Text / Picture Angler Original
Photographer | Hu Bin
<h1>Guide:</h1>
In the same way that tropical rainforests on land are the most concentrated areas of biodiversity, coral reef ecosystems in the ocean have also been called "tropical rainforests" in the oceans, "great walls on the sea" and "lungs of the ocean" by ecologists. Coral reefs are one of the richest ecosystems on earth. Coral reefs cover only 1% of the world's oceans, but they are home to a quarter of marine species, providing humans with a large source of protein. Coral reefs grow very slowly, it is easy to destroy them, but it takes a long time to restore them. What are the forms of coral reef ecosystems on Earth? How did coral reef ecosystems form? How do coral reef ecosystems work? What are the factors that threaten coral reef ecosystems? These are the four aspects of coral reef ecosystems that this article addresses.
<h1>First, there are two coral reef ecosystems on Earth</h1>
The distribution state of corals can be divided into three states: coral reefs where the bones of thousands of polyps accumulate; second, scattered coral forests; and third, individual corals that grow alone. Coral reefs form complex ecosystems. There are two types of reef ecosystems on Earth: warm-water coral reefs and cold-water coral reefs. Warm-water coral reefs are shallow sea type, and cold water coral reefs are deep sea type. What are the characteristics of the two coral reef ecosystems? Where is it distributed?
1. Warm water coral reefs
Warm-water coral reefs grow at depths of 10 to 60 m. There are three types of modern warm-water coral reefs in the world, mainly distributed in tropical and temperate oceans between the Tropic of Cancer. The vast majority of reef-building corals can only grow in tropical sea areas, and a small number of reef-building corals exist in temperate areas due to ocean currents.
(1) Type
According to the relationship between the reef and the coastline, warm water coral reefs can be divided into shore reefs, barrier reefs and atolls.
Shore reef (skirt reef): refers to the coast, the edge of the island around the growth and development of coral reefs, also known as skirt reef, edge reef. Growth requires substrates, which are hard volcanic rocks or bedrocks, such as the abundant shore reefs between Dongpingzhou and Guozhou Islands in the northern part of the port area, and coral reefs will not grow in the Pearl River Estuary because of salinity.
Barrier reef (offshore reef): refers to the coral reef growth place is a certain distance from the coast, and there is a continuous reef body to form a dike, the reef and the coast between the lagoon (xi) lake, waterways connected, such as Tagula Barrier Reef, New Caley-Donia Barrier Reef, Australia Queensland Great Barrier Reef, etc., Australia Great Barrier Reef is also known as "the world's seventh natural wonder".
Atolls: Mostly refers to circular or horseshoe-shaped coral reefs (outlying islands) formed in the oceans far from the mainland. The island was originally completely engulfed by seawater, and corals developed along the edge of the island and piled up to form an island reef surrounded by a lagoon in the center. Many of China's Spratly Islands and Maldivian Islands in the Indian Ocean belong to the atolls.
Types of warm-water coral reefs
(2) Distribution area
The main distribution areas of warm water coral reefs in the world are: the Bahamas Islands; the Antilles In the Caribbean Sea; the Central Caribbean; along the coast of Central and South America; the coast of Florida; the Gulf of Mexico; Bermuda; the Red Sea; the Maldives Islands in the Western Indian Ocean; Southeast Asia; the Island of Guinea; Australia; the Western Pacific; the Central Pacific; the Hawaiian Islands; the Eastern Pacific; the South China Sea of China.
2. Cold-water coral reefs
Cold-water coral reefs grow in cold water environments from 100 meters to more than 4,000 meters underwater and 4 °C to 12 °C. For example, cold-water coral forests have been found under the sea platform in the South China Sea, and there are species-rich cold-water coral reef biomes in the depths of the Norwegian Atlantic Ocean. The Hawaiian Islands have both warm and cold reef ecosystems.
Reef-making corals of cold-water corals are also stony corals, but there is no symbiotic zooxanthellae, feeding on plankton in the water and organic matter that settles down from shallow water layers, mainly soft corals. Soft corals are found in warm water and shallow seas, but in the cold water environment of the deep sea, they are rejuvenated and bred into forests, so they are called deep-sea corals, and the main species are red corals, gorgonian corals, bamboo corals, black corals and so on.
Cold-water coral forests are an important ecosystem in the deep sea. It is the "home" on which deep-sea creatures live. Some fish spawn in cold-water coral forests where juveniles grow.
