The freshwater pond has a variety of habitats for plants and animals;
Animals and plants living in deeper water at the bottom of the pond will have less light and oxygen to cope with and adapt to.
Living things at the edges of a pond (the margins) have more light and oxygen, but also have to cope with more wind etc.
Freshwater pond components
The freshwater pond consists of:
Producers such as reeds and water lily.
Consumers such as the stickleback fish, ducks and heron. They get their energy by eating the producers or eating other consumers.
Decomposers such as the rat tailed maggot and many types of bacteria, which generally live in the soil layer beneath the water. They break down dead plants and animals and recycle the nutrients back into the soil.
Changing components
A change in one part of a food web can have impacts on the whole ecosystem. For example, within the freshwater pond, an increase in the number of water lilies could starve the bottom of the pond of both light and oxygen; this would impact on bottom feeders which would impact upon fish. Similarly, if someone added predatory fish they would eat smaller fish such as sticklebacks and even small frogs, which would increase the numbers of slugs and flies normally eaten by the frogs.