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8.1 How do our actions impact the environment?
8.1 How do our actions impact the environment?
What are the resources provided by the earth?
Why is it important to conserve our natural environment?
How do the human activities affect the interactions within and between natural systems?
How do we conserve and be a responsible individual who exhibits care and concern for the prudent use of Earth’s resources?
[ Textbook 2A pg 84 - 87]
8.1.1 How does the environment influence the survival of organisms?
8.1.1 How does the environment influence the survival of organisms?
There is growing concern that parts of the Amazon rainforest will turn into grassland because of drought, fires and deforestation. PHOTO: REUTERS
The world's largest palm oil trader is still linked to deforestation in Indonesia despite committing five years ago to stop logging the archipelago's vast tracts of jungle - Greenpeace.
Globally, forests help fight climate change by soaking up large amounts of carbon dioxide (CO2) emissions.
But research published on Wednesday (July 13) shows that climate change is weakening the ability of large areas of forests around the world to recover from impacts such as water stress, wilder swings in the weather and other disturbances, suggesting that the climate change-fighting powers forests have are being diminished and that forest conservation and management plans might need a rethink...
Forests, which cover a third of the planet's land surface area, soak up about a third of humanity's CO2 emissions, mainly from burning fossil fuels.
They also provide ecosystem services that benefit people, such as regulating water flows, soil conservation, and materials such as medicines and timber. They also help regulate the weather and local temperatures.
Whatever happened to acid rain? - Joseph Goffman
Discover what causes acid rain, and how scientists were able to largely eliminate this major environmental threat.
Atmospheric industrial pollutants are the main cause of acid rain. Acid rain is damaging forests, plants, and agriculture, raising the acid level in lakes and ponds, killing fish and aquatic life, and damaging human health.... Besides the health hazard of many forms of life, acids rain causes many other problems. It corrodes or wears away, metal, painted surfaces, and even stone buildings and monuments.
Recent human activity has placed reefs in as precarious a position as at almost any time in their history. The last fifty years have witnessed an extremely dramatic decline in the health of many of the major reefs around the world, including reefs of the Caribbean, the Bahamas, and the Florida Keys as well as those in the Indian and Pacific Oceans, including the massive Great Barrier Reef of Australia. The outlook for these rich and complex ecosystems is about as bleak as any ecosystem on Earth. As it turns out, ocean acidification is one of several environmental threats to reefs, with warming, pollution, overfishing and physical destruction all exerting major threats to reefs in the future. As we will see, acidification is perhaps the greatest of all of these threats long term.
9 What is Ecology?
9 What is Ecology?
Ecology is the study of the interactions between livings organisms, and the interactions between organisms and their environment.
Abiotic and Biotic Factors
Abiotic and Biotic Factors
The environment of an organism includes the:
Non-living environment (abiotic):
Consists of the chemical and physical factors. E.g. light intensity, temperature, water, air and pH of soil or water.
Living environment (biotic):
Consists of all living things that are part of the organism’s environment, which it interacts with.
The Ecosystem
The Ecosystem
The ecosystem consists of the living (biotic) components and non-living (abiotic) components of the environment, through which energy flows and nutrients cycle.
The biotic and abiotic components interact with each other in many ways to form a stable system.
Hence, all ecosystems involve:
● living organisms
● a physical environment (land, water, air)
● a source of energy to make the whole thing work.
Level of Organisation in Biology
Level of Organisation in Biology
Population Community Ecosystem
Watch the video below and read the glossary of terms for all the definitions.
The Environment and its Composition
The Environment and its Composition
Abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. They help determine whether a species can survive in an area.
Some Abiotic Factors
Light
Air
Water
Temperature
Mineral salts
pH
List the abiotic factors and the biotic factors in the picture on the left.
Return of the Wolves and how they change rivers
Return of the Wolves and how they change rivers
Watch the video and list the animals and plants and describe their relationships that are affected by the return of the wolves. Can biotic factor affect abiotic factor?
Answer the questions in the padlet here.
The story of how the wolves change rivers is a poetic story of how we can re-store nature by a simple action of re-introducing wolves back to Yellowstone Park. However, As you learn more in this topic, you will understand the story is not so simple. Ecological relationships are more complex.
There were criticism about the over simplification of the situation.
