MODULE: EARTH & SPACE

ECOSYSTEMObservatory Chapter 10

PAGES 317 - 347

Ecosystems and Trophic Relationships

Ecosystems•It is a community of living organisms and nonliving factors interacting together in a given environment.

•They can vary in size and composition.

Trophic Relationships•All organisms need energy for survival.

•Food chains show trophic relationships and trophic levels.▫Producers▫Consumers▫Decomposers

•In a food chain, the arrow points in the direction that the organism will go after it is eaten.

grass rabbit wolf

ProducersAKA: ‘autotroph’ because they are self-feeding▫at bottom of food chain▫introduces energy into ecosystem▫self-feed with sunlight and soil nutrients

▫transforms inorganic into organic matter

▫Examples: plants, algae, certain bacteria

•Photosynthesis is a process that producers use to feed themselves.

carbon + water + light → glucose+ oxygen

dioxide energy

6CO2 + 6H2O + light → C6H12O6

+ 6O2

Primary Productivity in Ecosystems•Biomass is the total mass of all organic matter (plant and animal).

•Primary productivity is the amount of new biomass made by producers.

▫The amount depends on the number

of living organisms.

▫It allows for greater capacity of

ecosystem to supply energy

to organisms (to consumers).

▫3. access to nutrients for producers

C, N, K, P, etc.

▫4. temperature – certain weather

conditions promote growth

•Primary productivity depends on 4

factors:

▫1. amount of light (for radiation for

photosynthesis)

▫2. amount of available water (for

photosynthesis)

Consumers•AKA: ‘heterotroph’ because they eat other organisms▫Cannot make their own food

Consumers Consumer Types: Primary (1st order) herbivores

▫eat producers, granivorous (seed-eating), frugivorous (fruit-eating)

Secondary(2nd), tertiary (3rd ), quatiery (4thorder)

▫Eat consumers of preceding order▫2nd or higher = carnivore

OmnivoresCan be several different orders at once (bears)

Their order depends on what they have eaten or what eats them.

The same animal can be a different ‘order’ depending on their position in a food chain.

Decomposers•AKA: ‘detrivores’•Connected to all levels of food chain•They feed on detritus (dead organic matter)▫fallen leaves▫excrement▫animal remains

•Examples: worms, fungi, some bacteria, certain insects (sow bugs)

Detrivores/Decomposers

Food Web•It shows all the trophic relationships in an ecosystem.

•It can be considered as a ‘trophic network’.

Ecosystem Dynamics•This refers to material and energy flow.

•It is the exchange of material and energy between living organisms and between living organisms with their environment

•*** In ecosystems and in labs, the following law applies to both ……

Law of Conservation of Mass

•This means: ▫Nothing is lost.▫Nothing is created.▫Matter is only transformed.

•Producers are always changing inorganic matter into organic matter.

Law of Conservation of Mass•When producers are starved, they will die…the ecosystem will be at risk.

•Decomposers breakdown organic matter into inorganic matter▫N, K, P, etc.

•Ex. Composting is chemical recycling.

•Matter is always being circulated.

Chemical Recycling In Ecosystem

Decomposers

Environment

Producers

Detritus

Consumers

Inorganic Matter Flow

Organic Matter Flow

Energy Flow•Sunlight is the main energy source in an ecosystem.

•Radiant energy is •transformed into chemical energy by plants. (chem energy is

also stored in them)

Energy Flow•Energy gets transferred to animals when producers are consumed.

•Energy moves up the trophic levels since it stored in tissues.

•Animals use this energy for moving and heat.

•Energy of ecosystem is never recycled.

•Ecosystems need a continuous supply of energy that comes from the sun.

Disturbances•Disturbances are events that damage the ecosystem.▫Kills organisms▫Alter the available resources

Disturbances•Events vary in type, frequency, and seriousness.

•Disturbances can be either natural or human in origin.

Types of Disturbances•Depends on location of ecosystem.

▫Snowstorms▫Hurricanes▫Volcanoes▫Sandstorms

Frequency of Disturbances•Depends on location of ecosystem.

