How Does Sargassum Impact Marine Ecosystems and Human Life?
Sargassum is abundantly found in seas/oceans. More than 300 species of Sargassum are currently found around the world. The species called macroalga S. muticum (Yendo) Fensholt is covering the waste area around the ocean world. It is named as the most aggressive marine invader. Initially, Sargassum algae originated and spread over the world from South East Asia. In the 1940s S. muticum was introduced into the Pacific Northwest region along with Japanese oysters. Now, it’s widespread around the Atlantic coasts from Portugal to Norway.
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Sargassum Seaweed
The Sargassum weed is also known as gulfweed or sea holly, Around 150 species of brown algae are generally attached to the rocks along the coasts. While other species remain as free-floating algae in the open sea. The large quantities of floating sargassum in the tourist beaches create negative impacts but not create any health risks.
The floating rafts of sargassum are widespread over the ocean. It usually looks like a · sargasso island, which is not attached to the floor. The sargassum looks like branched leafy appendages and round berry-like structures provide oxygen to the aquatic features. The Pneumatocysts are buoyant and are filled with oxygen and help them to float on the surface of the water. The floating seaweeds will grow and provide feed for microbes and allow the fishes/turtles / marine birds/crabs and other species to breed in it. This helps to save the lives of marine life. Some fishes like sargassum, mahi mahi, jacks spend their whole lives within this sargasso island. When the sargassum loses its buoyancy, it sinks and reaches the seafloor. It starts decomposing and provides carbon to the fishes and other species in the deep sea. Hence, it plays a vital role in the deep-sea food chain.
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How Does the Sargassum Seaweed Develop?
As the Sargassum are brown-green algae, they enable photosynthesis through sunlight and convert light energy into chemical energy. which helps in the formation of glucose. These seaweed’s glucose will stay as the building block for its carbohydrates. Through this energy source, the seaweed will successfully grow around the habitat. During the photosynthesis process, the algae will absorb carbon dioxide and other nutrients in the form of nitrogen from the water and release oxygen into the atmosphere and dissolve the oxygen. This will enhance the lives of marine habitats. The photosynthesis will also take place in the sargassum kelp, when the algae are kept for dehydration.
During the absence of sunlight, the seaweeds will stop photosynthesis and start intaking oxygen and burn glucose. The seaweeds will utilize the sunlight effectively for the photosynthesis process while compared to the other terrestrial plants.
Usually, the red macroalgae will grow in the deeper seas. The brown algae are found in the middle level to absorb minimum sunlight. While, the green algae are found floating at sea level for maximizing the utilization of sunlight. They will start synthesizing their own food at their level with the available substrate, nutritional elements, temperature and sunlight. The sunlight penetration into the underwater will stay at 0.0005% which is sufficient for the red algae to grow up to 268 meters.
Unlike other terrestrial plants, they need no roots, stems, and real leaves for processing the food. The algae directly interact with the surface of the seaweeds by diffusion and active transport. Each cell will take its own responsibility to synthesize its food and share its nutrition.
All Sargassum will utilize the nitrogen as the major weed growth under the water. It is particular for the green algae development. The summer or warm days will favour boosting the growth of algae.
The Sargassum algae and other varieties of algae play vital roles in the global ecosystem. A study says that about 90% of atmospheric oxygen is synthesized by the seaweeds and it is 2-14 times more than that of terrestrial plants and trees and grasses. Researchers found that the best species of brown algae can develop half a meter in a day. Also, it will develop in centimeters within an hour.
Applications of Sargassum
All the dried seaweeds will contain phenol levels up to 20%. The physodes of Phaeophyta have tannin substances with phenolic character, which are widely available in marine algea.
The sea weeds are also identified as a rich source of bioactive compounds. The extracts exhibit antimicrobial properties against pathogenic microorganisms.
Pharmaceutical companies, physiologists and chemists have started paying attention to marine organisms, particularly on Sargassum weeds for screening bioactive substances.
The phenolic compounds and other secondary metabolites are found at a high level in the marine brown algae, namely phlorotannins.
