11. 09. 2025 Elliot Yu

How do the Sounds of Kelp Forests Change?

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The age-old question goes “If kelp falls in a kelp forest and no one is around to hear it, does it make a sound?” … or something like that.

The study of kelp forest soundscapes is new, but it is essential to understanding the ecosystem.

What are kelp forests?

Kelp forests are incredibly diverse and important ecosystems of organisms living within dense areas of (surprise) kelp in coastal regions.

Kelp forests, and more generally seaweed forests, act as major carbon storage for the planet and are, when compared to the woods, incredibly diverse, containing mammals, arthropods (shrimps), echinoids (sea urchins), brachiopods (a shelled animal that feeds via filter feeding) and much more.

What does the Ocean sound like?

The Ocean is surprisingly noisy. Sound is used to convey information over long distances, and to neighbours on the reef or in the grass. In water, sound travels farther than either light or chemical cues and moves almost five times as fast as it does in air.

Marine mammals like whales and dolphins are famously loud and use sound to communicate. Sperm whales can reach volumes louder than jet engines. But a shocking truth is that other marine animals contribute to the Ocean soundscape too! For example, did you know that some fish make hums and purrs?

Beyond marine animals, there are other sound sources in the Ocean. Geological sounds (earthquakes and landslides) and our own human activity (engines and drilling) have their own effects on the Ocean soundscape.

What do kelp forests sound like?

Kelp forests are an unfamiliar setting to most of us, so to assist on our adventure of the soundscape, we’ll venture through the woods at the same time.

In the woods, we hear distinctive, familiar noises. The twitter of birds, the chattering of rabbits and the chirps of insects dominate the soundscape. In kelp forests, we can hear the different calls of fishes and the frequent snapping of shrimp.

The noises of kelp forest can be separated by their pitches. Generally, lower tones contain the noises of marine mammals and fish. The higher tones we’d hear contain the clicks of snapping shrimp and the sound of echolocating dolphins (although this is higher than the human ear can hear so it’s silent to us).

These soundscape features often change in both environments over time due to natural factors, like seasonal changes, or human activity.

Daily changes in the kelp forest soundscape

As the night comes, the sounds of the daytime animals switch to the noise of nocturnal animals.

In the woods, hooting owls and squeaking bats take over the soundscape along with the occasional chirp from foxes. This daily change is seen in kelp forests too, where the activity of animals and therefore the volume of their sounds shifts over the course of the day.

For some species of fish, their noise peaks at sunset and dips at sunrise. As well as this, snapping shrimp are nocturnal, which shows in their activity, as they have peaks at sunset and sunrise but a decreased activity during the day.

Seasonal changes in the kelp forest soundscape

With the arrival of autumn and winter in the woods, some animals migrate or hibernate, removing their noises from the soundscape.

A seasonal change also occurs in the kelp forest, where the time of year can affect the presence of animals.

The Plainfin Midshipman fish makes nests near the coast and uses a humming noise to attract a mate. This humming is heard in the kelp forests during late spring and summer, consistent with their mating season. Contrasting this, the presence of snapping shrimps is maintained year-round.

Plainfin Midshipman fish humm during spring and summer. Posted by Ocean Generation. — *Photo by Sara Thiebaud*

Human influence on kelp forest soundscapes

On our walk through the woods, we come across barren spots without trees, caused because of storms or fires. Similarly in the Ocean, an abundance of sea urchins and a lack of suitable food can cause them to feast on kelp clearing the area and leaving a space overrun with small, malnourished sea urchins, with the East Fish camp in California having an urchin density of 26.8 urchins per square metre.

Although urchin barrens may seem like a natural environment, they are created by human activity, just as extreme weather can become more prominent because of global warming.

Normally, sea otters and the occasional fish prey on urchins before the situation gets out of hand. But, due to hunting and overfishing, sea urchin predation is decreased, allowing their population to spike and kelp forests to be removed.

Urchin barrens influence the kelp forest soundscape. Posted by Ocean Generation. — *Photo by Ed Bierman*

Sea urchin barrens influence the kelp forest soundscape as the region becomes less suitable for some species and more suitable for others. When hundreds of sea urchins move in, they change biodiversity.

A more direct human influence on woodland soundscapes is deforestation. The direct removal of trees by humans to clear space or for resources is easily a big issue, as it decreases habitat space, reducing biodiversity and harming ecosystems.

A similar situation happens with kelp as it can be harvested, as it has uses like in food and beauty products. As a consequence, the amount of kelp is decreased, showing little to no recovery after two years, and biodiversity can change to be unlike before harvesting.

Does human noise affect kelp forests?

Listening in our woods, we don’t only hear animal noises but also human noises. Cars on roads which cut through the woods or heavy machinery operating can create loud persistent noises which can disturb the soundscape, affecting the distribution of the animals.

