ECOLOGY

Ecology: the study of the interrelationship between organisms and their environment

Environment: the combination of external factors that surround and act on an organism

• there are two types of factors: biotic and abiotic

◦ biotic factors: living organisms in the environment that surround and impact an organism

‣ e.g trees, animals, plants

◦ abiotic factors: nonliving things in the environment that surround and impact an organism

‣ climatic(light, temperature, rainfall), edaphic (soil- texture, temperature,PH),aquatic factors (salinity, wave action, oxygen)

Habitat: the area in which an organism resides

Species: a group of organisms with common ancestry and characteristics that can reproduce to produce fertile offspring

Population: all of the same organism (species) living in a specific habitat

Community: all of the different species living in a specific habitat

ecosystem: the relationship between an organism and the abiotic factors of the environment

niche: an organisms role in a habitat

ECOLOGICAL STUDIES

These studies are carried out for numerous reasons:

• to find out the type of species in a habitat

• to find out the number/distribution of species in a habitat

• to determine the interrelationship between these species

HOW TO CONDUCT AN ECOLOGICAL STUDY

1. Collect Organisms

Organisms need to be collected before any data can be obtained. This can be done in many ways:

• Nets: butterfly and plankton nets can be used to catch organisms in the sea or above ground

• pooters: a jar with two straws, one covered with a protective mesh covering. a human sucks on one straw and this creates suction pressure in the other straw, great for capturing crawling animals

• Pitfall trap: a jar placed in the ground, with the top camouflaged so that crawling animals fall in

• tullgren funnel: a funnel with a lightbulb at the top and soil in the middle, a layer of mesh allows organisms, which crawl downwards to get away from the light, to fall through the soil and into the collecting jar

• capture/recapture method: organisms are captured, marked and released back into the environment where they can rejoin the ecosystem. a second batch of organisms are captured, and the amount of marked and unmarked organisms are noted

SAMPLING TECHNIQUES

1. Quadrats

A square whose area is known is used, and is thrown out randomly across the habitat. The number of species within each division of the quadrat is counted and the species population and density can be calculated. The percentage of area the species cover can also be estimated.

• this method is used for plants and sedentary organisms, a different method needs to be used for moving organisms

2. Line Transects

These lines are spread across a habitat, with markings regular intervals. The type of species are noted at each interval. This type of sampling is good for long stretches of habitats where the organism type experiences a gradual change across the ecosystem

3. Belt Transect

These are formed by the use of two parallel line transects of a known width. The organisms at each marking are counted.

• Often used with quadrats

POPULATION SIZES

Population sizes can be determined by the following quantities:

1. Population density: the number of organisms of a species present per metre square

• if multiple squares were used, it can be calculated by dividing the total number of organisms by the total number of quadrants they were found in

2. Total species number: the total number of organisms of a species found within a habitat

3. Species cover: the total estimated amount of area covered by a specific organism, found using a quadrat.

• if multiple squares were used, add the percentage of coverage of each square and divide by the total number of squares

4. Species frequency: the total number of quadrats that the organisms have been found in

If using the capture/recapture method, to find the population size simply multiply the number of organisms captured the first time by the number of organisms captured the second time, and divide that by the number of marked organisms captured the second time.

estimated population sise = 1st captured x 2nd captured

number of marked 2nd captured

Impact of abiotic factors on organisms

There are three types/categories that abiotic factors can be divided into:

1. Edaphic factors (soil related)

2. Climatic factors

3. Aquatic factors

Equatic factors

There are many factors of soil that can determine what organisms are living in them.

1. Texture/Size of Particles

there are four main sizes of particles, from largest to smallest they are:

• gravel

• Sand

• Silt

• clay

The size of these particles affect many things:

1. The water concentration: the smaller the particle size, the more water’s cohesive ability comes into play and the more water is retained in the soil. Conversely, soils with large particles dry out quicker.

2. The ventilation/air conecntration: the larger the particle size of the soil, the more oxygen, carbon dioxide and other gases are able to move freely in and out of the organisms that reside in it. This is the opposite for smaller sized particles.

2. Water

There is also water, which:

1. Is a raw material for plants in photosynthesis

2. Helps to dissolve mineral ions in to forms that can be used by plants

3. Prevents the dessication of organisms, especially those without waterproof exoskeletons.

3. Air

1. Has carbon dioxide, which is needed for photosynthesis

2. Has oxygen for respiration

3. Has nitrogen which is useful for plants in producing chlorophyll

4. Necessary for the breakdown of dead and decaying matter by saphrophytes

4. Mineral nutrients

1. Exist in a particular format, help plants with growth and homeostasis.

5. PH

1. The pH of the soil is usually at 6.0-7.5 because that’s where the plant roots arent too alkaline or acidic, which would prevent mineral absoprtion

6. Humus

1. The air concentration increases the amount of humus, which is a brown, sticky substance that is produced by saprophytes (e.g. fungi and bacteria) when they aerobically break down dead and decaying organisms into smaller components.