"Not only that, the story was dangerous. It’s simple focus risked undermining the reputations of hard-working scientists and conservationists.
It was also a distraction from the many other challenges that natural environments faced, such as fungal infestations, gas drilling, climate change and much more devastating invasive species such as lake trout, that cannot be controlled so easily.
Wolves are back in Yellowstone. Nature fixed it. Let’s get back to our desks."
You can read more about it in this article and it has a update of their claims.
“Overall, results were consistent with a landscape‐scale trophic cascade whereby reintroduced wolves, operating in concert with other large carnivores, appear to have sufficiently reduced elk herbivory in riparian areas to initiate the recovery of Blacktail Deer Creek’s riparian plant communities and stream channels,”
8.5 How does the environment influence the survival of organisms?
8.5 How does the environment influence the survival of organisms?
8.6 How an environment affects the adaptive traits of organisms living in it?
8.6 How an environment affects the adaptive traits of organisms living in it?
[ Examples given in the Textbook 2A pg 88 - 90]
The interaction of abiotic and biotic factors is also seen in many examples of amazing examples of camouflage in animals. The most fascinating example has to be the octopus.
Enrichment
In our activity on polar bear we have mentioned that these white polar bear are able camouflage in the icy environment. The polar bear fur however is not actually white. If you are interested. You can watch this video to find out more.
Mimicry
Mimicry
Singapore's surprising wild life | The Mimic Caterpillar | Wild City: Forest Life
The mimic caterpillar has evolved to look just like a weaver ant - one of the most aggressive and acidic ant species in the country. See how they protect themselves from predators in this way.
This species of ant is found in our forest. This is another strategy that animals have evolved to adapt to their environment.
8.7.1 Interactions between species
8.7.1 Interactions between species
The major types of interactions are mutualism, commensalism, parasitism and predation.
Types of Symbiosis
8.7.1.1 Commensalism
8.7.1.1 Commensalism
Commensalism is a relationship between two organisms where one receives a benefit or benefits from the other and the other is not affected by it.
Example whales and barnacles. Barnacles have the benefit of moving through waters attached to the whale. The whale receives no benefit, but is not harmed either.
Closeup of barnacles growing on the humpback whale
Examples of Commensalism
Examples of Commensalism
Think of more local examples which are similar to those shown in the video.
Local Examples
Pigeon Orchids and other epiphytes (e.g. ferns) growing on trees.
The greater racket-tailed drongos in our local forest have also been seen following in the trails of troops of long-tailed macaques to eat the insects that these monkeys stir up in their wake as they move in the tree canopies.
8.7.1.2 Mutualism
8.7.1.2 Mutualism
Mutualism is an interaction between two organisms in the ecosystem with benefit to both organisms in the interaction.
Fig wasp and Fig fruit
Fig wasp and Fig fruit
Mutualism- A Fig and Wasp Story
Mutualism- A Fig and Wasp Story
8.7.1.3 Parasitism
8.7.1.3 Parasitism
Parasitism is a non-mutual relationship between species, where one species, the parasite, benefits at the expense of the other, the host.
Parasite feeds on the host organism. Unlike predation, it does not result in the immediate death of the host, they generally do not destroy it. A parasite feeds on the host, but parasites are usually smaller then the host and reproduce at a faster rate. E.g. tapeworms can live in human digestive tract for long periods of time.
So have you wondered if zombies are real?
In the natural world there are parasites that can turn normal animals into zombies!
Cordyceps: attack of the killer fungi - Planet Earth Attenborough BBC wildlife
So if you find the word cordyceps is familiar, it is an expensive chinese herb that is used in either chinese cuisine especially soup and also chinese medicine.
The World's Most Expensive Fungus
Parasitic Plants - Mistletoes
Parasitic Plants - Mistletoes
In SCGS, there are 2 fragrant champaca (Magnolia champaca) trees. On one of the trees, you see branches darker green leaves that grow out of a swollen "sucker" like swelling on the branches of champaca tree. The leaves look different from that of the champaca.
The Malayan mistletoe (Dendrophthoe pentandra) is the food plant of the Painted Jezebel (Delias hyparete metarete), an attractive common garden butterfly (below left: butterfly emerging from pupa), The caterpillars of this butterfly can completely defoliate the mistletoe plant such that the plant can never recover. But this happens only when the mistletoe is not prolific and the caterpillars are plentiful. As such, the Painted Jezebel can be exploited as a natural control of this semi-parasite.These seeds are excreted stuck together, as the gummy covering that originally covered the seeds remain intact when passing through the digestive tract.
