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You may remember that we talked about ecosystems in our biology class in junior high school, and the pond where we usually raise fish is a typical small semi-open ecosystem.
In this semi-open ecological chain there are phytoplankton, plants, epiphytic algae, zooplankton, fish, benthic animals, aquatic insects, and microbial populations that can only be observed under a microscope.
When a new pond is built from excavation to build water, in the process of unconsciously the pond biome begins to form.
First of all, in the process of water injection, various organisms will be brought in; at the same time, the water body will be injected into the pond, and many spores, sporangia, dormant eggs, cocoons, etc. will germinate in the soil at the bottom of the pond, and soon become members of the newly formed community;
Secondly, because of the wind, water birds, insects, etc., aquatic organisms are brought into the pool;
At the same time, high winds can also scrape the spores of algae and the dormant eggs of rotifers and branches into the pond from a distance, and the dormant eggs of zooplankton are sticky and can be brought into the pond by the feet of waterfowl and aquatic insects:
Insects spawn on the water and are the main source of benthic populations in ponds.
The various organisms that inhabit and germinate after irrigating the fish ponds reproduce and grow rapidly, and the number of species that make up the community gradually increases;
Species gradually tend to become larger, the total biomass of the community increases, and the number of various communities changes from unstable to relatively stable.
At this point, I think everyone knows the source of various microorganisms, branches, rotifers and various algae in the pond.
However, with seasonal changes and the influence of human activities, some aspects and stages may have local or transient changes.
Characteristics of the fish pond biome: Fish ponds do not have large coastal plants, have some characteristics of the lake center area, and plankton play the most important role in the biological production process;
Next, we will talk about the fish, shrimp and crabs that we are most concerned about in this ecosystem that will produce economic benefits, which are autoplurgical organisms;
They mainly use zooplankton, phytoplankton, and benthic animals as natural food in this ecosystem;
Therefore, the number of phytoplankton in the pond is the key factor in raising our fish, shrimp and crabs, that is, an important factor in determining the productivity of the pond;
First of all, the lower phytoplankton, which are the most important and important producers in water bodies, provide sufficient sources of dissolved oxygen to water bodies through photosynthesis;
At the same time, through its own reproduction, it provides sufficient food for farmed animals and zooplankton;
In the process of their own reproduction, they can play a role in purifying water quality by decomposing the organic matter of the water body.
But phytoplankton also have their own laws of change, and we can master these laws in the process of breeding to make our farming more effective.
The first is seasonal variation: the amount and species of phytoplankton are different in each season, with summer biomass peaking and prone to blooms.
Due to the different phototropism of different phytoplankton, the light intensity of different water layers is different, and the change of light intensity of day and night will cause day and night changes and vertical changes of phytoplankton.
Phytoplankton photosynthesis increases with light intensity in a certain range, and when the depth of the water body is 2 times the transparency, the entire water body can be photosynthesized.
This is when the amount of phytoplankton reaches its highest value.
At the same time, because phytoplankton have no motility organs and go with the flow, the biomass is often higher than the upper outlet under the influence of wind.
According to the characteristics of the phytoplankton itself, it can be reduced to the species of 8 phylums: blue, hidden, gold, nail, yellow, silicon, naked, green algae.
Figure 1 shows the cyanobacteria phylum:
The following figure shows the cryptoalgae phylum:
Dinoflagellate phylum
Phyllonorycter
Phylum Diatoms
Xanthophyllum
Naked algae phylum
Phylum Green Algae
There is usually a standing stock for the determination of phytoplankton indicators in water
That is, the biological weight per unit of water volume or unit of water bottom area is biomass or existing quantity
The indicators of high-quality fertile water living water are: the amount of phytoplankton in the pond of flagella such as cryptoalgae: the southern fish pond changes between 20 and 100 mg/L, and the average value is 30~50 mg/L.
The average value of the northeast fish pond can exceed 100mg/L, and the highest can reach 200~300mg/L, because the pond water is shallow, the soil is fertile, the fertilizer source is sufficient, and the sunshine time during the growth period is long.