• This is because the air has oxygen, which is necessary for the saphrophytes to do their job.

• Humus has a lot of beneficial properties: it clumps up soil to increase air flow, and retains water and adds other mineral compounds that the saphrophytes release during their decomposing process

Climactic factors

1. Light

Light is a stimuli that affects the rate of photosynthesis of the plant, and it also controls the activity of all organisms in accordance with the seasons: e.g. flowers blooming in spring, leaves falling off in autumn, migration

2. Temperature

Temperature also affects the rate of photosynthesis and growth. It also affects the activity of animals (e.g. some animals hibernate in low temperatures)

3 Humidity

Humidity affects the rate of transpiration in plants. It also ensures that organisms have enough water to prevent desiccation.

4. Wind

Wind is essential in sexual reproduction, dispersal of seeds and the rate of transpiration in plants/animals and it also influences migration patterns in animals such as birds.

5. Water availibility

The amount of water in an organism is also essential. Plants need water for photosynthesis, and all organisms need water for metabolic reactions, and water also acts as a solvent.

6. Atmospheric Gases

Oxygen and carbon dioxide are responsible for respiration and photosynthesis respectively

Aquatic factors

1. Salinity

The concentration of salt in water, some organisms prefer fresh water, and some prefer marine/salt water.

• organisms can only survive at a specific salinity of water

2. Water movement/wave action

Organisms along river banks and in the sea have to be adpated to strong waves/currents

3. Dissolved oxygen

Underwater organisms obtain oxygen from dissolved oxygen in the water

Food chains

Every food chain includes:

primary producer: a green plant

Primary consumer: eats the primary producer

Secondary consumer: eats the primary consumers

Tertiary consumer: eats the secondary consumers

Some foods include a quaternary consumer, but no more than that.

Each level of feeding within a food cahin is called a trophic level.

Consumers can be divided into three types of groups.

1. Herbivores: consume plants (cows, grasshopers, snails, slugs, sea urchins)

2. Carnivores: consume other organisms (lizards, toads, spiders, centipedes, lions)

3. Omnivores: consume plants and other organisms (crickets, humans)

Predator/prey relationships

Predators: oragnisms that feed on other organisms

Prey: the organism that which a prey feeds on

Most predators are prey themselves, and most prey are predators. There are some exceptions, like the

apex predator: the predator at the top of the food chain, is not hunted by any other organism

• lion, haws, owls, tiger sharks

Predatory/prey relationships have two benefits: maintaining the population of an ecosystem and also getting rid of pests

Predators and prey evolve together. Predators evolve to catch their prey: speed, agility, hearing, poison, sharp claws, etc. But, prey also adapt to get away from predators: speed, agility, hearing, camouflage abilities, etc.

biological control: in an area that is overrun by unwanted organisms, predators of that oragnism can be introduced to that area to get rid of them— e.g. introducing lizards to get rid of grasshoppers

food webs: group of interlinked food chains

Decomposers/detrivitores

These are vital to the environment, as they promote the recycling of chemical elements in ecosystems.

Detrivitores: animals that pray on decomposing pieces of matter, breaking it down into smaller pieces.

• earthworms, milipedes, sea cucumbers

Decomposers: micro-organisms that prey on dead and decaying matter. They secrete digestive enzymes to break down the matter, while at the same time secreting compounds like carbon and nitrogen back into the soil (in the fomr of ions). These can be re-used by plants.

• e.g. bacteria, fungi

Symbiotic relationships

The close relationship between two organisms of different species in an ecosystem. There are three types.

Parasitism:

This is a symbiotic relationship where only one organism gains from the relationship. They feed off of another organism, called a host- usually through a vector or intermediate host

• e.g. tapeworms feed in human digestive systems, with pigs as intermediate hosts

• Ticks feed on cows

• Plasmodium bacteria in maleria feeds on blood cells in the liver, vector being the anopheles mosquito

Commensalism

A symbiotic relationship in which one organism gains something, but the other gains nothing and is unharmed.

• e.g. epiphytes: plants that are non parasitic that grow on high trees to absorb the maximum amount of sunlight possible

• Cattle egretes: live on cows, eat the ticks off of them and any other insect they come across

• Remoras: live on the backs of sharks, eat leftover food

Mutualism:

A symbiotic relationship in which both organisms benefit from the exchange. They probably cannot live without each other.

