•Ch2 – Interaction in Ecosystems•Ch3-Community Ecology•Ch4-Natures Recycling Programs•Ch5- Changing the Balance in Ecosystems

Interactions in Ecosystems2

• Ecosystems are made up of living things (biotic factors) and non-living things (abiotic factors), which are connected to each other in complex interrelationships.

• Nutrients are cycled within an ecosystem.producers consumers decomposers producers

Make Yourself a Venn Diagram with the following Terms

EcologyBiosphereOrganismCommunityEcosystemPopulation

The BiosphereThe biospheres is the global sum of all

ecosystems. It can also be called the zone of life on Earth. From the broadest biophysiological point of view, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, hydrosphere, and atmosphere.

• An ecosystem is made up of a community of organisms and the non-living environment.

• The living components of the ecosystem are called biotic factors, which include plants, fish, invertebrates, and single-celled organisms.

• The non-living components, or abiotic factors, include the physical and chemical components in the environment—temperature, wind, water, sunlight, and oxygen.

• Biotic and abiotic factors influence each other in an always changing balance called dynamic equilibrium.

Biotic and Abiotic Factors in Ecosystems2.1

VOCABULARY

ecology

organism

habitat

population

community

ecosystem

biosphere

biotic factor

abiotic factor

dynamic

equilibrium

limiting factor

Limiting FactorsLimiting factors are environmental influences

that constrain the productivity of organisms, populations, or communities and thereby prevent them from achieving their full biological potential which could be realized under optimal conditions. Limiting factors can be single elements or a group of related factors.

Answers1) Explain the difference between density

independent and density dependent limiting factors.

(2 marks)Density independent factors are limiting

factors that affect all populations regardless of their densities whereas density dependent factors only affect populations when they reach a specific density.

2) From the previous article “Yellow Perch in Lake Winnipeg”, identify and describe as many limiting factors as possible and classify them as density independent or density dependent.

Density Independent - depth of Lake Winnipeg (affects amount of sunlight in water, and space

available in lake) - temperature of water (affects which fish will live in the lake) - turbidity of water (affects which fish will live in the lake) - migration of yellow perch (depends on which fish are strong enough to travel) - eyes (helps yellow perch to hide from predators and hunt for prey) - drought (natural disasters affect water temperature, levels and turbidity)

Density Dependant - stunting (due to lack of food or over-abundant population of yellow perch,

they will stunt their growth instead of dying) - predation (yellow perch are eaten by northern pike and walleye) - parasitism (chestnut lampreys attach to yellow perch and feed of body fluids) - competition (rainbow smelt compete for space and food) - crowding (rainbow smelt crowd yellow perch)

3) Each of the statements below involves a situation that will affect the growth of a population. Classify each of the statements as DD (density dependent) or DI (density independent) and give a reason for your choice. (18 marks - 2 each)

a. Rainbow smelt and yellow perch attempt to occupy the same area. The more aggressive smelt survive; the perch do not.

DD - competition between species only occurs at certain densities

b. A severe flood brings a lot of sediment and silt into Lake Winnipeg. The turbidity of the lake increases greatly.

DI - natural disasters affect all populations regardless of density

c. A drought decreases the water level in Lake Winnipeg. The carrying capacity of the lake decreases.

DI - natural disasters affect all populations regardless of density

d. Due to the introduction of rainbow smelt, Lake Winnipeg becomes crowded and some fish species do not survive.

DD - crowding only occurs at certain densitiese. Since northern pike prey on yellow perch, an increase in the

perch population causes an increase in the pike population.DD - predation only occurs at certain densities f. Many fish die due to an increase in water temperature.DI - temperature affects all population densitiesg. Due to over-fishing, the number of walleye in Lake

Winnipeg decreases.DI - human activities affect all population densitiesh. A population is growing quickly when parasites cause

disease to spread quickly.DD - parasitism only affects certain population densities i. Since lake sturgeon migrate long distances to spawn, many

do not survive the trip.DI - behaviours of organisms affect all population

densities

ProducersPlants harness energy from the sun through

photosynthesisThey are the base of every food chain

Source of food for all other animals

Consumers4 Types

Herbivore: eats only plants Ex. Cows, horses

Carnivore: eats only meat Ex. Polar bear

Onmivore: eats plants and animals Ex. Humans, grizzly bears

Scavenger: carnivore that feeds on bodies of dead organisms Ex. Vultures

DecomposerDecomposers break down wastes and dead

organisms and return the raw materials to the environmentEx. Bacteria, fungi

• Nutrients are cycled back into the ecosystem, but energy only moves in one direction through the community from producers to herbivores to carnivores.

• Trophic level describes the position of the organism in relation to the order of nutrient and energy transfers in an ecosystem. Organisms that eat the same type of food belong to the same trophic level.