These seeds germinate and send out a specialised organ, the haustorium, into the host’s tissues. The haustorium taps the host’s supply of water and nutrients but the green leaves of the mistletoe manufacture its own food. These plants are thus termed semi-parasites.
Birds love the fruits of these mistletoes as well as the nectar that the flowers provide. In taking nectar, the birds assist in the pollination of the flowers. Flowerpeckers, sunbirds, parakeets, hanging-parrots and even bulbuls are attracted to these plants.
These are the semi-parasites which are popularly know as mistletoe. Malayan mistletoe (Dendrophthoe pentandra) is a common mistletoe plant that are semi-parasitic on our local trees. The mistletoe is spread by flowerpeckers and sunbirds that eat the fruits and excrete the sticky seeds when perching on the branches of shrubs and trees.
For more details checkout https://besgroup.org/2007/10/22/sunbird-and-flowerpecker-pollinating-mistletoe-flowers/
My friend, Angie Ng describes in detail how a male Scarlet-backed Flowerpecker (Dicaeum cruentatum) deposited a string of sticky seeds on her sui mei (Wrightia religiosa) plant thus:
“After comfortably positioning itself transversely across the branch, it turned its head… then it awkwardly stretched apart its legs, lowered its little body for a second or two and with a swagger, it moved a few steps to the left. With that quick swaggering action it wiped off a string of six gluey mistletoe seeds onto the branch of my sui mei.”
What kind of Symbiosis is shown here?
What kind of Symbiosis is shown here?
The Watchmen and the Blind Burrowers
Watch this short segment on the Yellow goby (it is related to a fish that you have seen before) and the pistol shrimps found in our local waters.
This is from the series Singapore's Wild Islands | Wild City |
More details here.
Predator and Prey in an Ecosystem
Predator and Prey in an Ecosystem
8.7.1.4 Predation
8.7.1.4 Predation
Predation is a relationship where one organism captures and consumes another. An organism which feeds on another organism for their food is called predator while the organism that is fed upon is termed as the prey.
8.7.1.5 Predation and population dynamics
8.7.1.5 Predation and population dynamics
Increasing the population size of prey will result in a corresponding increase in the population size of the predator because the predator has more food.
Prey populations decline as the population size of a predator increases because of increased predation pressure.
Population response of one species to a change in the other requires time for the population to grow, predator-prey interactions sometimes result in population cycles, in which both predator and prey populations each undergo regular increases and decreases, but the population cycles are out of phase with one another.
8.7.2 Interdependence within the ecosystem
8.7.2 Interdependence within the ecosystem
For the members of the community in an ecosystem to survive, a supply of energy is essential. How do organisms of an ecosystem obtain their energy?
Producers are autotrophs - manufacture organic molecules from simple inorganic substances using energy from light in photosynthesis. Examples include green plants, photosynthetic bacteria, green, brown or red algae.
Consumers are heterotrophs - animals that feed on other living organisms (ingestion) and obtain nutrition by digestion.
Primary consumers or herbivores - feed directly on producers
Secondary consumers or carnivores - depend indirectly on producers by feeding on primary consumers
Decomposers break down dead plants, animals and the waste of other organisms. Recycle them into chemical nutrients like carbon and nitrogen that are released back into the soil, air and water.
Decomposers include detritivores.
8.8 What are the processes involved in maintaining a stable ecosystem?
8.8 What are the processes involved in maintaining a stable ecosystem?
8.8.1 Food Chains, Food Webs and Flow of Energy
8.8.1 Food Chains, Food Webs and Flow of Energy
Feeding relationships can be represented by food chains and food webs.
Food chain shows the transfer of energy and materials (i.e. food) from organism to organism along feeding pathway. It includes a producer and consumers, but not the decomposers.
Each stage in a food chain e.g. producer is known as a trophic level.
Food web happens when more than one organism can be present at each trophic level.
For example, all the herbivores are at the same trophic level of primary consumer. Each species very often feeds on more than one type of prey, and each species also may be food for at least two or more predator species.