Distribution characteristics and species of cold-water coral reefs
The seabed topography includes continental shelves, continental slopes, trenches, basins, sea platforms and ridges. There are some mid-ridges of the ocean, which are long submarine mountains, also called central ridges; there are some large areas that are higher than the sea plains called sea platforms; and there are some chains of seas that accumulate after volcanic eruptions. These places are the bases for the growth of cold-water corals. In particular, 3/4 of the world's volcanic activity occurs in the middle of the ocean ridge, forming a seabed hot spring, and the biodiversity and tropical rainforest are comparable.
Summary: Cold-water coral reefs have no symbiotic algae, only a few corals have reef-building functions, cold-water coral reefs are mostly located in the northern hemisphere and deep sea; warm-water coral reefs are mostly located in tropical and temperate areas and shallow seas. The following discussions are all based on warm-water coral reef ecosystems.
<h1>How are warm-water coral reef ecosystems formed? </h1>
Coral reef ecosystems are made up of coral reef biomes and the surrounding marine environment. It is a rich and diverse collection of reef habitats, plants, off-reef swimmers, plankton and bacteria. It is also affected by the marine environment (currents, water temperature, light, nutrient salts, etc.).
The formation of coral reef ecosystems requires certain conditions and the participation of specific organisms, and the formation process is relatively long. Finally, it can form an ecological structure with different heights and heights, and the inside and outside of the reef can be formed, becoming a species-rich marine version of the "tropical rainforest". Become a "home" for fish creatures like a city.
Coral reef islands
1. Conditions for the generation of coral reef ecosystems
The prerequisite for the emergence of coral reef ecosystems is the presence of reef-building corals, which are very squeamish and have the following requirements for the sea.
Shallow waters, sufficient sunshine, clear water quality: 10-20 meters water depth range is its most ideal living environment, generally can not be deeper than 40-60 meters; because the growth of corals requires enough light for photosynthesis, so the sea water quality is required to be clear and visible. When the water depth exceeds 70 meters, the reef building is stopped, which also shows that the base of the islands and reefs in the South China Sea is within 70 meters underwater. As a result, warm-water coral reefs will only appear on the edges of continental coasts or on the edges of islands. Those that emerge from the south China Sea are called islands and reefs, and those that are submerged in the water are called reefs.
High salinity: The most suitable salinity range for reef-building corals is 27-40‰ (parts per thousand), while the salinity in the sea is not the same, so coral reefs do not exist at the mouth of rivers with too low salinity. Reef-building corals in the Persian Gulf, with a salinity of 42‰, thrive.
Warm water temperature: The growth of warm water corals is of course inseparable from water temperature, and the most suitable temperature is between 25 °C and 29 °C. Stop growing below 18 °C. There are two factors that affect the water temperature of a sea area, latitude and ocean currents, and in general, the water temperature of the sea near the equator is higher, which is suitable for warm water coral growth. But there are exceptions to everything, such as the water around the Lapagos Islands near the equator, which is cold because of the Peruvian cold current, where a penguin lives. From the eastern part of Taiwan to the Japanese island of Okinawa, although the latitude is high, there are warm currents passing through, so there are also some dominant species of reef-building corals. Tropical Africa and the west coast of South America, because of the rising cold current, there are no warm water reef-building corals.
High oxygen concentration: Warm water reef corals require high oxygen concentration waters to grow; cold water corals are anaerobic and release oxygen during cyanobacteria synthesis.
Low nutrient salt: The so-called low nutrient salt is popularly speaking, the nutrients can not be too much, the excess of organic nutrients will produce red tide, reef coral will die. Coral reef ecosystems are wonderful, requiring low nutrient salts, but also super productive, providing humans with a large source of protein. It belongs to the typical dedication of "horses do not eat grass, and horses run fast".
2. Coral reef ecosystem formation process
Coral reef ecosystems are built in the same way that humans build cities. First, participants such as building materials and construction workers are needed; then there is the planning and construction process. The formation process of coral reef ecosystems is carried out by nature, including two links: reef-building organisms and reef-building processes.
(1) Reef-building organisms
Who was involved in the construction of the reef? It turns out that these are living creatures, they are called reef creatures. Reef-building organisms are mainly reef-making corals, shellfish, and large calcified seaweeds. There are about 500 species of shallow reef corals in the Pacific Ocean and the Indian Ocean, and China's reef-building corals account for about 1/3 of the world.
Reef-building corals (stony corals)
Corals are divided into two categories, one is called stony coral and the other is called soft coral. Stony corals, also known as hard corals, are reef-making corals, represented by staghorn corals and rose corals. Soft corals sway with ocean currents like reeds. Corals and polyps are two different things, corals are skeletons with a lot of holes in them, and there are polyps living in them.
