Sediments from deep-sea mining could be very stressful for animals
According to a study by the Geomar Helmholtz Center for Ocean Research Kiel, deep-sea mining leads to stress in jellyfish, for example. Helmet jellyfish were tested and exposed to simulated sediment clouds, as the research team reports in the journal "Nature Communications".
According to Geomar, fine sediments are stirred up during the extraction of raw materials on the seabed, such as manganese nodules. Sediment clouds can spread dozens to hundreds of kilometers and affect animals not only on the sea floor, but also between 200 and 4000 meters water depth - the so-called pelagic. As there is usually very little sediment in this zone, it can be assumed that animals in this area react very sensitively to the sediment clouds caused by mining.
The inhabitants of the pelagic are the main food source for many fish, squid and marine mammals and therefore represent an important link in the marine food web, explained co-author Helena Hauss from the Norwegian Research Center (Norce). "They have evolved under far more stable conditions than surface-dwelling animals and are therefore potentially more vulnerable to changing environmental conditions."
Risk for pelagic inhabitants
Determining the stress level of a jellyfish is not easy, explained Geomar researcher Vanessa Stenvers. Changes in physiology, gene activity and the microbes on the animals were taken into account. The most noticeable visible effect was the adhesion of sediment particles to the jellyfish - whereupon the jellyfish began to produce excess mucus.
"Although the mucus helps the jellyfish to keep their microbiome stable, the continuous production of mucus requires a lot of energy and can account for a significant proportion of an animal's total energy budget," explained Stenvers. When there is a lot of sediment in the water, the activity of genes related to respiration, the immune system and wound healing is greatly increased.
Stress factors that lead to increased energy consumption must be compensated for with increased food intake, explained the research team. However, food is usually scarce in the deep sea - sediment in the water could therefore increase the risk of starvation for pelagic inhabitants.
Critics warn of environmental catastrophe
The commercial extraction of raw materials at the bottom of international seas harbors dangers of as yet unforeseeable proportions for local ecosystems - however, talks on how to deal with deep-sea mining ended in the summer without any binding decisions. At the meeting of the Council of the International Seabed Authority (ISA), the 36 member states only agreed on the goal of adopting a set of regulations in 2025.
No concrete solution was agreed on how to decide on deep-sea mining applications, which can now be submitted to the ISA for the first time. Some time ago, the Pacific state of Nauru announced its intention to mine manganese nodules on the seabed at a depth of 4,000 to 6,000 meters with the Canadian company The Metals Company (TMC). These ancient formations contain raw materials such as manganese, cobalt, copper and nickel, which could be used to produce batteries for electric cars, for example.
Critics warn of an avoidable environmental disaster. Many countries have not yet taken a clear position on deep sea mining. The USA is not an ISA member state. China has signaled that it wants to focus on deep-sea mining.
- The dispersal of fine sediments from deep-sea mining activities could potentially impact animals not only in the benthic zone but also in the pelagic, which is rich in sea creatures such as jellyfish, fish, squid, and marine mammals.
- The increase in sediment in the ocean could pose a risk for animals in the pelagic zone, as they may face difficulties in obtaining food due to competition with other organisms attracted by the sediment, leading to possible starvation.
- Climate change and deep-sea mining activities could further stress the environment and its inhabitants, including jellyfish, by altering their habitats and causing increased sediment deposits, which could negatively impact the marine food web.
Source: www.dpa.com
