Download ECOLOGY, POLLUTION AND ENVIRONMENTAL HEALTH

ECOLOGY, POLLUTION AND
ENVIRONMENTAL HEALTH
CASWELL MAVIMBELA
SMU
Biology Department
Office 022
I couldn’t wait for success, so I went ahead
without it. – Jonathan Winters
Ecology
Our greatest battles are that with our
minds. – Jameson Frank
Part 1: ECOLOGY
Part 2: POLLUTION
Part 3: ENVIRONMENTAL HEALTH
ECOLOGY
Learning outcomes
At the end of this lesson, you should be able to:
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Define term ecology
Understand the historical context of the development of ecology
Be able to synthesize meaning of the definition of ecology from its component
contextual parts
Understand the scope and levels of organisation of ecology
Be familiar with basic fundamental questions characteristic of ecological
investigation
Key concepts: Ecology; biotic; abiotic; habitat; population; community; ecosystem,
biosphere etc.
Introduction to Ecology
• How do you know you are
talking to a real ecologist? They
always answer any question the
same way.
• “Well it depends…”
Ecology is:
• A science of
dependency
• A probabilistic
science
The first ecologists?
Two Founders of Ecology
Ernst Haeckel
Eugene Warming
Definitions of Ecology
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The word ecology was coined by a German zoologist Ernst Haeckel in
1866 derived from two Greek words namely “oikos” = home or house,
and “-ology” = study of.
Haeckel – 1870 – By ecology we mean the body of knowledge concerning
the economy of nature – the investigation of the total relations of the
animal both to its inorganic and organic environment.
Tansley – 1904 – (Ecology is) Those relations of plants, with their
surroundings and with one another, which depend directly upon
differences of habitat among plants.
Elton – 1927 – Ecology is the new name for a very old subject. It simply
means scientific natural history.
• The term evolved, in 1927 Charles Elton described it as the study of
animals and plants in relation to their habits and habitats. Shortfalls
(fungi, protists, bacteria have their own kingdoms which are of equal
importance)
Definitions of Ecology cont’d
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Andrewartha – 1961 – Ecology is the scientific study of the distribution and
abundance of organisms.
Krebs – 1972, 2008 – Ecology is the scientific study of the interactions that
determine the distribution and abundance of organisms.
Ecologist study the patterns of distribution and abundance of organism in
nature and how these patterns are maintained in the short run, and how they
change during the course of evolution (Arms and Camp 1987)
Ecology is a branch of biology that examines the interactions of organisms
with their environments
Townsend et al. 2003 – Ecology is the scientific study of the distribution and
abundance of organisms and the interactions that determine distribution and
abundance.
Ecology, is defined by Begon et al (2006) as; the scientific study of the
distribution and abundance of life and the interactions between organisms
and their natural environment.
Some Definitions of Terms
• environment - biotic and abiotic factors that
influence organisms
• organism - individual living thing
• population - many individuals of one species living
close enough to each other to potentially
interbreed
• community - all interacting populations in a
particular habitat - includes plants, animals,
decomposer microbes - pond or forest
community - in practice often used when 2 or
more species discussed
Some Definitions of Terms
• habitat - place where microbe, plant or animal
lives
• ecosystem - community plus abiotic factors nutrients, water, soil, etc. - pond ecosystem
• biosphere - the earth
• autecology - relation of individual organism to
environment
• synecology - relation of populations or species to
other populations or species
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Intro. Continues
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The natural environment of an organisms includes its physical properties or factors, which
can be described as the sum of local abiotic, chemical and biotic factors
Abiotic factors (e.g. sunlight, temperature, water and soil)
Chemical factors (e.g. composition of air, soil, and substances dissolved in water)
Biotic factors (e.g. other living organisms sharing a habitat)
Levels of ecological organisation (LEO)
Hierarchical
system
Biosphere
Ecosystem
Community
Population
Habitat
Individual
2.1 Individual level
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Ecology can be studied at a wide range of levels from a small scale to large one
(Mader, 1998).
Individual level = lowest scale
Ecologist studies how an individual organism is adapted to its immediate
environment
Example 1: new born ungulate calf learn how to walk in few minutes, adapt
(outrun predators) or die (fall to prey/sausage)
Example 2: famous peppered moths observational study; behavioural ecology etc.
2.2 Habitat level
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A habitat in this case refers to a place where an organism lives (Arms and Camp 1987)
and reproduces in its environment.
Each species/individual occupies a particular position in the community = habitat
Spatial (where it resides) and functional sense (what role it plays)
What are the practical examples of a habitat? Forest floor, ocean edge or streams etc.
