Ecology Lessons 1-4
Ecology is the scientific analysis and study of interactions among organisms and their environment. It is an interdisciplinary field that includes biology, geography, and Earth science. Ecology includes the study of interactions that organisms have with each other, other organisms, and with abiotic components of their environment.
Ecologists seek to explain:
Life processes, interactions, and adaptations
The movement of materials and energy through living communities
The successional development of ecosystems
The abundance and distribution of organisms and biodiversity in the context of the environment.
Hierarchical Ecology
Biological organizations help to put ecology into a hierarchy of
Cells Tissues Organs Organ system Organism Species
Population Community Ecosystem Biome Biosphere (Earth)
Ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and minerals, soil), interacting as a system.
Ecosystems consist of:
Interactions among organisms
Interactions between organisms and their environment
Can be of any size (drop of water, belly button, rotting log, pond, forest, coral reef, Earth) but usually encompasses a specific limited space.
Life on Planet Earth (The Biosphere)
No one knows for sure how many species of animals exist on Earth. In fact, some10,000 species of animals are discovered each year, with over one and a half million species already described. Projections for the total number of species on Earth range from 2 million to 50 million.
Largest-ever analysis of microbial data reveals ecological law concluding 99.999 percent of species remain undiscovered. Earth could contain nearly 1 trillion species, with only one-thousandth of 1 percent now identified, according to a study from biologists at Indiana University. (2016)
Biosphere (a.k.a. the ecosphere, Biosphere I), termed the “zone of life” on Earth, is the worldwide sum of all ecosystems.
It is a closed system (meaning nothing freely enters or leaves Earth and its atmosphere apart from solar and cosmic radiation and heat from the interior of the Earth).
It is largely self-regulating (meaning sustainable without human help).
It is an ecological system integrating all living (Biotic) beings and their relationships, including their interaction with the elements (Abiotic) of the lithosphere, hydrosphere, and atmosphere.
Earth is the only planet known (solar system or universe) to have life. Life exists within three (3) spheres and are primary terrestrial and aquatic based.
Earths Spheres
Earths three (3) main spheres are: 1. Atmosphere, 2. Lithosphere, 3. Hydrosphere. These spheres can be broken down into many different layers.
Atmosphere
A layer of gases extending from the surface of the earth upwards hundreds of kilometres
Earths core has a mass great enough to create a force of gravity that can hold gases near its surface.
It consists of :
78% N2 (g)
21% O2 (g)
<1% Ar (g), CO2 (g), H2O (vap) and other gases
It is critical to life on earth as it:
Moderates earths temperature preventing excessive heating during the day and cooling at night.
Earths average temperature of 15°c would drop to -18°c without it.
It blocks incoming solar radiation (such as ultraviolet light (uv-rays)) which is linked to skin cancers
Layers of Atmosphere
Troposphere - where weather forms (0-16 km)
Stratosphere - where protective ozone layer exists (O3) (16-50 km)
Mesosphere - shooting stars (meteor showers) (50-80 km)
Thermosphere - temperature rises to 230°c - Northern/Southern Lights (80-640 km)
Exosphere - Air dwindles to nothing as particles drift out to space. (640 – 64,000 km)
Lithosphere (crust)
The outermost layer of the earths surface consisting of rocks and minerals make up:
Mountains, Ocean floors, the rest of earths solid landscapes
It ranges from 50-150 km in thickness.
Hydrosphere
Consists of all water on, above and below earths surface such as:
Oceans (97% of all water on earth)
Lakes, Ice, Groundwater, Clouds
Most known life exists in water (Aquatic ecosystem)
Biosphere II
Is an Earth systems science research facility located in Oracle, Arizona. Biosphere 2 was originally meant to demonstrate the viability of closed ecological systems to support and maintain human life in outer space, and the first mission was designed to house eight humans for two years. It served to observe the interactions between life systems in a building with five areas based on biomes.
Its five biome areas were a:
1,900 square meter rainforest,
850 square meter ocean with a coral reef,
450 square meter mangrove wetlands,
1,300 square meter savannah grassland,
1,400 square meter fog desert,
2,500 square meter agricultural system,
a human habitat, and a below-ground infrastructure
Ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and minerals, soil), interacting as a system.
Ecosystems consist of:
Interactions among organisms
Interactions between organisms and their environment
Can be of any size and are highly variable (drop of water, belly button, rotting log, pond, forest, coral reef, Earth) but usually encompasses a specific limited space.
Ecosystem survival depends on its sustainability and the relationship between its biotic and abiotic factors.
Sustainability is the natural ability to maintain ecological conditions without interruption, weakening or loss of value.
A sustainable ecosystem is a biological environment and series of habitats that can thrive and support itself without outside influence or assistance.
A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant, or other type of organism. The term typically refers to the zone in which the organism lives and where it can find food, shelter, protection and mates for reproduction.
