The ecology of a pond
Introduction
The pond
Plants
Animals
Questions
Read the following passage about the ecology of a pond. Then answer the questions. Check your answers by clicking on the button.
The pond is in the middle of a field. Sunlight shines on most of the pond all day, but a small section is always in the shade of a tall tree growing nearby. The water depth around the edge of the pond is 0.2m; the pond gently slopes towards the middle. The deepest part of the pond is 2.5 m. Large, odd-shaped stones and gravel cover the floor of the pond in the shallow, shaded part, but the floor at the middle is covered in a thick layer of mud.
Five yellow water lilies are growing in the deepest part of the pond, and their leaves cover the middle of the pond's surface. Sun-loving reedmace form a reed-bed in the shallow water around most of the pond.
Canadian pondweed floats in large clumps just below the surface of the water. This weed is an important source of food. It also helps to add dissolved oxygen to the pond water and removes carbon dioxide from the water during photosynthesis. Millions of tiny single-celled green algae float in the pond. They also add dissolved oxygen to the water and remove carbon dioxide during photosynthesis. Green algae are an important source of food for small invertebrates living in the pond.
Water snails cling to the undersides of the lily pads and feed on green algae that float near the pond surface. Water mites, water fleas and Cyclops strennus live among the stones and gravel in the shady part of the pond. These small invertebrates feed on algae.
Sticklebacks enjoy the shade provided by the lily pads and feed on algae and small invertebrates. Twenty common newts feed in the pond. Toothed pond skaters hunt for small flies that become trapped on the surface of the pond. Emperor dragonflies fly over the pond in the summer and lay eggs on plant stems beneath the surface of the water.
Tench (a type of fish) feed on debris that falls to the bottom of the pond. Tubifex worms live and feed in the mud at the bottom of the pond; water woodlice also crawl over the mud and feed from the debris at the bottom. Millions of bacteria decompose dead organisms and animal waste in the pond, and so help to recycle important mineral salts.
1. Use an ecology word to describe the pond.
2. Excluding the different kinds of algae and bacteria, how many different
organisms are described as making up the pond community?
3. What is the size of the common newt population?
4. Describe the habitat of Tubifex worms.
5. Give three reasons why Canadian pondweed and algae are important in the pond
(what is their ecological niche?).
6. Describe the ecological niche of the bacteria found in the
pond.
7. What physical factor prevents reedmace from growing all around the
edge of the pond?
8. What physical factor may prevent algae from growing in the deepest
parts of the pond?
9. What biotic factor prevents the pond from becoming overcrowded with
green algae?
10. Name two organisms in the pond that may be adapted to live in conditions
with low dissolved oxygen levels.