Despite the extreme conditions at the bottom of the Pacific Ocean, a remarkable number of organisms manage to survive
In the depths of the Pacific Ocean, in a vast area, where the light of the Sun does not reach, many mysterious sea creatures live. Only 10% of the organisms that live there have been studied and classified. The intense interest shown by mining companies due to the rare mineral deposits in the area has rekindled research efforts to map the unknown benthic fauna.
The vast abyssal plain of the Pacific Ocean
The bottom of the Pacific Ocean, also characterized as the abyssal plain, is its huge flat bottom located at a depth of 4,000 to 6,000 meters. Our knowledge of the area’s biodiversity, from research missions and scientific ventures, is still quite limited. Despite the extreme conditions at the bottom of the Pacific Ocean, a remarkable number of organisms manage to survive. Bacteria, fungi, sponges, crustaceans, molluscs, echinoderms and fish live in the dark bottom in extremely adverse conditions. Most species of organisms have evolved to withstand the enormous pressure from the seawater layers above them. They are also adapted to the constant cold, with temperatures ranging between 2 °C and 4 °C. In the abyssal zone there are, after all, no changes of seasons nor day and night, only eternal darkness and cold.
The Sun’s rays do not reach that great depth, so organisms have developed adaptations to survive without light. A typical example is biophosphorescence, that is, the ability of some organisms to produce light using specialized organs or microorganisms. Thus, even immersed in the dark, they manage to find their mate, attract their food or even repel their predators. Photosynthetic organisms cannot live without sunlight and food, which comes from the upper layers of the sea or from dead organic matter, is scarce. Some bacteria can, however, produce organic matter from simple chemicals, thus forming the basis of the food chain for these ecosystems.
Life in the abyssal zone is threatened by mining
Also in the Pacific Ocean is the Clarion-Clipperton Belt, an area roughly twice the size of India, stretching from Hawaii to Mexico. The area is characterized by muddy sediments and potato-sized solid nodules rich in minerals such as nickel, cobalt, manganese, zinc and copper. These metals are used in modern electronic devices, for example touch screens, rechargeable batteries, etc. Despite the fact that it is an inaccessible area where extreme conditions prevail, the exploitation of its minerals has already started since the 1960s. Today there are 17 companies contracts to extract the ores in an area that extends over 1.2 million square kilometers, while the exploitation of the area is under the control of the International Seabed Authority (ISA).
Mining processes affect the ecosystem of the abyssal zone in a way that is not yet understood. This is also due to the lack of environmental studies and knowledge about the organisms that survive there. The first comprehensive record of benthic animals was presented at the end of May in the journal Current Biology. The scientific team collected and analyzed more than 100,000 records of animals found in the Clarion-Clipperton zone. About 90% of the species in these records have not been described or classified. Of the more than 5,500 different species only 440 have been officially classified with scientific names. Although most are worms and arthropods, sponges and corals have also been found.
The environmental impact of the impending mining on the bottom of the Pacific Ocean is not yet known precisely. Environmental organizations and marine scientists are sounding the alarm about the potentially irreversible effects of mining on biodiversity, which will further affect fisheries and food security. It is also known that mining methods involve scraping the bottom and removing valuable substrates from the seabed and are therefore expected to radically alter the wonderful ecosystem of the abyssal zone.
Sources:
- M. Rabone et al. How many metazoan species live in the world’s largest mineral exploration region? Current Biology. May 25, 2023. doi: 10.1016/j.cub.2023.04.052.
