Unit 1: Sustainable Ecosystems In this unit you will learn about: Why sustainable ecosystems are crucial to life What people can do to help protect them

BIG Ideas People have the responsibility to regulate their impact on the sustainability of ecosystems WHY? In order to preserve them for future generations

BIG Ideas Ecosystems are dynamic Meaning they have the ability to respond to change - within limits though Beyond those limits the ecosystem cannot recover its ecological balance

1.1 Sustainability An ecosystem includes all the interacting parts of a biological community and its physical environment What are examples of the parts of an ecosystem?

Sustainability is the use of resources at levels that can continue forever To sustain is to endure and to support Sustainable ecosystems are ecosystems that are capable of enduring stressors and supporting organisms

The Need for Sustainable Ecosystems Easter Island Example Video There was once a thriving population and thick forests on the island They built houses, planted crops, built statues Cutting of trees was NOT sustainable for forest life Without forests the island ecosystem collapsed!

Without trees there was: – Loss of other plants – Loss of animals – Soil erosion – No materials to build houses, boats… and of course no way to move statues Overharvesting by humans caused an ecological imbalance = Loss of life

Ecosystems and Survival All organisms require sustainable ecosystems for survival Many organisms depend on more than one ecosystem for survival, such as migrating birds For example geese spend the summer in Canada and fly south in the winter

Parts of an Ecosystem Every ecosystem has biotic and abiotic parts Biotic refers to the living parts Ex: plants, animals and fungi Abiotic refers to the non-living parts Ex: water, oxygen, light, nutrients and soil

Biotic Characteristics Includes all living things as well as the interactions among them 1. Symbiosis interaction between members of two different species that live together in a close association Ex: mushrooms provide tree with water and some nutrients, tree provides mushroom with sugar

2. Predation occurs when one organism consumes another organism for food Ex: frog eats insect 3. Competition occurs when two or more organisms compete for the same resource Ex: dandelions compete with grass for sunlight, water, nutrients

Abiotic Characteristics The factors that living things need to survive 1.Water 2.Oxygen 3.Light 4.Nutrients 5.Soil

Cycling of Matter Ecological processes move matter from the biotic and abiotic parts of an ecosystem, and then back again, in continuous cycles

Cycling of Matter Ex: Hummingbirds consume water, insects, nectar to survive The hummingbird, water, insects and nectar are different forms of living and non-living matter The hummingbird uses the matter it consumes to fly, build muscle, reproduce etc.

Earth’s Spheres At any time, matter can occupy any of the 4 spheres that make up Earth: 1.Lithosphere: the hard part of Earth’s surface (land) 2.Hydrosphere: the salt water in the oceans (water) and fresh water on the continents 3.Atmosphere: the layer of air above Earth`s (sky) surface

Earth`s Spheres The lithosphere, hydrosphere and atmosphere are abiotic spheres 4. Biosphere: the living surface of Earth No other planet is known to have a biosphere!

Nutrient Cycles Ecosystems provide living things with the matter they need, including nutrients Nutrients are chemicals that are needed by living things and are continually cycled through ecosystems Ex: water, carbon, nitrogen and phosphorus

The Water Cycle Water continually cycles through the hydrosphere, atmosphere, lithosphere and biosphere through the processes of: – Evaporation – Condensation – Precipitation

The Water Cycle Heat from the Sun evaporates water from the hydrosphere The water vapour rises in the atmosphere and as it cools it condenses and forms clouds from these condensed water droplets The water falls back to the lithosphere as precipitation

What about the biosphere? As the water returns to the oceans through river systems and the ground, it erodes rocks and picks up other materials It is also absorbed by plants or consumed by animals The movement of water among Earth’s spheres is critical to the operation of sustainable ecosystems

The Carbon Cycle Like water, carbon moves through Earth’s spheres as it is cycled through ecosystems Carbon dioxide gas moves from the atmosphere into the biosphere and back again CO 2 is also released back into the atmosphere when organisms die and are decomposed by micro-organisms

