What is a "red ghost" red tide?

Red tide, commonly known as "red ghost", is also known as "harmful algal bloom" internationally. Red tide, also known as red tide, is an abnormal phenomenon in marine ecosystem. It is caused by the explosive reproduction of red tide algae in the family Algae under specific environmental conditions. Seaweed is a huge family. Except for some large algae, many of them are very tiny plants, and some are unicellular plants. Depending on the species and quantity of organisms that cause red tides, seawater sometimes appears in different colors, such as yellow, green and brown.

After the occurrence of red tide, a large number of red tide organisms gathered in the gills of fish except that the seawater turned infrared, which led to the suffocation and death of fish due to lack of oxygen. Second, after the death of red tide organisms, algae consumed a lot of dissolved oxygen in the water during the decomposition process, which led to the anoxic death of marine organisms such as fish, and also released a lot of harmful gases and toxins, which seriously polluted the marine environment and seriously damaged the normal marine ecosystem. Third, fish eat a lot of toxic algae. When the red tide occurs, the pH value and viscosity of seawater will also increase, and the plankton of non-red tide algae will die and rot. Red tide algae also died in large numbers due to explosive proliferation and excessive aggregation.

Red tide is produced under specific environmental conditions, and there are many related factors, but marine pollution is one of them. A large amount of wastewater containing various organic substances is discharged into seawater, which promotes the eutrophication of seawater and is an important material basis for the proliferation of red tide algae. A large number of studies at home and abroad show that marine phytoplankton are the main organisms that cause red tides. There are more than 260 species of marine phytoplankton in the world that can form red tides, and more than 70 of them can produce toxins. Some toxins secreted by them can directly lead to a large number of deaths of marine life, and some can even spread through the food chain, causing human food poisoning.

More than 30 countries and regions in the world have been harmed by red tides to varying degrees, and Japan is one of the countries that suffered the most. In recent ten years, due to the increasingly serious marine pollution, the red tide disaster in China has also increased, from a few scattered sea areas to a sea area, and some important breeding bases have been particularly seriously affected. Studying and preventing the occurrence and harm of red tide is a complex systematic project, involving biological oceanography, chemical oceanography, physical oceanography and environmental oceanography.

Red tide is a harmful ecological phenomenon that some phytoplankton, protozoa or bacteria in seawater proliferate explosively or gather highly under specific environmental conditions, causing discoloration of water body. Red tide is a historical name, not necessarily red, but actually a general term for many red tides. With the different causes, types and quantities of red tides, the water will show different colors, such as red or brick red, green, yellow, brown and so on. It is worth pointing out that some red tide organisms (such as Gymnodinium, Gymnodinium, Pyrodinium, etc. Sometimes it doesn't make the sea water appear any special color.

The ocean is a complex ecosystem in which living things and environment, living things and living things are interdependent and mutually restricted. The material circulation and energy flow in the system are in a relatively stable dynamic balance. When the red tide appeared, this balance was broken. In the early stage of plant red tide, due to the photosynthesis of plants, the water body will have high chlorophyll a, high dissolved oxygen and high chemical oxygen consumption. This change in environmental factors has led to the failure of some marine organisms to grow, develop and reproduce normally, leading to the escape or even death of some organisms, which has destroyed the original ecological balance.

The main reasons for the destruction of fish, shrimp, shellfish and other resources by red tides in offshore waters are:

(1) destroys the bait base of fishing grounds, resulting in a reduction in fishery production.

(2) Abnormal reproduction of red tide organisms will cause mechanical blockage of economic organisms such as fish, shrimp and shellfish, which will suffocate these organisms.

(3) In the later period of red tide, a large number of red tide organisms die, which can cause serious environmental hypoxia or produce harmful substances such as hydrogen sulfide under the action of bacterial decomposition, so that marine organisms die of hypoxia or poisoning.

(4) Some red tide organisms contain biological toxins or metabolites, which can directly kill fish, shrimp, shellfish and other organisms.

When human beings pollute the ocean unscrupulously for self-interest, the angry ocean will retaliate against human beings through red tide, destroy fishery production, threaten human health and even kill people.

Marine phytoplankton is the main organism that causes red tides. Microcystins in red tide algae accumulate in shellfish and fish through the food chain. After eating by mistake, people may be poisoned or even die. People also call red tide toxin "shellfish toxin".

Shellfish toxin is the most toxic organic compound known at present. According to the symptoms of human poisoning, it can be divided into paralytic shellfish poisoning (PSP), diarrheal shellfish poisoning (DSP), forgetful shellfish poisoning (ASP), neurotic shellfish poisoning (NSP) and imported fish poisoning. In recent years, new toxins and their components have been continuously discovered. Paralytic shellfish poisoning was found in the red tide in the East China Sea this year. This toxin used to have only 8~ 12 components, but now it has been found to have more than 30 components.