Every habitat is unique, characterised by particular ranges of temperatures, humidity,
soil, vegetation structure, food type, competitors, predators and other factors that
make up the organisms environment (Mader, 1998)
The functional sense (the role an organisms plays) brings about the concept of
ecological niche of an organism
Ecological niche of an organism is the role the organism plays in its community including
its habitat and its interactions with other organisms, includes the resources an organism
uses to meet its energy and nutrients requirements and survival demands
Niche is affected by both abiotic (climate and habitat) and biotic factors (competitors,
parasites, predators)
2.3 Population level
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A population is defined by Mader (1998) as the existence of all organisms of the
same species within a specified area.
An emphasis is based on the factors that affect growth and regulation of
population size.
Ecology = studies factors affecting growth + regulations of populations size and
distribution of organisms (where & why in a particular place at a particular time)
2.3.1 Characteristics of Populations
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At any one point in time, populations have a certain size
So, population size is defined as the number of individuals contributing to the
population’s gene pool
2.3.1.1 Factors affecting the size of a population
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Population depends upon a balance between natality (births), mortality (deaths),
emigration (movement of individuals out of a defined population) and immigration
(movement of individuals into a defined population).
Look at the diagrammatic representation of factors influencing population size,
increase in pop size (natality, immigration), decrease in pop size (mortality,
emigration)
Life either add individuals or removes them (quite gross but a fact) for balance
Change in Population size = (Natality + Immigration) – (Mortality + Emigration)
The Fundamental Equation of
Ecology – Harper 1977
ΔN=B–D+I–E
Change in Number =
Births – Deaths +
Immigration Emigration
John L. Harper – 1925-2009
A graph showing exponential population growth
2.3.2 Species interaction
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Species interact in different ways, and may have impact in the relative distribution
and abundance
Member of two different populations may interact in a symbiotic relationship
There are three forms of symbiotic relationship that may exist: parasitism,
commensalism and mutualism
Parasitism: similar to predation in that an organism called a parasite derives
nourishment from another called host just as predators derived nourishment from
their prey e.g. viruses (HIV), protists (malaria), bacteria (Streptococcus sp.) etc.
Commensalism: is a symbiotic relationship where one species is benefiting and the
other is neither benefiting or harmed e.g. provision of home, transportation,
protection etc.
Mutualism: both species benefit from the relationship e.g. bacteria that reside in
the human gastro-intestinal tract are provided with food and they in turn provide
us with vitamins
2.4 Community level
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Populations do not occur in isolation, they form part of a community
A biological community is define by Mader (1998) as an assemblage of populations
interacting with one another within the same environment. What are the
examples of a community within the campus?
2.4.1 Characteristics of a community
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A community is characterised by four elements i.e. size, boundary, diversity and
abundance
Communities differ from each other in terms of size
No two communities can have the same size
Community does not remain the same through out its existence
It fluctuates in size and composition with time
It is sometimes difficult to have clear delineating boundaries between different
communities
Composition of a community refers to the listing of the various species in that
community
Diversity includes two elements i.e. the number of species and the relative
abundance of individuals of different species
2.4.2 Factors maintaining composition and diversity of species
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“it goes without saying that species in a community may change both in time and
space which can affect the number of species and their abundance”
Some of these factors include competition (C) and predation (P)
C & P particularly by dominant species over others may lead to their possible
extinction or removal from the community
Competition: species utilize same food source and exist no specialization between
species
Predation by dominant and efficient species may monopolise all available prey and
also by preventing one prey species from eliminating other through competition
(phenomenon not always the case)
What maintains species diversity and prevents one or more species in a trophic
level from eliminating the other through competition? 1. when species are in
potential competition for a food supply, the resource may be subdivided in some
way, e.g. specialization. Different species may feed on a particular range within the
community or even during different times. Variety of habitats in a community
characterised by its own diversity may attract different species
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Another cause of diversity may be the creation of different habitats within a region
by periodic disturbance
A community that forms if the land is undisturbed and that perpetuates itself for
as long as no disturbance arises is called the climax community. When this climax
community is disturbed – either by natural forces or man-made activities such as
floods and fires or removal and overexploitation respectively, it begins the process
of returning to its original state by a process known as ecological succession that
produces a climax community again.
There exist two types of ecological succession: primary and secondary succession
Primary succession takes place in a barren or lifeless land with limited soil or no
soil at all (very slow process)
Secondary succession is the series of community changes that takes place in
disturbed areas that have not been totally stripped off their soil. It is the most
widely occurring phenomenon than primary. It is important to note that ecological
succession is a process that takes place over relatively long periods with secondary
succession being the least with about a few years to a hundred (Arms & Camp, 87)
The third cause of diversity of species within communities lies with the climate.
