Lesson video

Hello, my name's Ms. Gilyeat, and I'm your Geography teacher for today.

In today's lesson, we are going to be learning about the different threats to the oceans.

Let's get started.

So, our lesson outcome for today is that you can explain the main threats to oceans and how they affect marine environments.

We have got four keywords for today's lesson.

The first one is ocean current, which is the continuous movements of seawater in the ocean.

The second is overfishing, which is catching too many fish, so the breeding population becomes too depleted to recover.

The third, food chain, which is a sequence that shows how a group of living things are linked by what they eat.

And finally, ocean acidification is when the ocean becomes more acidic because it absorbs too much CO2 from the air.

We've got two learning cycles.

So first of all, we're gonna look at the threat of pollution and overfishing on the ocean, and then we're going to look at some of the different threats of climate change.

So let's get started with the first learning cycle.

Now, there are lots of different threats to our oceans, but here are some of the main ones.

So pollution, litter, chemicals, and oil spills harm marine life and water quality, so lots of stuff that shouldn't be in the ocean is getting into it.

The second is overfishing, so this is catching too many fish reduces fish population, and it also affects the whole ocean food chain.

So yes, we can collect too many fish, which means that that species number has gone down, but that also has another impact on other animals within the ecosystem.

Climate change, so warmer waters, rising sea levels, and ocean acidification can damage ecosystems. And finally, habitat loss, so destruction of coral reefs, mangroves, and wetlands affects animals and plants in the area.

All of these are examples of how humans in the Anthropocene are putting massive pressure on ocean health.

Okay, let's first of all have a look at pollution in a little bit more detail.

So, plastic pollution is one of the biggest environmental and social problems the world faces.

8 to 12 million tonnes of plastic enters the ocean every single year.

Plastic pollution harms and kills wildlife.

Plastic pollution collects in ocean garbage patches, and we're gonna learn about what those are in a minute.

And microplastics, which are tiny, tiny little pieces of plastic are entering food chains.

So first, we'll think about how the impact that plastic in the ocean can have on its wildlife.

Now, many animals mistake plastic for food, so they think that what they see is food, so they eat it.

This can fill their stomachs and cause them to starve.

They don't feel hungry because their stomach is full of plastic, so they don't eat any more food and then they do sadly starve, or they might not be able to digest the food because their stomach is full of plastic.

Sharp plastic can injure mouths or bodies, and animals can also get trapped in plastic rings, nets, or bags.

So you can see here that sadly, the turtle has had a bit of plastic, it looks like fishing equipment attached to it.

A lot of the plastic in the ocean is found in ocean garbage patches, which are large areas in the ocean where plastic accumulates due to circular ocean currents called gyres, okay? So if you have a look at the slide here, you can see the arrows on the slide show where some of the ocean currents go.

So the two arrows are to show the cold currents and warm currents.

You don't need to pay too much attention to those.

But you can see that in general, currents go in circles, and what that actually means, that the plastic in the ocean collects in the middle of these circles, okay? Now, the largest ocean garbage patch in the world is called the Great Pacific Garbage Patch, which is located between Hawaii and California, and it contains millions of tonnes of plastic waste, making it a huge environmental problem.

Okay, let's check what we've learned so far.

What feature can be found in the middle of the Pacific Ocean between Hawaii and California? The Great Pacific Garbage Patch.

Well done if you got that one correct.

So as I've put here, the Great Pacific Garbage Patch is located between Hawaii and California.

It contains millions of tonnes of plastic waste, making it a huge environmental problem.

Well done if you got that right.

Okay, on to our second threat to the ocean.

Now, an oil spill happens when oil accidentally leaks into the ocean or onto land, and it usually happens from oil tankers, pipelines, or oil rigs.

So the photograph that we've got on the slide there is an image of an oil rig.

This sticky, black liquid spreads over the water and harms sea animals, plants, and the environment.

Oil makes the water dirty and dangerous, harming the food chain and marine life.

Even after a spill is cleaned up, oil can stay in the water and cause damage for many years to come.

So if you have a look here, you can see on the slide an image of a pelican which is sadly completely covered in oil, okay? And because it kind of mixes and spreads over a large area, it's really, really hard to clean up, so it can have a massive effect on ecosystems for years after.

Oil sticks to birds, fish, and sea turtles, making it hard for them to move, breathe, or stay warm.

And oil can also block sunlight and poison sea plants and coral reefs, which marine animals need to live.

Now, one of the biggest oil spills in history happened in the Gulf of Mexico in 2010 when an oil rig called Deepwater Horizon exploded.

Now, on the slide here, you can see an image of where the disaster happened.

And these are some of the impacts of the oil spill.

So, over 130 million gallons of oil leaked into the ocean.

It harmed fish, dolphins, sea turtles, and birds.

And the oil also damaged coral reefs and coastlines for years after.

Okay, let's check what we've learned.

So can you tell me how can oil spills affect the environment? You could either write a note down in your book or have a quick chat to the person you're sat next to.

