Chapter 1 Notes
INTODUCTION:
Ecosystem - a set of relationships between organisms of an environment and between the organisms and their environment.
Sustainability - the ability to maintain a steady level without exhausting natural resources or causing severe ecological damage.
Sustainable System - a system that survives, functions, and is renewed over time; a system in which people can continue to live well for many generations.
Paradigm Shift - a rare and important change in the way humans view the world and is often controversial at first. (ex: Earth is flat)
SECTION 1-1:
Amphibians have been around for 400 million years, but are now disappearing.
The health of amphibians indicates the health of their ecosystem.
Frogs live in 2 ecosystems: water (young tadpoles) and land (older frogs). Hazards in both.
Frogs also part of 2 different food chains.
Food chain – step by step sequence of who eats who in an ecosystem, starting with producers and ending with consumers.
Producer - an organism that uses photosynthesis or another form of chemical synthesis to make food.
Consumer - an organism that must eat producers or other consumers to survive.
Frogs help control insect populations and help break down detritus.
Detritus – waste from plants and animals (including dead remains)
Herbivores – animals that eat plants.
Carnivores – animals that eat other animals.
Omnivores – animals that eat both plants and animals.
Decomposers - organisms that break down detritus to get nutrients for their own use also releasing nutrients to the soil and water.
Possible reasons for frog disappearances:
Loss of habitat: drained wetlands, cut trees, roads.
Air and Water Quality: frog’s thin skin helps them breathe, but also lets in pollutants. Acidic water hinders ability to reproduce and may cause deformities.
Ultraviolet Radiation: susceptible due to thin skin.
Climate Change: Hot, dry weather bad for frogs.
SECTION 1-2 and 1-3:
Extinct - A species that is no longer found anywhere. Ex: Blue Walleye
Endangered - A species that is close to extinction in all parts of Canada or in a significantly large location. Ex: Atlantic Salmon
Extirpated - Any species that no longer exists in one part of Canada, but can be found in another. Ex: Atlantic Walrus
Threatened - Any species that is likely to become endangered if factors that make it vulnerable are not reversed. Ex: Beluga Whale
Vulnerable - Any species that is at risk because of low or declining numbers in some places. Ex: Smallmouth Salamander
Extinction rates are rising dramatically along with human population growth.
Many mass extinctions in the past. Possibly caused by asteroids.
Extinctions also caused by climate change, competition pressure from other species, overhunting, loss of habitat, pollution, and expansion of agriculture (pesticides).
Approx. 500 species have inhabited earth. 90% of these have become extinct or evolved into new species.
Biodiversity – the number of species in an ecosystem.
A reduction in biodiversity caused by an extinction can cause a “domino effect” because every organism in an ecosystem is connected to all the other organisms.
SECTION 1-5 and 1-8:
Pests – organisms that cause problems for humans.
“Pests” can be beneficial in ecosystems:
- mosquitoes are important food for fish and birds
- insects pollinate, decompose dead plants and animals, and loosen (aerate) soil.
- “weeds” feed animals, pump nutrients back into the soil, and stabilize soil on steep slopes.
Ecology – the study of the interaction of living things with each other and their environment.
There are 2 types of factors that affect organisms in an ecosystem:
1) biotic - factors caused by the presence and roles of other living things
2) abiotic - non-living factors or influences on organisms (ie. Sunlight, temperature, strength and direction of wind)
Organisms do not live alone:
A population is members of the same species living in the same area. Ex: trout in a pond.
A community is a collection of all the populations of all species in an area. Ex: All species in a pond.
An ecosystem includes the community of living things and the physical environment.
Ecotone – the area between ecosystems where organisms from both ecosystems interact.
Ecosystems with greater biodiversity tend to be stronger, because organisms often have more than one food source.
Artificial ecosystem - planned or maintained by humans
Natural ecosystems - living community is free to interact with the physical and chemical environment (not maintained or planned by humans, but may not be untouched by humans)
SECTIONS 1-10 and 1-11:
The sun is the source of all energy for all ecosystems
The sun provides the energy to light and warm the earth, to evaporate water, and to provide food for plants (photosynthesis).
Photosynthesis - process by which green plants use sunlight energy to produce carbohydrates (sugars).
When sunlight hits an object, some of the energy is absorbed and some is reflected.
Some materials reflect better than others.
Albedo is the measurement of the percentage of light that an object reflects.
The higher the earth’s albedo, the less energy available to heat the earth.
Snow has a very high albedo. Clouds also reflect a lot of light.
Trophic levels – a way to group living things by the way they get their energy.
• 1st Trophic Level: organisms that can make their own food (also called autotrophs). Ex: plants
• 2nd Trophic Level: Primary consumers… Organisms that feed on the producers. They rely directly on autotrophs for their source of energy.
• 3rd Trophic Level: Secondary consumers… Rely on primary consumers for their source of energy. Still dependent on autotrophs (indirectly).
• 4th Trophic Level: Tertiary consumers… Carnivore eats a secondary consumer (another carnivore)
Heterotrophs - Consumers, no matter of their trophic level. They cannot make their own food.
Every organism in an ecosystem is involved in many food chains. These food chains go together to form a feeding relationship called a food web.
The lower the biodiversity, the simpler the food web and the more in danger the organisms are.
Producers use sunlight to make molecules of sugar. This sugar provides the energy that drives ecosystems
Most of the energy acquired by an organism is not stored. It is used for staying alive (moving, body heat, etc.)
A lot of energy is lost in each step up a food chain; There is less energy available to secondary consumers than there is to primary consumers
Thermodynamics - the study of energy changes.
2 laws of thermodynamics:
#1- although energy can be changed from one form to another, it cannot be created or destroyed
#2- during any energy change some energy is lost to heat.
Since energy is lost at each step, there can only be a maximum of about 5 trophic levels in a food chain.
SECTION 1-12:
Each organism has their own ecological niche in an ecosystem
Ecological niche- everything an organism does to survive and reproduce, including its place in the food web, its habitat, breeding area and the time of day it is most active
Each species of an ecosystem tends to have a different niche helping reduce competition between species. Ex: owl and hawk
Exotic Species – A species brought to a new area.
Exotic species will come into competition for a niche with species already there. Humans often cause this by moving organisms around.
Zebra Mussels…
• Introduced to the Great Lakes from Western Asia.
• Probably released from ships
• Spread quickly because lots of food
• Attaches to hard objects
• Blocks intake pipes
• Zebra mussels reducing pearly muscle populations, by sticking to them and stealing their food.
Zebra mussels are not all bad…
• They are food for some species and their shells provide homes.
• Have not completely wiped out any species.
• They eat algae that is caused by pollution and blocks out sunlight.
• They filter pollution from water.