Polyps are a primitive invertebrate that lives in the ocean and originated in the late Cambrian period. Polyps are coelenterates with brown zooxanthellae symbiotic in their bodies. During the day, zooxanthellae produce sugars through photosynthesis, provide nutrients to the polyps, remove metabolites and provide oxygen, and the polyps use its stingers to protect zooxanthellae from being eaten by other organisms. And get carbon dioxide and calcium ions from the water to build their limestone reefs. At night, polyps reveal their "killer" nature, using tentacles to capture plankton in water bodies. The beautiful color of corals stems from the symbiotic zooxanthellae.
Corals and polyps
The polyps release eggs and sperm, fertilize in the sea, and then follow the currents of the sea until they find a suitable place to live, and then begin a new life course and form a new coral reef.
Coral reproduction
Coral algae
This is a large marine calcified algae, which contains a large amount of calcium carbonate in the cell wall, and the degree of calcification of the algae is high. It can act as a binder (similar to glue) to cement reef crevices or coral debris of different sizes. Some species are very similar in appearance to reef-building corals, so they are called coral algae, which is not the same as algae plants such as kelp and seaweed.
Chē qú (chē qú) shell
This is a large shellfish, there are 9 species, is the largest bivalve shellfish in the ocean, known as the "shell king", the maximum body length can reach more than 1 meter. It is found in tropical waters from the Indian Ocean to the Pacific Ocean , where coral reefs are attached to filaments. The double shells are thick and can be nested within each other, and the shells are wavy and curved. When the shell is opened in the seawater, its mantle film is brilliantly colored and has various patterns, which are related to its symbiotic zooxanthellae.
Coral algae and bricks
(2) Reef building process
Reef-building organisms themselves are reef-building materials, intertwined with each other when they are alive, and solidified together to form a hard reef body after death. Coral bones are porous and brittle, and the reef body alone cannot carry too much weight. The texture of chē qú is delicate and firm, and the coral algae is sticky, and after calcification, they are bonded to each other, which is very strong. This is the same principle we pour concrete. Below is the specific process of coral reef ecosystem formation.
Process 1: Reef-building corals construct reef discs. How do polyps work to produce limestone reefs? Polyps are hydra-type animals that absorb calcium from the ocean to form the bones of corals. After the death of the polyps, layer by layer piles up like pyramids, and after millions of years of accumulation, the main body of the coral reef is formed.
Process 2: Soft corals increase "vegetation". The coral reef made of stony coral is like a stone mountain, which needs to be dotted with "woods", which are soft corals, mainly red corals, gorgonian corals, bamboo corals and so on. Like mountain forests on land, tall bamboo corals resemble trees, low fan-shaped corals and sponges resemble shrubs, and moss mosses cling to the seabed. With the continuous expansion of coral reefs, it has formed a "underwater city with high-rise buildings".
Process 3: Calcified coral algae bond shellfish and coral stumps together like "glue" to make the reef disc stronger.
Process 4: Parrotfish make sand. In the process of continuous growth of coral reefs, there is a kind of fish that plays the role of sand maker, it is a hawkfish, hawkfish eat coral, absorb the algae in the coral as nutrients, and grind the coral limestone with pharyngeal teeth, forming sand after excretion. It then accumulates under the action of the waves to form an outcropping reef, or the sand of the island.
Process 5: Seagrass and seaweed in the sediment area of the seabed form a "seabed pasture". Under the joint action of reef and sediment, a lagoon with a different salinity of water and the outer sea is formed on the coast and inside the atolls. In this way, as this structure solidifies and transforms marine nutrients, attracting fish and other organisms to "settle down" here, coral reef biomes and ecosystems are constructed.
3. What is the role of coral reef ecosystems?
The role and use of warm water coral reefs is very large, not only providing human beings with a source of protein, but also a treasure trove of medicinal uses, such as in modern medicine, a drug called prostaglandin is extracted from the sea fan; a drug called lichen insectoid is extracted from the rhizome of coral. Cold-water corals can be made into jewelry, and the best coral stones are listed alongside pearls and amber as the three major organic gemstones in the West. In addition to the above uses, there are the following functions:
Protecting the coastline: Coral reefs, mangroves, and artificial coastal defense forests can play a role in protecting the coast, especially some shore reefs are as wide as 800 to 2000 meters, acting as energy dissipation zones and buffers for waves, and minimizing damage when an earthquake occurs in the ocean causing a tsunami. Lagoons in the atolls are natural havens because of the protection of the reef.
Provide human beings with a source of protein: there are coral reefs on the coasts of more than 100 countries around the world, and a large number of fish and other organisms live around the reefs, providing people with the necessary source of living materials and proteins, and even around the deep-sea coral reefs, a large number of fish are gathered to become deep-sea fisheries.
