American Oceans

Kelp vs Seaweed: Unveiling the Key Differences and Benefits

When it comes to the marine world, there’s often confusion surrounding the terms ‘kelp’ and ‘seaweed.’

Forest of Seaweed

While they may seem interchangeable, these two words actually refer to different types of marine life that serve a variety of purposes. Understanding their differences can provide insight into their uses and the roles they play in the ecosystem.

Seaweed is a general term referring to over 10,000 marine-based species, encompassing plants and micro-algae that can be classified into three groups: brown, red, and green.

These various types of seaweed grow in a range of sizes, and their colors determine how much light they absorb through photosynthesis, which in turn dictates their position within the ocean’s depths.

seaweed growing into the deep sea

On the other hand, kelp is a type of brown seaweed, found specifically in cold waters such as the North Pacific Ocean.

Kelp is known for its size, as it tends to be larger than most other seaweeds.

While both kelp and seaweed share certain characteristics, it is essential to recognize their unique properties and uses within the marine environment and beyond.

Overview of Kelp and Seaweed


Kelp and seaweed are both marine algae species, but they differ in several aspects.

What is a kelp forest?

Seaweed is a term used to describe over 10,000 species of marine algae, including red, brown, and green varieties. These groups are distinguished by their differing light absorption rates, which influence both their color and their position in the ocean.

Conversely, kelp is a specific type of seaweed that thrives in cold waters, such as the North Pacific Ocean.


While seaweed encompasses a vast array of different species with dramatic variation in size, kelp is consistently larger in comparison.

sargassum seaweed

Kelp, often also referred to as rockweed, shares more similarities with plants than other types of seaweed, and it is noted for its high calcium content.

The distinct color groups of seaweed have direct effects on their ability to absorb light via photosynthesis, determining how close to the ocean’s surface they grow.

Meanwhile, kelp, a type of brown seaweed, boasts a rich nutrient profile consisting of vitamins, minerals, and carbohydrates. This makes it particularly valuable for various applications, including fertilizer and nutritional supplements.

Uses in Gardening

  • Seaweed – Often used as a versatile fertilizer for plants, owing to its high nutrient content.
  • Kelp – Typically found in cold waters and frequently utilized as a natural supplement for its numerous health benefits.

Although kelp and seaweed share some common characteristics, they are indeed different species of marine algae, each with distinct traits and applications in agriculture, health, and nutrition.

Habitat and Distribution

Kelp Forests

Kelp, a type of large brown algae, typically thrives in cool, relatively shallow waters close to the shore in colder seas.

School of fish swims through kelp forest

These aquatic plants grow in dense groupings, forming underwater forests that provide essential habitats and food sources for thousands of marine species, including fish, invertebrates, and marine mammals.

Kelp forests are widespread in temperate and polar regions, with millions of people living within 50 kilometers of these vital ecosystems.

Often found along rocky coastlines, kelp anchors itself to rocks and uses its blade-like fronds to capture sunlight for photosynthesis. The rapid growth rate and high productivity of these underwater forests rival even the most productive tropical rainforests on land.

Seaweed Ecosystems

Seaweed, a more general term, encompasses various types of algae including kelp.

Green Seaweed

Seaweed ecosystems are diverse and can be found in various marine environments such as oceans, rivers, and lakes. They grow in a wide range of conditions, from shallow and cool saltwater along rocky shores to deeper and warmer waters.

Some seaweeds, often referred to as sea vegetables, are even edible for humans.

Seaweed ecosystems provide important habitats and food sources for numerous marine organisms. They also serve essential roles in nutrient cycling, water purification, and coastal erosion prevention.

These diverse ecosystems support various types of marine flora and fauna, contributing significantly to the overall biodiversity of the world’s oceans.

Nutritional Benefits and Uses

When discussing the nutritional benefits and uses of kelp and seaweed, it is essential to understand the key differences and unique properties that each type of marine plant offers.

person eat seaweed and enjoy its benefits

Kelp Benefits

Kelp, a type of brown seaweed, is known for its rich nutritional content. Packed with vitamins, minerals like iodine, and antioxidants, kelp offers various health benefits. For example:

  • It may help prevent cancer due to its antioxidant properties.
  • Kelp can promote cardiovascular health by providing essential nutrients and vitamins.
  • It may reduce fat absorption in the gut, thus supporting weight loss efforts.

These benefits make kelp a popular choice for those looking to improve their overall health through dietary changes.

Seaweed Benefits

Seaweed, while encompassing a broader range of marine plants, also offers many nutritional benefits. Some of the advantages of incorporating seaweed into one’s diet include:

  • Improved gut health, as seaweed contains prebiotic fibers that support beneficial gut bacteria.
  • Boosting immune system function due to its high levels of vitamins and minerals.
  • Potential protection against certain types of cancers, as seaweed contains compounds with antioxidant properties.
  • Heart health support, as some types of seaweed have been shown to help reduce cholesterol and blood pressure levels.