Compared to food chains, food webs are;
more stable
more resistant to disruption
Freshwater pond food web
List 2 - 3 food chains from the 2 food webs.
Marine Food Web
Draw a food web of our local forest using the food chains that are shown below:
(You may search online to see what they look like and paste the picture in your food web)
Ashoka tree → Tailed Jay butterfly → Black-bearded Gliding Lizard → Pit viper
Ashoka tree → Tailed Jay butterfly → Racquet-tailed Drongo
Ashoka tree → Termites → Long-tailed Macaque → Reticulate Python
Yellow stem fig → Termites → Pangolin
Yellow stem fig → Plantain Squirrel → Reticulate Python
Yellow stem fig → Long-tailed Macaque → Reticulate Python
State the adaptive features of each of the organism shown.
8.8.2 Pyramid of Numbers
8.8.2 Pyramid of Numbers
The number of organisms in a food chain can be represented graphically in a pyramid. Each bar represents the number of individuals at each trophic level (feeding level) in the food chain.
The pyramid of numbers usually shows that the number of organisms at each trophic level gets smaller towards the top and at the same time, there is an increase in the body size of the animal. What is the general shape of the pyramid?
Ecological Pyramids
Explain these anomalies.
The pyramid of numbers does not take into consideration the biomass and size of each organism. For pyramid 2, the large biomass of one oak tree is able to support the energy needs of a large number of insects. Whereas grass has a small biomass, therefore a large population of grass is needed to support the energy needs of rabbits.
8.9 Flow of Energy in a food chain
8.9 Flow of Energy in a food chain
Energy is transferred from one organism to another in a food chain, but only some of the energy is available to the next organism in the food chain.
This is because energy that is lost as heat cannot be converted into other forms of energy by living organisms. Thus heat is lost from ecosystems. In fact, only about 10% of what is ingested by a consumer is available to be passed on to the next trophic level of the food chain.
When constructing a pyramid of energy, every bar should be labelled with the corresponding trophic level (producer, primary consumer, etc.) and the units. The steps of the pyramid should be drawn to scale.
Reasons for loss of energy
1. Not all the food is ingested e.g. herbivores - cellulose and woody xylem tissues; leftover food.
2. Energy to drive life activities (respiration, cell division & growth).
3. Heat produced is lost.
4. When organisms die, decomposed by decomposers during decay.
Chemical energy from food is oxidised during respiration to release energy for cell activities.
Most energy is lost as heat energy.
Heat energy does not return to the Sun or re-enter an organism.
Energy flow is one way.
Known as non-cyclical flow of energy. Energy transfer in a food chain is unidirectional!
Why do most trophic levels not go beyond four in a food chain?
As chemical energy is transferred from one trophic level to the next, there is a loss of energy so that the total amount of energy decreases progressively down a food chain.
The chemical energy manufactured by the producer is completely dissipated into the surroundings by the fourth or fifth tropic level.
There is not enough energy in the last organism to sustain another trophic level.
Some Animals Are More Equal than Others: Keystone Species and Trophic Cascades (Enrichment)
8.10 How can we help to maintain a stable ecosystem?
8.10 How can we help to maintain a stable ecosystem?
Take action to conserve the environment as it contributes to the stability of the ecosystem - evaluate the impact of human activities and technology on the environment
[Read Textbook 2A pg 103 – 105]
8.10.1 The Carbon Cycle
8.10.1 The Carbon Cycle
Carbon is the backbone of life on Earth. We are made of carbon, we eat carbon, and our civilizations—our economies, our homes, our means of transport—are built on carbon. All living things are made of carbon. We need carbon, but that need is also entwined with one of the most serious problems facing us today: global climate change.
Looking at another perspective WHERE carbon is stored.
What happens when this carbon that is stored in these various regions are released into the atmosphere?
There is a short term carbon cycle and a long term carbon cycle.
Summary:
Summary:
Carbon moves from the atmosphere to plants.
Carbon moves from plants to animals.
Carbon moves from plants and animals to soils.
Carbon moves from living things to the atmosphere.
Carbon moves from fossil fuels to the atmosphere when fuels are burned.
Carbon moves from the atmosphere to the oceans.