Provides an excellent habitat for fish organisms.
Participate in the earth's carbon, nitrogen and other cycles: seaweed consumes and absorbs carbon dioxide and produces oxygen; cured calcium and nitrogen elements generate organic matter, participating in the global carbon and nitrogen cycle.
Monitoring environmental change: Coral reefs and algae are very sensitive to changes in the environment, which facilitates people's access to first-hand information on environmental changes.
It helps people to study the paleoclimate of the Earth: coral reefs and Antarctic ice cores record the historical changes and paleoenvironment of the marine climate, and corals grow like trees with annual rings, with a very accurate time-burning function, known as the "geological clock".
<h1>How do coral reef ecosystems work? </h1>
Coral reefs play a key ecological role in the oceans, maintaining the ecological balance between the oceans and the planet. Coral reef ecosystems include reef flats, reef slopes, lagoons(xi) lakes, sandy grasslands; ocean currents outside reefs, plankton (phytoplankton, zooplankton), swimming organisms (such as sharks, groupers), etc., which constitute an efficient mechanism, and its operation includes the following three points: food chain circulation; ecological balance; and ecological collaboration.
Coral reef ecosystems
1. Food chain circulation
Coral reefs are a metropolis where marine life gathers, and almost all kinds of creatures can be found in coral reef ecosystems, which are the habitat of many economic fish, shrimp, crabs, shellfish and so on. These fish and shrimp organisms form an interconnected food chain. The formation of the food chain is inseparable from the productivity of coral reefs. The so-called productivity is colloquially speaking, the production capacity, what can be produced, and the organisms that can be fed.
First of all, it is inseparable from the role of ocean currents and tides, the nutrients in the ocean (plankton, minerals, etc.) will circulate around the world with the currents, why can the world's four major fisheries attract a large number of fish? It is because these locations are at the intersection of cold and warm ocean currents, which is an enrichment area for nutrients. The material in the ocean current is scattered and drifts with the waves, at which point the huge coral reef acts as a nutrient "collector". As a result, more than 1,200 species of coral reef ecosystems have been formed: benthic plants, phytoplankton, zooplankton, symbiotic algae and autotrophic bacteria.
Fish and organisms survive because of the presence of a large number of primary producers. Lower reef benthic organisms feed on primary producers, such as benthic shrimp, shells, etc. Then shrimp and shellfish become food for fish. Shrimp and scallops play a very important transit role in the food chain. Finally, a food chain of fish eating fish, animals eating fish, fish eating animals, snails eating fish and so on is formed. After the fish organism dies, it is decomposed by bacteria, completing the cycle of the food chain.
Small fish chase and prey on plankton near coral reefs, while sharks feed on bait fish
2. Ecological balance
Coral reef ecosystems are one of the most biodiverse and productive marine natural ecosystems, and the organisms living in the reef are diverse, perform their duties, restrict each other, and maintain a dynamic balance of organisms.
Corals and algae coexist, and algae are the food of some fish and organisms, they either nibble on algae or eat corals, and from a third-party point of view, they are the destroyers of coral reefs. For example, crown of thorn starfish dissolves coral fiber with digestive enzymes, and a large number of crown of thorn starfish can eat coral reefs beyond recognition within a few days, causing serious damage to the coral reef ecology. But the snail is its natural enemy and can control the number of crown-of-thorn starfish.
Sea urchins feed on seaweed, a large number of sea urchins like locusts sweep across a body of water, but sea otters, beautiful protrusion head fish eat sea urchins, sea urchin spikes are poisonous, but beautiful protoglove head fish are not afraid of sea urchin stingers, sharp teeth easily bite open the hard shell of sea urchins.
There are also spotted butterflyfish that like to eat polyps and algae, and octopuss that eat butterflyfish. Parrotfish eat coral, seemingly destroyers, in fact, help coral growth, because algae is too lush will suffocate corals, in addition, parrotfish can also make sand. In short, the ecosystem of the coral reef seems to be designed, maintaining a dynamic balance relationship. As human beings, we cannot arbitrarily disrupt this balance, otherwise it will cause a crisis in the coral reef ecosystem. There have been cases where lionfish have invaded other seas and caused the balance of the local coral reef ecosystem to be destroyed.
