Golden Fishing Village

A large number of Vibrio were found in the dead crabs. Li Ji frowned and said, "Pond Vibrio in freshwater crabs should mainly occur in the hot season. It's only mid-June now, so it shouldn't happen, right?"

After confirming that it was a pond Vibrio infection, Ao Yuanzang became anxious. This pathogen is very powerful and has a violent onset. The mortality rate can reach 30% to 50%, and the bacterial flora of this bacteria has explosive power, which means that there are already crabs infected and dead. It is estimated that there are already a large number of crabs infected with bacteria underwater.

Seeing that Li Ji had determined the condition, his student raised the agar culture medium and asked, "Teacher, do you still want to do a bacterial flora culture test?"

Li Ji said cautiously, "Do one, and provide two-way verification."

It is not uncommon for Vibrio to be infected in crab farming in summer, especially in recent years, due to government support and large market demand, the river crab farming industry has developed rapidly.

In order to pursue maximum benefits, the stocking density of river crabs is very large, and farmers will use feed with higher protein content to make them grow faster.

In this way, after the crab dies, it will not float up like fish, but will hide at the bottom of the farm, causing the conditions of the breeding waters to deteriorate. In addition, the fresh ice fish and high-protein feed fed are easy to deteriorate, and the physical condition of the river crabs will decline after eating. If they are not eaten in time, they will quickly rot and pollute the breeding waters.

In this way, in the high temperature season, Vibrio will multiply and infect river crabs, causing the occurrence and spread of Vibrio disease in river crabs.

However, this is aimed at breeding ponds. In a water area as large as Longxiang Lake, river crabs should not be infected. The water quality in the lake is absolutely excellent, and the breeding environment is also good. As the saying goes, "raising crabs starts with raising water." The water in Longxiang Lake is good, so there should not be large-scale Vibrio infection.

He told Li Ji what he thought, and Li Ji nodded and said, "You know a lot."

Ao Muyang smiled bitterly and said, "It's okay, after all, I am your last disciple, Teacher Li."

Hearing this, Li Ji glared at him and said, "My last disciple only knows this much? It's embarrassing for me. There are more than just two conditions for triggering Vibrio. Temperature and humus high protein water quality. Look into the lake again. Is there any problem?"

Ao Muyang looked into the lake. The sun was shining, the water was clear, and dozens of small boats were slowly floating on the lake. From time to time, people cheered.

He thought for a while and said, "No problem."

Li Ji said patiently, "Open your eyes and look carefully."

Old Ao opened his eyes as wide as he could, and his eyes hurt, but he still didn't see anything.

Li Ji was helpless: "I asked you to open your eyes to observe more and use your brain to observe. You actually opened your eyes wide. You... Alas!"

I was careless in accepting a disciple!

Lao Ao wanted to improve, so he continued to look into the lake. In order to see farther, he stood on tiptoe and stretched his neck. Ao Yuanzang followed him to look. A row of cormorants standing on a small boat by the lake also took the same posture. Of course, they were not imitating the two people. This was their nature to wait and see.

Li Ji pointed to the lake and said, "Look down. Why are you stretching your neck? What's in the lake? Water plants, Elodea."

Ao Muyang nodded and said, "Yes, there is Elodea."

Lu Hu gave him a batch of Elodea in his early years. He found that it was very helpful for aquatic products after raising it in the backyard breeding pond. Elodea is food for crabs, so when Long Xian Lake started to raise crabs, he planted a lot of algae in the lake. It has been two years now, and it is growing well.

Li Ji analyzed: "The water quality of Longxian Lake is clear, which is related to the abundance of algae, but too much algae is not a good thing, especially now that the weather is hot. After the algae die and sink to the bottom of the pond, they will quickly rot and stink, causing a large oxygen debt in the bottom mud. And you have to know that the lake bottom is lacking in oxygen all day in June and July, and shrimps and crabs crawling on the grass and swimming on the edge are very serious, which can easily lead to excessive ammonia nitrogen and nitrite in the lake bottom mud, and anaerobic bacteria multiply in large numbers, breeding Vibrio group."

This is true, Ao Muyang nodded, there are many algae, fish, shrimps and crabs in Longxian Lake, and few people come to fish on a large scale all year round. There are only two activities such as crab fishing in autumn and grass carp fishing in winter, which will indeed bring pressure to the lake ecosystem.

Li Ji added: "More than that, the more tourists come to the lake, the more garbage the lake receives. Although you have arranged people to trawl and clean up the garbage, what is cleaned up is solid garbage. The bacteria brought by the garbage itself have entered the lake and cannot be salvaged and eliminated. Perhaps this is the source of infection."

Ao Muyang nodded heavily and asked: "Then how to eliminate Vibrio?"

Li Ji said: "From the analysis of the cause of Vibrio, it can be found that the biggest factor causing Vibrio outbreaks is dissolved oxygen. The dissolved oxygen in the water is too low, the oxygen debt of the bottom mud is large, and harmful substances such as ammonia nitrogen, nitrite, and hydrogen sulfide cause stress to river crabs, weakening their ability to resist the invasion of external adverse factors. And low oxygen conditions Under these conditions, aerobic microorganisms are suppressed, anaerobic microorganisms rise, and easily form dominant species, thus reaching or even far exceeding their pathogenic threshold. "

This is a very skillful statement. Ao Yuanzang cast a look of help to Ao Muyang, who spread his hands and said, "Add oxygen to the bottom of the lake?"

Li Ji said, "This is a way to cure the root cause, and there must be a way to cure the symptoms. I will go back and ask my colleagues who specialize in crustacean zoology and aquatic pathology."

Ao Muyang immediately bowed and said, "Teacher Li, thank you for your trouble. I will prepare a feast for you later!"

Li Ji smiled and said, "Don't look back. It's better to do it today than to wait for a day. Let's prepare it tonight."

Ao Muyang: ┓(`)┏

When we came to dinner, Li Ji also brought a solution to the outbreak of Vibrio infection.

The first is to determine the area of ​​bacterial infection. According to his colleagues' professional analysis, with the scale of Ambergris Lake, it is not the entire lake that is experiencing a Vibrio infection crisis, but a problem with a certain area of ​​the lake bottom.

The reason why crabs died is that freshwater crabs have a sense of territory during the shell-changing season. They will not easily leave their territory, nor will they easily let other crabs enter their territory.

After determining this area, we have to take the second step, put oxygen generators and oxygenators into the water area, and organize people to clean up the lake bottom of the relevant water area, take away the leftover bait and dirt, and remove the rotten weeds at the bottom of the lake.

At the same time, we need to spray medicine on the bottom of the lake to kill bacteria. Now there are Vibrio inhibitor effervescent tablets, which are like bricks, scattered and thrown into the lake. It happens that there is no water fluctuation at the bottom of the lake, and the effervescent tablets can be safely used in the problem water area.

Li Ji also told him that there are still many waters where Vibrio infection has broken out. The main reason is the drought this year. Except for a heavy rain in spring, there has been no rain so far. There is no new water source in the lake and pond, and no oxygen is brought in.

There is nothing Ao can do about this. He can't control the weather.

After hearing his answer, Li Ji sneered: "You are evading. You haven't thought of a solution, but you just say you can't do it!"

Ao Muyang thought about it and said, "Then, let's have a Dragon King praying for rain?"

Li Ji, who was drinking, almost choked: "Pray for rain? You don't have a brain? Can this work? You must find a way to make it rain artificially!"