How red tides are formed! Junior biology !! Be concise and to the point

Red tide is a phenomenon in which certain organisms living in the ocean multiply rapidly or aggregate in large numbers when encountering suitable environmental conditions, causing a large area of sea water to change its color. When the red tide comes, the respiratory organs of marine organisms are "clogged" by plankton that bloom in large numbers, causing a large number of marine organisms to die; At the same time, the rapid reproduction of plankton and the death of marine organisms consume a large amount of oxygen in seawater, making seawater a "stagnant water" where organisms cannot survive. Red tides can also produce toxic substances, which are also quite harmful to the environment and humans.

There are two main reasons for the occurrence of red tides: one is due to the development of human economy and life, which has caused an increase in the amount of sewage discharged from rivers and artificial sewage, resulting in a large surplus of nutrients in many sea areas; Second, a large number of artificial breeding ponds are discharged, causing serious pollution in local areas. In addition, changes in the natural marine environment and world climate conditions in recent years, such as poor seawater mobility and rising global temperatures, will also have an impact on the formation of red tides.

Red tides are mainly caused by the explosive proliferation of some phytoplankton, protozoa, and bacteria in the water caused by eutrophication (excess of nutrients in the water body) caused by excessive nitrogen and phosphorus content in the water.

Hope my answer will be helpful to you!

Red tide refers to the phenomenon that some plankton in seawater suddenly multiply in a short period of time, resulting in a lack of oxygen in the water and the death of fish. The main cause of red tide is the high content of organic matter, especially nitrogen and phosphorus, in seawater.

The result of overnutrition in the water and the proliferation of microorganisms.

The abundance of organic matter such as nitrogen and phosphorus in the water body causes the algae bloom of single-celled organisms.

Due to the discharge of wastewater containing chemical nutrients, the water surface is overgrown with algae plants.

Environmental pollution, water over-trophication, algae blooming.

1. Red tide, also known as red tide, is a bloom phenomenon. It is a kind of marine disaster, when a certain population of red tide organisms in the sea area has a certain number of individuals, and the external environment such as temperature, salinity, light, and nutrition reaches the most suitable range for the growth and proliferation of red tide organisms, red tide organisms can enter the exponential proliferation period, and it is possible to develop into red tides relatively quickly. Red tide is an anomaly in marine ecosystems.

It is caused by the explosive proliferation of red tide algae in the seaweed family under specific environmental conditions. Seaweeds are a large family, and with the exception of some macroalgae, many are very tiny plants, some of which are unicellular organisms. Depending on the species and number of organisms that cause red tides, the water sometimes takes on different colors such as yellow, green, and brown.

2. Causes:

1) Seawater enrichment. Due to the large amount of urban industrial wastewater and domestic sewage discharged into the sea, the nutrients in the water body increase sharply, resulting in eutrophication of the sea area. At this time, nutrients such as nitrogen and phosphorus in the waters; The content of trace elements such as iron and manganese, as well as organic compounds, has greatly increased, promoting the proliferation of red tide organisms.

2) Sea temperature. The temperature of seawater is an important environmental factor for the occurrence of red tides, and 20-30 is the suitable temperature range for the occurrence of red tides. Red tides may occur in the range of 26-37 salinity, but when the salinity of seawater is 15-, thermocline and halocline are easy to form.

The presence of temperature and halocline provides conditions for the aggregation of red tide organisms, which can easily induce red tide.

3) Human activities. With the rapid development of modern chemical and agricultural production and the increase of population in coastal areas, a considerable part of industrial and agricultural wastewater and domestic sewage in human production activities are directly discharged into the ocean without treatment. At the same time, due to the increase in the degree of coastal development and the expansion of marine aquaculture, it has also brought about the pollution of the marine ecological environment and the aquaculture industry itself. The development of the maritime industry has led to the introduction of exotic harmful red tide species; Changes in the global climate have also led to the frequent occurrence of red tides.

4) In the early stage of plant red tide, due to the photosynthesis of plants, high chlorophyll a, high dissolved oxygen, and high chemical oxygen consumption will occur in the water body. The change of such environmental factors has caused some marine organisms to fail to grow, develop and reproduce normally, resulting in the escape or even death of some organisms, destroying the original ecological balance.

Red tide is a complex ecological anomaly, and the causes of its occurrence are also complex. The cause of red tides is still inconclusive, but scientists believe that red tides are caused by organic pollution of coastal waters. Under normal conditions, the nutrient content of the ocean is low, which limits the growth of phytoplankton (some flagellates (or dinoflagellates) are also food for some fish and shrimp).

However, when domestic sewage, industrial wastewater (mainly food, paper, printing and dyeing industries) and agricultural wastewater containing a large amount of nutrients flow into the ocean, coupled with other physical and chemical factors in the sea area that are conducive to the growth and reproduction of organisms, red tide organisms will multiply sharply and form red tides.

