Why do red tides occur in summer?

Red tide refers to the increase in the amount of phytoplankton in the water, the phenomenon of discoloration of seawater, the color usually changes between dark red and brown, red tide not only makes fish (especially farmed fish with nowhere to flee) die due to gill congestion, but also when some red tides occur, the toxic substances in the organism are enriched by shellfish through the food chain, which becomes the cause of shellfish poisoning.

Red tides can occur in a variety of organisms depending on the region and time of day, such as red tides caused by dinoflagellates that occur in the northeastern United States and become shellfish poisoning, red tides caused by filtophila that break out in the spring in the North Sea, and red tides caused by green dinoflagellum that occur in the Seto Inland Sea of Japan in the summer and cause the death of farmed yellowtail snappers. Most of these red tide creatures swim through flagellar movement, which can form red tides and cause shellfish poisoning incidents. Canada has reported shellfish poisoning caused by red tides caused by a non-swimming diatom.

Red tides have been known for a long time since the Egyptian and Japanese chapters of the Old Testament of the Bible, but in recent years, they have become a social problem due to the frequent occurrence of marine eutrophication. In the Seto Inland Sea, known as the "Ginza of red tides," the number of red tides has increased dramatically since eutrophication in 1965, but the number of occurrences has gradually decreased since the 80s when phosphorus emission restrictions have taken effect (Figs. 6-7).

Red tides are usually characterized by the explosive proliferation of a small number of specific species of red tide organisms in the sea, and the formation of red tides is promoted by the increase of nitrogen and phosphorus loads under specific nutrient environmental conditions.

Most red tide organisms do not float in the water throughout the year, but exist as dormant spores in the sediment for a considerable period of time. Environmental changes in the sediment cause dormant spores to germinate, releasing free cells into the water (the cause of red tides). When encountered, the population expands and forms red tides.

After the formation of red tide, when the surrounding environment is not suitable for proliferation due to nutrient depletion and other factors, the free cells become dormant spores again and settle in the mud to dormant until the next year, and wait until the water temperature rises from winter to spring, which is the key to the germination of dormant spores.

In our country, spring is the peak period of red tide, and our school has done this, usually going out to investigate in the month.

For phytoplankton, water temperature, light and nutrients are the constraints on their reproduction, with light mainly limiting the distribution of phytoplankton with depth. For water temperature, in the spring has met the requirements of phytoplankton growth, and at this time the nutrients are higher, there will be a large peak, to the summer, the nutrients are almost consumed, there will be a trough, in the autumn due to the weakening of the thermocline, the nutrients are replenished again, there will be a small peak in late autumn, the limiting factor in winter becomes the water temperature, the overall is in a relatively stable state. This two-peak, one-valley pattern is prevalent in temperate coastal zones.

Of course, red tides are not all caused by phytoplankton, and some zooplankton can also be caused by zooplankton, but in general, spring is the most common.

Red tides are not the only ones that occur in summer.

Red tides are caused by eutrophication of water bodies, but in summer the temperature is suitable for red tides (in fact, organisms gather together, but I don't remember whether they are microorganisms or algae) to grow.

Every once in a while, the ocean turns blood-colored and a large number of dead fish surface. This phenomenon may seem like a plague in the Bible, but it is much more mundane. It's just algae.

Red tides occur when there is a sudden surge in the number of algae of a specific molded species, and the numbers are so large that they are visible to the naked eye. They happen all over the world. In the Gulf of Mexico, the culprit for red tides washing the Texas to Florida coastline is often a microscopic algae called Karenia Brevis.

It produces toxic chemicals that can cause symptoms ranging from sneezing and eyes** to disorientation, vomiting, and difficulty breathing. It is often fatal to fish, shellfish, sea turtles and other wildlife.

Due to the specific depth at which the algae live, the water takes on a red color. Light waves do not penetrate seawater evenly, and some wavelengths travel farther than others. Algae that cause red tides grow at depths that absorb green and blue light frequencies and reflect red light.

Not all algal blooms are red; Some are blue, green, brown, and even purple. Not all algae will harm humans or animals. Why and how certain species of algae bloom wildly and wipe out entire marine life remains a scientific mystery.

The worst red tide ever recorded occurred in 1946, when a massive amount of algae that stretched 150 miles along Florida's coastline killed more than 50 million fish, along with hundreds of dolphins and turtles. When the corpses of the Dead Sea creatures washed ashore, tourists flocked away from the beach. Smaller incidents are more common, but equally costly.

