Transcript Biology 20 Unit B Chapter 4 notes 2014x

CHAPTER 4: CHARACTERISTICS IN
ECOSYSTEMS
Pages 84-131 Nelson
1
Section 4.1


Recall: An environment includes
biotic and abiotic
components.
Interactions between organisms
and their environment can be
divided into four levels:
individuals, populations,
communities, and ecosystems.

Individuals
Species: organisms that are able to breed with
one another and produce fertile offspring.
Population: a group of individuals of the same
species living in a specific area

Community:
all of the individuals in all of the
interacting populations at a given time
Ecosystem: a community of populations together
with the abiotic factors that surround and effect it.
ECOSYSTEM INTERACTIONS


ECOLOGY: the study of interactions between
organisms and their biotic & abiotic environment
Recall examples of interactions:
Biotic-Biotic:
moose eating grass
Abiotic-Biotic:
sunlight on plants
Abiotic-Abiotic:
river eroding rocks
BIODIVERSITY WITHIN ECOSYSTEMS

ECOTONE: a transition area between ecosystems
ecosystems don’t have sharp boundaries


organisms move back and forth from one ecosystem to another
therefore the ECOTONE between 2 ecosystems has greater
biodiversity

see Fig. 1 p.87

remember, areas with greater biodiversity are MORE STABLE
ROLES WITHIN ECOSYSTEMS

NICHE:
an organism’s role in an ecosystem
-its place in the food web
-its habitat
-its breeding area
http://en.wikipedia.org/wiki/File:Dung_beetle_working-001.ogv
NOTE: each species in an ecosystem tends to have a
different niche (read page 90)
Niche

Helps us to understand how organisms in an
ecosystem interact with each other.
The
ecological niche of a
population is the role that
its members play in an
ecosystem.
Eg. Honeybees gather nectar
from flowers to make honey
- Pollinators
Community Ecology: Feel the Love - Crash
Course Ecology #4
http://www.youtube.com/watch?v=GxE1SSqbSn4
COMPETITION FOR NICHES
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if a new species enters an ecosystem (called
an EXOTIC SPECIES), it often causes a
disturbance
Why???
it competes for a NICHE already occupied by
a native species
it may have no natural predators
it may bring new disease that native species
aren’t immune to
Read ‘Intro of exotic species’ p.91-92
Attack of the killer Cane Toads in
Australia!

introduction of exotic species
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Cane toad vs. fresh water crocodile …
who wins?
https://www.youtube.com/wat
ch?v=w2bwUlu3eMc
http://www.newscientist.com/article/dn1422
1-australian-crocs-hit-by-cane-toad-waveof-death.html#.UiawBjasim4
What is another
example of an
exotic species that
was introduced in
Australia?
Ahhh a cute bunny rabbit!
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European rabbits first arrived in
Australia with the First Fleet in 1788,
but they only became a pest after 24
wild rabbits were released for hunting
near Geelong in Victoria 150 years ago.
By the 1920s, Australia's rabbit
population had swelled to 10 billion.
So in 1950 the biological control agent,
Myxoma virus, was introduced to
Australia's mainland.
http://www.abc.net.au/science/articles/2009
/04/08/2538860.htm
Are there examples of
exotic species in Canada?
To combat the reduced effectiveness of
myxoma virus, calicivirus, or rabbit
haemorrhagic disease (RHD), was
released in Australia in 1995.
11 invasive species threatening Canadian habitats
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From parasites to crabs and living slime affectionately dubbed "rock snot," invasive
species can wreak havoc when introduced into a new habitat.
1. Asian carp
Source: http://www.cbc.ca/news/technology/story/2012/02/23/f-invasive-species.html
2. European green crab
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The European green crab preys on mussels, clams and other crabs, threatening shellfish
stocks on the Atlantic coast. It's a naturally aggressive and territorial crab species, found
near Prince Edward Island, Quebec's Magdalen Islands, Nova Scotia's Cape Breton Island
and the waters off southern Newfoundland, where it was first discovered in 2007.
According to Fisheries and Oceans Canada, unless controlled, the crab's impact will surely
be felt in Newfoundland's ecosystem.
And then there is…#3-8
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Purple loosestrife
Sea lamprey
Zebra mussel
Gypsy moth
Emerald ash borer
Round goby
9. Didymo deserves it’s own page!
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(aka rock snot)
And…10-11
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Asian long-horned beetle
Gypsy moth
his beetle from China attacks hardwood trees such as
maples. It first appeared in North America in 1996 in
New York state. In Canada, it was first found in 2003 in
an industrial park between Toronto and the city of
Vaughan.
Larvae of the gypsy moth are known to eat the
leaves of about 300 plants, causing widespread
damage.
Task
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What outcomes have we covered so far?
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Section 4.2
Terrestrial and Aquatic Ecosystems
Nelson Pages 94-100
Curricular Outcomes:
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20–B1.1k
Define and explain the interrelationship among species,
population, community and ecosystem
20–B1.2k
Explain how a terrestrial and an aquatic ecosystem
supports a diversity of organisms through a variety of
habitats and niches
Curricular Outcomes:
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20–B1.3k
Identify biotic and abiotic characteristics and explain
their influence in an aquatic and a terrestrial ecosystem
in a local region
20–B1.4k
Explain how limiting factors influence organism
distribution and range
1. ABIOTIC FACTORS IN
TERRESTRIAL ECOSYSTEMS
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
abiotic factors are the non-living components of an ecosystem

