csec biology- ecological studies

ECOLOGY

4 P R E P A R E D B Y : M U H A M A D N A B E E L U D D I N

Biology

Ecology

It is the scientific study of ecosystems

Can you define the following words?

Species

Habitat

Population

Community

Ecosystem : it is a biological community of interacting organisms and their physical environment.

Biosphere is the global sum of all ecosystems.

Ecosystem

Is made up of two components

A. Biotic factors: all the living organisms

Abiotic factors: The physical or non-living part of the ecosystem. Examples of abiotic factors includes:

• Water

• Sunlight

• Soil: structure

• Humidity/moisture

• Atmospheric gases

• Pressure and sound (for marine habitats)

• Can you add to this list?

Abiotic factor- Light

Photosynthesis

Light intensity affects photosynthesis rate

Plants living on forest floor prefer shade, other prefer greater light intensity

Abiotic factors-light

Length of day/night affects flowering and fruiting of plants in seasonal regions of Earth

Abiotic Factors-soil

Importance of Soil Anchorage

Provision of nutrients/minerals

Provision of water

Air to plants and soil organisms

Soil Formation-Weathering of rocks

There are three main methods

Physical: e.g. action of water waves

Chemical: e.g. acid rain

Biological : action of microorganisms or plant roots

Components of soil

Four components of soil

Mineral matter

Organic matter

Water content

Air content

How will the above affect plants and animal lives?

Types of Soil

Clay Loam Sand

Lots of clay, little sand and

little humus

1/2 sand, 1/3 clay and 1/6

load

Lots of sand, little clay and

humus

Many small clay particles Mixture of large and small

particles

Many large particles of sand

Water drains poorly (high

retentivity)

Water drains well Water drains too easily (low

retentivity) so soil is dry

Small air spaces, little air Intermediate size air space Large air space

Heavy to dig Intermediate Light and easy to dig

Can be waterlogged easily Intermediate Minerals are leached out of

soil more quickly

High water holding capacity Intermediate Low water holding capacity

Biotic Factors

Symbiosis- Revision

Symbiosis: is a close and often long-term interaction between two or more different biological species

Three main types:

Mutualism

Commensalism

Parasitism

Mutualism

Mutualism is the way two organisms of different species exist in a relationship in which each individual benefits.

Explain how the organisms benefit from each other

Mutualism

Mutualism: Clown fish and Sea anemones

Sea anemones capture their prey by paralyzing them with discharged cnidoblasts. But Clownfish are not affected

Suggest what the sea anemone gains from this relationship

Image source: http://facstaff.cbu.edu/~seisen/ExamplesOfMutualism.htm

Mutualism in leguminous Plants

Commensalism

In ecology, commensalism is a class of relationship between two organisms where one organism benefits without affecting the other.

Commensalism: leopard shark and remora

Parasitism

Parasitism is a non-mutual symbiotic relationship between species, where one species, the parasite, benefits at the expense of the other, the host.

Ecological Study Techniques

A sample study is done , i.e. a small portion of an area is studied

Why?

It is impossible to count all the number of plants of animals in an area

Precausion

Avoid degrading the habitat/environment

Avoid removing organism from their natural habitat

Ecological Study Techniques

1. Quadrats It is a square metal or wood frame of known area

It is used to estimate the number of species in an ecosystem

E.g. to estimate # of weeds in an area

A sample area is studied, then, the information is used to estimate the number of species in the entire area

E.g. 1m2 Quadrats are thrown 10 times at random in a 300 m2

area. The average per throw is calculated. That number is then multiplied by 300 to estimate the total number in the area

Example showing how the number of weeds in an area can be estimated

Total # =90

Average per throw = 90/10 =9 (density)

Estimated number in 300 m2 = 9 * 300

=2700 species

Quadrat

(Throws)

1 2 3 4 5 6 7 8 9 10

Organisms 10 5 6 7 10 11 10 13 8 10

Quadrats

Square quadrat framefor determining

population densities

Subdivided quadrat frame

for determining % cover of species

Quadrat frames, constructed from wood or metal, are used to investigate the distribution

of species

Ecological study using Quadrat

http://4.bp.blogspot.com/-xSCznJPd_ak/TckwoD5nAQI/AAAAAAAAAIw/24m4xT5wYi0/s1600/quadrat.jpg

Ecological Study Technique

2. Nets Nets are used for sampling small moving animals such as insects.

They can also be used to estimate the number of species in pond.

http://wiki.bugwood.org/uploads/Fig27_bugnet.jpg

Nets

Using sweep nets for ecological studies

Ecological Study Technique

3. Transects Line transects are used in habitats where there is a clear change in

conditions and the distribution of the vegetation or sessile (immobile) animal from one point to another.

E.g. of area that can be studied : river banks and swampy areas

A line transect is one in which all individual organisms touching the tape/string are recorded

Ecological Study Technique

Jars/bottles and pitfall traps Bottles can be used to set pitfall traps, so that they cannot escape

easily

Jars/bottles can be used to study aquatic organisms, e.g. a person may collect a few sample of water from a stream, river, trench, then take the sample to a lab, and then identify microorganism using a microscope, or by culture technique (using agar plates)

Line Transect

http://teacheratsea.wordpress.com/2013/07/31/julia-harvey-determining-population-sizea-day-in-my-life-cruising-july-27-2013/

Pitfall trap

http://www.bbc.co.uk/bitesize/standard/biology/biosphere/investigating_an_ecosystem/revision/3/

Transects

Belt transect involves laying a tape through the area of study and sampling the population with Quadrats positioned at regular intervals alongside the tape

Species Frequency

The percentage frequency of a species is the percentage of sample units (usually Quadrats) in which the species occurs.

E.g. If a species X occurs in 10 out of 25 Quadrats thrown randomly, what is its frequency?

Solution: = 10/25 * 100 = 40 %

Density

Density of a population is the number of organisms in 1m2 found using a quadrat of sides 1m.

Average number of organisms inside the quadrat on ten throws is the density.

Check slide 22

ANY QUESTIONS?

Lab # 20

Aim:

Introduction