Intro to Ecosystems

Ecosystems - Introduction

What are ecosystems?

All living things need energy to survive. Producers such as plants get their energy from sunlight. Consumers like us get energy by eating other living things. So one way that living things interact with each other is by eating and being eaten. These interactions are shown by food chains and food webs.

Living things also interact with their physical environment. For example, many animals breathe air, swim in water or use rocks and sand for shelter. A collection of living things that interact with each other and with their environment is called an ecosystem.

The branch of science that studies ecosystems is called ecology.

Multiple Choice

An ecosystem is a collection of both living things and non-living things, interacting with each other in a shared environment.

• True

• False

• Unsure

Multiple Choice

Ecology is the study of?

• The internal structures of living things

• Organisms interacting with each other and their environment

• Describing, classifying, and naming organisms

• The chemical reactions that take place in living things

Ecosystems

Ecosystems have a wide range of scales. They can be as large as a rainforest or as small as a rock pool. As long as there are living things interacting with each other and with their physical environment, there is an ecosystem.

An ecosystem can also form part of a larger ecosystem. For example, a rock pool forms part of a larger coastal ecosystem.

Biotic and abiotic factors

An ecosystem needs both living and non-living components to function. Scientists use special terms to describe the interactions between these components

Biotic and abiotic factors

Biotic

Living things in an ecosystem are called biotic factors. This word comes from the Greek "bio-" meaning life. Examples of biotic factors include animals, plants and bacteria.

Biotic and abiotic factors

Abiotic

Non-living things in an ecosystem are called abiotic factors. The prefix "a-" means not, so "abiotic" means not living. Abiotic factors include air, water, temperature, currents and other features of the physical environment.

Labelling

Label the following.

Drag labels to their correct position on the image

Abiotic

Biotic

Abiotic

Biotic

Abiotic

Biotic

Book work activity

Describe two interactions between a biotic and abiotic factor in a marine ecosystem. One example has been provided for you below.

Seagrass - Sunlight - Seagrass absorbs sunlight to carry out photosynthesis.

Book work activity

Plastic pollution can be found in many marine ecosystems.

Describe whether plastic waste could be considered part of these ecosystems – as another abiotic factor. Explain your answer.

Exploring Marine Ecosystems

When you dive beneath the surface of the ocean it becomes clear that marine ecosystems are very different from land ecosystems. All of the living things are adapted to life underwater. The abiotic factors they interact with include sand, waves and ocean currents.

But there are also many similarities between life on land and under the sea. Producers are needed to carry out photosynthesis. This converts the Sun's energy into stored energy in sugars that can then provide food for consumers. On land, the most common producers are plants. In the ocean, this important role is played mainly by algae.

Exploring Marine Ecosystems

Algae are a diverse group of organisms, including:

• seaweed: large, multicellular organisms that look like plants

• phytoplankton: microscopic organisms that float near the water surface

• algae in coral: microscopic organisms that live inside the tissues of corals, providing them with sugars in return for a safe place to live

Note: Phytoplankton also include some types of bacteria that are able to photosynthesize.

Exploring Marine Ecosystems

Another difference between land and marine ecosystems is the surrounding sea water. The properties of sea water vary from place to place and with water depth. The survival of many marine organisms depends on:

• water temperature

• the amount of dissolved salt, or salinity

• the amount of acid, as measured with the pH scale – a pH of 7 is neutral, less than 7 is acidic and greater than 7 is basic, or alkaline

Exploring Marine Ecosystems

Coral reef ecosystems are very sensitive to these conditions. They grow best with:

• a water temperature of 23–29°C

• a salinity of 32–40 parts per thousand (ppt)

• a pH of 8.4–8.6

Multiple Choice

Salinity is a measure of?

• Water depth

• How acidic or basic something is

• The amount of dissolved salt

• Water temperature

Multiple Choice

Select which of the following pH values of sea water is best suited to a coral reef ecosystem

• 3.5 - strongly acidic

• 6.5 - weakly acidic

• 8.5 - weakly alkaline

• 12.5 - strongly alkaline