affect the type and number of organisms that can live there

Describe abiotic components that cause the two terrestrial
ecosystems below?
Canadian Biomes – Page 94
Edmonton
TERRESTRIAL ECOSYSTEMS IN ALBERTA
1. TAIGA (BOREAL FOREST)
ECOSYSTEMS
Northern & Central AB forests

Warm, wet summer; Cold, dry
winter
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Dominated by CONIFERS:

PINE trees, SPRUCE trees

cone-bearing trees that have
needles
-Reduce water loss ( S.A., thick
cuticle)
-Pyramid shape of tree  heavy snow
weight
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Canopy (tree tops): find seed-eating birds, red & flying
squirrels
Forest Floor: find shade-loving plants (shrubs, ferns, mosses),
moose, deer, bear, weasels, grouse, owls, etc.
2. MUSKEG ECOSYSTEM:
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More Northern Taiga (colder!)
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PERMAFROST
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Water never drains away…
beneath soil (never melts!)
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Water soaks into the PEAT (decomposing
organic matter)
Forms the MUSKEG or BOG (swampy!)
Very Acidic soil
Find black spruce trees, mosses, lichens,
caribou, mosquitoes!
Very SLOW DECOMPOSITION
Soil formation is very slow… damage to this
ecosystem takes many years to repair…
BOG MUMMY
A bog body is a human cadaver that has been naturally mummified within a peat
bog.
3. GRASSLAND (“Prairies”)
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Southern AB
Nutrient-rich black earth

Short-lived grasses provide large biomass for
decomposition
More sunlight, less precipitation
limited diversity (no canopy, etc.)
Find “grasses and grazers” (various grass species,
bison, deer) rabbits, gophers, hawks, grasshoppers,
etc.
4. DECIDUOUS
FOREST
ECOSYSTEM
 Central AB
 Between grassland and
taiga biomes
 Dominated by
deciduous (leavelosing) trees
aspen poplar, balsam
poplar & birch
 Rich, fertile soil (lots of “leaf litter”)
 MOST DIVERSITY!
 Canopy, understory, & forest floor
 Bears, moose (“browsers”), deer, weasels, woodpeckers,
shrubs, etc. etc.
 See Fig 6 p.96
AQUATIC ECOSYSTEMS
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Water covers 2/3 of earth
97% is saltwater (oceans)
Evaporation from oceans = freshwater (most in form
of snow & ice on earth)
ALBERTA aquatic ecosystems = ponds, rivers, and
lakes
ALBERTA LAKE ECOSYSTEMS
Sketch Fig 7 page 99
LITTORAL ZONE
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extends from lakeshore to where plants are no
longer rooted in the lake bottom
Shallow, lots of sunlight
Most productive part of lake - algae and plants
performing photosynthesis
Plants can be floating (algae), emergent (water
lilies) or submerged (seaweed)
LIMNETIC ZONE
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Area of open water where there is still enough
sunlight for photosynthesis
Plankton is food for consumers
AUTOTROPHIC PLANKTON (tiny plants & algae)
HETEROTROPHIC PLANKTON (tiny invertebrate
animals)
PROFUNDAL ZONE
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Deepest part of lake, no sunlight
not found in ponds or shallow lakes
Only nutrients = decaying matter (detritus) that
falls from the limnetic zone
Find lots of decomposers (bacteria), few bottomdwelling fish, & invertebrates
LOW O2 LEVELS due to lack of plants and lots of
decomposers
Wow, what at catch!
Wow, um already then!
FYI – Random fact of the day - GIANT CATFISH
ARE “BOTTOM FEEDERS”
Section 4.3 -Factors Affecting Ecosystems
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Factors Affecting Terrestrial Ecosystems
Soil
1.
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Litter-upper layer of soil-decomposed plants
Topsoil-under the Litter-small rocks mixed with
humus (decaying matter)
Subsoil-below Topsoil-mostly rock particles, very
little organic matter
Bedrock-layer beneath soil, composed of rock
4.3 Continue
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Available Water
2.
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
Amount of water will determine what can
grow.
Leaching is a problem, can dissolve
nutrients and minerals and take them deep
in the soil.
Plants in these areas must have deep roots
to be able to use these materials
4.3 Continue
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Temperature
3.
 Plants
and animals must be adapted to
temperature.
 Hotter is not always better! But why?
Sunlight
4.
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Plants need the sun for photosynthesis
4.3 Aquatic Ecosystems
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Chemical Environment
1.
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
Dissolved oxygen, organic material
(decaying plants and animals)
Dissolved minerals and pollutants
Temperature/Sunlight
2.