• e.g. leguminious plants have root nodules which are nitrogen fixing nodules, they convert the nitrogen in the air to nitrate which the plant can use to make food and for survival. The root nodule in exchange gets food and protection

• Coral phalyps have algae in their digestive system, so that the algae can give off oxygen in the photosynthesis process for respiration, and the coral can give off carbon dioxide for the algae’s photosynthesis

There are other relationships between organisms:

1. Camouflage (animals disguising as one another)

2. Pollination (bees depending on insects)

3. Support (birds using trees to build nests)

4. Protection (using the environment to protect them; grasshoppers living in long grass)

5. Competiton (foghting for food, space, mates, shelter, one species always prevails)

Energy flow in ecosystems

When an organism obtains or makes food, they always lose some of the food (in this case, termed biomass - biological mass) and energy in different processes. These may include:

• respiration (loss of carbon dioxide/heat)

• faeces

• waste from metabollic processes (urea)

Since biomass and energy are being lost by each organism at each trophic level, that means that there is even less organic material for each organism to obtain when they eat another organism.

• only 10% of organic compound material actually makes it to the next organism

This is why food chains usually don’t have more than five trophic levels, because affter that the organic compound concentration is practically inconsequential.

When these organisms at the end of the food chain aren’t consumed, they die. And then decomposers do their job and release the organic compounds back into the soil, restarting and keeping the energy flow going.

• can also be represented by ecological pyraminds

Recycling of nature’s materials

Water

• water is recycled for photosynthesis and transpiration

• Ensure the hydration of cells of all living organisms

• Provides an environment for aquatic organisms

Carbon

• there is a carbon cycle, carbon is constantly being produced in different forms from different organisms

• Sustains photosyntheis

• Main component in organic food for animals

The carbon cycle

Nitrogen

1. waste of animals/plants creates urea

2. bacteria convert urea to ammonium

3. nitrifying bacteria turns ammonium into nitrite then nitrates

4. denitrifying bacteria turns nitrates into nitrogen

5. nitrogen used in fertilizers and atmosphere, absorbed into animals and plants

6. nitrogen fixing bacteria turn nitrogen to ammonia

7. Repeat

• important for nutrient composition in roots

• Provides proteins for animals and decomposers

Recycling of waste materials

biodegradable materials: can be decomposed by living organisms (bacteria and fungi) (e..g food, farmyard, garden waste, paper, bagasse)

non biodegradable materials: cannot be decomposed by living organisms (e.g. plastics, metals- lead, iron, copper)

IMPORTANCE OF RECYCLING

• Conserves natural resources

• Reduces energy consumption

• Reduces pollution

• Reduces need for disposal of actual garbage

• Prevents wasting useful materials

CHALLENGES OF RECYCLING

• hard to convince people to separate their trash

• Hard to transport collect and store said trash

• Time consuming and dangerous to clean the trash (e.g. lead batteries) before recycling

• Some countries in the caribbean would be impacted negatively economic wise by using these recycled materials

The impact of humans on the environment

Humans have impacted the environment severely. They have made it so that nonrenewable products (such as fuels - like fossil fuels, oil and petroleum as well as minerals - such as bauxites, iron and coal) and renewable products such as trees, plants and animals are on the decline.

The decline of renewable products can mainly be accounted for by:

• Overfishing (whales, turtles, and sea eggs)

• Over mining (aluminiun, bauxite)

• Overhunting (elephants, minks)

• Deforestation

EFFECTS OF DEFORESTATION

• loss of habitats

• Loss of plant and animal life

• Less photosynthesis, increase in carbon levels in air, contributin gto global warming

• Affects the water cycle

• Soil erosion

-> soil erosion results in less trees plants, and agricultural crops being planted

Negative impact of human activity on environment

Humans destroy the environment in many ways, but the most apparent ways are:

• The loss of habitats and organisms living in them

• The release of waste and harmful substances into the natural environment, which is known as pollution

Pollution: the contamination of the natural environment with the release of harmful substances

Pollution caused by argicultural practices

1. Pesticides (insecticides, fungicides, and herbicides): harm organisms that they weren’t intended to harm

2. Nitrate and phosphate ions: they are present in chemical fertilisers, which when deposited into a water body, cause the eutrophication of the water body. this entails the excess growth of green algae on the top of the water body, which absorbs oxygen. the plants under the sea are left with little oxygen, which kills them. Saphrophytic organisms to break them down, which also requires oxygen resulting in lower, unlivable oxygen levels.

3. Carbon dioxide: produced by the burning of fossil fuels and it is responsible for greenhouse effect which leads to gloval warming. Also is absorbed by the ocean which contributes the ocean acidification.