The Carbon Cycle Carbon enters the lithosphere when the remains of organisms are trapped underground After millions of years, these remains are converted into fossil fuels such as coal, oil and natural gas CO 2 is returned to the atmosphere when humans burn the fossil fuels and wood for energy

The Carbon Cycle Plants and algae attain carbon in the form of CO 2 from the atmosphere during the process of photosynthesis Animals release CO 2 as waste product from the process of cellular respiration

The Nitrogen Cycle Earth’s atmosphere is 78% nitrogen (N 2 ) Most organisms cannot use nitrogen in that form An important part of the nitrogen cycle involves processes that convert the nitrogen into usable forms

The Nitrogen Cycle Ex: in terrestrial ecosystems some soil bacteria convert nitrogen (N 2 ) into ammonium (NH 4 + ) and other types of soil bacteria convert ammonium (NH 4 + ) into nitrate (NO 3 - ) Plants absorb both forms of nitrogen through their roots but most of it is absorbed in the form of nitrate (NO 3 - )

The Nitrogen Cycle Ex: in aquatic ecosystems cyanobacteria convert nitrogen (N 2 ) into ammonium (NH 4 + ) which is then absorbed by plants Nitrogen in the form of ammonium and nitrate can also enter both terrestrial and aquatic ecosystems when humans fertilize soil

The Nitrogen Cycle Bacteria found on land and in water convert nitrate (NO 3 - ) back into nitrogen gas (N 2 ) returning it to the atmosphere Nitrogen is also returned to the atmosphere as ammonia (NH 3 ) during volcanic eruptions and when fossil fuels are burned

The Nitrogen Cycle In a sustainable ecosystem the amount of nitrogen converted into usable forms is equal to the amount of nitrogen returned to the atmosphere = Balance Excess ammonium (NH 4 + ) and nitrate (NO 3 - ) eventually enter the lithosphere becoming part of rocks this nitrogen will only return to the atmosphere after rocks are broken down over time

The Phosphorus Cycle Unlike carbon and nitrogen, which both exist as gases in the atmosphere, phosphorus is stored in the lithosphere Phosphorus is stored in rocks and in sediment When rocks are broken down into smaller pieces from weathering, phosphorus in the form of phosphate (PO 4 3- ) is released into the soil

The Phosphorus Cycle Humans mine the lithosphere for phosphate rock which can be used to maker fertilizers and detergents Once in the soil the phosphate is absorbed by plants through their roots The phosphate continues to move through the biosphere as animals eat the plants and other animals

The Phosphorus Cycle Decomposers break down dead organisms and animal waste, releasing the phosphate back into the soil Therefore bacteria and other decomposers ensure that phosphorus is recycled within the biosphere

The Phosphorus Cycle Phosphate enters aquatic ecosystems through leaching and runoff from land Aquatic plants absorb the phosphate and are later consumed by animals, followed by bacteria returning the phosphate to the water when they decompose dead organisms Some of the phosphate that enters aquatic ecosystems settles to the bottom to become part of the sediment rather than part of the biosphere

Human Activities and Nutrient Cycles Human activities can throw off the balance in a sustainable ecosystem by affecting nutrient cycles

Human Activities and Nutrient Cycles Fertilizers and the Phosphorus Cycle Example Some aquatic ecosystems experienced excessive algal growth Lake Erie algal growth increased by as much as 30 times, upsetting natural balances Eutrophication: the process in which deposits of excess nutrients cause an overgrowth of algae

Human Activities and Nutrient Cycles The alarming rate of eutrophication during the mid-20 th century suggested that human activities were the cause In 1968, 58 lakes in Ontario were experimented on They found that when excess phosphorus was added to the water eutrophication occurred

