What happens to the population size of each of the pond organisms when the perch population size is decrease? how many of the species in the food web are affected by a population change in a single species?

Many species would be affected by a decrease in perch(a fish). Most of the ponds organisms would populate and eventually out grow their living capacity.

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.