Paralytic shellfish poisoning is the most important and common toxin in all red tide toxins, and there is no radical cure at present. Humans eat shellfish containing paralytic toxins by mistake for 5 to 30 minutes. Mild people have tingling and numbness around their lips, which gradually spread to the face and neck, and tingling in fingers and toes, accompanied by headache, dizziness and nausea. In severe cases, incoherent speech, aphasia, tingling sensation extending to limbs, stiff hands and feet, dyskinesia, general weakness, dyspnea and rapid heartbeat occur; The critically ill, with muscle paralysis, obvious difficulty in breathing and feeling suffocated, will die within 24 hours under the condition of lack of oxygen.

Symptoms of diarrhea toxin are similar to food poisoning. These toxins are tumor promoters, especially damaging human liver cells and posing a potential threat to human health. Neurotoxins can cause nerve conduction disorders. After eating shellfish and fish containing neurotoxins for 3 hours, people will suffer from dizziness, head nerve mechanism disorder, pupil dilation, body heat and cold uncertainty, nausea, vomiting, diarrhea and other poisoning situations. Severe cases are accompanied by arrhythmia, acute asphyxia, and sometimes dyskinesia after drinking.

According to statistics, since the 1960s, 600 people in China have been poisoned by eating poisonous shellfish by mistake, and 29 of them have died. During the period of 1976~ 1978, there were many poisoning incidents of edible snails in Zhoushan and Ningbo, Zhejiang Province, and the toxin came from Gymnodinium. 1986 Dongshan, Fujian 136 people were poisoned, 1 people died. In 2002, more than 50 people in Ningde, Qingtian, Luoyuan and other places in Fujian were poisoned by trypanosoma, and 3 of them died.

At present, many countries have strict regulations on the toxin content in shellfish. For example, according to Canadian regulations, it is forbidden to eat paralytic shellfish poison when it exceeds 80 μ g/100g, the content of diarrhea toxin shall not exceed 200 μ g/g, and the content of amnesia shellfish poison shall not exceed 20 μ g/g. Countries are increasingly demanding the quality of imported aquatic products. EU inspection of imported aquatic products includes 63 indicators, including chemical indicators of freshness, natural toxins, parasites, microbial indicators, toxic chemicals of environmental pollution, heavy metals, pesticide residues and radiation. Due to a complete set of monitoring and management measures for seafood, although toxic red tides often occur in the coastal areas of some countries in Europe and America, seafood poisoning incidents are rare.

The detection of seafood toxins in China is mainly for export, and most seafood sold in the domestic market has not been tested for any toxins. Although the General Administration of Quality Supervision, Inspection and Quarantine issued the Safety Requirements for Pollution-free Aquatic Products in 200 1 year, which stipulated that the content of paralytic shellfish poisoning should not exceed 80 μ g/100g, and the content of diarrheal shellfish poisoning should not exceed 80 μ g/100g, and began to carry out the quality certification of pollution-free aquatic products, the coverage of certification was very small, and the certification was only for cultured products.

With the rapid development of modern chemical industry and agricultural production and the increase of population in coastal areas, a large number of industrial and agricultural wastewater and domestic sewage are discharged into the sea, and a considerable part of them are directly discharged into the sea without treatment, which leads to the increasingly serious eutrophication in offshore and harbor areas. At the same time, due to the increase of coastal development and the expansion of marine aquaculture, it has also brought pollution to the marine ecological environment and aquaculture itself; The development of shipping industry leads to the introduction of harmful alien red tide species; The change of global climate has also led to the frequent occurrence of red tides.

Before 1500 AD, the Old Testament once described a red tide in a river-"The river turned into blood. The fish in the river is dead ... this river can't drink any more. "

Red tide in Korea occurred in August of 20001year, and appeared on the sea in various regions of Korea.

Hundreds of fishing boats are busy shuttling. But instead of fishing, fishermen are constantly throwing loess into the sea to control the rapidly expanding red tide. The South Korean government has invested 65.438+0.2 billion won and put 80,000 tons of loess into the southern waters of South Korea.

On August 6, toxic red tide organisms were detected near Lishui City, Jeollanam-do, southwestern Korea. On August 10, gymnosperms were also detected near Nanhai county, gyeongsangnam-do, South Korea, with a density of 1 ~ 2 cells/ml. The "practical consultation meeting on red tide countermeasures" between the two places began to pay close attention to developments.