Science and Social Policy As a result of the work done on the effects of excess nutrients in Ontario’s lakes, a multi- billion dollar phosphorus control program was established This was done to restore and maintain the chemical, physical and biological integrity of the waters of the Great Lakes Basin Ecosystem

1.2 The Biosphere and Energy All activities require a source of energy Even though energy takes many forms, all energy originates from the same source, which is solar energy from the Sun Solar energy gets converted and stored as chemical energy by primary producers

Photosynthesis and the Sun’s Energy Lots of energy reaches Earth from the Sun, there is also lots of energy loss from Earth when it is reflected back as heat The atmosphere traps some of this heat, warming the Earth making it more habitable Matter is used over and over as it moves through Earth’s 4 spheres - Nutrient Cycles

Photosynthesis Plants, algae and some bacteria contain chlorophyll which allows the biosphere to harvest some of this solar energy Chlorophyll is a pigment that gives leaves their green colour Photosynthesis uses chlorophyll and light to put together carbon, hydrogen and oxygen to make life’s universal energy supply = a sugar called glucose

Photosynthesis Therefore photosynthesis converts solar energy into chemical energy Sugars are in a class of molecules called carbohydrates (= carbon + oxygen + hydrogen) If plants are going to make glucose sugar then they need these 3 elements They gain hydrogen from water (H 2 O) and carbon and oxygen from carbon dioxide (CO 2 )

Photosynthesis Plants absorb water using their roots and they absorb carbon dioxide through small pores in their leaves called stomata The chemical formula for photosynthesis: Light Energy 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Carbon Dioxide Water Glucose Sugar Oxygen

Photosynthesis Photosynthesis is vital for the biosphere It produces glucose which is an energy source for the plants and the organisms that eat the plants – converts solar energy into chemical energy! Photosynthesis also adds oxygen to the atmosphere, which many organisms require for life Photosynthesis also removes carbon dioxide from the atmosphere

Trophic Levels A trophic level is a category of organisms that is defined by how the organisms gain energy Matter and energy are transferred between trophic levels within the biosphere

Trophic Levels Primary producers are organisms that can make their own food Consumers are organisms that cannot make their own food – therefore must eat other organisms to get the matter and energy they need to survive

Top Carnivore Carnivore Herbivore Plants Trophic Levels Example

Trophic Levels What about decomposers? All the levels of the food web are linked to decomposers They ultimately move the nutrients from decaying organisms, as well as waste from living organisms, back to the abiotic parts of the ecosystem as they take in the nutrients they need to survive

Trophic Efficiency Biomass is the mass of living cells and tissues that has been assembled by organisms using solar energy Meaning, it is the total mass of living organisms in an area Trophic efficiency is a measure of how much of the energy in organisms at one trophic level is transferred to the next highest trophic level

Trophic Efficiency Trophic efficiency is always less than 100% because organisms use much of the energy from the biomass they consume for their life functions Trophic efficiencies are usually low, only about 10%

Trophic Efficiency Trophic Efficiency Example

Trophic Efficiency Why is only 10% transferred to the next trophic level? The rest of the energy is used up by the organism to sustain its life For ex: a herbivore may not eat the entire plant – not all the biomass is consumed Also energy is lost as heat

Trophic Efficiency The inefficiency of energy transfer among trophic levels results in fewer carnivores than herbivores, and fewer herbivores than plants

Water Pollution Bioaccumulation is the ingestion of toxins at a rate faster than they are eliminated Biomagnification is the increase in the concentration of a toxin as it moves from one trophic level to the next Therefore the two terms are related

Water Pollution DDT Example DDT was an insecticide used in North America When DDT entered the environment in runoff from land, it was absorbed by algae in the water Microscopic animals ate the algae, then small fish ate them and bigger fish ate those etc.

DDT Example At each trophic level in the food chain the concentration of DDT in the tissues of the organisms increased At high concentrations the DDT affected reproduction in the birds that ate the fish – thinning of egg shells = less eggs survived Ban on DDT resulted in healthier bird population