The same is true for animals in the Ocean. Loud noises like drilling and seismic surveys are loud and the noise can be emitted for tens of kilometres, causing confusion and hearing damage in marine mammals and fish.

Other sounds like engine noises from low flying planes and boats can act as background noises which decrease the distance that animals can hear and communicate.

Sound disturbances can normally be mitigated in kelp forests by kelp’s ability to attenuate (absorb and decrease) sound. However, because of the removal of kelp forests, this mitigation can quickly be removed.

The building of docks and other structures may seem like they could bring back attenuation, but they can also transfer noise from cars and docking boats into the Ocean, affecting microenvironments.

What can we do?

It may seem daunting that humans can cause all of this damage, but not all change is bad. Just as forests can be replanted and wildlife protected, as can kelp forests.

The growth of kelp can be stimulated, and areas can become marine protected areas, which can allow areas to be conserved. An example of this is in New Zealand, where an urchin barren has recovered back into a kelp forest within a marine protected area over the period of 20 years.

Looking at how we live our lives, like where our fish comes from or our usage of boats can make a difference in helping this delicate ecosystem.

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Elliot Yu

How Do Sea Otters Make Themselves at Home in the Kelp Forest?

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5. 09. 2025 Elliot Yu

Is Seaweed the Secret to Ditching Plastic? Explained.

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Plastics play an essential role in modern human civilisation. They are incredibly versatile, providing function in almost all aspects of our lives.

Why plastic is a problem for us and the Ocean?

Fossil-based plastics are infamous for their long-lasting impact on the environment, taking up to hundreds or thousands of years to fully break up. Along the way, they harm wildlife and people both as large plastic items and microplastics.

The impact of this is demonstrated perfectly in the Ocean, where wildlife can unknowingly eat or interact with plastics. It has been observed that every species of sea turtle has been affected by entanglement in plastic.

Plastics have another big problem. They’re sourced from oil, which contributes to their damage to the environment. 3.4% of global emissions were contributed by the plastic lifecycle in 2019, with 90% of that being emissions from production and converting fossil fuels into plastic making materials.

What's wrong with plastic - for us and the Ocean? Explained by Ocean Generation.

What are microplastics?

Microplastics are plastic particles less than 5mm in size formed from the breakup of plastic. They’re found across the planet, from deep in the Ocean to the snow high in the mountains. They’ve even been found in the human body. We don’t fully know yet what that means for our health, but we do know they harm marine life and can travel up the food chain.

Single use plastics, like plastic bags and straws, are big contributors to plastic waste, making up approximately half of all plastic waste. We only use them once and then throw them out, which means more and more plastic needs to be made to maintain supply.

What is the solution to our plastic usage problem?

Recycling is one solution to this problem, but in 2019, the OECD estimated that only 9% of plastics are recycled.The rest is disposed of in landfill sites (50%), incinerated (19%), or goes unregulated into uncontrolled landfills, fires or the environment, including our Ocean (22%). On top of this, not all plastics are recyclable. Is there another solution?

What are bioplastics?

According to European Bioplastics, “bioplastics” are either bio-based, biodegradable, or both. Bio-based plastics are plastic alternatives which, rather than using fossil fuels to source the plastic, use biological feedstock (materials) like starch or cellulose.

Bio-based plastics are not necessarily biodegradable. Biodegradability has no clear definition or criteria, but in general, a product is biodegradable if a substance can be broken down into water, biomass and gasses. As a result of this definition, biodegradable fossil-based plastics can be considered as bioplastics.

What are the different types of bioplastics?

There are 3 distinct generations of bioplastics, all defined by what they’re made of:

1^st generation bioplastics use food crops like corn or soybeans.
2^nd generation bioplastics use non-food crops like grass and wood.
3^rd generation bioplastics use seaweed and algae.

What are bioplastics made of? Posted by ocean Generation.

What’s the major difference between using seaweed and crops?

The major difference between crop-based and seaweed-based bioplastics is where they are planted.

The first two generations of bioplastics use fertile land which could be used for growing other crops.

Seaweed bioplastics are bio-based plastics and derived from seaweed. Seaweed bioplastics don’t have the same problems as the other generations as seaweed grows in the Ocean (which there is much more of than fertile land on Earth), and require only sunlight, atmospheric CO₂ and the naturally nutritious waters of the Ocean.

They are a relatively new discovery; the first seaweed bioplastics company was established in 2010. Lady Gaga’s music career began before bioplastics were commercial.

How are seaweed bioplastics made?

The first step is letting the seaweed spores grow before they are put into a seaweed farm. They are then harvested a few months later.

The seaweed contains molecules that can be extracted via chemical processes. These have gelling and film-making (like plastic wrap, not movies) properties which make them useful in bioplastic production.