4. Carbon monoxide: also produced by the burning of fossil fuels and binds the haemoglobin in the blood more than the oxygen we inhale. This results in respiratory issues and energy level issues in humans, leading to dizziness, headaches, and even unconsciousness and death.

5. Sulphur dioxide: also produced by the burning of fossil fuels, and is responsible for the production of acid rain- this decreases the pH of the soil, damages plants, animals, and corrode buildings. It also produces smog- this smog can cause a plethora of respiratory illnesses.

6. Oxides of nitrogen: produced by motor vehicles and power stations, they are very toxic and also produce acid rain

7. Carbon particles(smoke): also calls from burning fossil fuels in the industry as well as cigarette smoke, produces smog which blackens buildings and covers leaves which reduces photosynthesis.

8. Dust and other particulate matter: mainly produced by mining and cause respiratory illnesses and coat leaves, which prevents photosynthesis

9. Heavy metal ions (iron, lead, calcium) produce from extracting and purifying metals, as well as burning fossil fuels, they are toxic organisms and can damage body tissues and organs.

Pollution caused by Improper disposal of garbage

• toxic chemicals from the garbage may pollute the surrounding soil and the water water

• Greenhouse gases are produced, especially during the burning of this garbage

• Hydrogen sulphide, which is very toxic is released into the air

• Plastics may leak into surrounding waterbodies, negatively affecting aquatic organisms

• Bacteria may leak into sewage causing a plethora of diseases - e.g cholera.

• It is unsightly damaging eco-tourism in countries

• Attract rodents, which spread diseases

Pollution of wetland/marine ecosystems

Wetland ecosystem: an ecosystem where land needs water, usually the water covers the land all year round (e.g mangrove ecosystems)

Marine ecosystems: that are under the sea, containing dissolved, salty, compounds

Polluting these ecosystems results in:

• A loss of biodiversity

• A loss of habitats and the organisms that live in them

• Protection from floods

• Protection from soil erosion

• Natural resources that come from these ecosystems

• Nursery grounds, which young and developing organisms. This may result in the extinction of the organ

• Nesting and breeding grounds for other organisms

Greenhouse effect and global warming

Carbon dioxide, water vapour, dinitrogen monoxide, methane, and other gases form a layer around the Earth, that traps heat in the form of radiation from the sun, resulting in the warming of the earth. This is known as the greenhouse effect.

This causes:

• A rise sea level (melting ice caps)

• Unpredictable weather patterns

• Severe weather patterns

• Flooding of low lying areas

• Changes in ecosystems (immigration, emigration)

• Certain diseases become more widespread

Conservation and restoration of the environment

The environment can be conserved by:

• using renewable sources, instead of nonrenewable sources

• Ensuring that waste is properly disposed of (if waste can be used as compost use it)

• Recycling substances that can be recycled (e.g. glass)

• Putting laws and legislations in place that limits how much people can take from the environment, whether it be hunting animals, or deforestation

• Creating national parks and exhibitions that protect the countries, natural flora and Fauna)

• Implement animal breeding programs to revitalise nearly extinct species

• Re-use, reduce, recycle!

Other methods pollution:

• educational measures can be put in placed educate people of the issue

• Monitoring programs can be implemented to keep an eye on ecosystems

• International laws can be agreed upon by countries to prevent this pollution

To reduce pollution:

• Dispose of waste using appropriate methods that are harmless

• Using alternative energy sources, such as carpooling or walking

Using natural biodegradable pesticides

• Avoid fossil fuils

• Treat all sewage in sewage plants and dump the water back into the ocean and use the sludge as fertiliser

• Call Eton bicycle auto recyclable waste

• Use use aerosol and refrigerant that do not contain chlorofluorocarbons

• Ensure gas emissions are cleaned before they enter the environment

Human populations

There are four main factors that affect the growth of a population: the birth rate, the death rate, the rate at which organisms move into the population, and the rate at which organisms move out of the population.

• growth measured using a sigmoid curve

When organisms first colonise an area, the birth rate is higher than the death rate, resulting in the increasing size of the population. However, eventually the birth rate and the death rate become even resulting in the area, reaching its carry capacity- the maximum number of organisms it can hold before the population is limited.

The population can be limited by:

• food

• Overcrowding

• Looking for mates

• Predators

• Diseases begin to emerge

The population can be reduced by:

• natural disasters

• Invasive species

• Pests

Right now, humans are still in a period of exponential growth. This is because:

• Humans have advanced in modern medicine

• Humans have adapted better housing, cleaner water supplies and sanitation

• Humans have a better agricultural understanding

• Humans have a better nutritional understanding