• Food chains show a single pathway taken by nutrients and energy through the trophic levels.

• In reality, ecosystems have more complex food webs, showing the different cross-linked food chains.

Trophic Levels and Energy Flow2.4

VOCABULARY

trophic level

food chain

food web

Interactions in Ecosystems• Energy flows through ecosystems.

• This energy comes from an outside source: the Sun.

• Ecologists represent food and energy flows in food chain, food web, and pyramid diagrams.

2

Interactions in Ecosystems

Activity

Using the food web on the right, predict what might happen if a disease killed all the krill in the ecosystem. Which species would be affected, and how? Try drawing a new food web.

2CHAPTER

Ecological Roles and RelationshipsVOCABULARYnutrients

producer

autotroph

phytoplankton

consumer

heterotroph

herbivores

primary consumer

zooplankton

carnivore

omnivore

detrivore

decomposer

biodegradation

predation

predator

prey

predator–prey

cycle

• An ecosystem is a complex network of interactions.

• All organisms must take in water, food, and nutrients. Nutrients are elements and compounds that organisms need to live and grow.

• Organisms can be producers, consumers, herbivores, carnivores, or decomposers in ecosystems.

• Eventually nutrients cycle back into the ecosystem for the producers.

Symbiosis2.3

VOCABULARY

symbiosis

mutualism

commensalism

parasitism

host

parasite

• Symbiosis refers to any close relationship between two different species. There are three types of symbiotic relationships:

1. Mutualism is a relationship in which both species obtain some benefit from the interaction.

2. Commensalism is an interaction in which one organism benefits while the other is unaffected.

3. Parasitism occurs when one organism (the parasite) lives and feeds on, or in, the body of another organism (the host).

ILLUSTATIVE EXAMPLES

Commensalisms :Commensalism usually occurs between a

species that is either vulnerable to predation or with an inefficient means of locomotion, and another species with a relatively effective system of defence.

Ex. Of CommensalismThe Anemone crab on its

host sea anemone.

One especially amazing example of commensalism occurs between the Pearlfish and a particular species of sea cucumber. The Pearlfish spends the day inside the alimentary tract (‘intestines’) of the sea cucumber, and at night emerges from its anus to feed on small crustaceans! In this manner it gets a safe place to live; and while not appearing to gain any benefit from the relationship, the cucumber is not harmed.

Parasitism :In a parasitic relationship, the host species is

always exploited to some degree, although often in such a way that its health is impaired only slowly. This allows the parasite to exploit its host over a longer period. Many parasites only spend a portion of their lives in the relationship, either to reproduce, or during an initial growth stage.

Parasites can be divided into two basic categories, Ectoparasites and Endoparasites, the former referring to external parasites, and the latter internal parasites.

Ectoparasites Endoparasites

Mutualism :Mutualism is one of the most interesting forms of

symbiosis, as it is a benefit to both species involved.

the Boxer crab, carries a pair of small anemones in its claws. When approached by a predator it waves these around presenting the stinging tentacles so as to deter the marauder. The anemones benefit from the small particles of food dropped by the crab during feeding.

Mimicry ;Mimicry is a form of symbiosis where a species may

mimic the colours, patterns, or even behaviour of another species for one of two reasons. Either to be able to get closer to unsuspecting prey or in the case of a harmless species; to gain protection by imitating a predator or poisonous species.

One of the most interesting mimic species is the Mimic octopus. It takes on the form of a variety of different animals by bunching up or elongating its arms to mimic anything from a stingray to a Lionfish or even a sea-snake. It could be that this species employs mimicry both as a means of defence and predation

A particular type of mutualistic interrelationship that many divers will have encountered is ‘Cleaning symbiosis’, The fish being cleaned are often termed ‘client fish’ and the sites they go to to be cleaned are known as ‘Cleaning stations’ ... in tropical waters these areas of the reef are quite clearly defined by the numbers of stationary fish and their attendant cleaner organisms.

• Ecologists use three different types of ecological pyramids to illustrate ecosystems:

1. Pyramid of energy: represents how much energy is available in each trophic level

2. Pyramid of numbers: represents the actual number of organisms present in each trophic level

3. Pyramid of biomass: represents the total mass of living things in each trophic level

Ecological Pyramids2.5

VOCABULARY

ecological pyramid

food pyramid

pyramid of energy

pyramid of

numbers

pyramid of

biomass

Energy Pyramid2nd Law of Thermodynamics: energy is not

transferred from one object/organism to the next with 100% efficiencySome of the energy is lost to the environment

Energy Pyramid shows the amounts of energy that moves from one level to the next

Sample Energy Pyramid

Energy TransferOnly about 10% of energy is transferred from

one level to the nextThe other 90% is used by the organism to carry

out its life processes or it is lost to the environment