In just 10 years of ageing, U.S. fishing and tourism have lost an estimated $1 billion to red tides, and costs are expected to rise.

<> climatic conditions: no wind or light breeze, blind heat, dry, muggy, high water temperature, etc.

Biological factors: This is a very important condition, because the essence of red tide is that the proliferation of red tide organisms reaches a limit or even exceeds this limit, if the red tide organisms proliferate normally and the number is stable, even if all other conditions are met, it will not cause red tide.

Biological factors, mainly the abnormal proliferation of some red tide organisms (for many reasons), caused the ...... of red tidesAnd the consequences of everything that follows.

Chemical factors: mainly the untreated discharge of sewage and some wastewater from factories, which leads to eutrophication of water bodies.

Environmental factors: For example, the water cycle of seawater stirs up nutrients from the lower layers to the upper ......Triggers eutrophication of surface waters.

1) Strengthen the occurrence of red tide: in May and September every year, in the red tide prone season, strengthen the systematic recording and analysis of meteorological, water temperature and other data, and timely carry out the possibility of red tide, so that farmers can quickly take emergency measures to avoid losses;

2) Pay attention to environmental protection: it is necessary to strengthen the control of factory sewage and domestic sewage discharge standards to make full use of the self-purification capacity of the sea area;

3) Emergency measures for the occurrence of red tide: For the water body where red tide occurs, you can first splash fungus algae net or cyanobacteria net to kill red tide organisms, increase oxygen appropriately, prevent and control hypoxia of breeding animals, and then use microecological preparations Zen base photosynthetic freeze-dried powder, EM freeze-dried powder or bottom modifier, multi-effect bottom modified particles, etc., to regulate the water body.

1.The mass reproduction of red tide organisms will consume a large amount of dissolved oxygen in the water body, which will lead to the hypoxia floating head of the farmed organisms, and even die;

2.Red tide organisms will secrete some mucus, or produce mucus after death, and in the process of respiration or filter feeding of farmed organisms, the respiratory organs will be blocked by mucus and suffocate to death;

3.Once the red tide organisms die, they produce toxins, which are released in the water, causing poisoning or death of farmed organisms.

4.Red tide organisms affect the survival rate of seedlings;

5.Red tide organisms form a dominant group in the pond, inhibit the growth of beneficial organisms, and destroy the balance of the pond breeding environment.

6.Red tide reproduction increases the occurrence of diseases in farmed organisms.

Red tide refers to an ecological anomaly phenomenon in which some tiny marine plankton in the ocean burst or accumulate at high density in a short period of time under certain conditions, causing the color change of seawater. Red tide is a serious marine hazard that often turns the sea water red or brown, which not only pollutes the environment, but also poses a great threat to the marine aquaculture industry.

The main hazards of red tide occurrence:

1. Toxins released by red tide organismsThe toxins released by red tide organisms can cause the death of marine fish, shrimp, shellfish and other organisms, or enrich the toxins in seafood and eventually have a toxic effect on other animals that eat them, including humans. If a consumer accidentally ingests a fresh dried scallop, it may be poisoned immediately, ranging from numbness of limbs, vomiting and coma, to death from shock. It is now known that there are 63 species of plankton that can secrete a large number of toxins to cause red tide in the coastal areas of China, and the largest number are 32 species of dinoflagellates, 24 species of diatoms, 3 species of cyanobacteria and 1 species of protozoa, collectively referred to as red tide organisms.

2. Some red tide organisms can secrete sticky secretions, and the sticky secreted by red tide organisms hinders the eating and breathing of marine organisms, and in severe cases, they will suffocate to death.

3. When a large amount of oxygen is consumed by red tide organisms, the dissolved oxygen in the water body is reduced, and a large number of marine organisms die due to lack of oxygen.

4. When a large area of red tide blocks the sunlight, it affects the photosynthesis of marine organisms, and then affects the survival of plants in the ocean, the food of fish and other animals, and makes them die of lack of food.

Measures to control the occurrence of red tides:

1. Spray chemicals to directly kill red tide organisms, or spray flocculants to make red tide organisms stick together and settle to the bottom of the sea.

2. The mechanical method uses mechanical equipment to suck the seawater containing red tide onto the ship for filtration, and separates and kills the red tide organisms.

3. Build an isolation zone and use a fence to isolate the area where red tide occurs to avoid polluting other sea areas after spreading.