Oxygen dissolves better at certain
temperatures
Temperature is usually greater, the closer
the water to the sunlight
Aquatic Systems continue…
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Water Pressure
3.

Gets higher the lower you go
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4.3 Aquatic Systems Continue
Summer Lake Levels
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4.3 – Aquatic Systems
Seasonal Mixing
This figure shows the change in
populations of 2 populations of
paramecia (single-celled
organisms) placed in 3 different
beakers.
a) compare the growth of
species 1 in Beaker A with the
growth of species 2 in Beaker B
b) What evidence suggests that
the populations of paramecia
affect each other?
c) suggest a conclusion that can
be drawn from the populations
changes
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4.4 LIMITS ON
POPULATIONS AND
COMMUNITIES IN
ECOSYSTEMS
Pages 108-112
Biotic Potential (p108)
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Field mice can reproduce every 6 weeks and can have litters of 6 or
more. A population of 20 mice could become 5120 mice in six
months! What factors prevent a population explosion of mice?
Biotic potential is the maximum number of offspring that a
species could produce if resources are unlimited

Regulated by four factors: birth potential (max #/birth),
capacity for survival (# reach reproductive age), breeding
frequency, and length of reproductive life (age of sexual maturity
and # of fertile years)
You afraid of a few mice?
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http://www.youtube.com/watch?v=zWVw-j8eYSk
Limiting Factors and Carrying capacity
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Recall that limiting factors are factors that restrict
or limit the number and types of organisms able to
survive in a particular environment
Limiting factors prevent populations from obtaining
their biotic potential
The carrying capacity is the maximum number
of individuals that can be supported by an ecosystem
At what level do the deer
reach their CARRYING
CAPACITY?
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
ex. the small black spruce forest at Elk Island (the
bog) can support 20 squirrels
sketch growth curve here!
Factors Affecting Population Change:
Density Dependent vs. density Independent Factors
Density Dependent
factors brought on by pop. size
may limit further growth and /
or reduce pop. #’s
• May cause reduced birth rate
and increased emigration
 Biotic factors
 When populations are small,
density dependent factors do
not limit growth
 Examples include: disease,
parasites, predation,
starvation
•
Density Independent
•
any abiotic factors that will
affect a pop., regardless of
its size
•
Daily and seasonal temp.
extremes
•
Natural disasters,
including drought,
floods, forest fires,
etc.
Competition: 2 Types
- intERspecific competition (between 2 diffERent
species)
- intrAspecific (sAme species competing)
Intraspecific Competition
Interspecific Competition
Tasks to be completed:
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

Read Section 4.4 in your Text – Pages 108-111
Complete the Section 4.4 Questions – Pages 111- 112 –
1-2, 5
4.5 CHANGES IN
ECOSYSTEMS
Collapsed permafrost block of coastal
tundra on Alaska’s Arctic Coast.
Pages 113-122 Nelson
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CHANGES IN ECOSYSTEMS
1.
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
TERRESTRIAL ECOSYSTEMS
Forestry Practices: (Add your own notes such as
pros and cons of each tecnique)
“SLASH & BURN” (P113)