How is red tide formed? Red tides are formed by some uh-red algae in that sea water that lives in the nutrient-rich water.

The types of organisms associated with the formation of red tides are as follows:

Red tide organisms include plankton, protozoa and bacteria, among which the poisonous and harmful red tide organisms are mostly dinoflagellates, followed by diatoms, cyanobacteria, algae, cryptoalgae and protozoa.

1. Dinoflagellates. A single-celled assemblage plant with biflagella, indefinite in shape. Often distributed in fresh water and seawater, some dinoflagellates are harmful to their activities, and their survival will carry some special smells.

Some can form "red tides" and "algae flowers", which make the local sea water red, yellow or brown.

2. Diatoms. Diatoms belong to the producers in the food chain. If the marine environment is polluted by eutrophication or other reasons, some diatoms such as Osteocystis, Rhomboform, Box Algae, Ceratotrina, Rhizophorae, and Streptowee are overly reproductive, forming red tides, making the water quality poor, and bringing serious harm to fisheries and other aquatic animals.

3. Cyanobacteria. Also known as blue-green algae, a class of large single-celled prokaryotes with a long evolutionary history, negative Gram stain, flagellar, chlorophyll a, but no chloroplasts (algae different from eukaryotes), and can carry out oxygen-producing photosynthesis. Some cyanobacteria are polluted by nitrogen, phosphorus and other elements to lead up the "red tide" of sea water and the "bloom" of lakes after being polluted by eutrophication oaks, which brings serious harm to fisheries and aquaculture.

4. Golden algae. Also known as golden brown algae, golden brown, in addition to chlorophyll, there are still more carotenoids. Single-celled swimming species, without cell wall, with cell wall, their constituent substance is mainly pectin.

There are often one or two apical flagella (three are rare), and the flagella are equal or unequal in length. The stored food is oil and wheat albumin.

5. Cryptoalgae. unicellular, with a broad anterior end, obtuse rounded or obliquely flattened; Most species have flagella and are motility. The photosynthetic pigments of cryptoalgae include chlorophyll a, c, carotene, etc.

There is also phycobilin. Pigment body 1 2, large leaf-shaped. The color of cryptoalgae varies greatly.

It is mostly yellow-green, yellow-brown, but also blue-green, green or red.

Plankton blooms.

Red tide is a catastrophic marine phenomenon produced after the ocean is polluted, due to the excessive organic matter and nutrients, some tiny planktonic algae, protozoa or bacteria in the ocean burst reproduction or aggregation, causing water discoloration With the rapid development of industrial and agricultural production, water pollution is becoming more and more serious, and red tide is becoming more and more serious.

Red tides not only cause serious harm to the marine environment, fisheries and aquaculture, but also have a certain impact on human health and life safety. During the disappearance period of red tide, red tide organisms die and decompose in large numbers, depleting the dissolved oxygen in the water, and the decomposition products produce a large number of harmful gases, which are foul smelling, and coastal fishermen talk about the discoloration of red tide.

Red tides get their name because they turn the surface of the ocean red, and how harmful are they to marine life? So, what causes red tides?

Do we know that the wastewater and sewage containing organic matter in cities, as well as chemical fertilizers from farmland, are continuously flowing into the sea and inland seas through rainwater, and these waters contain a lot of nitrogen? Nutrients such as phosphorus, as well as a lot of carbon, can sometimes bring benefits to marine fisheries if done in moderation? But if there are too many of these nutrients, there will be a large number of plankton in the ocean, these substances consume the dissolved oxygen in the seawater, making it difficult for fish to breathe oxygen.

In recent years, the phenomenon of red tide has occurred frequently in the waters of various countries around the world, and the damage caused is immeasurable. In recent years, there has also been a red tide phenomenon in coastal areas in China? In order to reduce the occurrence of red tides, it is necessary to reduce the amount of nutrients and organic matter discharged into the offshore sea and protect the ecological environment of the ocean?

The harmful ecological phenomenon of discoloration of water caused by the explosive protozoa or bacteria of certain phytoplankton, protozoa or bacteria in Hengshui is called red tide, and the occurrence of self-deprecation has natural factors, but human beings discharge and dump waste into the ocean uncontrollably, causing the rapid reproduction of other algae plankton, which is the main reason for the current discovery of hemorrhoids. Red tides can disrupt the ecological balance of the ocean, marine fisheries and aquatic resources, and endanger human health.

Organisms that are able to reproduce in large numbers and cause red tides are called red tide creatures.

Including plankton, protozoa and bacteria, among which the poisonous and harmful red tide organisms are mostly dinoflagellates, followed by diatoms, cyanobacteria, golden algae, cryptoalgae and protozoa.