With these benefits in mind, it is evident that both kelp and seaweed are valuable additions to a healthy diet.

Culinary Applications and Recipes

Kelp and seaweed have been widely used in various cuisines for their unique flavors, texture, and nutritional benefits.

With their versatility in both raw and cooked forms, these marine plants have found their way into several dishes in the form of seasonings, ingredients in salads, sushi, and more.

Kelp-based Meals

Kelp, a large, brown seaweed, lends a satisfying density to dishes when rehydrated and softened. It is commonly used in:

  • Salads: Rehydrate kelp in cool water, drain, and slice before adding to salads for a unique texture and flavor.
  • Seasonings: Dried kelp can be powdered and used to add umami flavors to various dishes, including sauces and soups.
  • Broth: Cooking beans and simmering broths with kelp can enhance the dishes’ taste and nutritional content.

Seaweed-based Meals

Seaweed, with its great diversity in size and species, makes for an interesting addition to many dishes.

  • Sushi: Nori, a type of red seaweed, is commonly used to wrap sushi rolls, offering a delicate, crisp texture.
  • Seasonings: Crushed seaweed can be used as a flavorful and nutritious sprinkle on salads, rice, and noodle dishes.
  • Snacks: Some seaweeds, like wakame and nori, are enjoyed as dried, ready-to-eat snacks, often seasoned with spices and other flavors.
  • Beignets: One creative example is making seaweed and tofu beignets, small fried dough balls, combining yuzu kosho, and lime mayonnaise for a flavorful condiment.

Environmental Impact and Sustainability

Kelp and seaweed, both members of the marine algae family, have a significant impact on the environment and offer sustainable solutions to some pressing global issues. These aquatic plants play a crucial role in combating climate change and promoting ocean health.

Research indicates that kelp, a type of macroalgae, has an impressive capacity to reduce the effects of global warming.

Thanks to its rapid growth rate, sometimes reaching up to two feet per day, kelp can effectively remove carbon from the atmosphere and transfer it to the deep sea.

This process allows for the permanent removal of carbon, therefore mitigating the consequences of climate change.

Seaweed, on the other hand, demonstrates its environmental benefits through its ability to absorb carbon dioxide more efficiently than trees. This incredible capability enhances water quality by extracting harmful nutrients, such as nitrogen, from the ocean.

Additionally, the cultivation of seaweed ensures minimal disturbance to the ecosystem, as it does not require the use of fertilizers, pesticides, or freshwater resources, thereby promoting sustainability.

Both kelp and seaweed contribute to the overall health of marine ecosystems. As natural habitats for a variety of marine species, these algae forests provide essential nutrients, shelter, and breeding grounds, which in turn support the survival and development of diverse aquatic life.

The cultivation of seaweed and kelp can have positive environmental outcomes, as well.

Sustainable seaweed farming has the potential to reduce overfishing and support the growth of healthier, more biodiverse marine environments.

Furthermore, kelp farming can mitigate the effects of ocean acidification and warming temperatures, thus protecting sensitive ecosystems, such as coral reefs and seaweed habitats.

Economic Importance and Market Trends

The economic importance of seaweed and kelp has been growing steadily in recent years, with the global seaweed market experiencing rapid expansion.

seaweed farmer

Seaweed farming represents a significant sector within the blue economy, providing jobs, food, and other valuable resources.

Seaweed farming is the fastest-growing aquaculture sector, as noted by NOAA Fisheries.

In Alaska, for example, there was a 200 percent increase in commercial kelp harvest between 2017 and 2019. This growth is not limited to small farms, with commercial-scale operations emerging in larger markets across Asia, where the majority of seaweed production currently takes place.

Seaweed holds great potential in supporting rural and remote communities, where job opportunities in aquaculture can help to enhance the local economy.

The Australian Seaweed Institute, as described by the World Economic Forum, aims to establish a seaweed farming industry in Australia, with the goal of mitigating climate change and creating jobs in the process.

Market trends indicate that various seaweed products, such as nori and kelp, are gaining popularity among consumers.

This is likely due to increased awareness of the nutritional benefits of seaweed – it is rich in vitamins, minerals, and antioxidants – and the growing interest in more sustainable food options.

As a result, companies and entrepreneurs are investing in seaweed-related businesses and product development, further increasing the economic importance of this resource.

Some key points about the seaweed and kelp market trends are:

  • Fastest-growing aquaculture sector
  • 200% increase in commercial kelp harvest in Alaska (2017-2019)
  • Majority of production currently in Asia
  • Emerging market opportunities in rural and remote communities
  • Increasing popularity of seaweed products due to health and sustainability factors

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