2.5 Ecosystem level
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An ecosystem consists of a community (group of living organisms) and
the physical environment (Starr & Taggart 1989) and chemical
environment (Mader 1998) in which they live.
The living organisms are the biotic components of the ecosystem while the
physical and chemical environment forms the abiotic components.
In an ecosystem, living things are classified b the ways in which they
source out their food; autotrophs and heterotrophs each occupying its
own trophic level.
In an ecosystem, organisms interact with each other and the environment.
According to Starr and Taggart (1989) this interaction is characterized by 1)
the flow of energy, and 2) a cycling of materials both of which have a
consequences for community structure and the environment.
2.5.1 Basic components of an ecosystem
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Components of an ecosystem can be subdivided into the biotic (includes all living
organisms) and abiotic components (includes water, carbon dioxide, various
minerals, oxygen and continuous supply of energy from the sun).
2.5.1.1 Biotic components of an ecosystem
Autotrophs produce their own food or organic nutrients for themselves and others;
therefore they are regarded as primary producers. These autotrophs can further be
broken down into chemoautotrophs (includes bacteria that obtain energy by oxidising
inorganic compounds such as nitrite, ammonia and sulphides to synthesize
carbohydrates) and photoautotrophs (photosynthesizers which uses energy from the
sun, water and atmospheric carbon dioxide to produce carbohydrates, proteins and
nucleic acids and so forth).
Heterotrophs are consumers of the preformed organic nutrients. They are classified
into herbivores (animals that graze directly of plants), carnivores (feed on other
animals), omnivores (animals that feed on both plants & animals) and detrivores
(organisms that feeds on detritus – decomposing particles of organic matter).
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Note: within detrivores are decomposers which break down dead organic matter
into simple inorganic substances that are released back into the ecosystem and
can be taken up again by producers.
2.5.1.2 Abiotic components of an ecosystem
• Autotrophs synthesize organic nutrients from available inorganic nutrients (carbon
oxide, water and solar energy) through photosynthesis.
• Energy from the sun is converted into a useful form by autotrophs for
heterotrophs
• This phenomenon resonates well with the laws of thermodynamics (first law) in
that energy cannot be created or destroyed (support idea that ecosystem is not
self-sustaining i.e. relies in continuous source of energy).
• Second law states that with every transformation of energy from one level to
another, some energy is degraded or lost between such levels as heat.
• Energy produced by plants (gross productivity) is used to satisfy cellular their
needs and is thus lost as heat. The remaining energy (net productivity) becomes
available for heterotrophs to use and in most cases it is reduced to about 55%.
• Secondary and tertiary consumer will use this energy for cellular respiration (which
is subsequently lost as heat) and increased body weight. The latter use of energy is
called secondary productivity.
2.5.2 Structure of ecosystems
Ecosystem structure continues…
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A pyramid of numbers tells how many organisms there are in each trophic level.
The number of primary producers ought to be high in order to support organisms
at the subsequent trophic level because not all of the food eaten is useful. Energy
efficiency drops as the trophic level ascend. The number of organism occupying
the highest trophic level ought to be few so they can benefit from the availble
energy.
A pyramid of biomass shows relationship between biomass and trophic level by
quantifying the amount of biomass present at each trophic level. Typical units for a
biomass could be grams per m2, or calories per m2. Biomass pyramids provide a
single snapshot in time of an ecological community.
The pyramid of energy also called the pyramid of productivity is one such useful
pyramid in ecology. It shows production or turnover of biomass at each trophic
level. Instead of showing a single snapshot in time, productivity pyramid show the
flow of energy through the food chain. 10% rule in ecological pyramids of energy
and biomass.
2.5.3 Biogeochemical Cycles
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Biogeochemical cycles or nutrient cycles are pathways by which chemical elements
or molecule moves through both biotic (biosphere) and abiotic (lithosphere,
atmosphere and hydrosphere) components of Earth. In effect, the elements are
recycled, although in some cycles there may be places (called reservoirs) where
the elements are accumulated or held for a long period of time. Elements,
chemical compounds, and other forms of matter are passed from one organism to
another and from one part of the biosphere to another through the
biogeochemical cycles.
There are many biogeochemical cycles but he most well-known and important
cycles includes the carbon cycle, the nitrogen cycle, the oxygen cycle, the
phosphorus cycle, and the water cycle.
2.5.3.1 Biogeochemical Cycles
Water
Nitrogen
Carbon Dioxide
Phosphorus
Sulfur
What are biogeochemical cycles?
