1. Ecosystems: Everything Is Connected
Chapter 7: Aquatic Ecosystems.
Environmental Science and the Earth

2. Ecosystems: Everything Is Connected
Example of the idea that “everything is connected”
In 1995, scientists interested in controlling gypsy moths, which kill oak trees, performed an experiment.
Photo by R. Jowsey

3. Everything Is Connected: Example
The scientists removed most mice, which eat young gypsy moths, from selected plots of oak forest.
The number of young gypsy moth eggs and young increased dramatically.

4. Everything Is Connected: Example
The scientists then added acorns to the plots.
Mice eat acorns, therefore the number of mice soon increased, and…
The number of gypsy moths declined as the mice ate them as well.

5. Everything Is Connected: Example
This result showed that large acorn crops can suppress gypsy moth outbreaks.

6. Everything Is Connected: Example
Oh but there is more!!!
Interestingly, the acorns also attracted deer, which carried ticks.
Young ticks soon infested the mice.
Photo by R. Jowsey

7. Everything Is Connected: Example
Wild mice carry the organism that causes Lyme disease.
Ticks can pick up the organism when they bite mice.
Then the ticks can bite and infect humans.

8. Everything Is Connected: Example
This example shows that in nature, things that we would never think were connected—mice, acorns, ticks, and humans—can be linked to each other in a complex web

9. Defining an Ecosystem
The mice, deer, moths, oak trees, and ticks in the previous example are all part of the same ecosystem.
An ecosystem is all of the organisms (biotic) living in an area together with their physical (abiotic) environment.

10. Defining an Ecosystem
Ecosystems can be large like an oak forest or coral reef, or they can be small like the vacant lot next door to your home.
The Natick
projects.

11. Defining an Ecosystem
Just like living things are connected, so to are ecosystems.
Things move from one ecosystem into another.
Soil washes from a mountain into a lake, birds migrate from Michigan to Mexico, and pollen blows from a forest into a field.

12. The Components of an Ecosystem
In order to survive, ecosystems need at least five basic components:
A source of energy
Mineral nutrients
Water
Oxygen
Living organisms
Photo by R. Jowsey

13. Biotic and Abiotic Factors
An ecosystem is made up of both living and nonliving things.
Biotic factors are the living and once living parts of an ecosystem, including all of the plants and animals.
The biotic parts of an ecosystem interact with each other in various ways (food webs, symbiosis, etc).

14. Biotic and Abiotic Factors
While living things interact with each other in an ecosystem, they also interact with the non-living factors in an ecosystem.
The non-living components of an ecosystem are known as abiotic factors.

15. Biotic and Abiotic Factors
Identify three biotic and three abiotic factors that are in the cold northern ecosystem of Denali National Park in Alaska (shown in photo).

16. Biotic Factors

17. Abiotic Factors

18. Organisms An organism is an individual living thing.
You are an organism, as is an ant crawling across the floor, an ivy plant on the windowsill, and a bacterium in your intestines.
Organisms are classified into 4 major groups: Bacteria, Plants, Protists, and Animals.
Period 1 Organism
Peter Creed

19. Species A species is a group of organisms that are closely related.
In order for two organisms to be classified into the same species, they must meet thesefour criteria.
The two organisms must able to:
Successfully mate
in a Natural Environment (not a lab or zoo, etc.)
and produce viable offspring (healthy, able to survive to adulthood)
and those offspring are fertile (can reproduce).
All humans, for example, are members of the species group sapiens and the genus group Homo. This produces the scientific name for humans; Homo sapien.

20. Species The photo shows a zedonk.
A zedonk is a cross between a zebra and a donkey.
The zedonk is a sterile animal and cannot reproduce. Therefore, a zebra and a donkey are NOT the same species.

21. Species
Zebras and donkeys can successfully mate, in a natural environment and produce viable offspring.
Are zebras and donkeys therefore members of the same species? Why or why not?

22. Populations
A population is all the members of the same species that live in the same place at the same time.
An important characteristic of a population is that its members usually breed with one another rather than with members of other populations.
Populations have really cool names: pod of bottlenose dolphins, gaggle of Canadian geese, murder of crows, smath of jellyfish.

23. Populations
The Bison will usually mate with another member of the same herd, just as the wildflowers will usually be pollinated by other flowers in the same field.