Clear cutting in the Amazon
Clear cutting in patches in
Canada
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“Clear Cutting”
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“PRESCRIBED BURNS” ex. used at Elk Island to create
grasslands for bison
2. AQUATIC ECOSYSTEMS

EUTROPHICATION
of lakes
-oligotrophic to eutrophic (remember Fig 4 p.116)
Classification of lakes by the nutrient input which also
determines the primary producers.
Oligotrophic lake: Nutrient-poor, photosynthesislimited, clear water, O2 rich.
Eutrophic lake: Nutrient-rich, high photosynthesis,
murky water, O2 poor.
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Sketch Lakes here:
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Oligotrophic lake:
Eutrophic lake:
POLLUTION of lakes
-organic solid waste (sewage, food wastes)
-disease organisms (“beaver fever”)
-dissolved minerals (fertilizers)
-thermal energy (decreases O2 levels)
-organic compounds (oil, pesticides)
Lake Wabamum
Power Plant Retires
(demo of stacks):
http://www.youtube.co
m/watch?v=RNpApbh
7Wcw
An aerial image of Lake Wabamun from
August 2005 shows the oil slick that killed
156 birds.
INDICATORS OF WATER QUALITY
BACTERIA COUNTS
-ex. coliform bacteria from
animal waste
-can lead to beach closures!
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DISSOLVED OXYGEN
-more O2 = more diversity of
organisms
-find more O2 in cold, less
polluted lakes

No Beach for you!
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The blue-green algae that bloom in
lakes and waterways produce a
toxin that is harmful to humans —
and this toxin, microcystin, is
present in lakes in every Canadian
province, a new study has found.
Blue-green algae, or
cyanobacteria, can kill fish,
increase the cost of water
treatment and devalue shoreline
BIOLOGIST SANDRA COOK AND LIFEGUARD JULIEN
CLERK-LAMALICE AT O'BRIEN BEACH ON MEACH
properties. The algae also produce
LAKE, CLOSED DUE TO BLUE-GREEN ALGAE.
microcystin, a known potent liver
toxin to humans and mammals that
is classified as a possible human
carcinogen.
http://www.sunnewsnetwork.ca/sunnews/sciencetech/archives/2012/08/20120814093516.html
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pollution increases the natural eutrophication process of water. Why?