The extraction process leaves behind residuals. These leftovers can be turned into seaweed pellets which can feed back into the bioplastic making process, reducing waste. They can also be converted into methane which comes with the disadvantage of being a greenhouse gas. However, if captured and stored, it can be a carbon effective source of methane, which can be used in the chemical industry, or as a cleaner fuel than fossil fuels.

Our molecules can be mixed with other substances like nanoclays or silver nanoparticles to improve strength or change properties like making them antimicrobial.

Seaweed bioplastics are already used commercially in places like food packaging – that’s pretty kelp-ful!

Seaweed is a macroalgae growing in the Ocean.

What is the environmental impact of seaweed bioplastics?

The life cycle assessment of seaweed bioplastics looks at its carbon footprint from harvesting it from farms in the Ocean to its disposal in bins. Pilot scale assessments (these represent full production at a smaller scale) show that their production released more carbon than plastic, however, models show that scaling up production to full scale makes their carbon output less than plastics.

What are the downsides of seaweed bioplastics?

Making seaweed bioplastics relies heavily on farming and harvesting seaweed. This may present a problem when scaling up seaweed farms, especially to the size of being able to match plastic production, if this is even possible. Seaweed farms take up space in the Ocean, and they affect organisms that are living in areas where farms are viable, like seagrasses and corals by blocking light or choking them.

This problem can be mitigated by moving seaweed farms into the open Ocean and optimising growth by growing two different species in the same space. This can be done by growing buoyant kelp and non-buoyant seaweed next to each other to best use space.

Seaweed can also wash onto the coast from farms and decay, releasing pollutants that were absorbed over the life of the seaweed, affecting the local environment and limiting biodiversity.

There is also the problem that not all bioplastics are biodegradable. While it may be entirely possible that seaweed bioplastics specifically are biodegradable, there isn’t yet enough literature to suggest that this is the case.

On top of this, the definition of biodegradability has no specific time frame in which a material should be broken down in, meaning this vagueness could be taken advantage of.

This reintroduces a problem that we were trying to solve, simply sourcing the plastics from elsewhere.

Which plastic or alternative is the bets to choose?

Which plastic (or alternative) is the best to choose?

There are many factors that go into considering a product: the production, the functionality (how good it is at what it’s supposed to do) and the environmental cost.

However, it can be difficult to remove bias. Take single use paper bags for example. At first glance, they seem much more environmental than single use plastic bags as they’re biodegradable, but when put into practice, they have a higher carbon footprint in production than plastic bags and aren’t as strong. So, it’s difficult to tell which of these is better.

As more research goes into seaweed bioplastics, we may find solutions to the problems associated with them and have a more accurate understanding of their impact as they are produced on a larger scale. For now, it is better to avoid single use items altogether, and to use seaweed bioplastics where available.

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Elliot Yu

How Do Sea Otters Make Themselves at Home in the Kelp Forest?

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3. 09. 2025 Peter Reynolds

What Happened to the Steller’s Sea Cow? Explained.

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There are two theories about what happened to Steller’s sea cow. Let’s unpack them.

Steller’s sea cow was a 7-metre-long, 5-tonne cousin of the manatee; known to graze peacefully in kelp forests. But just 30 years after the sea cow’s discovery – it vanished from the Ocean forever.

In this article we’re going to explore two theories for why this marine species disappeared. Both involve hunting, but one requires an understanding of the habitat that Steller’s sea cow called home: the kelp forest.

By looking at this complicated history, we can begin to understand the complex interactions going on under the Ocean surface, and learn lessons about how we can best preserve these incredible ecosystems in the present.

Steller's sea cow was a 7-metre-long, 5-tonne cousin of the manatee. Posted by Ocean Generation. — *Steller’s sea cow sketch by Biodiversity Heritage Library*

The story of Steller’s sea cow starts with a shipwreck.

On the 6th November 1741, the Svyatoy Petr was shipwrecked on an isolated and uninhabited island, now known as a part of the Commander Islands chain. For several months, the crew of sailors, cartographers, geographers, and natural historians had been carrying out one of the first scientific explorations of the North Pacific.

Stranded for nearly a year, the remaining crew salvaged materials from the wreckage, and built a ship that could cross the Ocean back to Russia.

One of the most consequential outcomes of this failed expedition was the presence of a curious and observant naturalist, George Wilhelm Steller. For almost a year, he made meticulous observations, sketches, and notes on the unfamiliar and captivating wildlife that surrounded him, which have been left to us as an invaluable historical and ecological artefact.

