We will lead you into the Xuwen Coral Reef National Nature Reserve to explore the coral reef.
Corals belong to the molluscs of the coelenterate phylum Polyp family, corals exist in groups, by many polyps united together to form living tissue, underneath the living tissue is calcareous bones, which are formed by polyps constantly accumulating calcium carbonate. The living unit of the coral is the polyp, which resembles a retractable floret with only one opening at the top through which food enters. The mouth is surrounded by one or more circles of tentacles used to prey on small animals. Under the mouth is a sac-shaped intestine. Corals use tentacles to filter seawater impurities and obtain food from them. Calcium, magnesium, and some suspended microorganisms in seawater are all foods for corals.
From an ecological point of view, corals are usually divided into two types, one is reef-building coral (stony coral) and the other is non-reef-building coral (soft coral). Stony corals can form coral reefs during their growth, while most soft corals cannot.
▲Reef-making coral (stony coral)
▲Non-reef-building corals (soft corals)
The suitable growth temperature of reef-building corals is between 20-30 degrees, and low temperatures below 18 degrees and high temperatures above 30 degrees are unfavorable environments for most corals, which will cause coral bleaching or death. From the distribution of global water temperature, reef-building corals are mainly distributed in the sea between 25 degrees north and south latitudes, and grow most abundantly in the tropical seas between the Tropic of Cancer. Reef-building corals are distributed in shallow seas with clean water quality and medium flow rate, and coral larvae must attach to hard substrates such as rocks, reef blocks, coral bones, etc.
1 The value of coral reefs
Corals are good indicator organisms for assessing environmental pollution in tropical waters.
About 500 million people worldwide live directly on coral reef ecosystems.
The three-dimensional spatial structure framework of the coral reef ecosystem provides a good habitat for a variety of marine life, with more than 2500 species of fish and 700 species of reef-building stony corals in the coral reef area; the global coral reef area accounts for <0.2% of the total marine area, but it is pregnant with 30% of marine life.
▲Actually take a picture of coral growth in Xuwen Coral Reef National Nature Reserve
Corals convert carbon dioxide into calcium carbonate, which helps reduce carbon dioxide levels in the atmosphere and mitigates the greenhouse effect.
The hard bones of corals can resist the impact of waves on the coast, reduce the impact of waves, protect the coast, and have a de-wave and revetment effect.
Corals are the filters of seawater, and countless tiny polyps use their tentacles to constantly filter various particles in seawater to obtain nutrients and keep seawater clean.
Corals can be widely used in paleogeomorphological and paleogeographic studies as well as climatic studies.
2 Coral reefs are distributed along the coast of mainland China from the Tropic of Cancer to the south
Coral reef ecosystems are one of the most biodiverse and productive typical ecosystems on Earth and are known as "rainforests in the ocean". China's south China coast has rich coral reef resources, mainly distributed in Xuwen Coral Reef National Nature Reserve, Nanpeng Archipelago Marine Ecological National Nature Reserve, Guangdong Daya Bay - Dapeng Bay area, Guangxi Weizhou Island - Xieyang Island waters, Hong Kong waters, the northernmost edge to the Fujian Zhangzhou Dongshan surrounding the sea.
▲Carry out a survey of coral reef resources in Xuwen Nature Reserve
In the 2019 survey of the Nanpeng Islands Marine Ecological National Nature Reserve, for the first time, at least 15 species of reef-building stony corals were found in the waters of the Nanpeng Islands located on the Tropic of Cancer, including a large area of stony coral communities dominated by staghorn corals and rose corals, and the number of species and distribution area were much higher than those in the Dongshan sea area (5 species) where the distribution of reef-building corals along the coastal coast of Mainland China was located. This survey confirms that there are coral reef ecosystems distributed along the coast of mainland China from the Tropic of Cancer to the south.
▲Coral seedling cultivation work
3 Escort the healthy growth of coral reefs with the power of science and technology
Xuwen Coral Reef is the only modern coral reef that has developed and been well preserved along the mainland of China, and Xuwen Coral Reef National Nature Reserve has continuously carried out coral reef survey, water quality monitoring, coral reef restoration, artificial seedlings and planting in order to protect coral reefs and their ecosystems, and escort the healthy growth of coral reefs with the power of science and technology.
▲Fixed-point release of coral artificial ecological reefs
Carry out the survey of the water quality environment and coral reef biological resources in the protected area. Persist in carrying out environmental monitoring of water quality in protected areas once a quarter, and timely grasp the changes in ecological factors of water quality in protected areas. At the same time, the distribution of corals, the ecological health status of corals, and the status of substrate organisms in the protected area are monitored and investigated by using conventional methods of ecological surveys.
▲Coral seedlings are planted on the seabed
Carry out research on artificial ecological restoration of coral reefs. The first is to carry out coral transplantation and planting, transplanting laboratory-bred coral seedlings to damaged coral reef areas for solid growth to enrich the number of living corals, thereby promoting the recovery of corals in reef areas, so far, a total of more than 2500 coral seedlings have been cultivated and transplanted. The second is to release artificial ecological reefs, according to the results of the survey of water quality and biological resources in the diagonal tail sea, targeted design, development and production of artificial ecological reefs to promote the growth and restoration of corals in the protected areas, up to now a total of 220 artificial ecological reefs have been produced and released, and certain restoration results have been achieved.
▲Actually photograph the growth of corals in the protected area
The results of the coral reef resource survey in recent years show that the average coverage rate of reef-building stony corals in Xuwen Nature Reserve has basically remained at about 15%, and the main dominant species are basically stable, mainly including angle-hole corals, gyroscopic corals, honeycomb corals, coastal corals, chrysanthemum corals, etc. The coverage rate of stony corals in some survey sites has increased significantly, by more than 10%, while the number of new dead corals found in the survey is very small.
Source: Guangdong Forestry
Editor: Lin Chao, Luo Yin, Jin Yaping