3. Ecological collaboration
There are many holes and crevices in the coral reef structure, providing a variety of habitats for organisms with different habits, and creating favorable conditions for fish organisms to inhabit, hide, breed seedlings, and take bait. But these organisms do not exist in isolation, and symbiotic relationships are one of the manifestations of common coral reef ecological collaboration. Here are some examples of symbiosis and collaboration:
Doctor fish with ferocious fish
The doctor fish, also known as fluttering, has a mouth like pliers, hides in a coral reef cave, and is a "sitting doctor", and its "customers" are mostly ferocious fish, such as moray eels, groupers and so on. Ferocious fish treat other fish with great evil, but they treat doctor fish very kindly, patiently and lovingly. It turns out that no matter how fierce these fierce fish are, they can't resist parasites, bacteria and so on. Without a doctor fish cleaning work, they will get sick and die. It just so happens that this doctor fish does not need extra remuneration, just try to eat some parasites to fill the stomach. They are an example of a symbiotic relationship, as are the relationships between fish and green sea turtles and sharks.
The symbiotic relationship between doctor fish and grouper
Clownfish and anemones
Clownfish and anemones have an inseparable symbiotic relationship, so clownfish are also called anemone fish. Clownfish in order to avoid the attack of other large fish to the anemone to seek protection, the anemone's tentacles are poisonous, many marine creatures dare not approach, and the clownfish body surface has a special surface mucus, can freely enter and exit the anemone from it. Clownfish can help with the hygiene of the anemones, and by the way, they can also pick up leftover food from the anemones.
The symbiotic relationship between clownfish and anemones
Polyps and zooxanthellae
There are zooxanthellae in the body of the polyp, they belong to the symbiotic relationship, the form of symbiosis in the body is very common, such as man and mites belong to the symbiotic relationship, the microorganisms in the human gastrointestinal tract and the human are also symbiotic relationship.
As for teamwork, manta rays and sharks are representative species, and manta rays like to work together to drive plankton into lagoons on coral reefs, do the same direction of circling, concentrating plankton in the center of the manta ray herd, and then feasting.
<h1>What are the factors that damage coral reef ecosystems? </h1>
Corals grow on average only about 10 centimeters per year. A coral reef takes thousands of years to complete, and destroying it is easy. Corals have survived on Earth for hundreds of millions of years, but are now suffering a great deal of damage, with about 1/10 of the world's corals destroyed and another 1/3 estimated to disappear in the near future. What are the actions of humans that destroy them? There are four main reasons.
1. Wanton mining of che qu
Natural damage is easy to recover, such as typhoon transit will damage coral reefs and benthic organisms, but it will not take long to recover, and will not lead to the degradation of coral reef ecosystems. Human activities are different, such as the waters of the South China Sea, because the digging of bricks will get high returns, fishermen will frantically illegally dig pots. Even the use of reef blasting to destroy the excavation of the reef, destroyed the reef, so that the reef was blown out of the gully, but also changed the structure of the reef, affecting the safety of the island and reef.
2. Damage to coral reefs caused by fishing operations
The large trawling operation used for fishing has resulted in devastating fish catches near the reef, tearing off coral branches.
3, Marine oxidation
Ocean acidification is the most dangerous factor for coral reefs, the main cause of ocean acidification is carbon emissions, global carbon emissions make the ocean absorb excess carbon dioxide, and the pH value of seawater is acidic. How does carbon dioxide make seawater sour? The acid here is not the sour taste of the sour plum soup we refer to, but refers to the fact that the sea water is originally weakly alkaline, and after the seawater absorbs carbon dioxide, the PH value continues to approach the acidic direction. People call the phenomenon of declining pH of seawater oceanification ocean acidification. The consequence is that the calcium carbonate in the seawater is slower, and the calcium in the seawater is not sufficiently obtained by corals and fish when the shell bones grow and develop. Coral reefs that live in weakly alkaline water cannot adapt when facing an ocean of acidification. The cellular osmolality of living organisms will also change, such as corals, mollusks, and echinoderms will have impaired physical function and die. Similar to organ failure in the human body.
Marine fish have a certain ability to regulate and balance pH, and are theoretically less affected by ocean acidification. But it has not been fully confirmed. But at least it will have an impact on the bones and ear stones of the fish, and will affect the behavior ability of the fish.
4, sea warming
The growth of marine flora and fauna requires a suitable temperature range, but there is a certain adaptability to temperature changes. If the temperature exceeds a certain range, the coral reef will bleach. Warming of the sea, even at 1 degree, has a huge impact on coral reefs. The main cause of seawater warming is the excessive emission of carbon dioxide, which affects the ozone layer and causes the earth to have a greenhouse effect.
<h1>postscript:</h1>
There are several places on the earth where biodiversity is very concentrated, tropical rainforests on land, and coral reefs in the ocean are treasures that nature has given to mankind. By understanding them, we can better use them and protect them.
Some of the pictures are from the Internet, invaded and deleted
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