In the distant South China Sea of China, people accidentally discovered an "oasis"-"cold spring of hippocampus" biological community in the deep sea. In the dark depths of the deep sea, the "cold spring of hippocampus" provides shelter for a variety of benthic organisms and nourishes the huge oasis life.
"Haima Cold Spring" is a huge active cold spring found at the bottom of the Pearl River Mouth Basin.
Cold spring is another important discovery after submarine hydrothermal solution. Below the seabed sedimentary interface, fluids such as methane, hydrogen sulfide or hydrocarbons overflow from the seabed in the form of gushing or leakage, forming submarine cold spring activity.
Plumes have been found in different marine sedimentary environments in major sea areas of the world. At present, according to multi-beam water data, tens of thousands of cold spring leakage points have been found, with at least 100 active methane leakage areas, mainly distributed on the continental margin. It is estimated that the total amount of methane leaked into the ocean by submarine cold springs can reach 400,000 ~ 6,543.8+0.22 million tons every year, which is one of the important natural sources of methane in the atmosphere. In addition, gas hydrate with shallow burial and high saturation often develops near cold springs, which is an important window to study methane leakage and migration mechanism after gas hydrate decomposition. Therefore, it is of great scientific significance to carry out cold spring investigation and research.
There are seven cold spring areas in China's offshore waters, of which Okinawa Trough 1 cold spring area is found in the East China Sea, and the other six cold springs are all distributed in the South China Sea. From 2065438 to March 2005, Guangzhou Marine Geological Survey of China Geological Survey (hereinafter referred to as "Guanghai Bureau") discovered a huge active submarine cold spring in the Pearl River Mouth Basin for the first time by using the 4,500m unmanned submersible (ROV) independently developed by China, and named it "Haima Cold Spring". In the following years, Guanghai Bureau continuously upgraded the technical equipment of the "Haima" ROV, organized many large-scale "Haima Cold Spring" surveys to enjoy the voyage, and the major ocean universities and scientific research institutions in the United Nations comprehensively used a variety of high-precision survey equipment to conduct systematic-scale cold spring surveys.
Based on the breakthrough of multi-platform technology, "Haima" opened the door to a new world of "Haima Cold Spring" for us, and the colorful cold spring biological community made a magnificent appearance. ...
Primary producer chemical energy self-maintenance products
Anaerobic archaea and sulfate-reducing bacteria in seawater actively participate in the chemical reaction of methane oxidation and sulfate reduction in cold spring fluid, providing carbon source and energy for chemoautotrophic organisms.
When methane comes into contact with seawater with little dissolved oxygen, special bacteria will grow. These bacteria consume methane and sulfate in seawater and release hydrogen sulfide. Although hydrogen sulfide is toxic to most animals, chemoautotrophs can use this chemical as food, and finally supply heterotrophs with energy and carbon sources. Therefore, these self-sustaining chemicals have become the main producers of cold spring ecosystem.
The bottom of the "hippocampus cold spring" area is covered with white or orange bacterial mats with a diameter of several centimeters to hundreds of meters. These bacteria are usually composed of large sulfur-oxidizing bacteria (one of chemoautotrophs). The adaptability of giant bacteria narrows the gap between oxygen supply and electron donors, so they often appear in cold springs with high total oxygen consumption and large methane overflow.
The main consumers are benthic organisms, such as mussels, clams and tubular worms.
Chemosynthetic bacteria and archaea constitute the bottom of the cold spring food chain, supporting a variety of benthic organisms, including deep-sea bivalves (clams, mussels, caps, etc. ), worms (tube worms and ice worms), polychaetes and other primary consumers.
Because chemosynthetic clams (scientific name "companion clams") can collect hydrogen sulfide by rooting sediments on their feet, they usually live in the area where methane leaks a lot in the "cold spring of hippocampus". Hydrogen sulfide overflows upward with methane liquid, and clams rely on sulfur-oxidizing bacteria in gills for nutrition. With a stable supply of hydrogen sulfide, these clams can live for a century, growing to more than15cm.
The deep-sea clam found in the "cold spring of hippocampus" can extend hundreds of meters away, which is particularly spectacular. Similarly, there are a large number of chemoautotrophic bacteria in the gills of deep-sea clams. Usually mussels only appear in the mouth of active cold springs, which is one of the earliest biological communities in the ecological succession cycle of cold springs.
As the longest-lived macrobenthic organism in the world, the longest tube worm found in "Haima Cold Spring" area can reach1.6m.. Usually, tubular worms only appear in the environment with low flow rate in cold springs. In the late stage of cold spring development, when the velocity of cold spring decreased, tubular worms replaced mussels as the main species. They have no mouth and digestive system and live on nutrients produced by bacteria in their own tissues. These bacteria obtain sulfur ions from cold spring fluid and oxygen from seawater to synthesize organic substances necessary for the survival of tubular worms. Because tubular worms can extend their "roots" to the bedrock for more than one meter, even if the hydrogen sulfide is completely exhausted on the surface, it still exists underground, and tubular worms can still live in groups.
Secondary consumers are fish, crabs, starfish and other creatures.
In addition to mussels, clams, tubular worms and other symbolic biological communities of cold springs, "Haima Cold Spring" also gathers a variety of benthic organisms, such as eel, Alvin shrimp, crustacean shrimp, starfish, conch, sea snake tail, etc., which constitute the secondary consumers of the cold spring ecosystem.
Through the underwater camera function of the "Haima" ROV, the researchers found a vibrant ecological scene in the "Haima Cold Spring" area: spider-like white crabs and giant king crabs leisurely devoured everything that could be eaten in the cold spring on the seabed; Soft purple sea cucumbers resembling earthworms are intertwined and distributed in groups to distinguish them from mussel communities. Tiny blind brown shrimp, scallop, crustacean, sea gill, sea snake, fish, etc. , gathered in the dense jungle of fine-tube insects hovering up and down, forming a small ecosystem, very lively!
Third-level consumers: deep-sea carnivorous species such as octopus and kingfoot.
Not only secondary consumers such as fish, crabs and starfish can be seen everywhere. Giant octopus was even found in the "cold spring of hippocampus" area. The most surprising thing is that at the bottom of "Haima Cold Spring" with a depth of nearly 1400 meters, "Haima" ROV successfully captured two "the largest insects in the world"-25 cm long kingpoda (commonly known as deep-sea water lice).
The deep-sea otter is a typical deep-sea carnivorous species. In addition to feeding on the carcasses of fish, crabs, shrimps, squid and whales, they also actively prey on some slow-moving marine organisms, such as sea cucumbers, sponges, nematodes, radiolarians and other benthic animals, becoming the third-level consumers in the cold spring ecosystem. These large organisms will eventually be decomposed by microorganisms, thus returning to nature and forming a complete cold spring ecosystem.
(Author: Guangzhou Marine Geological Survey of China Geological Survey)