So, oil sticks to birds, fish, and sea turtles, making it hard for them to move, breathe, or stay warm.

And oil can block sunlight and poison sea plants and coral reefs, which marine animals need to live.

Well done if you got that right.

Okay, now, not only oil and plastic can pollute the ocean, but you can also have chemical pollution as well.

So, chemical pollution can enter the ocean from many different places.

So, farms, pesticides, and fertilisers that farmers use to help the plants grow and get rid of pests, obviously these will be used on land.

However, those chemicals can end up in rivers, okay, as they flow through the soil, and rivers eventually lead to the ocean, so the rivers can act as a highway for those chemicals to enter the ocean.

Factories, some factories release waste or spill harmful chemicals into nearby water, and again, that water can then eventually reach the ocean.

And sewage and wastewater.

Dirty water from homes and businesses can carry soaps, oils, and chemicals into the ocean.

All of these can have massive negative effects.

Okay, so let's have a look at what these impacts of chemical pollution may be.

The first one is polluted water can make seafood unsafe to eat and be bad for people's health, okay? So if you imagine the marine life that we might catch for our food, if the chemicals have entered those animals, then that can be dangerous for them but also for us if we eat them.

They can poison fish, whales, and other sea creatures.

And when small animals die, bigger animals lose their food, and the whole ecosystem is affected.

Finally, some chemicals cause algae to grow too fast, blocking sunlight and killing coral reefs and plants, okay? So that especially happens if fertiliser collects in the water.

It means that algae grows, and therefore there's too much algae and other plants and animals in the ocean don't get sunlight, and therefore they can't grow.

Okay, let's check what we've learned.

So, name three sources of chemical pollution that can enter the ocean.

So have a look at these images.

Can you think what they stand for? Okay, so well done if you got that.

So farms, factories, and sewage wastewater are all sources of chemical pollution.

Okay, so overfishing happens when people catch too many fish, so the breeding population becomes too depleted to recover, okay? So, naturally, yes, we can catch a few fish, and that will be absolutely fine because the fish will reproduce and the ecosystem will carry on.

However, if we catch too many of these fish, then the population can't recover and eventually it will die out.

So this causes fish populations to get smaller and can harm the entire ocean environment.

Now, billions of people rely on fish for their food, and fishing provides a livelihood for millions of people.

So, if we caused those populations to die out, it was our fault, but it can also affect the people that live in those areas because it's one of their main food sources, especially people that live in coastal areas.

An example of this is the Atlantic cod collapse.

So, in the 1990s, fishermen caught so many Atlantic cod off the coast of Canada that the fish population dropped dramatically.

This caused the fishing industry to shut down for years.

Other animals in the food chain that depended on cod for food were also affected, and the ocean ecosystem took a long time to recover.

Okay, let's check our understanding.

So, true or false? Overfishing is when people catch fish for a long period of time.

That is false, and can you tell me why? Overfishing happens when people catch too many fish from the ocean faster than the fish can reproduce and increase the population.

Well done if you got that right.

Okay, we're on to our first task for this lesson.

So, on the slide, I have got an article about the oil spill in the Gulf of Mexico.

What I would like you to do is read the article on the Gulf of Mexico oil spill and explain how oil spills can have long-term environmental effects.

And what I mean by that is how an effect might not just last a day or a week or even a couple of weeks, but how it can last for years, okay? So read the article and have a go at the task.

Secondly, what I'd like you to do is read the effects of overfishing and organise them into social, environmental, or economic effects.

So it might be worth using three different coloured highlighters for this.

If you've not got highlighters, you could use a letter or a number to put into those three different categories.

Now remember, a social effect is how it affects people, an environmental effect is how it affects nature, and an economic effect is to do with money and business.

So pause the video and have a go at the categorization task.

Okay, let's have a look at the answer.

So I've got an example answer here for the first task.

You didn't need to write exactly this, but hopefully you've got something along these lines: Oil spills have long-term effects because they continue to harm the environment and wildlife years after the spill happens.

For example, in the Gulf of Mexico, dolphins were still being unwell long after the 2010 Deepwater Horizon spill.

Coastal plants also died, which led to more erosion and loss of important habitats.

These lasting impacts show that even after the oil is cleaned up, the damage to the ecosystem can go on for many years.

Okay? Well done if you got something similar.

You could always pause the video and add a little bit of extra detail to your own answer if need be.

Okay, so on the slide here, I've got the answers to task 2, so pause the video and check that you have got those correct.

Okay, we're moving on to our second learning cycle for this lesson, which is looking at the threat of climate change to the ocean.

Okay, these are some of the main general effects of climate change on the ocean.

So, warming oceans is a big one, so yes, we are seeing our land temperatures increasing, but also, the ocean temperature is going up as well.

Ocean acidification is a big one, and we're gonna learn about what that is in a minute.

Changes to marine life and rising sea levels.

Now, climate change causes the ocean temperature to increase, so the sea water is getting warmer.