Unnatural Eutrophication: a process in which nutrient
runoff from agricultural lands or livestock operations causes
photosynthetic organisms in ponds and lakes to multiply rapidly
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Human-caused eutrophication wiped out fisheries in Lake Erie in the
1950s and 1960s
•FYI - Dr. David Schindler is an ecologist who
worked at the Experimental Lakes Project in
northern Ontario
–He performed
several classic
experiments on
eutrophication that
led to the ban on
phosphates in
detergents
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David Schindler, Killam Memorial professor of ecology at the
University of Alberta, holds a deformed white fish caught in Lake
Athabasca, near Fort Chipewyan, during a Sept. 16 press conference
in Edmonton. (Jason Franson/Canadian Press)
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BIOLOGICAL O2 DEMAND (BOD)
-measures how much O2 is needed by decomposers
-more decomposers = greater BOD = less O2 dissolved
in lake for fish, etc.
Tasks to be completed:
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
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Read Chapter 4.5 in your textbook – Pages 113-121
Make your own notes on:
 Forestry Practices – page 113 – 114
 The effects of fire – page 115
Go through “Selling Water” –page 120-121 #1-5
Complete Section 4.5 Questions – Page 122 – #5
Chapter 4 Review: P130 #1-8
Section 4.3 Questions Page 107 #1-4, 7
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1. The amount of organic matter in an ecosystem can increase through
runoff from soil, surface waters, fertilizer use, release of sewage
emissions, litter from plant material, animal wastes, and die-offs of
plants and/or animals, etc.
2. It is possible to have two ecosystems with identical rainfall and
temperature support different plants. For example, Europe and North
America both have deciduous forest ecosystems with similar
temperatures and rainfall. Both have tall trees, shrubs, ferns etc., but
since they are in different geographic locations, the species of each
plant type might be different.
3. The oxygen concentration in the hypolimnion is high initially due to
spring turnover. The oxygen concentration gradually falls as the oxygen
is consumed by bacteria that decompose dead plant and animal
materials. In extreme situations, oxygen may be completely consumed.
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
4. The lower, cooler layers of water have no source of oxygen
input, so it is gradually consumed. The surface layers receive
more oxygen when wind and waves disturb the surface, allowing
oxygen to dissolve.
7. Trout can exist only in cooler, oxygen-rich waters. They
survive below the thermocline in lakes that stratify and remain
high in oxygen, not in shallower, warmer waters. Catfish are
always found close to the bottom since they are bottom
feeders. They can live in shallow, warm waters and can also
tolerate low oxygen levels. Neither of these situations can
support trout
Section 4.4 Questions – Page 111 #2-3, 5
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2. (a) The carrying capacity is the maximum number of
individuals in a population that the environment can sustain. If
the supply of food in the winter months is a limiting factor
(a factor that limits the carrying capacity), then providing
seeds during winter months would increase the number of cedar
waxwings and artificially raise the carrying capacity.
(b) The increase in the number of falcons may be due to the
banning of DDT. As well, the question suggests that the bird
watchers seeing the falcons are also the people feeding the
waxwings. The falcons are probably also attracted to the bird
feeders, to eat the nice supply of cedar waxwings.
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3. (a) Wolves prey on the moose population. With a declining wolf population, there
will be less predation on the moose. Assuming that the cause of the wolf decline is
not affecting the moose population, you would expect an increase in the moose
population.
(b) The wolf population will probably not decrease to zero because the increased
moose population provides the remaining wolves with a plentiful supply of food.
Assuming that humans are not the cause (hunting, habitat loss, introduction of a
competitor or disease, climate change), you would expect the wolf population to
recover. In a natural population, the size will fluctuate from year to year. There
are many factors that affect population size, availability of prey, water,
availability of mates, competition, disease, forest fire, and available
space/habitat. Prior to Europeans settling in North America, the wolf survived for
thousands (perhaps hundreds of thousands) of years. Eventually, all species go to
extinction, but it is unlikely that the wolf population would go extinct in a few
generations without the influence of humans.
(c) The wolf population will increase again when conditions become favorable—
when whatever conditions caused the decline have changed. For example, if the
cause of the decline was a small moose population that the wolves rely on for
food, then as soon as the moose population increases (due to less predation by
smaller wolf numbers), the wolf population will recover and start increasing in
numbers.
(d) decrease in wolves → increase in moose → decrease in plant material →
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decrease in moose → increase in plant material → increase in moose → increase in
wolves

5. (a) Predator species C is the best controlling agent because it causes
the only steady decline in the population of pine bark beetles.
(b) The eggs of predator species D might be eaten by the pine bark beetle
because the beetle population increases and the predator D population
decreases.
(c) The population of predator species A may be consistently lower than
that of the pine bark beetle because the pine bark beetle somehow has a
negative effect on the predator. Also, since each predator individual
requires many prey individuals to survive, predator populations are usually
smaller than prey populations.
(d) If the population of predator species C exceeds its carrying capacity
in the environment, its population would probably crash, whereas any
surviving pine bark beetles would cause their population to rebound.
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Section 4.5 P122 #4-5
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4. (a) Over time, a lake decreases in depth and fills in with sediment.
(b) Deeper lakes tend to be colder. Since water is most dense at 4 ºC,
in deeper lakes, the water at the bottom would always be at or close to
this temperature. Also, more of the water in a deep lake is in the
profundal zone and receives no heat energy from the Sun to warm it up.
(c) In warmer lakes, there are a greater number and variety of plants
found in the littoral zone.
(d) Cold, deep lakes have populations of trout and salmon in the layers
with higher oxygen levels. Brown trout can tolerate less oxygen and are
found where other species of trout cannot survive. Bass can also
tolerate lower oxygen levels. Carp and catfish are especially tolerant of
low oxygen levels. As the lake eutrophies, the trout and salmon will
disappear first, followed by the brown trout, the bass, and, finally, the
catfish and carp.
(e) Turtles eat the plants that grow in the later stages (but not in the
early stages) of an oligotrophic lake
5. (a) Nitrates and phosphates come from the sewage-treatment plant.
(b) The highest level of eutrophication would be at B, where the
nitrate and phosphate levels are highest.
(c) The BOD increases from A to B because more organisms live at B.
Some are decomposing organic wastes, whereas others are taking
advantage of the increased nutrients. The organisms consume oxygen.
(d) The BOD decreases from B to C because C has fewer nutrients and
the oxygen is consumed mainly by decomposers.
(e) If the sewage treatment plant were doing a good job, the drop in
dissolved oxygen would not be as great.
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