Spirogyra belongs to algae. For most of the year, its spores lurk at the bottom of the sea. After the water temperature rises to a suitable temperature, spores begin to develop and float to a depth of 3-5 meters. Since August of that year, the seawater temperature along the South China Sea has been between 24℃ and 25℃, and frequent rainfall has washed a lot of nutrients into the sea, leading to the rapid development of red tides. It is considered that dinoflagellate can produce a hemolytic toxin, and the number of individuals in seawater reaches more than 3000 /ml, which may lead to large-scale fish death.

At 6: 00 p.m. on June 4, 65438, the South Korean government issued the first red tide notice of that year, which was aimed at the south of the Korean Peninsula, and the center was located at the southern end of Gaoxing County, South-South Province. The sea water here has turned crimson, and it is still expanding. According to the investigation by the Fisheries Promotion Institute, the number of individuals of Spirogyra in this water area reached 180 ~ 600 /ml that day.

On June 5438+09, the density of dinoflagellate in South Korea (Happy County) reached 3400 ~ 4000 /ml. By the afternoon of the 22nd, the crimson red tide zone had intermittently covered a narrow sea area of about 200 kilometers, forming a frightening momentum.

2 1, near Sheliang Island, Tongying City, South Gyeongsangnam-do, fish deaths began to appear in several fishing grounds within about 4 nautical miles.

On the 25th, the National Fisheries Promotion Agency issued a red tide notice to the waters west of Happiness Peninsula in Jeollanam-do and southeast of Juji Island in Gyeongsangnam-do.

At 5 pm on the 26th, the red tide notification was changed to red tide warning. In this way, the eastern part of the South China Sea and the southern part of the East China Sea are within the red tide warning range.

Releasing loess is an internationally recognized method to deal with red tide. Loess can be adsorbed on the cell membrane of red tide organisms in the form of particles or combinations, driving the red tide organisms to sink to the seabed. The water temperature there is low, the light is weak, and the nutrients are relatively insufficient, which is not conducive to the growth of red tide organisms.

Philippine Red Tide Tongying City, Gyeongsangnam-do, South Korea is located in the southeast of the Korean Peninsula, and the sea area near Tongying City is one of the areas with the highest red tide density. On the afternoon of 17, a red tide warning was issued in Gaoxing County, Jeollanam-do, west of Tongying. On the afternoon of 18, the red tide area spread to Sheliang Island in Tongying City. On that day, the local people mobilized cargo ships and trawlers to throw 260 tons of loess. On 19, another 200 tons of loess are concentrated in the sea area with dense fishing grounds around 10 nautical mile. In addition to constantly throwing loess into the sea, the fishing village also purchased more than 20 red tide scavengers. Each machine filters 200 tons of seawater every hour, and eliminates red tides for 24 hours.

In order to cut off the nutrient supply chain of red tide organisms, measures to reduce fish feed are generally adopted in various fishing grounds. Some areas stopped eating for more than 1 week. The number of fish deaths in various fishing grounds was nearly 6.5438+0 million, and the loss exceeded 400 million won.

On September 3, 20001year, the Central American Isthmus Fisheries and Aquaculture Organization announced that a serious red tide was attacking the Pacific coast of Central America, among which Costa Rica, Guatemala and El Salvador were the most seriously affected.

According to the organization, the red tide in Costa Rica formed at the end of 1999, but there is no sign of disappearing. On the northern coast of Guanacaste, the toxin index absorbed by shellfish is more than 38 times of the maximum limit for human beings to bear such toxins. In the central coastal areas, the toxin content of shellfish also greatly exceeds the standard.

On September 4th, Guatemala Red Tide Monitoring Committee announced that the national marine industry had entered a "red alert state", forbidding fishing and selling any shellfish, and warned consumers not to eat shrimp heads, fish heads and their internal organs.

Two major seafood production bases in El Salvador were severely hit by red tide. In addition to banning the sale of shellfish products in China, the government also "temporarily stopped" importing any seafood products from Guatemala.

This red tide has the widest impact, the longest duration and the most serious economic loss since 1987. In Costa Rica, 5 1 person was poisoned, and the economic loss exceeded 1.5 million dollars. Fishery production in El Salvador and Guatemala also suffered heavy losses.

Central American countries also held an emergency meeting in San Jose, Costa Rica, on September 1 1 to discuss ways to jointly deal with red tides.

In June, 2003, 5438+065438+ 10, the Philippine Office of Fisheries and Aquatic Resources (BFAR) issued a red tide warning to several coastal areas in the Philippines. The fishery and shellfish industry in the affected areas could not be sold because of the red tide toxin, resulting in a loss of nearly $3 million.

The alarm has not been lifted, and the content of red tide toxin is still relatively high.