▫Flooding in spring▫Monsoons in summer

Seriousness of Disturbances•Depends on location of ecosystem.

▫Ice storm ▫Flooding

Natural Disturbances•Example: Storms can affect land. There is also a mixing of the surface and subsurface waters that will eventually affect the ocean depths.

Natural Disturbances•Is normally an environmental phenomena.▫Volcanoes▫Forest fires▫Droughts▫Floods▫Frost periods▫Heat waves

Human Disturbances•It is where humans are the major source of a disturbance

•It can be as small as littering to large-scale projects.▫Logging▫Oil spills at sea▫Nuclear power plant meltdown

Ecological Succession•After a disturbance, the ecosystem will try to recover and gain a balance.

•Changes made to gain a balance is ecological succession.

Ecological Succession•Change to plant population will alter animal population and vice versa.

•The presence or lack of an organism can also bring change to an ecosystem.

Ecological Footprints

•Ecological footprints are estimates of the surface area humans or populations require to obtain the resources for satisfying all their “needs” and to ensure the disposal of their waste.

Ecological footprint

•Land used to grow fruits and veggies•land used to raise animals•Land used to grow trees for lumber•Land used to drill for oil, minerals…•Factories•Waste

Ecological carrying capacity

•The earth ~1.8 hectares per person

•Canada’s average: 7.6 hectares per person…

•(1 hectare = 100m x 100m)

• http://www.footprintnetwork.org/en/index.php/GFN/page/calculators/

Ecotoxicology:

•The study of the ecological consequences of polluting the environment with various substances and radiation, released by human activity.

Contaminants

•Any type of substance or radiation that is likely to cause harm to one or more ecosystems.

•Inorganic (lead, arsenic, mercury, phosphorus, nitrogen oxides….)

•Organic (insecticides, pesticides, PCBs, benzene in crude oil)

•Microbial (viruses and bacteria)•Radioactive (uranium, plutonium, radon)

•PCBs were widely used as coolant fluids in transformers, capacitors and electric motors. It is a Organic Pollutant, banned in 2001. Concerns about the toxicity of PCBs are largely based on compounds within this group that cause endocrine disruption and neurotoxicity. Therefore, the current maximum containment levels as stated by the EPA for PCBs in drinking water systems is 0.5 ppb.

Toxicity factors

•Concentration: ex. drinking water containing more than 0.01 ppm of lead is considered toxic

•Type of organism it comes in contact with: ex herbicides kill weeds but not the crops

•Length of exposure: ex. cigarette smoke

Toxicity Threshold

•level of concentration above which a contaminant causes one or more harmful effects in an organism.

•LETHAL DOSE•The amount of contaminant necessary, in

a SINGLE DOSE to cause the death of an organism

LD50

•The dose that causes death among 50% of individuals.

Bioaccumulation

•Some contaminants cannot be eliminated by an organism.

•Bioaccumulation is the tendency of contaminants to accumulate over time in the tissues of living organisms.

Bioconcentration or bioamplification

•The concentration of contaminants in tissues increases with each trophic level.

Biotechnology

•How are we trying to solve the problem of contamination?

•1) Bioremediationusing microorganisms to decompose organic contaminants (biodegradation)

•2) Phytoremediation:•Using plants or algae to eliminate

contaminants from a site.•they absorb contaminants and can then

be destroyed.

•3) Wastewater treatment•it can contain

▫sand and other particles▫pathogens (can cause disease)▫decomposing organic waste▫nutrients that would stimulate algae

growth▫chemicals

treatment

•a) Septic tank•Solids settle to the bottom•Collected as “sludge” and treated

•Liquids go into drain field•Microorganism in the soil treat the liquid

•b) waste-water treatment plant•connected to urban sewer system•steps:• i) primary/physical treatment

▫removes large debris▫filter sand▫sedimentation

• ii) Secondary/biological treatment•microorganisms eliminate contaminants•second sedimentation

• iii) Disinfection•chemicals (chlorine, ozone) or radiation (UV)

destroys disease-causing microorganisms

•http://videos.howstuffworks.com/discovery/30941-dirty-jobs-sewage-treatment-video.htm