Types of Ecosystems
There are two (2) general types of ecosystems
1. Aquatic: an ecosystem in a body of water. (marine or freshwater)
2. Terrestrial: an ecosystem found only on land and on biomes. Six primary terrestrial ecosystems exist:
1. tundra – low temp, short grow season
2. taiga – aka: boreal forest, coniferous forest, pine, spruce (trees that don’t lose leaves)
3. temperate deciduous forest – warm, moist summer (dominated by trees that lose leaves)
4. tropical rain forest – no dry season, at min avg. 60 mm rain per month
5. grassland – vegetation dominated by grass
6. desert – barren, little precipitation, hostile living conditions
Biome a community of plants and animals with common characteristics for the environment they live in and can be found over a vast range of continents. It is defined by climate and a specific set of biotic and abiotic features.
Biotic Factors – living components of an ecosystem
Organisms
Organism remains (decomposing tissues)
Waste products (feces)
Abiotic Factors – the non-living components of an ecosystem
Temperature
Weather
Air (O2, CO2, N2, etc)
Minerals
Water
Light
The Suns Energy
Without the sun and the energy, it provides from light, life on Earth would cease to exist in a matter of days (and that might be generous)
All biotic (living) and abiotic (nonliving) factors interact with the suns radiant energy and collaborate to support all life on earth.
Everything from heat, food, breathable air, and drinkable water rely on the sun’s energy.
Radiant energy – the energy radiated from the sun. It consists of both visible (what you can see) and invisible light (ultraviolet, infrared, gamma rays, x-rays, radio waves)
This energy continuously bombards the earth and provides life with energy.
Distribution of Radiant Energy
70% of radiant energy is absorbed by the hydrosphere and lithosphere and transformed into thermal energy (heat energy).
- 19% by clouds and atmosphere
- 51% by land and ocean
30% reflected back out to space by either the clouds or surfaces of the earth (ice, water, land)
- 6% by atmosphere
- 20 % clouds
- 4 % earth's surface
Energy for Life
Light energy is readily available to support life but cannot be stored.
Chemical energy is needed by all forms of life to perform life functions such as movement, growth and reproduction. It is not readily available.
A process is needed to convert light energy into chemical energy for life to survive.
Photosynthesis
The process by which producers convert light energy into chemical energy which can be stored for later use.
CO2 +H2O C6H12O6 + O2
light energy
A process that can only occur with the availability of the sun's light. No light = No photosynthesis
Organisms that photosynthesize are called Autotrophs (create their own food)
Examples: Plants, Algae and Cyanobacteria
Chemical Energy
Sugars formed in photosynthesis store the chemical energy needed for life processes.
This energy can be stored for later or are used as building materials to create such things as carbohydrates.
This stored energy can be used by consumers who cannot create their own energy through a process known as…
Cellular Respiration
Performed continuously by both producer and consumer.
Used by producers in the absence of sunlight (whether it be shade or night)
A process by which energy is released (not stored) in order to help carry out all life functions such as movement, growth and reproduction.
C6H12O6 + O2 CO2 +H2O + Energy
(sugar)
One process supplies the other. A sustainable and cyclical process.
No light = No producers? Life?
Some organisms do not rely on photosynthesis and may never come into contact with light. These organisms can rely on other processes such as chemosynthesis (the process of getting the energy from chemicals like methane gas, sulphuric gas, hydrogen sulfide.)
Ecological Niche - is the role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces. A species' niche includes all of its interactions with the biotic and abiotic factors of its environment.
Producers and Consumers
two categories of species that have very different but important roles in their environment.
Producers (autotrophs – meaning self feeding/nourishing) are organisms that produce complex organic compounds (such as carbohydrates (sugars), fats, and proteins) from substances in their surroundings, generally using energy from light (photosynthesis) or inorganic chemical reactions (chemosynthesis).
Consumers (heterotrophs) are organisms that cannot produce their own food, relying instead on the intake of nutrition from other sources of organic carbon, mainly plant or animal matter.
Hierarchy of Consumers
Food Chain
Food chains illustrate who eats whom (relationship between producer/consumer) and the direction of energy flow in the ecosystem.
Ex. Acorn Red squirrel Weasel Goshawk
100% 10% 1% 0.1%
Shows how energy passes through an ecosystem.
All organisms continually use and release energy to their environment.
Energy is continuously lost at a rate near 90% from all levels of the food chain.
Ecologists refer to the trophic level, or feeding level, to describe the position of an organism along a food chain.
Food chains are rarely longer than 4 organisms as energy available depreciates quickly.
Food Web
A more accurate, but still incomplete, way to illustrate interactions between organisms in an ecosystem is with a food web. This shows a series of complex interconnecting food chains. They are useful to figure out what may happen when a species is removed from or added to an ecosystem. Arrows always indicate the direction of energy flow in both a food web and food chain.
Ecological Pyramids
Ecological pyramids display the relationships between trophic levels in an ecosystem.
There are three (3) main types:
Pyramid of Energy – shows the direction of energy flow through an ecosystem. Energy always flows from producer to tertiary consumer.
