1. The Biosphere Life on Earth

The biosphere Regroups all living organisms on our planet. **** Biogeochemical Cycles p. 256-259 There exists a fine balance between all the spheres E.g. biogeochemical cycles

a) Biomes The interconnection of the spheres on our planet form distinct biomes. Definition: Large region of the world with distinctive climates, wildlife and vegetation

a) Biomes Factors determining terrestrial biome distribution: Latitude Altitude Temperature Precipitation Soil Type Winds Exposure to sunlight Proximity to water

a) Biomes Factors determining aquatic biome distribution: Salinity Turbidity (water clarity) Temperature Direction and strength of current Presence of oxygen Nutrients Exposure to sunlight Water depth

2. Ecosystems

2. Ecosystems Definition: A community of living organisms interacting with one another and with the nonliving components of the environment they inhabit In other words: how living things interact with their surroundings (both living and nonliving components)

a) Trophic levels The main type of interaction has to do with an animals trophic level Trophic level: The feeding connections among living organisms in an ecosystem (a food chain)

a) Trophic Levels i) Producers Create organic matter from inorganic matter (water, minerals, sunlight) of the ecosystem In other words they are autotrophs; they can feed themselves without consuming others

a) Trophic Levels Ii) Consumers Heterotrophic organisms that feed on other living organisms Are all heterotrophs (incapable of producing food for themselves. Different degrees of consumers 1st order: eats the producer directly 2nd order: eats the 1st order who ate the producer 3rd order: eats the 2nd order who are the 1st order who ate …. Well you get the picture

Consumer precision Just because a creature is a 1st order consumer in one food chain, he might be a 2nd order consumer in another chain Herbivore Carnivore Omnivore

a) Trophic Levels Iii)Decomposers: Organisms that feed on the waste and remains of other living organisms Breakdown organic matter into inorganic matter Are also heterotrophs E.g. bacteria, fungi,

3. Material Transfer These trophic networks (food webs) allows for a transfer of energy, a flow of materials and a chemical recycling. Material and energy flow is the exchange of matter and energy between the living organisms in an ecosystem and between those organisms and their environment

3. Material Transfer Chemical recycling: Natural phenomenon by which decomposers make inorganic matter available in an ecosystem by breaking down organic matter

The complexities and links between the environment and its living creatures makes very easy to disturb.

More definitions Biomass Primary productivity of an ecosystem Total mass of organic matter in an ecosystem at a given time Primary productivity of an ecosystem Definition: The amount of new biomass generated by the ecosystems producers Factors: Amount of water Amount of light Amount of nutrients Temperature

Disturbances

Disturbances Definition: Types: Event that damages an ecosystem. It can lead to the elimination of organisms and alter the availability of resources. Types: Natural Disturbances Triggered by environmental phenomena E.g. ice storm Human Disturbances Triggered by human activities E.g. logging

Ecological succession Definition: The series of changes that occur in an ecosystem after a disturbance and that continue until the balance of the ecosystem is restored

Ecotoxicology

Ecotoxicology Definition: Study of the ecological consequences of polluting the environment with various contaminants Contaminants: Any type of substance or radiation that is likely to cause harm to one or more ecosystems

Ecotoxicology Types of contaminants: Toxicity of a contaminant depends on: Its concentration The organism it comes in contact with The duration of exposure

Ecotoxicology 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 to cause the death of an organism

Ecotoxicology Bioaccumulation Bioconcentration (or bioamplification) Tendency among certain contaminants to accumulate over time in the tissues of living organisms Bioconcentration (or bioamplification) Phenomenon by which the concentration of a contaminant in the tissues of living organisms tends to increase with each trophic level.