Scientists have warned that the world’s deep sea oceans will be starved of food by 2100.
The deep sea begins at around 650 feet below the ocean surface where sunlight penetration begins to fade. At about a half mile depth surface light will not penetrate. The water is very cold with very little oxygen. The weight of the water above causes massive pressure and the life that lives there has evolved to survive these conditions.
We know very little about this dark and cold habitat. We do know that because there is no sunlight, plants can’t grow. These organisms rely instead on falling organic matter produced in the zones above where sunlight penetrates. Highsea’s estimates that there are 500,000 to 10 million species in the deep sea and that most have yet to be discovered. The habitats are known as well. There are great plains, volcanoes. mountain chains, geysers and cold water reefs.
Deep-sea corals, sponges and other habitat-forming organisms provide protection from currents and predators, nurseries for young fish, and feeding, breeding, and spawning areas for hundreds of thousands of species.
Commercially important deep-water fish and crustacean populations found in the high seas include crabs, shrimp, cod, Pacific cod, orange roughy, armorhead, grenadier, Patagonian toothfish (aka Chilean sea bass), jacks, snappers, porgies, sharks, groupers, rockfish, Atka mackerel, and sablefish.
Deep-sea species tend to be slow growing, late maturing and low in reproductive capacity. Many deep-water fish species live 30 years or more. Some, such as orange roughy, can live up to 150 years.
Because deep-sea species live in rarely disturbed environments and tend to be slow growing, late maturing and endemic, they are exceptionally vulnerable to extinction.
Scripps Institution of Oceanography reports on the alarming study that concludes that starvation of deep sea species will occur within a few decades.
Organic compounds produced through primary production – the creation of chemical energy by algae and other phytoplankton through photosynthesis – sink to the deep ocean and make up much of the food supply there. Most of the deep sea currently experiences a severe lack of food, but according to Sweetman and his research team, it is about to receive even less. That’s because the phytoplankton deep sea organisms rely upon are themselves facing a dwindling supply of nutrients in the surface oceans as warming makes waters more stratified.
Sweetman continued: “Abyssal ocean environments, which are over 3,000 meters deep, are some of the most food-deprived regions on the planet. These habitats currently rely on less carbon per square meter each year than is present in a single sugar cube. We’ve shown that large areas of the abyss will have this tiny amount of food halved by 2100. For a habitat that covers half the earth, the impacts of this will be enormous.”
The researchers also describe an imminent, significant temperature increase that will happen at the deepest parts of the ocean.
“Deep-sea ecosystems are not just going to experience a reduction in food, but will likely also experience an increase in ocean temperature of 1°C within 85 years,” said Andrew Thurber, co-author of the study and a professor at Oregon State University. “This is very worrying because increasing temperature will increase the metabolism of animals and microbes that live in the sediment, meaning they will require more food at a time when much less is available.”