The Living World: Ecosystems (Chapter 10)                                

1 Ecosystem – A community of living organisms interacting with one another and with the nonliving components of the environment they inhabit. ST EST AST

Levels of Ecological Organization Individual ( A Moose) Level 2 Population (Herd of Moose) Level 3 Community: (Herd + Birds + Squirrels + etc Level 4 Ecosystem : Living + nonliving components in the environment

Examples of Ecosystems: Forest Lake Aquarium Island

Interactions within Ecosystems 1 .1 Interactions within Ecosystems Trophic Relationships The feeding connections among the living organisms in an ecosystem (a food chain) ST EST AST

Simple food “chain”

More realistic food “web”

Producers – autotrophic (self nourish) organisms with the ability to create organic matter from inorganic matter in an ecosystem through photosynthesis. Plants use sunlight to make sugars for energy. Plants Phytoplankton (algae)

Inorganic vs. organic matter Matter that is not necessarily produced by living organisms. (e.g. Water, mineral salts, carbon dioxide) Organic Matter that enters into the composition of living organisms and that is usually created by them. (e.g. proteins, carbohydrates, fats)

Consumers – heterotrophic (other nourishment) organisms that feed on other living organisms and/or their products such as eggs, fruit etc.

Consumers First order (or primary) consumers: feed on producers (eg: a deer eats grass, birds eat seeds). They are herbivores. Second order consumers: feed on first order consumers (eg: a wolf eats a deer, a cat eats a bird). They are carnivores. Third order consumers: feed on second order consumers Fourth order consumers: feed on third order consumers etc. etc.

Omnivores: Consumers that eat several orders at once. (eg: bears eat berries and fish, humans eat grain and meat).

Decomposers – organisms that feed on the waste and remains of other living organisms. Decomposers are detritivores which are heterotrophs that can be eaten by consumers Feed on detritus which is dead organic matter such as fallen leaves, dead wood, animal remains, etc Examples are: worms, some bacteria, certain insects such as the sow bug

Trophic Network – Food Web

1 .2 Ecosystem Dynamics Material and Energy Flow – the exchange of matter and energy between the living organisms in an ecosystem and between those organisms and their environment. Law of conservation of Mass – nothing is loss and nothing is created; Matter is transformed ST EST AST

Material Flow and Chemical Recycling Chemical recycling – is a natural phenomenon by which decomposers make inorganic matter available in an ecosystem by breaking down organic matter.

Flow of inorganic matter Chemical Recycling Decomposers Detritus Consumers Producers Flow of inorganic matter Environment Flow of organic matter

Energy Flow: the sun is the main source of energy for ecosystems Thermal energy lost in the environment Radiation energy Primary Consumer Secondary Consumer Producer

Biomass and Primary Productivity in Ecosystems 1 .3 Biomass and Primary Productivity in Ecosystems Biomass – the total mass of organic matter in an ecosystem at any given time. ST EST AST

Primary productivity of an ecosystem is the amount of new biomass generated by its producers Factors that affect primary productivity are: Light (radiation energy) from the sun Amount of water (necessary for photosynthesis) Essential nutrients (carbon, nitrogen, phosphorus, and potassium) Temperature – weather promotes growth of producers

2 Disturbances A disturbance is an event that damages an ecosystem. It can lead to the elimination of organisms and alter the availability of resources. E.g. flooding, storms, oil spills, volcanic eruptions ST EST AST

2.1 Natural Disturbances Events triggered by environmental phenomena rather than humans but can be very damaging nonetheless. (storm churning waters = surface + subsurface waters to mix) E.g. volcanic eruptions, drought, flood, forest fires, frost, freeze rain & heat waves ST EST AST

2.2 Human Disturbances Humans and their actions are a major threat to ecosystems from individual acts like littering to large scale projects. E.g. logging, mining, oil spills, housing projects, industries, pollution, etc. ST EST AST

Ecological Succession 2.3 Ecological Succession Ecological succession – the series of changes that occur in an ecosystem after a disturbance and that continue until the balance of the ecosystem is restored. ST EST AST

A forest recovering after acid rain

Ecological Footprints 2.4 Ecological Footprints Ecological footprints are estimates of the surface area individual humans or populations require to obtain the resources for satisfying all their needs and to ensure the disposal of their waste. Land & water used to produce goods Land & water used to dispose of waste Ecological Footprint Land & water occupied = + + EST

Ecological Carrying Capacity

3 Ecotoxicology is the study of the ecological consequences of polluting the environment with various substances and radiation, released by human activity. EST SE

Contaminants – is any type of substance or radiation that is likely to cause harm to one or more ecosystems. 3.1 Class of contaminants Examples Inorganic Lead, arsenic, mercury, nitrogen oxides, phosphorus Organic Insecticides, pesticides, benzene, polychlorinated biphenyls (PCBs) Microbial Viruses and harmful bacteria Radioactive Uranium, plutonium, radon EST SE

Toxicity Toxicity of each contaminant depends of the following three factors: Concentration – more concentrated higher the risk Type of organism it comes in contact with Length of exposure

Toxicity threshold – the level of concentration above which a contaminant causes one or more harmful effects in an organism LD50 – indicator used to determine toxicity dose that is lethal to 50% of individuals

Bioaccumulation and Bioconcentration of Contaminants 3.2 Bioaccumulation and Bioconcentration of Contaminants Bioaccumulation – the tendency among certain contaminants to accumulate over time in the tissues of living organisms. EST SE

Bioconcentration (also called Biomagnification or Bioamplification)- the concentration of a contaminant in the tissues of living organisms tends to increase with each trophic level.

4 Biotechnology Biodegradation – the breaking down of organic matter into inorganic matter by microorganisms EST

Bioremediation – a biotechnology for cleaning up a polluted site, using microorganisms that decompose the contaminants.

Phytoremediation – a biotechnology that uses plants or algae to eliminate contaminants from a site.

Wastewater Treatment Wastewater – water that is discharged after household or industrial use and that is polluted as a result of human activities. Wastewater can contain: Sand or other particles Pathogens Nutrients that stimulate the excessive growth of algae Chemicals

Septic Tanks and Wastewater Treatment plants Two main methods for treating wastewater are: Septic Tanks and Wastewater Treatment plants

Checkup Pg 342 # 1-15, A and C ST and AST Pg 342 # 1-26, A - C EST Pg 342 # 18-23, B SE Eco-sketch Complex Task (ST & AST) Pg 323 – Vermicomposting from cafeteria (optional)