Lesson video

Hello, my name is Mrs. Grey and I'm so excited that you've decided to join me to learn geography today.

Today's lesson is in our unit of ice and glaciers, how are cold places affected by a warming planet? And the title of today's lesson is "Antarctic Food Webs".

By the end of the lesson, you will be able to describe what food webs are and explain how Antarctic food webs work.

There are some keywords that we'll come across in today's lesson.

They are producer, consumer and apex predator.

A producer is an organism that makes its own food using sunlight.

A consumer is an organism that eats other organisms for energy, and an apex predator is an organism at the top of the food chain with no natural enemies.

Today's lesson on Antarctic food webs is split into two learning cycles.

The first, what are Antarctic food webs? And the second, how are Antarctic food webs changing? So let's take a look at that first learning cycle.

What are Antarctic food webs? A food chain shows how energy moves from one living thing to another in nature.

For example, phytoplankton, krill, blue whale.

The blue whale eats the krill, the krill eats the phytoplankton.

Food webs show us more of the complexity of the natural world.

So not necessarily one thing, it only eats one other thing.

So you can see this food web here.

There's more of a complex system.

It's not just as simple as one food chain.

They're interlinked.

Some animals eat other things, not just one thing.

Unlike a food chain, which is linear, a food web is complex and interconnected.

Every species depends on several others for its survival.

A quick check then.

True or false? A food web is linear.

Is that true or false? So pause the video, write down your answer and then come back and let's see how you got on.

Okay, true or false, a food web is linear? That's false.

Why is it false? A food web is not linear.

It's a complex and interconnected.

So food webs demonstrate the flow of energy from producers to consumers to apex predators.

Producer.

Consumer.

Apex predator.

So food webs demonstrate how energy flows from producers through to consumers up to apex predators.

Another little check for us now then.

Fill in the missing words.

So look at the flow diagram there at the bottom.

Fill in the missing words.

So pause the video, write down your answer and then come back and let's see how you got on.

Okay, how did you get on? Fill in the missing words.

So the missing words were producer there at the bottom and apex to go before predator there at the top.

Did you get that? Well done.

Now, Antarctica is one of the most extreme environments on Earth.

Look at that image there, you can see how extreme the environment is there in Antarctica.

So Antarctica's food webs are adapted to cold temperatures, limited vegetation and seasonal changes.

So those food webs have had to adapt to the extreme environment of Antarctica.

And this is an example of an Antarctic food web.

You can see there producers at the bottom.

You can see the consumers in the middle and the apex predators at the top, and you can see how the arrows show that flow through.

Now, phytoplankton are producers in the Antarctic food web.

This is an image of phytoplankton, Phytoplankton are microscopic plants that use sunlight to create energy through photosynthesis.

A quick check for us now then.

What are phytoplankton? A, microscopic plants, B, consumers, C, producers? So pause the video, write down your answer and then come back and let's see how you got on.

Okay, how did you get on? What are phytoplankton? And the answer is A and C.

Microscopic plants and producers.

Did you get those? Well done.

Krill and squid, they're consumers in the Antarctic food web.

So have a look at the Antarctic food web there.

Can you see where krill are and squid? So they are consumers in that food web.

The krill feed on the phytoplankton and zooplankton and the squid feed on the krill.

These organisms provide energy for the higher levels of the food web.

Another check for us now then.

Which of the following are producers in the Antarctic food web? Is it A, krill, B, phytoplankton or C, killer whale? So which of them are producers? So pause the video, write down your answer and then come back and let's see how you got on.

Okay, how did you get on? Which of the following are producers in the Antarctic food web? The answer is phytoplankton, B.

Did you get that? Well done.

So leopard seals and killer whale, they are apex predators in the Antarctic food web.

So have another look there at that Antarctic food web.

Leopard seals and killer whales, they are apex predators in that web.

Here's an image of a leopard seal and an image there of a killer whale.

Now, these are apex predators.

Those apex predators help to regulate populations and to maintain balance in the food web.

The leopard seals feed on fish, squid and penguins.

Killer whales are the ultimate predator.

They feed on seals, fish and sometimes other whales.

So we're on to our first task of the lesson now then.

Question one.

Give one example of each of the following from the Antarctic food web.

So give an example of A, a producer, of B, a consumer and of C, an apex predator.

So give one example of each of those.

Question two A.

If the population of squid declines, what will happen to the penguin population and why? So you've got an image there of the Antarctic food web.

So have a look at that, identify the squid, identify the penguin.

What do you think will happen to the penguin population if squid declines? And then explain, why do you think that? Two B, if the population of krill declines, what will happen to the producers? So another look there, have another look at the Antarctic food web.

If krill declines, what's gonna happen to the producer there at the bottom? And then explain why you think that.

Okay, so pause the video, have a look at those questions.

Make sure you have a really good look at the Antarctic food web to answer those questions.

Write down your answer and then come back and let's see how you got on.

Okay, how did you get on? So give one example from each of the following from the Antarctic food web.

So A, an example of a producer is phytoplankton.

An example of a consumer, krill or squid.

An example of apex predator, leopard seal and killer whale.

For two A, if the population of squid declines, what will happen to the penguin population and why? So the penguin population will also decline.

This is because there are less squid for the penguins to eat.

And then two B, if the population of krill declines, what will happen to the producers? The producers will increase in numbers.

