(1) Under normal circumstances, the number of fish and plankton in the water will fluctuate within a certain range, which is realized by negative feedback regulation mechanism. A large number of fish will die after freezing injury, and the change of biomass is far beyond the normal range, which shows that the self-regulation ability of the ecosystem is limited.

(2) After the freezing disaster, the dead fish are decomposed, and rich inorganic salts are released into the water, which leads to the proliferation of algae; The pHotosynthesis of algae consumes a lot of CO 2 in the lake, thus improving the ph value of the lake.

(3) Removing sediment or throwing fry can restore the ecological balance of Xinghu Lake as soon as possible.

So the answer is:

(1) Negative feedback (or feedback) self-regulation ability is limited.

(2) Dead fish decompose, and rich inorganic salts are released into the water body, which leads to the proliferation of algae; The pHotosynthesis of algae consumes a lot of CO 2 in the lake, thus improving the ph value of the lake.

(3) removing sediment or throwing fry.