Far exceeding previous years!On the Suzhou River, the dead fish appeared?The reason may be ...

This summer, the high temperature day of more than 35 degrees Celsius in Shanghai has exceeded 40 days, and the high temperature day of over 40 degrees has also broke the historical record. On the Suzhou River, the Mother River of the Shanghai Beach, a large number of fish flipped through the white belly. It is reported that since this year, the Suzhou River Management Station has received 13 incidents of large -scale dead fish in Suzhou River, which has far exceeded previous years. Daofu on the water said: "When there are many times, the dead fish appears, and the weight of the day is several tons."

So, is the urban river dead fish incident caused by high temperature? Jiefang Daily · Shangguan News reporters verified with Ma Xuzhou, an expert in the School of Aquatic and Life of Shanghai Ocean University, to explain how to prevent the fish from "heat stroke".

The main cause of death is hypoxia

In fact, a large area of ​​dead fish comes from the citizens to release fish groups for various reasons, and their main causes are hypoxia. First of all, the higher the temperature, the lower the solubility of the oxygen in the water. At present, the extreme high temperature will cause the Suzhou River to dissolve the saturation and saturation greatly. The survival conditions of the releaseers are really worrying; again, the release fish often purchases from the vegetable market. It is basically injured during fishing and transportation. The body surface inflammation is heavier and it is not easy to survive.

It is worth noting that after the release but death, the dead fish has a greater oxygen consumption to the water body. As organic matter, they are oxidized to inorganic objects. This process not only affects living fish, but also is not good for the ecological environment. In reality, the dead fish actually flies up and waited until the river managers came to salvage the "corpse". They had been corrupted and fermented in the water for 24 hours. From the perspective of water quality, the nitrogen phosphorus content increases. Although it provides nutrition for aquatic plants, the group of dead fish is equivalent to excessive fertilization, causing rich nutritionalization, and even algae such as algae.

Therefore, as a 13 -year -old Marine Associate Professor who has been engaged in fish breeding for 13 years, Ma Xuzhou bluntly stated that in such a high temperature season, "the more you put, the more you die." Unable to adapt quickly, "Even if it is not extremely high temperature, it is good to live a third."

This summer, due to the high temperature and drought, the water level in the Rhine in Germany declined

Can you avoid the summer water to avoid summer water?

Jiefang Daily · Shangguan News reporters have learned that at present, not only are there high temperatures and temperatures in many places in China, many major rivers in Europe and other places are facing drought disasters, and the water level has decreased or even the riverbed bottom. So, some people understand that the water temperature is lower, can the fish avoid cooling down and cool down, or even cooler than others?

But in fact, it's not. As far as Ma Xuzhou's experience is concerned, the lower limit of the temperature of the suitable survival of the aquatic animals is 0 degrees, and the upper limit is 39 degrees. In fact, it will have a fatal effect at 35 degrees Celsius. , Lost enzyme activity, threatening life activities. In Weishan Lake, he himself experienced about 30 cm in the water level under more than 40 degrees Celsius, and the fish in the lake began to die in large quantities.

A dried lake bed shot in Croatian Sagulb on August 15

In terms of physical perspective, the smaller the density of the upper layer in the water body, that is, the distribution of "upper light". Generally, the clear water body is mainly dissolved in the water surface, and the higher the liquidity, the better. If it is a static water body, the oxygen is dissolved on the upper layer, and the amount of dissolved oxygen in the lower layer is very small. At the same time, floating plants that can make oxygen also live on the surface, about 20 cm underwater. The sediments of the lower layer of the water body are basically oxygen.

Therefore, the fish in the water instinctively chose the water layer to breathe the gas with a relatively large oxygen -containing oxygen, and the water temperature there was also higher -it may not be possible to swim to the deep water "summer".

In Hanoi, Vietnam, people release red carp by the lake to celebrate the sacrifice festival

Choose timing and selection scientific reservation

Today, with the construction of the "One River and One River", the Suzhou River has not only changed its long -term governance, but the 42 -kilometer shoreline in the central urban area is basically connected. Release. As netizens said, Mo Rang's release will become killing.

Even in the appropriate waters, you should follow science and choose to choose seeds. Ma Xuzhou said that on the one hand, the best time for artificially releasing is autumn and winter. Professionals only choose to discharge under the environment of 5 to 10 degrees Celsius, because as a temperature -changing animal, the ability of fish to move above 10 degrees is enhanced. And less than 5 degrees frostbite; on the other hand, professionals also disinfect them before putting fish, such as using 3%salt water similar to seawater.

According to Vietnamese customs, people worship the stoves and release the red carp in the sacrifice festival

In the fish species, the release can only be indigenous fish, and it cannot be a breeding variety that is hybrid. For example, catfish should choose black catfish with a maximum of only 100 grams, and should not choose large catfish with artificial cultivation and delivery of the table. In addition, artificially breeding ornamental fish such as goldfish and koi cannot be put in a natural river. They cannot adapt to the environment and cannot survive. In the procedure, the release units shall be bidded, issued to a certificate, and clarify the variety. Those who may cause biological invasion or formed hybrids shall be demonstrated.

It is also worth noting the release tools. The standard method is to use the cage to allow the fish to swim autonomously after entering the water. After the cage is lifted, the dead fish are all in the box. Ma Xuzhou warned that the density of the fish was too large, as if the crowd was stepped on, and the water pressure would be unconscious.

Author: Xu Ruizhe

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