When the water is too warm, corals, which are animals that live in coral reefs, get stressed, okay? So they don't like the temperature that's got higher, okay? And when they get stressed, they can lose their bright colours.

This is called coral bleaching.

So, on the slide here, this is an example of a coral reef which has become bleached.

Corals may struggle to survive and can die, which affects all the animals that live in the coral reefs as well.

So it not just causes the actual coral to die, but the animals that live in it can die as well.

Coral reefs protect coastlines and support fishing and tourism, so their loss affects both ocean life but also people as well.

Okay, let's check what we've learned.

So, what has happened in this picture? Climate change causes the ocean temperature to increase.

This can cause coral bleaching, which is where coral loses its colour.

Well done if you got that right.

Sea levels are rising as well.

So the ocean level is rising because of melting ice from glaciers and ice sheets.

And also, warmer water expands, so it causes the ocean level to go up as well, okay? So as you can see here, you've got some ice that's on the left, which is probably either in the Arctic or Antarctica.

When that melts, that causes the ocean level to actually go up, okay? Sea levels rising impacts on marine environments.

Beaches, mangroves, and wetlands can be flooded or lost.

And rising waters can change or destroy habitats where marine animals live.

Coastal flooding will have a significant impact on people too.

Look at the flood projection map of London, and what impacts do you think this will have? So if you have a look at the map that we've got on the slide, the area that has been shaded in the darker blue shows the projected flooding in the future due to sea level rise.

So, you can see that there's some areas of land which have been shaded in, so those are areas that are going to become flooded.

So what impacts do you think that might have? Have a quick chat with the person you're sat next to.

So people will have to leave their homes.

Businesses will be flooded.

Transport networks will be affected.

There's the cost of the flood damage and the economic cost of preventing flooding.

So there's lots of social and economic effects of that flooding.

Okay, what I would like you to do is suggest one social, one environmental, and one economic effect of flooding.

So you could either write these down or have a quick chat with the person you are sat next to.

So a social one could be people will have to leave their homes.

An environmental one is rising waters can change or destroy habitats where marine animals live.

And finally, an economic one is cost of the flood damage.

Well done if you got any of those, but there are other ones you could have had too.

Now, ocean acidification is when the ocean absorbs extra carbon dioxide from the air, which makes the water more acidic, and that's having many negative effects.

So as we've learned in previous lessons that we are burning fossil fuels, which is releasing greenhouse gases such as carbon dioxide into the atmosphere, okay? So, some of that carbon dioxide is absorbed by vegetation, and some of it is absorbed by the ocean.

But if you mix carbon with water, okay, it creates carbonic acid.

So the sea water or the ocean water can become in areas slightly more acidic.

Now, the effects of this are acidic water makes it harder for creatures like corals, clams, and oysters to build their shells and their skeletons.

And when corals and shellfish suffer, the whole habitat can break down, affecting many other animals in the food chain.

So, an example of where this is happening is ocean acidification in the Great Barrier Reef in Australia.

So, rising CO2 levels have made the ocean more acidic around the reef.

This acidification slows coral growth and weakens coral skeletons.

Scientists have observed more coral bleaching and reef damage, and this threatens the many fish and animals that depend on the reef for food and shelter.

The reef also protects Australia's coastline from storms and supports tourism and fishing jobs.

So yes, it's having a massive environmental impact, but that environmental impact is affecting the people and the businesses that are there as well.

Okay, let's check our understanding.

So true or false? Ocean acidification is when water is polluted from human activities on land.

So that's false, and can you tell me why? Ocean acidification is when the ocean absorbs extra carbon dioxide from the air, which makes the water more acidic.

Well done if you got that right.

Okay, we're on to our final task for this lesson.

So, what I would like you to do is create a poster making people aware of the threat of climate change on the ocean.

So your poster should include information on warming oceans, sea levels rising, ocean acidification, and a real-life example of where this is happening.

Make sure that your poster has all this information.

Use bright colours to make people see it as well, okay? So, pause the video and get going with your poster.

Okay, here's mine on the slide, but I'm sure you got a lot more detail than I did, okay? So, I've got a section there on warming oceans, so rising ocean temperatures disrupt marine ecosystems, fuel stronger storms, and threaten biodiversity.

Rising sea levels, so melting ice and expanding warmer water are causing sea levels to rise, endangering coastal cities and habitats.

And ocean acidification.

Increased carbon dioxide is making oceans more acidic, harming coral reefs and shell-forming marine life, okay? So, well done on your poster.

You could always have a quick check of your partner's poster to make sure that they ticked off everything in the criteria.

Okay, here we've got a summary for today's lesson.

Now, plastic pollution harms marine life and spreads through ocean currents.

Oil spills and chemical pollution damage marine ecosystems. Overfishing reduces fish population and disrupts marine food chains.

Climate change warms oceans and causes coral bleaching.

And rising sea levels and ocean acidification threaten coastal and ocean habitats.

Now, that's it for me for today's lesson.

Well done.

I'm sure you've done a fantastic job.

And I'll see you next time.

Bye.