The ocean area represents more than 70% of the earth's surface. Due to the vast distribution of the ocean, the various types of marine areas, the different depths of the ocean itself, and the unique characteristics of the interface between the ocean and land, the diversity of marine life and multiple close connections with terrestrial ecosystems were formed. Marine life plays an important role in life on land and in the entire biosphere and has a significant ecological impact.
Marine life includes coastal wetlands and offshore life (such as mangrove communities in tropical and subtropical estuaries and bays), seagrass communities in coastal waters shallow sea biomes, and deep sea ocean biomes. There are a large number of aquatic plants and plankton living on the surface of shallow sea areas and deep sea areas, whichcan carry out photosynthesis and are major producers of marine life. Particularly in ocean areas far from land, seawater is poor in nutrients and autotrophic plankton which carry out photosynthesis are the main primary producer and the basis for the survival of other marine animals, such as cyanobacteria and nitrogen-fixing cyanobacteria. The depths of the ocean are dark places where light cannot penetrate and where there is no primary productivity. However, there are also a large number of animals that rely on food transferred from the water surface to survive. These animals have developed particular adaptation skills. such as the formation of light organs and areas of weak light. Particularly developed vision, enlargement of prey organs, male and female symbiosis, etc. In short, marine life has formed a complete three-dimensional system of distribution andof energy use around the ocean and land.
(1) Marine organisms are the greatest environmental purifiers on Earth. Various organic materials, metabolites, and environmental releases produced by terrestrial organisms enter the ocean through rivers or the atmosphere, and settle on the seafloor and dissolve in water. Marine organisms capture these substances, stabilizing the seafloor sediment layer and cleaning the seafloor. body of water. eutrophication and increasing water transparency. Without a large amount of marine life, organic pollution of seawater will continue to accumulate, the terrestrial ecology will not be balanced, and terrestrial life will not survive.
(2) Marine life provides abundant products to life on land. A large number of marine plants and animal products supplement the terrestrial organic food chain. In certain regions, the marine economy constitutese the main dependence of humanity. As the world's population increases and land resources become scarcer, the development of marine resources will become increasingly important. Land animals along the coast depend on marine life for their survival. For example, mangroves provide an important range for birds, crustaceans, reptiles, seagrasses, algae and other plants that provide food sources for birds and terrestrial animals.
(3) Damage caused by abnormal growth of marine life. Due to accelerating human activities and rapid consumption of land resources, a large amount of organic matter and toxic pollutants are released into the ocean, leading to a decrease in offshore wildlife, an increase in plankton, or excessive growth of seagrass beds, leading to improper developmentfree from marine life. As a result, a large-scale regional epidemic has emerged. This affects the living environment of terrestrial organisms. Protecting marine ecology and marine life is another challenging task of the 21st century.
Knowledge points
Sea water temperature
Sea water temperature is a physical quantity that reflects the thermal conditions of the sea water. The water temperature of the world's oceans generally ranges between -2°C and 30°C, with the annual average water temperature exceeding The area above 20 ℃ accounting for more than half of the total surface area of the ocean. Sea water temperature exhibits cyclical and irregular changes in days, months, years, and years, which mainly depend on the ocean heat budget and its temporal changes. Direct observation shows that the diurnal variation of sea water temperature is very small, that the water depth varies from0 to 30 meters and that the annual variation can reach a water depth of around 350 meters. At a water depth of around 350 meters there is a constant temperature layer. However, as depth increases, water temperature gradually decreases (approximately 1° to 2°C for every 1,000 meters of depth). At a water depth of 3,000 to 4,000 meters, the temperature reaches 2° to 1°C. Sea water temperature is one of the most important factors in the hydrological conditions of the oceans. It is often used as a basic indicator to study the properties of water masses and describe the movement of water masses. The study of the spatio-temporal distribution and temperature changes of sea water is not only an important part of oceanography, but also important for disciplines such as meteorology, navigation, fisheries and hydroacoustics.