The components extracted from sargassum kelp are used for the production of food proteins and particularly for myofibrillar proteins.
The expert researchers are extracting the gel enhancer from the Sargassum 2021 (S. tenerrimum). These compounds are made of phenolic substances.
The sea algae are the richest source of protein than that of the yolk of eggs.
FAQs on Sargassum: Biology, Uses, and Benefits
1. What is Sargassum?
Sargassum is a genus of large brown seaweed, a type of macroalgae, belonging to the class Phaeophyceae. Unlike most seaweeds that are attached to the seafloor (benthic), many Sargassum species are uniquely adapted to a free-floating (planktonic) existence in the open ocean. It is commonly known as gulf-weed and is characterised by its branching thallus with berry-like, gas-filled bladders that help it stay afloat.
2. What is the scientific classification of Sargassum?
The taxonomic classification of Sargassum places it within the kingdom of protists. Its classification is as follows:
Kingdom: Chromista
Phylum: Ochrophyta
Class: Phaeophyceae (Brown Algae)
Order: Fucales
Family: Sargassaceae
Genus: Sargassum
3. What biological adaptations allow Sargassum to thrive in the open ocean?
Sargassum has several key adaptations for its pelagic lifestyle. The most important feature is its small, berry-like, gas-filled sacs called pneumatocysts or gas bladders. These structures provide buoyancy, allowing the alga to float at the ocean's surface where it can access sunlight for photosynthesis. Additionally, its ability to reproduce asexually through fragmentation allows it to proliferate rapidly, forming vast floating mats.
4. What is the ecological importance of Sargassum?
Ecologically, floating Sargassum is vital. It creates a unique, mobile marine habitat known as the Sargasso Sea. These floating mats serve as critical environments in the open ocean, providing:
A nursery ground for juvenile fish, sea turtles, and invertebrates.
Food and shelter for a diverse range of marine species, including crabs, shrimp, eels, and seabirds.
A breeding ground for species specifically adapted to this environment, such as the Sargassum fish.
5. How does free-floating Sargassum differ from seaweed found on coastlines?
The primary difference lies in their habitat and structure. Typical coastal seaweeds (like kelp or Fucus) are benthic, meaning they are attached to a solid substrate like rocks or the seabed using a root-like structure called a holdfast. In contrast, pelagic Sargassum is planktonic; it floats freely throughout its life cycle and lacks a holdfast, relying on its gas bladders for buoyancy in the open ocean.
6. What are the main uses and benefits of Sargassum for humans?
Sargassum offers several benefits and has diverse applications. It is a rich source of nutrients like proteins, carotenoids, and polysaccharides. Key uses include:
Agriculture: Used as a potent biofertiliser and soil conditioner due to its rich mineral content.
Animal Feed: Processed into feed for livestock.
Pharmaceuticals: Studied for its anti-inflammatory, antioxidant, and antimicrobial properties.
Biofuel Production: Explored as a potential source for producing biogas and bioethanol.
7. Is it safe for humans to swim in waters with large amounts of Sargassum?
While fresh, floating Sargassum in the open ocean is generally harmless, it can pose risks when it washes ashore and decomposes. As it rots on beaches, it releases hydrogen sulfide gas, which smells like rotten eggs. In high concentrations, this gas can cause respiratory irritation, dizziness, and headaches. Direct contact with the decaying seaweed can also cause skin irritation for some individuals.
8. Why can massive Sargassum blooms sometimes be an environmental problem?
While beneficial in the open ocean, excessive Sargassum blooms, sometimes called 'golden tides', can be detrimental to coastal ecosystems. When massive quantities wash ashore, they can:
Smother coastal habitats like coral reefs and seagrass beds by blocking sunlight.
Cause anoxia (oxygen depletion) in the water as the large biomass decomposes, leading to fish kills.
Hinder sea turtle nesting by blocking access to beaches for nesting females and trapping hatchlings.
Negatively impact tourism due to foul odours and inaccessible beaches.