This is because there are not as many krill to eat them.

Did you get those questions right? Well done.

So we finished our first learning cycle there on what are Antarctic food webs? Now we're gonna have a look at our second one, how are Antarctic food webs changing? So Antarctic food webs are changing due to overfishing.

Fishing too much.

Krill is a key species in the Antarctic food web that is being overfished.

This is an image of krill there and this is being overfished, and the krill populations are decreasing, because they're being overfished.

Now, when krill populations decline, species like penguins, seals and whales that depend on krill for food, they face significant food shortages.

They haven't got enough food to eat, because the krill populations are being overfished and are declining, there's not enough of them.

Now, all organisms in the Antarctic food web are interconnected.

So a disturbance to one of the organisms affects the others.

For example, overfishing of krill, that leads to a decline in krill populations, which means that seal and whale predator number also decline.

So can you see how all of those organisms are interconnected there? So one little disturbance, that can cause huge issues for the rest of the food web.

Another check for us now then.

True or false? Overfishing of krill affects the leopard seal population.

Is that true or false? What do you think? So pause the video, write down you answer and then come back and let's see how you got on.

Okay, how did you get on? True or false, overfishing of krill affects the leopard seal population.

That's true.

Why? The leopard seal feeds on squid that in turn feed on krill, so the population of seal may decline, because they have less to eat.

So if we've not enough krill, then the squid are gonna decline in numbers, because there's not enough krill for the squid to eat.

Then the leopard seal population is gonna decline, because they haven't got enough squid to eat.

So again, all of these are interconnected.

Now, species that depend on krill must compete harder for food, because those populations of krill are declining.

And this had numerous ecological consequences, for example, it results in a change in their behaviour, they have less breeding success and lower survival rates.

So those species that are dependent on krill, they're having to compete harder and harder and harder for food and it's having all these ecological consequences.

Now, in 2016, the Ross Sea Marine Park was established to protect marine diversity by limiting human activity.

So you can see Antarctica there and the Ross Sea Marine Park is identified.

That's being set up to try and protect the diversity, the biodiversity of the marine life.

So another check for us now then.

Which of the following are ecological consequences of declining krill populations? It A, changes in predator behaviour, B, limited predator breeding success, C, lower predator survival rates? What do you think? So pause the video, write down your answer and then come back and let's see how you got on.

Okay, how did you get on? Which of the following are ecological consequences of declining krill populations? And it's all of them.

It causes changes in predator behaviour, limited predator breeding success and lower predator survival rates.

Did you get that? Well done.

So the Ross Sea Marine Park have several key protections.

Let's have a look at them.

It has no-take zones, protection of key species and a refuge for krill-dependent species.

Let's have a look at each of those in a little bit more detail.

So no-take zones are certain areas where all forms of fishing are prohibited.

This allows marine life to thrive without human interference.

So some of those zones on that map there that are the Ross Sea Marine Park, they have no-take zones.

So no fishing is allowed.

Now, protection of key species safeguards those young fish.

This ensures the population stability of those fish, like with krill there.

And the refuge for krill-dependent species provides a sanctuary for species that rely heavily on krill, such as penguins and seals.

So you can see the penguins and the seals there.

There's areas that are a refuge for those species, providing a sanctuary for them.

Okay, we're on to our final task of the lesson now then.

Fill in the gaps to show how organisms in the Antarctic food web are interconnected.

So the first is a something of krill, that leads to something in the krill populations, which leads to seal and whale predator numbers something.

So fill in those three gaps.

So pause the video, write down you answer and then come back and let's see how you got on.

Okay, how did you get on? So it was overfishing of krill causes a decline in krill populations, which leads to seal and whale predator numbers declining.

Did you get those? Well done.

Okay, question two.

Below is a paragraph about the Ross Sea Marine Park.

There are six mistake, find and correct them.

So established in 2020, this initiative aims to protect marine biodiversity by regulating animals activities.

Key protections include the creation of take zones where all fishing is prohibited, allowing marine life to thrive undisturbed.

It also jeopardises key species to promote population stability.

Additionally, it provides a no help for krill-dependent species, like penguins and seals, ensuring the preservation of unimportant ecosystems. So there are six mistakes in that paragraph.

You'll need to find the mistakes and then correct them.

So pause the video, have a good read through that paragraph, identify the mistakes, correct them and then come back and let's see how you got on.

Okay, how did you get on? So this is what it should look like.

Established in 2016, this initiative aims to protect marine biodiversity by regulating human activities.

Key protections include the creation of no-take zones, where all fishing is prohibited, allowing marine life to thrive undisturbed.

It also safeguards key species to promote population stability.

Additionally, it provides a refuge for krill-dependent species, like penguins and seals, ensuring the preservation of vital ecosystems. How did you get on there? Did you identify all of the mistakes and were you able to correct them? Well done.

So we're at the end of our lesson today now on Antarctic food webs.

Let's have a little look at what we've learned.

Food webs display the transfers of energy within one location.

Antarctic food webs contain phytoplankton which are producers, krill and squid which are consumers and leopard seals which are apex predators.

Changes to food webs arising from overfishing can affect different species.

The Ross Sea Marine Park Area has been established to help protect young fish.

Thank you for joining me for today's geography lesson.

I've really enjoyed it and I hope you have too.

I'll see you next time.