Short-term Carbon cycle or Biological Carbon cycle
Short-term Carbon cycle or Biological Carbon cycle
Only takes days, months, or years for carbon to circulate through the environment. This involves
the movement of carbon from carbon source to the autotrophs i.e. from environment to algae or plants, hence entering in food chains
the release of fixed carbon present in the bodies of organisms or in the fuel to the environment
processes include photosynthesis, respiration, decomposition and combustion
Long-term Carbon cycle or Geological Carbon cycle
Long-term Carbon cycle or Geological Carbon cycle
In long term carbon cycle, instead of carbon being converted to sugars, carbon is reused in fossil fuels like coal. When plants are buried and compacted for millions of years, they become hydrocarbons. Volcanic activity – and more recently – human burning of fossil fuels restores this stored carbon to the carbon cycle.
The formation of fossil fuels occurs on a slow geological time scale, but humans release carbon dioxide containing it on a very fast time scale.
When you drive your car on gasoline, you take advantage of the Earth’s carbon reserves deposited hundreds of millions of years ago. These fossil fuels are released into the air as carbon dioxide and water vapor.
The carbon geological cycle takes much longer than the previously described biological cycle. In fact, carbon usually takes millions of years to travel during the geological cycle. Carbon may be stored for long periods of time in air, water bodies – mostly ocean surfaces – and ocean sediments, soils, rocks, fossil fuels, and in the ground.
The level of carbon dioxide in the atmosphere is affected by the carbon stored in the ocean and vice versa. Carbon dioxide dissolves from air in water and reacts with water molecules to form carbonate ions which interact with Ca+2 ions to form CaCO3 which is the main component of the shells of marine organisms.
[reference: https://readbiology.com/what-is-carbon-cycle/]
Steps in the carbon cycle
1 Carbon enters the atmosphere as carbon dioxide from respiration and combustion.
2 Carbon dioxide is absorbed by producers to make carbohydrates in photosynthesis.
3 In feeding, animals consume the plant, passing the carbon compounds along the food chain. Most of the carbon they consume is exhaled as carbon dioxide formed during respiration. The animals and plants eventually die.
4 The dead organisms are broken down by decomposers in the process of decomposition, and the carbon in their bodies is returned to the atmosphere as carbon dioxide.
5 Dead bodies of organisms buried in the Earth for millions of years produce fossil fuels such as coal, natural gas and oil. Combustion of these fossil fuels releases carbon dioxide into the environment.
Relating Carbon Cycle to Climate Change
Over the past 800,000 years, atmospheric carbon dioxide levels have risen and fallen. Low concentrations correspond to ice ages—eight such periods are visible in the graph below.
In the 800,000 years before the modern era, CO2 levels never once rose above 300 ppm. Now, however, CO2 levels are 405 ppm. As our emissions continue, it is likely that atmospheric concentrations will increase past 500 ppm, maybe past 600 ppm. Temperature increases are lagging behind CO2 increases.
Atmospheric carbon dioxide concentrations, 800,000 years ago to present
Sir David Attenborough: The Truth About Climate Change
Sir David Attenborough: The Truth About Climate Change
NASA: Keeping Up With Carbon
NASA: Keeping Up With Carbon
The Carbon Cycle
NASA | A Year in the Life of Earth's CO2
NASA | A Year in the Life of Earth's CO2
Time-lapse history of global CO2 emissions by humans 1751-2008
Time-lapse history of global CO2 emissions by humans 1751-2008
LATEST DISCOVERY
LATEST DISCOVERY
"Not all caterpillars grow up to be beautiful butterflies. Some become living milkshakes for their dads, who guzzle caterpillar body fluids to attract the ladies. "
Science discovery can be dramatised by writers to attract readers to their site. This latest discovery of adult individuals stealing bodily liquids from the young has led the scientists to coin a new term "kleptopharmacophagy", which means "consuming stolen chemicals."
"Multiple adults were observed scratching many caterpillars along a stretch of coastal vegetation" that spanned more than 1,600 feet (500 meters), the researchers reported. They then saw the butterflies actively drink "from the wounded and oozing caterpillars" for hours, with the butterflies sometimes gathering in mixed-species groups. So intent were the butterflies on drinking from the caterpillars that not even the touch of a human observer could distract them, the study authors wrote.
Read on to find out more about these Milkweed butterflies.
https://www.livescience.com/butterflies-drink-their-babies.html
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