24. Communities
An organism does not live alone and neither does a population.
A community is a group of various species that live in the same place and interact with each other.

25. Communities
A pond community, for example, includes all of the populations of plants, fish, and insects that live in and around the pond.
All of the living things in an ecosystem are members of the same community.
Photo by R. Jowsey

26. Communities
The most obvious difference between communities is the types of species they have.
Land communities are often dominated by a few species of plants. In turn, these plants determine what other organisms live in that community.

27. Communities
For example, the most obvious feature of a Colorado forest might be its ponderosa pine trees.
This pine community will have animals, such as squirrels, that live in and feed on these trees.

28. Habitat
The squirrel discussed above lives in a pine forest. The pine forest is the squirrel’s habitat.
A habitat is where an organism lives.
The habitat of the salamander in this photo is a damp forest floor.

29. Habitat
Every habitat has specific characteristics that the organisms that live there need to survive.
A coral reef contains sea water, coral, sunlight, and a wide variety of other organisms.
If any of these factors change, then the habitat changes because everything is connected.

30. Niche An organism’s niche is the role it plays in an ecosystem.
Often describes where an organism “fits” in a food chain.
Example: A woodpecker’s niche is eating insects

31. Chapter 7: Aquatic Ecosystems. Environmental Science and the Earth
How Ecosystems Work
Chapter 7: Aquatic Ecosystems.
Environmental Science and the Earth

32. Life Depends on the Sun
The ultimate source of energy for almost all living things is the sun.
Energy from the sun enters an ecosystem when a plant uses sunlight to make sugar molecules in a process called photosynthesis.

33. Photosynthesis
Plants, algae, and some bacteria capture solar energy and use it to drive a series of photo-chemical reactions that convert carbon dioxide and water into glucose and oxygen.

34. Photosynthesis
When an animal eats a plant, some energy is transferred from the plant to the animal.
This energy is used to move, grow, and reproduce.
Photo by R.L. Jowsey

35. The Chemical Equation for Photosynthesis
Sunlight
6 CO2
6 H2O
C6H12O6
6 O2
Carbon Dioxide Water  Sugar Oxygen

36. Autotrophs are Producers
Plants and other organisms that undergo photosynthesis are known as Autotrophs.
Autotrophs have cells with chloroplasts (tiny organelles within the cell) which are the site of photosynthesis.
The green pigment chlorophyll is responsible for photosynthesis.

37. Transfer of Energy
When a rabbit eats a clover plant, the rabbit gets energy from the carbohydrates (glucose) the clover plant made through photosynthesis.

38. Transfer of Energy
When a coyote eats a rabbit, some of the energy is transferred from the rabbit to the coyote.
Rabbits and Coyotes are heterotrophs – also called consumers.

39. What Eats What? What Eats What in an Ecosystem Energy Source Examples
Producer
Makes its own food through photosynthesis or chemical sources
Grasses, ferns, flowering plants, trees, some bacteria
Consumer
Gets energy by eating producers and other consumers
Mice, starfish, elephants, turtles, humans, and ants

40. Types of Consumers in an Ecosystem
Herbivores – eat autotrophs (producers).
Carnivores – eat other heterotrophs (consumers).
Photo by R.L. Jowsey

41. Types of Consumers in an Ecosystem (cont)
Omnivore – eat both producers and consumers.
Decomposer – breaks down dead organisms in an ecosystem and returns nutrients to the soil, water, and air.
Photo by R.L. Jowsey

42. Types of Consumers in an Ecosystem
Photo by R.L. Jowsey

43. Energy Transfer
Each time an organism eats another organism, a transfer of energy occurs.
We can trace the flow of energy as it travels through an ecosystem by studying food chains, food webs, and trophic levels.

44. Food Chains and Food Webs
A food chain follows the flow of energy from one organism to the next as each organism eats another organism.

45. Food Chains and Food Webs
A food web includes multiple food chains interconnected within an ecosystem.

46. Trophic Levels
Each step through which energy is transferred in a food chain is known as a trophic level.

47. Trophic Levels
Each time energy flows into the next trophic level, some is lost and less energy is available to the next trophic level.
Only about 10% of energy transferred is available to the next trophic level.

48. Trophic Levels and Energy Pyramid
Energy Pyramids
One way to visualize the loss of energy at each trophic level is to draw an energy pyramid.
Trophic Levels and Energy Pyramid