• Earth system has four parts
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Atmosphere
Hydrosphere
Lithosphere
Biosphere
• Biogeochemical cycles: The chemical
interactions (cycles) that exist between the
atmosphere, hydrosphere, lithosphere, and
biosphere.
• Abiotic (physio-chemical) and biotic
processes drive these cycles
• Focus on carbon and water cycles (but could
include all necessary elements for life). N cycle weakly touched on!
What is common amongst them?
• Each compound (water, carbon, nitrogen)
typically exists in all four parts of the Earth
System
• There are
– ‘Pools’
– Fluxes in and out of pools
– Chemical or biochemical transformations
• Transformations
– are important
– can lead to positive & negative consequences
Transformations
Examples of Transformations
1. Carbon cycle: Organic compounds to CO2
(processes: respiration, decomposition, or fire)
2. Carbon cycle: CO2 to organic compounds (process:
photosynthesis)
3. Nitrogen cycle: N2 to NO3 (atmospheric nitrogen to
plant utilizable nitrate) (process: N-fixation)
4. Nitrogen cycle: N2 to NH3 (plant utilizable ammonia)
(process: Haber-Bosch Industrial N-fixation)
5. Water cycle: Liquid water to water vapor (process:
evaporation and evapo-transpiration)
6. Water cycle: Water vapor to liquid water (process:
condensation)
Biogeochemical Cycle :
• chemical elements are required by life from the living
and nonliving parts of the environment.
• These elements cycle in either a gas cycle or a
sedimentary cycle
• In a gas cycle elements move through the
atmosphere.
• Main reservoirs are the atmosphere and the ocean.
• Sedimentary cycle elements move from land to water
to sediment.
Carbon Cycle
• What are the
2 main processes
in the carbon
cycle?
Carbon Cycle
• Carbon (C) enters the biosphere during
photosynthesis:
• CO2 + H2O (carbon dioxide+ water)--->
C6H12O6 + O2 + H2O(sugar+oxygen+water)
• Carbon is returned to the biosphere in cellular
respiration:
• O2 +H2O + C6H12O6 ---> CO2 +H2O + energy
Carbon Facts
• Every year there is a measurable difference in the
concentration of atmospheric CO2 with changes in
the seasons.
– For example, in winter there is almost no
photosynthesis ( higher CO2 )
– During the growing season there is a
measurable difference in the
concentration of atmospheric CO2 over
parts of each day.
Nitrogen cycle
Nitrogen Facts
• Nitrogen (N) is an essential constituent of
protein, DNA, RNA, and chlorophyll.
• Nitrogen is the most abundant gas in the
atmosphere.
• Nitrogen must be fixed or converted into a
usable form.
Oxygen Cycle (Photosynthesis)
Sources of Oxygen:
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Photosynthesis and respiration
Photo disassociation of H2O vapor
CO2 and circulates freely throughout the biosphere.
Some combines with Ca to form carbonates.
Some combines with nitrogen compounds to form nitrates.
Some combines with iron compounds to form ferric oxides.
Some in the troposphere is reduced to O3 (ozone).
Ground level is a pollutant which damages lungs.
Phosphorus
(P) Cycle
Phosphorus (P) Cycle
Component of DNA, RNA, ATP, proteins and enzymes
- Cycles in a sedimentary cycle
- A good example of how a mineral element becomes part of an organism.
- The source of Phosphorus (P) is rock.
- Phosphorus is released into the cycle through erosion or mining.
- Phosphorus is soluble in H2O as phosphate (PO4)
-Phosphorus is taken up by plant roots, then travels through food chains.
- It is returned to sediment
Sulfur (s) Cycle
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Component of protein
Cycles in both a gas and sedimentary cycle.
The source of Sulfur is the lithosphere (earth's crust)
Sulfur (S) enters the atmosphere as hydrogen
sulfide (H2S) during fossil fuel combustion, volcanic
eruptions, gas exchange at ocean surfaces, and decomposition.
• SO2 and water vapor makes H2SO4 ( a weak sulfuric acid),
which is then carried to Earth in rainfall.
• Sulfur in soluble form is taken up by plant roots and
incorporated into amino acids such as cysteine. It then travels through the
food chain and is eventually released through decomposition.
Summary
• The building blocks of life :Water ,Nitrogen, Carbon
Dioxide, Phosphorus, Sulfur
• Continually cycle through Earth's systems, the
atmosphere, hydrosphere, biosphere, and
lithosphere, on time scales that range from a few
days to millions of years.
• These cycles are called biogeochemical cycles,
because they include a variety of biological,
geological, and chemical processes.