback turtles (critically endangered species) and 300’000 seabirds that are accidentally killed by our activities every year in the world (WWF).
We are also transporting more and more goods via sea freight. This encourages the proliferation of invasive species. Indeed, these are generally contained in the ballast tanks of ships (in the form of eggs or juveniles most often) that once at their destination purge the ballast tanks, allowing the species to colonize the environment. However, if they manage to travel and introduce themselves into a new ecosystem, this is not a proof of invasion. Indeed, not all species survive in these ecosystems. A species is considered invasive when it manages to reproduce into a new ecosystem and increase its population size. If few species are able to do so, consequences can be disastrous. This is the case, of the lionfish (Pterois volitans) introduced in the 1990s in Florida and which today has colonized the whole Caribbean and the Eastern Atlantic, from north of America to north of Brazil. It is today responsible for major disturbance of the whole ecosystem, because other species do not recognize it as a prey, they are naive in front of this newcomer. Thus the hunting capacity of the lionfish is increased tenfold, which leads to a decrease of native populations and competition with other species.
Fauna is not the only one concerned by our activities. Indeed, coral reefs, which are the shelter of a third of marine species and protect coasts from tidal waves, are now threatened by ocean acidification, as scientific studies have shown. This phenomenon is a consequence of increased release of CO2 into the atmosphere, part of which is recycled in oceans. pH of seawater has gone from 8.2 before the industrial revolution to 8.1 today, and could even reach 7.9 or 7.8 by the end of the century according to some studies. The main consequence of this is to affect the renewal capacity of the oceanic plankton. Species that compose it become unable to structure their calcareous skeleton (which degrades with acidic pH) which leads to a decrease in the size of their populations. Unfortunately, these species are at the basis of the trophic chain and they contribute to oxygenation of the environment. Their disappearance could thus lead to a depletion of the environment in oxygen which would lead to the disappearance of some species.
Corals are also impacted by this phenomenon of acidification, because their structure is weakened by these changes in pH. In addition, the greenhouse gases that we emit each year actively participate in the climate warming process, which results in increasing the temperature of the seas and oceans. However, the rise of 2°C or 3°C in water temperature causes coral bleaching, which is a rupture of the symbiosis between unicellular algae and corals. Eventually, this can lead to the disappearance of many coral reefs, because corals can not live without this symbiosis. Tourist activities (diving, snorkeling…) are also a source of damage for these organisms. Let’s not forget to admire their beauty without damaging them! Today, 40% of the world’s coral reefs are threatened (mainly in the Indian Ocean and the Caribbean), while 10% are irretrievably lost. The remaining 50% are threatened by global warming.
And there is more, we continue to use fertilizers that promote algae growth in aquatic environments. Indeed, it is the well-known phenomenon of eutrophication, excessive contribution of nitrogen on our crops promotes the growth of algae; excess nitrates are released into rivers and reach the sea. Unfortunately, the algae reduce the oxygen content of the water, which contributes to a decrease in fish species. Consequences for biodiversity can be dramatic, as the entire food chain is disrupted.
However, we can still act as a « free man ». Free to choose products from sustainable fishing or organic farming. Free to buy from local sources to reduce the flow of container ships on the main sea routes and reduce invasion of species. Free to respect the origin of species and let them live in their native environment. Free to reduce our use of plastic and our greenhouse gas emissions to limit pollution and consequences for biodiversity. Free to take care of our planet and simply protect it!
So let’s do something about it! Every initiative counts and will contribute to preservation of this wonderful ecosystem. It is time to act…
Let’s become free to contemplate the purity and beauty of our « soul » without worrying about its unknown future.