2. What is Marine Biodiversity?

March 19th, 2020

In the beginning was the Word. Genesis is invoked at the outset of the day on biodiversity. This is not tied to the location but draws our attention to the ongoing relationship between Homo sapiens and the rest of nature. Axel Kahn, president of C3E4 (Joint Advisory Committee on Ethics of INRAe, Cirad, IFREMER, and IRD), reminds us that anthropocentrism has long urged humans to make the best use of their environment. Human consciousness gives them a particular responsibility. From this awareness and responsibility emerges the will to preserve nature, whether driven by survivalism or love for what is called "nature." Humans realize that endangering their environment jeopardizes their own nature. Within this nature, there are private spaces, common spaces, and - increasingly rare - untouched spaces. Among the common or untouched spaces, the sea holds a significant place. We will later see that biodiversity protection is linked to the level of appropriation of spaces by individuals.

Let's start by understanding the characteristics of marine biodiversity. Today, biodiversity is no longer defined as a collection of species, "a collection of stamps" in the words of Philippe Cury, but as a series of functions performed by species or groups of species. The loss of these functions is always harmful and can lead to the loss of ecosystem services, directly detrimental to humans. For example, fish supported 10% of global food security in 2015. Another example: mangroves or coral reefs protect coastal ecosystems from oceanic disturbances. The sea is also the primary carbon reservoir, making it a central element in the fight against climate change. It is estimated that the sea contains several billion species, of which only 1% is documented. The organisms inhabiting it have significant potential in the pharmaceutical field. Some species are adapted to the most extreme conditions, implying the existence of exceptional molecular mechanisms that humans have yet to discover. The genetic resource behind these molecules has become the object of strong desires, as we will see in our post on the high seas treaty. Oceans host the largest species in the world, including the blue whale and other large cetaceans. Most of the unknown organisms belong to the micro or even nanoscopic realm. Phytoplankton forms the basis of the food chain, nourishing zooplankton. Plankton as a whole refers to all suspended organisms that move with the current, including jellyfish and diatoms. The latter alone produce 25% of the oxygen we breathe.

Biodiversity is the constitutive matrix of living systems in which we evolve. More than just a collection of species, it is a vital component of the terrestrial system. The loss of a species is lamentable in itself, but it primarily reflects the progressive weakening of this matrix. Marine ecosystems are peculiarly invisible to humans, making them silent victims. They are notably affected by plastic pollution and changes in atmospheric composition. The resilience they provide against climate change could prove much less effective in the case of bio-desertification. Therefore, we speak of cumulative effects of biodiversity loss and climate change. The decline of marine biodiversity is synonymous with overall dysfunction. Soon, we will see how the concept of the "aquasphere" appears in international vocabulary to characterize its specificities and counter the responsible mechanisms. But before that, join us tomorrow for a deep-water reflection where we will discuss black smokers and rare earths.