Product Code Database
Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, ocean algae. The term includes some types of Rhodophyta (red), Brown algae (brown) and Chlorophyta (green) macroalgae. Seaweed species such as provide essential nursery habitat for fisheries and other marine species and thus protect food sources; other species, such as algae, play a vital role in Blue carbon and producing at least 50% of Earth's oxygen.
Natural seaweed ecosystems are sometimes under threat from human activity. For example, mechanical dredging of kelp destroys the resource and dependent fisheries. Other forces also threaten some seaweed ecosystems; for example, a wasting disease in predators of purple urchins has led to an urchin population surge which has destroyed large kelp forest regions off the coast of California.
Humans have a long history of cultivating seaweeds for their uses. In recent years, seaweed farming has become a global agricultural practice, providing food, source material for various chemical uses (such as carrageenan), cattle feeds and fertilizers. Due to their importance in marine ecologies and for absorbing carbon dioxide, recent attention has been on cultivating seaweeds as a potential climate change mitigation strategy for Biosequestration, alongside other benefits like nutrient pollution reduction, increased habitat for coastal aquatic species, and reducing local ocean acidification. The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate recommends "further research attention" as a mitigation tactic.
The number of seaweed species is still a topic of discussion among scientists, but it is most likely that there are several thousand species of seaweed. (2012). 9780878936021, Oxford University Press Inc. ISBN 9780878936021
| Submerged. |
| In intertidal zones on rocky shores. |
| Cultivated for food. |
| Also known as kelp 8–30 m under water and cultivated for food. |
| Giant kelp forming floating canopies. |
| Intertidal zones in temperate climate and cultivated for food. |
| Pelagic especially in the Sargasso Sea. |
Seaweed occupies various ecological niches. At the surface, they are only wetted by the tops of sea spray, while some species may attach to a substrate several meters deep. In some areas, littoral seaweed colonies can extend miles out to sea. The deepest living seaweed are some species of red algae. Others have adapted to live in tide pool. In this habitat, seaweed must withstand rapidly changing temperature and salinity and occasional drying.Lewis, J. R. 1964. The Ecology of Rocky Shores. The English Universities Press Ltd.
Macroalgae and macroalgal detritus have also been shown to be an important food source for benthic organisms, because macroalgae shed old fronds.. These macroalgal fronds tend to be utilized by benthos in the intertidal zone close to the shore. Alternatively, pneumatocysts (gas filled "bubbles") can keep the macroalgae thallus afloat; fronds are transported by wind and currents from the coast into the deep ocean. It has been shown that benthic organisms also at several 100 m tend to utilize these macroalgae remnants.
As macroalgae takes up carbon dioxide and releases oxygen in the photosynthesis, macroalgae fronds can also contribute to carbon sequestration in the ocean, when the macroalgal fronds drift offshore into the deep ocean basins and sink to the sea floor without being remineralized by organisms. The importance of this process for blue carbon storage is currently a topic of discussion among scientists.
| + Seaweed production
! Country
! tonns per year, cultured and wild | |
| China | 20,351,442 |
| Indonesia | 9,962,900 |
| South Korea | 1,821,475 |
| Philippines | 1,500,326 |
| North Korea | 603,000 |
| Chile | 427,508 |
| Japan | 412,300 |
| Malaysia | 188,110 |
| Norway | 163,197 |
| United Republic of Tanzania | 106,069 |
Gim (김, Korea), nori (海苔, Japan) and zicai (紫菜, China) are sheets of dried Porphyra used in soups, sushi or onigiri (rice balls). Gamet in the Philippines, from dried Pyropia, is also used as a flavoring ingredient for soups, salads and . Chondrus crispus ('Irish moss' or carrageenan moss) is used in food additives, along with Kappaphycus and gigartinales seaweed. Porphyra is used in Wales to make laverbread (sometimes with oat flour). In northern Belize, seaweed is mixed with milk, nutmeg, cinnamon and vanilla to make "dulce" ("sweet").
Alginic acid, agar and carrageenan are gelatinous seaweed products collectively known as or . Hydrocolloids are food additives.Round F. E. 1962 The Biology of the Algae. Edward Arnold Ltd. The food industry exploits their gelling, water-retention, emulsifying and other physical properties. Agar is used in foods such as confectionery, meat and poultry products, desserts and beverages and moulded foods. Carrageenan is used in salad dressings and sauces, dietetic foods, and as a preservative in meat and fish, dairy items and baked goods.
Seaweeds are used as animal feeds. They have long been grazed by sheep, horses and cattle in Northern Europe, even though their nutritional benefits are questionable. Their protein content is low and their heavy metal content is high, especially for arsenic and iodine, which are respectively toxic and nutritious.
Last updated on May 29, 2017, 16:46 Adding seaweed to livestock feed can substantially reduce methane emissions from cattle, but only from their feedlot emissions. As of 2021, feedlot emissions account for 11% of overall emissions from cattle.
Seaweed extract is used in some diet pills. Other seaweed pills exploit the same effect as gastric banding, expanding in the stomach to make the stomach feel more full.
Seaweed is under consideration as a potential source of bioethanol.
Alginates are used in industrial products such as paper coatings, adhesives, dyes, gels, explosives and in processes such as paper sizing, textile printing, hydro-mulching and drilling. Seaweed is an ingredient in toothpaste, cosmetics and paints. Seaweed is used for the production of bio yarn (a textile).
Several of these resources can be obtained from seaweed through Biorefinery.
Seaweed collecting is the process of collecting, drying and pressing seaweed. It was a popular pastime in the Victorian era and remains a hobby today. In some emerging countries, seaweed is harvested daily to support communities.
Seaweed is sometimes used to build roofs on houses on Læsø in Denmark.
The so-called "stinging seaweed" Microcoleus lyngbyaceus is a filamentous cyanobacteria which contains toxins including lyngbyatoxin-a and debromoaplysiatoxin. Direct skin contact can cause seaweed dermatitis characterized by painful, burning lesions that last for days.
Sea have replaced kelp forests in multiple areas. They are "almost immune to starvation". Lifespans can exceed 50 years. When stressed by hunger, their jaws and teeth enlarge, and they form "fronts" and hunt for food collectively.
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