1. DP Environmental systems
and societies
Topic 2
The ecosystem

2. 2.2 MEASURING
ABIOTIC COMPONENTS
OF THE SYSTEM

4. Key Abiotic Factors
Marine Freshwater Terrestrial
• salinity • turbidity • light intensity
• pH • pH (insolation)
• temperature • temperature • slope
• dissolved oxygen • dissolved • drainage
• wave action oxygen • soil moisture
• flow velocity • temperature
• particle size
• mineral content
• wind speed

5. Marine
Ecosystems

6. Limiting Factors
• Too much or too little of a
single physical factor can
adversely affect the function
of an organism.
• Limiting factors are physical
or biological necessities
whose presence or absence
in inappropriate amounts
limits the normal action of
the organism.

7. Light is needed for photosynthesis and
vision.
• Blue light penetrates deepest.
• Limited also by particles in the water.

8. Temperature
influences the
metabolic rate,
the rate at which
reactions proceed
within an
organism.

9. • Most marine organisms are
ECTOTHERMIC having an internal
temperature that stays very close
to that of their surroundings.
• A few complex animals (mammals
& birds) are
ENDOTHERMIC, meaning they
maintain a stable internal
temperature.
• Ocean temperature varies in both
depth and latitude.
• Ocean temperatures vary less than
on land.

10. Salinity greatly affect cell membranes and
protein structure.
• Disrupts cells osmotic pressure.
• Varies because of rainfall, evaporation and
runoff from land.

11. Dissolved Gases are necessary for
photosynthesis and respiration.
• CO2 dissolves more easily in
water than O2.
• CO2 is more abundant in deep
waters than surface water.
• O2 decrease dramatically where
light penetration decreases.

13. Zonation in a lake

14. Measuring abiotic (and biotic)
components in the field

18. Transects
• Line transects are used
to illustrate a linear
pattern along which
biotic and abiotic factors
change

19. Biotic factors
Abiotic factors
What is missing from this graph?
Units, labeling…

20. Zonation
Changes in the distribution of animals with
elevation on a typical mountain in Kenya.

21. Change in the relative abundance of a species
over an area or a distance is referred to as an
ecological gradient.

22. Setting up stage quadrats of 100m2 in
the meadow area of the ecological
gradient

23. Setting up group quadrats of 1m2

24. Setting up sampling quadrats of
0.1m2 in the meadow

25. Using the light meter in the forest
group quadrat of 1m2

26. Soil Temperature

27. Taking a soil
sample with a
soil borer
(auger) in the
forest section of
the gradient

28. Results of soil
borer sample,
Chemical analysis
of the soil can be
seen in the
background

29. Testing the meadow area for
pH, phosphates, nitrates and potassium

30. Collecting samples in Ziploc bags
for analysis back in the lab

31. Taking observations in the forest
Notice the absence of plant growth on
the forest floor

32. Chemical testing in the forest

33. Insect sampling with net in the
meadow

34. Setting up 0.1m2 sampling quadrats for
biomass analysis

35. 2.3 MEASURING
BIOTIC COMPONENTS
OF THE SYSTEM

37. Classification Review

38. Life Segmented
Prokaryote
worms
Virus Archaea
Eukaryote Worms
Bacteria Roundworms
Sponges Flatworms
Protist Fungi
Invertebrates Cnidarians
Mold/Mildew
(Fungus like)
Echinoderms
Zygote
Protozoans
(Animal like)
Club Plants Animals Gastropod
Eg. slug/snail
Algae
(Plant like) Sac Bivalve
Mollusks
Vascular Cephalopod
Nonvascular
Eg. moss
Seeds Arthropods
Seedless
(spores)
Eg. ferns Vertebrates
Angiosperms Crustaceans
(flowers)
Reptiles Mammals
Gymnosperms Centipedes &
(just seeds) Monotreme millipedes
Eg. pines Lizards and
snakes (egg laying)
Birds Insects
Marsupials
Turtles
(develop outside)
Amphibians Fishes Spiders
Alligators & Placental Mammal
crocodiles (placental)

39. Classificati
on of
Organisms

40. Dichotomous keys
• Use this key to classify a tree

41. 2.3.2 Abundance of organisms.
Methods for Estimating Population Size
1. Quadrats
2. Capture/Mark/Release/Recapture
(Lincoln Index)

42. • Knowing population size is important in
making environmental decisions that would
affect the population.
• Making a decision on an estimate that is
too high  extinction.
• Making a decision on an estimate that is
too low  unnecessarily hurt people that
depend on the animals for food & income.

43. • When estimating population size it is
important to collect RANDOM SAMPLES.
• A sample is a part of a population, part of
an area or part of some other whole thing,
chosen to illustrate what the whole
population, area or other thing is like.
• In a random sample every individual in a
population has an equal chance of being
selected.

44. Using Quadrats
1. Mark out area to be sampled.
2. Place quadrates (1m2, 10m2) randomly
within the area.
3. Count how many individuals are inside
each of the quadrates.
4. Calculate the mean number of individuals
per quadrate.
5. Pop. Size = mean x total area
area of each quadrat

45. RANDOM SYSTEMATIC
QUDRATS QUDRATS
Quadrat sampling is suitable for plants
that do not move around and are easy to
find.

46. Quadrat method can be used to determine:
 POPULATION DENSITY = number of
individuals of each species per area.
 PERCENTAGE FREQUENCY = percent
of each species found within an area.
 PERCENTAGE COVER = percent of
plant covering a given area.

47. Lincoln index - Capture/Mark/
Release/Recapture
1. Capture as many individuals as possible
in the area occupied by the animal
population, using netting, trapping or
careful searching.
2. Mark each individual, without making
them more visible to predators and
without harming them.

48. 3. Release all the marked individuals and
allow them to settle back into their
habitat.
4. Recapture as many individuals as
possible and count how many are
marked and how many are unmarked.
10 marked
14 unmarked

49. Capture and Marking

50. 5. Calculate the estimated population size
by using the Lincoln Index:
population size = N1 X N2
N3
N1 = number caught and marked initially
N2 = total number caught in 2nd sample
N3 = number of marked individuals
recaptured
Most suitable for animals that
move around and are difficult to find.

51. Assumptions:
1. The population of organisms must be
closed, with no immigration or
emigration.
2. The time between samples must be very
small compared to the life span of the
organism being sampled.
3. The marked organisms must mix
completely with the rest of the
population during the time between the
two samples.
4. Organisms are not hurt or
disadvantaged by being caught and
marked and therefore all organisms
have an equal opportunity of being
recaptured

52. Change in the relative abundance of a
species over an area or a distance is
referred to as an ECOLOGIAL GRADIENT
Also known as Zonation.

53. Changes in the distribution of animals with
elevation on a typical mountain in Kenya. Another
example of Zonation

54. DIVERSITY is a generic term for heterogeneity. If may refer to:
1. Genetic diversity is the total number of
genetic characteristics of a specific
species.
2. Habitat diversity is the diversity of
habitats in a given unit area.
3. Species diversity
a. Species richness – total number of
species.
b. Species evenness – relative
abundance of each species.
c. Species dominance – the most
abundant species.

55. Figure a
and b have
the same
species
richness,
but
different
species
evenness.

56. Simpson’s diversity index
- High value means high diversity
• D is a measure of the diversity
• N = total number of species
• n = total number of individuals
• Range is 0 to 1 (1 the best)

57. How would you interpret this graph?
• Higher species diversity, means better change of
surviving disease?
• Areas of high infection have killed off a lot of species?