From a massive population to extinct:

One creature left a particularly strong impression on George Steller. He wrote in his journal of ‘gigantic manatees grazing all about the island’s lagoons’. These cousins of the manatee would often exceed 5,000kg in weight. He observed that they were very sociable creatures, sticking in large herds and eating kelp floating at the Ocean surface as though it were grass, ‘in the same way as horses and cattle’.

Although Steller wrote that they were so numerous that ‘that they would suffice to support all the inhabitants of Kamchatka’, a twist of fate left them extinct by the 1760s. To understand them, scientists have had to look at historical evidence and their closest living relatives, dugongs and manatees.

Sketch of a Stellers sea cow. Posted by Ocean Generation.

Story One: Hunting

Steller’s crew hunted sea cows as a source of food whilst stranded on Bering Island. Steller recalled a story in his journal about the psychological stress this placed on them. Whilst hunting a female sea cow, a male aggressively followed and tried to ram their boat, following all the way to shore long after the female had died. They also hunted other creatures including otters and seals.

This is the most common theory for the extinction of the sea cow: they were exploited for their meat, fat, and hides, the latter of which would be used in the construction of boats. This theory suggests that the hunting was so widespread and unsustainable that the population was put under great stress and collapsed within 30 years.

Story Two: Loss of Keystone Species

In the past few decades, a group of scientists have put forward an alternative theory.

This theory pays attention to the complex dynamics of kelp forests, and the role that sea otters play as ‘keystone species’: species that play a disproportionate role in managing the ecosystems they call home. As we explained in a recent article, sea otters’ appetite for sea urchins prevents overgrazed ‘urchin barrens’ emerging – desolate stretches of rock with little to no vegetation – in the place of lush and biodiverse kelp forest. Do read this article if you want to learn more!

Difference between an urchin barren and healthy seafloor. Posted by Ocean Generation. — *Urchin barren photo by Ed Bierman, healthy seafloor photo by Zachary Randell*

Whilst Steller’s sea cows were hunted on these expeditions, sea otters were the main pursuit. When the first groups returned with the fur pelts of sea otters, traders were so astonished at their thickness and quality that they sold for nearly 100 rubles a pelt – 25 times more than the equivalent pelt from land animals. It’s been said that they were, at some points, worth more than gold! In the wake of the euphoria that ensued, the sea otter population collapsed so quickly and dramatically that they were observed to be at the brink of extinction around the Commander Islands by 1753.

Kelp forests create a complex habitat for a diversity of species, with one study in Norway suggesting that the average piece of kelp in their study site supported 8,000 individual organisms. If sea otters are lost to hunting, the kelp forests can be transformed into urchin barrens, as there are no otters to control sea urchin populations. As kelp is lost, the Steller’s sea cow loses their source of food, a change to their environment that might have ultimately resigned them to extinction.

Sketch of a sea otter by Steller. — *Sketch of a sea otter by Steller*

Which theory about the extinction of Steller’s sea cow is it?

Both theories are reasonable. Ecosystems are complex and difficult to understand completely, and it is probably a bit of both. As I have been reminded by one of the scientists who proposed the second theory, ‘the lack of good data from the extinction of sea cows means that we are unlikely to ever really know.’

Sea cows may be extinct, but this story is not irrelevant, and shouldn’t be the cause of doom and gloom or eco-anxiety.

As scientists have better understood the role of sea otters as a ‘keystone species’ that maintain kelp forests, we have become more capable of putting conservation programmes in place that work. The recovery of sea otter populations in the Pacific is arguably one of the greatest success stories of conservation, bringing back both populations of sea otters and the coastal ecosystems they engineer such as kelp forests. At the moment, we can look to innovative projects such as the Monterey Bay Aquarium’s surrogacy programme for hope, which raises orphaned pups so that they can be reintroduced back to the wild. (You can see them on the aquarium’s live stream here!)

We may have lost Steller’s sea cow, but we can still restore kelp forests for the countless other species that call it home.

Steller had a sense for the value of sea otters, though he may have primarily seen them as creatures to hunt. He even wanted to bring some home as pets. ‘The sea otter,’ he wrote, ‘deserves the greatest respect from us all’. Although he couldn’t have understood the complex work that they do as a ‘keystone species’ as we do today, we can all wholeheartedly agree with him.

Sea otters are guardians of kelp forests. Posted by Ocean Generation.

Cover image via Biodiversity Heritage Library

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Peter Reynolds

How Do Sea Otters Make Themselves at Home in the Kelp Forest?

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How do the Sounds of Kelp Forests Change?

The age-old question goes “If kelp falls in a kelp forest and no one is around to hear it, does it make a sound?” … or something like that.

What are kelp forests?

What does the Ocean sound like?

What do kelp forests sound like?

Daily changes in the kelp forest soundscape

Seasonal changes in the kelp forest soundscape

Human influence on kelp forest soundscapes

Does human noise affect kelp forests?

What can we do?

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