According to the person in charge of BFAR Red Tide Monitoring Team, the affected areas include Palavig Bay in Zambales Province, Honda Bay in palawan island, Mantavorn and Milagros Bay in Masbat Province, Juag Reef Lake in Sosogon Province, San Pedro Bay between Fete Island and Samar Island, Barit Bay in Davao Region and Dumankilias Bay in Zamboanga Region. These areas are famous for their rich shellfish, and shellfish sales are the main source of income for local fishermen. The local government had to issue a shellfish ban to prohibit toxic shellfish from entering the market, which suddenly reduced the shellfish sales in the Philippines that year.

In August 2002, two red tides occurred in ElandsBay, a remote fishing village near Cape Town, 200 kilometers north of the west coast of South Africa, resulting in a large number of lobster deaths. Nearly 300 tons of lobsters landed in the first red tide of turtles in the southwest coastal area of Florida. Local residents rushed to pick them up, but they were strongly forbidden by the Fisheries Bureau and the police. The approach adopted by the Fisheries Bureau is to collect live lobsters as much as possible and send them to safe waters for release to reduce resource losses. However, after two days of rescue, only about 60 tons of lobsters were released.

According to scientists from the Fisheries Bureau, lobsters have been killed by red tides every 10 years since 1940, and the situation has been more serious in the past 10 years. They have done all kinds of research, including the change of meteorological model, but they still can't find out the cause of red tide flooding. Because it is the season suitable for lobster breeding, and most of the dead lobsters are below the fishing length limit, it is expected that the impact of this red tide on resources will appear in a year or two.

From July to mid-June, 2005 10, 2 16 turtles were stranded on the beach between Pasco County and Collier County, and most of them died. Red tide is thought to be the reason why these turtles ran aground.

According to the monitor's records, 76 turtles ran aground on the coast between Pinelas County and Collier County in 2006, while only 66 turtles ran aground in the same period in 2005. On April 24th, authorities buried a turtle weighing about 70kg and washed up on Naples Beach in southwest Florida. The cause of turtle's death is still unknown.

AllenFoley, a wildlife biologist at the Florida Wildlife Research Institute, said that the red tide remains on the beach may be the main reason for the high mortality rate of turtles in 2006.

At the end of 2006 10, a large-scale red tide appeared in the waters near Tianjin and Huanghua in Bohai Bay, and its biological species was identified as Phaeocystis globosa. According to experts, this is the first red tide of Phaeocystis in Bohai this year.

10 year 10 On October 27th, Cangzhou Oceanic Administration found an anomaly in Huanghua sea area, and a large area of brown floating objects appeared on the sea surface. Intuitively, the floating objects on the water surface are transparent spheres with a diameter of 0.5~2.0 cm, and the outer membrane is light brown, which is identified as Phaeocystis globosa, thus it is determined that red tides occur in this sea area. The monitoring personnel found that red tides occurred in Huanghua sea area from Qikou Village (at the border with Tianjin) to the coastal waters of Huanghua Port, with the vertical coastline depth of 35 kilometers and the maximum within 20 kilometers.

On June 1 65438+1October1day, Tianjin Marine Environmental Monitoring Center Station monitored the 300 square kilometers of sea areas such as Tianjin Port and Dagu Anchorage, and found that the serious red tide areas were mainly concentrated in the coastal waters about 20 kilometers away from the shore, and the density of Phaeocystis globosa gradually decreased from the coastal waters to the far sea.

According to Hebei Marine Environmental Monitoring Center, the content of nutrients in the seawater where the red tide occurred was not high, but the number of phytoplankton cells was high. In addition, the weather conditions are special, the temperature and water temperature are higher than in previous years, and the weather system is stable, which is conducive to the growth and reproduction of phytoplankton.

Yellow Red Tide This red tide has a great influence on fishery production in Huanghua. The fishing season in Bohai Sea is from September to 165438+ 10 every summer. The appearance of red tide makes most fishermen have to stop their fishing boats in the harbor and wait for the red tide to end before going out to sea again.

In March, 2008, the red tide caused by algal blooms made the output of Namibian oyster industry lose about 70%. Namibia's oyster industry has been negatively affected as never before, and it is almost on the verge of collapse. The local oyster farmers living near Walvis Bay reported that they suffered three times the loss in just six weeks.

Red tide has caused the domestic oyster trade to lose a considerable number of shellfish products, and also delayed the expansion plan of foreign markets by nearly 1 year.

Nowadays, red tide has become a worldwide public hazard. Red tides frequently occur in more than 30 countries and regions, such as the United States, Japan, China, Canada, France, Sweden, Norway, the Philippines, India, Indonesia, Malaysia and South Korea.