Organisms of an ecosystem

Please get in touch with your teacher or tutor in case you have a question related to this lesson

Slide 1

In this presentation we’re going to look at how the organisms of an ecosystem effect each other. What happens to the other organisms if the environment changes, and some organisms die off? What happens if microorganisms enter the ecosystem? They could have harmful or good effects on some organisms in the environment. What happens to the other ones? What happens to the other organisms if we introduce species like lantana or cane toads? Is there enough food to go around? Do they destroy the habitat? Finally, we’ll look at the impacts that different plants and animals have on ecosystems.
 
Slide 2

In this presentation, we’re going to talk about a number of different topics, and how these impact the organisms in an environment. First, we’ll discuss environmental changes and what they can do to organisms. Next, we’ll look at the effects of microbes on the environment: they might kill off plants or animals, or they might enrich the soil. Invasive species have had dramatic effects on the Australian environment. We’ll discuss different invasive species of plants and animals in some detail. We’ll then look at the effects that different plants have on the environment, and finish by looking at what different animals can do to the environment. Of course, the most destructive animal of all is the human being.
 
Slide 3

Our environment is not static. At one time, the sea levels around Australia were much lower, and there were land bridges connecting mainland Australian to New Guinea and Tasmania. Temperatures were once lower, and we received a lot more rain. Many factors can change the environment. Their effects can be both positive and negative. Some key things that affect the environment are climate change. Raising and lowering of temperatures, and increases and decreases in rainfall can have dramatic effects on our environment, and the organisms that live in our ecosystems. Natural disasters such as Earthquakes and volcanoes can lead to a destruction of habitats. Ash clouds from volcanoes can block out the sunlight. The availability and depletion of natural resources can lead to loss of habitat or lack of food for organisms. Finally, introducing species such as the rabbit and the cane toad can have devastating effects on the environment. Other organisms compete for food, and the introduced species can kill native organisms, destroy their habitats and take their homes.
 
Slide 4

Our environment is made up of both abiotic and biotic factors. The abiotic factors are the things like water, rocks and sunlight. They are the non-living parts of our environment. The biotic factors include all the living organisms. Every living organism has an effect on the environment, regardless of whether it is a tiny bacterium or a colossal animal like a dinosaur. Microscopic plants and giant trees also affect our environment. Organisms interact with the environment for survival, food and somewhere to live. They use the resources such as food and water from the environment and modify other parts of the environment as they make their homes.
 
Slide 5

Our environment contains millions of tiny organisms that we cannot see. These are called microorganisms. They’re too small to be seen with the unaided eye. You need a powerful magnifying glass or microscope to see them. Some types of microorganisms that you may have heard of include bacteria, protozoa, and algae. Some times of fungi are also microorganisms, although others can be large. Another word for a microorganism is a microbe. We can find microbes everywhere in Earth’s biosphere. Their present effects the environment that they grow in. They can have many different effects. Some, such as nitrogen-fixing bacteria, are beneficial as they take nitrogen from the air and turn it into a form that can be used by plants. Others, like pneumococcus, cause infections. Still others have no real effect that can be noticed by the human eye.
 
Slide 6

Microbes can have a number of different beneficial effects. For example, their metabolic activities can provide important substances for the environment. Some microbes provide beneficial effects for the plants and animals they are associated with. Other microbes can be used in food production, like making cheese and yoghurt, and others are useful in biotechnological processes. Let’s look at some examples of helpful microorganisms. We all have E-Coli in our intestines. They help with the digestion of food. Streptomyces are a class of bacteria that are used to make antibiotics called tetracyclines. Rhizobia are nitrogen-fixing bacteria. They live in the soil and help to convert nitrogen from the air into a form that plants can use as nourishment. They often live around the roots of legume plants like peas.

Slide 7

Other microbes are harmful as they can cause diseases in humans and animals. Some of these diseases are particularly dangerous. For example, streptococcus pyogenes can cause a number of life-threatening infections like scarlet fever and pneumonia. Bordetella pertussis causes whooping cough, and Mycobacterium tuberculosis causes a life-threatening infection called tuberculosis that can affect many organs of the body. Finally, Staphylococcus aureus is also known as golden staph. It lives on the skin and in the nose, and can cause mild or severe infections. The use of too many antibiotics has led to the development of strains of this bacterium that resist treatment with antibiotics.
 
Slide 8

Plants provide many benefits to our environment. They trap energy from the Sun and convert it into food energy through a process called photosynthesis. This takes place in the green leaves of plants. This gives them a vital role in the food chain as producers. Animals eat producers and pass the energy on to other animals when they, in turn, are eaten. Another benefit of plants is that they absorb carbon dioxide from the air and release oxygen gas during the day time. This occurs as a byproduct of photosynthesis. The oxygen released by the plants is used by animals which, in turn, release carbon dioxide (CO2) to the atmosphere. The plants then use this carbon dioxide during photosynthesis, and the cycle continues. The result is a balanced ecosystem, at least in terms of oxygen and carbon dioxide.
 
Slide 9

Living in Australia, we’ve all heard of the consequences of introducing species like the rabbit or cane toad into a country where they have no natural predators. The introduction of some species from another country has no ill effect. For example, introducing roses to Australia has had no harmful effects. However, in many cases, introducing a creature like the cane toad or the rabbit, or a plant like English Ivy or Lantana can have devastating effects for the environment. We call these invasive species. They can damage the environment, cause economic problems, or they can have an impact on the health of wildlife or humans. We’ll discuss some of the problems caused by invasive species of plants and animals later in the presentation.
 
