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š¬ Think about it
In a cricket team, even the player who does not bat much still matters. Remove them and the team feels it. Nature is the same. Even a small fish can change the whole pond. Let us find out how.
How does a pond with fish have more flowers around it?
- Fish eat dragonfly larvae, so ponds with fish have fewer dragonflies.
- Dragonflies usually eat bees, flies and butterflies.
- With fewer dragonflies, more bees and butterflies are found.
- These insects pollinate flowers, so more seeds are formed.
Fish Lead to More Seeds
Pond has fish
↓
Fewer dragonflies
Fish eat the dragonfly larvae.
↓
More pollinators
More bees and butterflies survive.
↓
More seeds in nearby plants
What does this fish study really show?
- Biotic parts (fish, dragonflies, pollinators, plants) affect each other.
- Abiotic parts (temperature, water, nutrients) also play a role.
- So even one organism can change the whole community.
- Overfishing by humans can upset this balance.
Example:
Removing fish from the pond is like removing one player who changes the result of the whole match.
In this Activity, we will read about a study comparing two ponds to see how fish affect seed production in nearby plants.
Materials needed
The study figure (Fig. 12.3 and Fig. 12.4) and your notebook.
Procedure
1. Researchers studied two ponds — Pond A with fish and Pond B without fish.
2. Compare the number of dragonflies, bees and butterflies in both ponds.
3. Look for a relationship between dragonflies and bees or butterflies.
4. Ask why Pond A (with fish) had fewer dragonflies.
2. Compare the number of dragonflies, bees and butterflies in both ponds.
3. Look for a relationship between dragonflies and bees or butterflies.
4. Ask why Pond A (with fish) had fewer dragonflies.
Observation
Pond A with fish had fewer dragonflies but more bees and butterflies. It also had more flowering plants around it.
Explanation
Fish eat dragonfly larvae. Fewer dragonflies means more pollinators. More pollinators means more seeds. So fish indirectly help nearby plants make seeds.
ā Summary
- Two ponds compared
- Fish reduce dragonflies
- More pollinators result
- More seeds form
Important Points
- Every organism in a community has a role.
- Biotic and abiotic components affect each other.
- Removing one organism can change the whole system.
ā Test Yourself
-
Why did Pond A have fewer dragonflies?
View Answer
Because fish in the pond ate the dragonfly larvae. -
What do dragonflies usually eat?
View Answer
Flies, bees and butterflies. -
How do bees and butterflies help plants?
View Answer
They pollinate flowers, which helps plants produce seeds. -
How can overfishing upset a pond?
View Answer
Removing fish changes the balance of dragonflies, pollinators and plants. -
Does every organism in a community matter?
View Answer
Yes. Even one organism can affect many others through these links.
Important Definitions
- Direct effect — when one organism affects another straight away, like fish eating larvae.
- Indirect effect — an effect passed on through other organisms, like fish helping plants make seeds.