Pyramid of Biomass - Describes the relationship between biomass (the mass of living organisms in a given area) and the trophic levels. Generally, the greater biomass is represented by the producers and becomes less and less as the tropic levels increase. An inverted pyramid can be represented in such a case where the producers are capable of reproducing at an accelerated rate and therefore not needing a greater biomass to support the trophic levels above.
Pyramid of Numbers - Describes the relationship between organism numbers (the quantity of living organisms in a given area) and the trophic levels. Generally, the greater number of organisms is represented by the producers and becomes less and less as the tropic levels increase. An inverted pyramid can be represented in such a case where the producer is capable of supporting numerous trophic levels at one time.
You are what you eat?
All life on earth requires water and nutrients. Water makes up the liquid aspects of cells and nutrients are a source of building materials and chemical energy.
Water and nutrients are composed of physical matter.
You obtain matter through eating, breathing and drinking but this matter does stay forever.
Every part of every cell in your body is replaced over time.
Approx. 2 million blood cells are replaced every second in your body.
You are a fantastic recycling machine!!
The cycle of matter happens between organisms as part of what comes out of one organism somehow influence what goes into another
Biogeochemical Cycles
As matter cannot be created or destroyed, it must be produced or obtained from chemicals that already exist in the environment.
Therefore biogeochemical cycles involve movement of matter (cycles) through the biotic and abiotic environment on earth.
These cycles are:
1. Water Cycle
2. Carbon Cycle
3. Nitrogen Cycle
The Water Cycle
- The cycle of processes by which water circulates between the earth's oceans, atmosphere, and land, involving precipitation as rain and snow, drainage in streams and rivers, and return to the atmosphere by evaporation and transpiration.
The Carbon Cycle
- The series of processes by which carbon compounds are interconverted in the environment, involving the incorporation of carbon dioxide into living tissue by photosynthesis and its return to the atmosphere through respiration, the decay of dead organisms, and the burning of fossil fuels.
All living things contain carbon.
Carbon is found in the atmosphere and dissolved in the oceans as carbon dioxide (CO2)
Carbon, from the atmosphere, is used by plants to make carbohydrates through the process of photosynthesis
These carbohydrates can be used to build other carbon-containing compounds within the organism
Carbon is returned to the environment through the process of cellular respiration.
Decomposers can release the carbon found in dead organism and waste through cellular respiration as well.
Carbon dioxide can dissolve in water to form carbonic acid, which can be used by water plants as a source of carbon.
While large quantities of carbon cycle through photosynthesis and cellular respiration, most of earths carbon is not cycled.
Carbon exists as Fossil Fuels (coal, oil, natural gas) the decomposed organisms stored over millions of years and limestone formed from dead marine organisms.
Carbon sinks are locations of storage where carbon can enter and leave in relatively short periods of time. (plant tissue, dissolved CO2 in oceans, atmosphere)
The Nitrogen Cycle
All organisms need nitrogen to make protein (muscles & enzymes) and DNA.
The atmosphere is composed of 78% nitrogen gas, N2 but plants cannot use nitrogen in this form, it must be supplied in other forms:
ammonium ion (NH4+)
nitrate ion (NO3-)
Without bacteria, movement of nitrogen would almost STOP completely!
Making Nitrogen Useable
Nitrogen Fixation
The process of converting N2 gas into usable sources, such as ammonium (NH4+)
This accomplished by bacteria or lightning.
Denitrifying Bacteria:
The process of converting nitrates (NO3-) back into nitrogen gas (N2)
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is atmosphere nitrogen, making it the largest source of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems.
Human Influence on Nitrogen Cycle
Until last century, plants got all nitrogen naturally.
Now we have artificial fertilizers which contain industrially produced nitrates.
Estimated that ½ of N2 is now fixed is artificially.
Burning of fossil fuels also releases nitrogen compounds.
TOTAL = +140 million tonnes per year of extra nitrogen moving through cycle thanks to farming and fossil fuels.
Nitrogen overload – more Nitrogen than the ecosystems can sustain.
Nitrogen overload – more Nitrogen than the ecosystems can sustain.
Human Additions to nitrogen cycle have impacts on:
Soil (saturation and soil acidification)
Atmosphere (acid rain)
Freshwater Ecosystems (Eutrophication)
People (contaminating well water -> anemia)
Marine Ecosystems (Algal Blooms)
Overall Biodiversity (preferential advantage to species limited by nitrogen)
Eutrophication and Algal Blooms
Eutrophication is the greatest threat to aquatic life if there is an unnatural increase of fertilizer in a body of water.
Eutrophication is the process that occurs when high concentrations of nitrogen and phosphorus, which are both fertilizers, pollute the water and boost plant growth. After the algae blooming period, the algae will die and fall to the bottom of the lake and decompose.
The decomposition of the algae fuels bacterial growth, whose metabolism consumes oxygen in water needed for living organisms.