Slide 10

Invasive plants have adverse effects on ecosystems and plant diversity, often taking over and choking out native plants. Some examples of invasive plants include mosses, herbs, some shrubs, flowering plants, trees and vines. One particularly problematic invasive plant in Australia is Lantana. It was introduced from Central and South America and now covers much of Australia’s bushland. It has very pretty flowers, but it is highly toxic to animals and humans. For example, it can kill livestock, and it chokes out native plants and forests. It limits the natural regeneration of native flora, and can lead to economic losses, competing with tree seedlings for light and nutrients.
 
Slide 11

Morning glory is a vine with beautiful blue or purple, trumpet-shaped flowers that was introduced to Australia from Central and South America. It is now considered a highly invasive weed. It grows very quickly in moist environments. In fact, it can reach the top of tree canopies and form dense foliage that blocks out the Sun and smothers other plants. It is considered to be an ecosystem destroyer, and is described as a noxious weed in NSW and Queensland. It is difficult to eradicate. After chopping off stems and roots, their ends should be quickly painted with herbicide. Follow up treatment will be required.
 
Slide 12

Water Hyacinths are another noxious weed. They were brought to Australia from western Brazil as a decorative plant. However, they grow quickly and can choke our waterways. A patch of water Hyacinth can double in size in 6 days. It clogs up waterways, preventing plants below the water from receiving sunlight and oxygen, and also depleting the water of the oxygen required by fish.

Slide 13

Some other examples of invasive plants include pampas grass, bone seed, prickly pear, the Indian rubber vine, Scotch broom and fountain grass. All of these plants are considered to be noxious weeds in one or more states of Australia.
 
Slide 14

Animals also have effects on the environment. They are useful to humans in different ways, providing food, materials for clothing and transport. For example, cows give us meat, milk and leather. We can ride horses or use them to pull carts. Animals are part of food chains, and so have impacts on each other and plants as they have to share resources such as water and food. However, they can have a negative impact on water supplies and water quality. They can deposit waste in or nearby streams, causing them to become polluted and stir up the muddy bottoms of water sources, making them cloudy. Some animals such as beavers can also block the flow of water.
 
Slide 15

Many animals introduced to Australia have become invasive species. They have spread to a degree where they become a danger to the environment. The main reason for this is that their populations are not controlled by predators. The new environment that they are introduced into does not contain natural predators against them. Invasive animals continue to use the resources of this new environment, without checks, and threaten the native plants and animals through competition for food, hunting and stripping plants bare.
 
Slide 16

An example of an invasive species that has been introduced to Australia is the Cane Toad. Cane toads were brought to Australia from Hawaii for reasons of pest control as they eat cane beetles. However, no one even thought to check whether they would eat the species of cane beetles that live in Australia. Unchecked by predators, cane toads quickly spread across Queensland. They are now found in Queensland, the Northern Territory, and parts of Western Australia and New South Wales. One of the defense mechanisms possessed by the cane toad is its ability to excrete toxic ooze from pores on its skin. This means that many animals that try to eat a cane toad end up dying instead. They are toxic at all stages of their life style, and the ingestion of cane toads can kill native predators. They will also eat just about anything they can swallow including insects, native frogs, smaller toads, small mammals and snakes. They breed very quickly and rapidly adapt to new environments, competing with native species for both food and habitats. This ability, together with their lack of native predators means that their numbers increase rapidly and they are a big threat to native wildlife.
 
Slide 17

Rabbits are another species that was introduced to Australia by the European settlers. In 1859, European wild rabbits were introduced to Australia so that they could be hunted for sport. Of course, they lacked native predators and reproduced very quickly, so their population exploded. In one year, a female rabbit can have between 18 and 30 babies. With such rapidly growing populations and voracious appetites for native plants, rabbits have pushed native plant species to the brink of extinction. Australia is now home to at least 150 million rabbits.
 
Slide 18

Asian carp originated in China and spread throughout Asia and Europe. They were released into the wild in Australia on a number of occasions in the 18 and 1900s, and were used to stock fish farms. They are now the most prominent large freshwater fish in the Murray-Darling basin. They are large fish with big appetites that reproduce quickly. They compete with native fish for food and habitat and prey on the eggs of other fish species, thereby disrupting the balance of aquatic ecosystems.
 
Slide 19

Starlings were introduced to Australia to eat the insect pests that were attacking farm crops. Unfortunately, they do more serious damage to the farm crops themselves. They form huge flocks of often more than 3,000 birds. When such a flock feeds on fruit and grains, it can cause serious damage to farm crops.
 
Slide 20

There are a number of means that have been tried, and continue to be tried to control invasive species. The best control is, of course, never to introduce new species at all. People need to be educated about the dangers of transporting wildlife to new areas, and legislation should be used to limit the introduction of new species. Quarantine inspections are another way to prevent the inadvertent introduction of new species. Once invasive species are present, action should be taken to promote the harvest of the invasive species. In some instances, specific diseases such as Myxomatosis have been introduced to selectively target the introduced species and reduce its numbers.

Continued research is necessary to come up with new and better ways to control invasive species.
 
Slide 21

Let’s end by summarising the main points from this presentation. Every organism affects the ecosystem that it lives in, by competing for resources or disturbing it in some other way. Microbes are organisms that cannot be seen by the unaided eye. They can have both positive and negative effects on ecosystems, releasing nutrients into the ecosystem or causing diseases. Australia has a long history of problems with invasive species. These are exotic or alien species that have been introduced to a new environment where they have no natural predators and have an adverse effect on the environment. Some examples are lantana, the cane toad and the rabbit. Invasive species of both plants and animals have adverse effects on ecosystems. They compete for resources, kill native flora and fauna, and invade native habitats. We need to be very mindful of the effects that plants and animals have on our environment and take steps to avoid the introduction of new species to ecosystems where they can do irreparable harm.