Most species within the class Phaeophyceae are predominantly cold-water organisms that benefit from nutrients upwelling, but the genus Sargassum appears to be an exception.

Although the seaweed acquired a legendary reputation for covering the entirety of the Sargasso Sea, making navigation impossible,[5] it has since been found to occur only in drifts.

Many Chinese herbalists prescribe powdered Sargassum—either the species S. pallidum, or more rarely, hijiki, S. fusiforme—in doses of 0.5 grams dissolved in warm water and drunk as a tea.

Different species of Sargassum have folk applications in human nutrition and are considered a rich source of vitamins, carotenoids, proteins, and minerals.

Many bioactive chemical compounds that are classified as terpenoids, sterols, sulfated polysaccharides, polyphenols, sargaquinoic acids, sargachromanol, and pheophytin were isolated from different Sargassum species.

This community is being affected by humans due to overfishing, trash and other types of pollution, and boat traffic, which could eventually lead to the demise of this diverse and unique habitat.

Isopods of the species Bathyopsurus nybelini at depths of 5002–6288 m in the Puerto Rico Trench and Mid-Cayman spreading center have been observed consuming Sargassum.

They even exhibit several adaptations for it, such as microbiomes capable of breaking down the seaweed and fixing nitrogen, specialized swimming strokes, and serrated, grinding mouthparts.

[19] In tropical Sargassum species that are often preferentially consumed by herbivorous fishes and echinoids, a relatively low level of phenolics and tannins occurs.

[21] Once ashore, Sargassum provides vital nutrients such as carbon, nitrogen, and phosphorus to coastal ecosystems which border the nutrient-poor waters of the western North Atlantic tropics and subtropics.

[24] Coastlines in Brazil, the Caribbean, Gulf of Mexico, and the east coast of Florida saw quantities of Sargassum wash ashore up to three feet deep.

[25][21] The first major Sargassum inundation event occurred in 2011 and had a biomass increase of 200 fold compared to the previous eight years average bloom size.

[34] Massive amounts of floating Sargassum present a physical barrier preventing corals and seagrasses from receiving sufficient light, fouling boat propellers, and entangling marine turtles and mammals.

[44] Phosphates and iron transported via the trade winds from North Africa have been reported to have a fertilizing effect on Sargassum growth; further data is required to understand its role in causing inundating blooms.

[49][50] Researchers have recently begun using Moderate Resolution Imaging Spectroradiometer satellite imagery and ocean current data to track and forecast inundation events with a high level of accuracy.

[51] The effects of deforestation, waste-water runoff, and commercial agriculture fertilizer on facilitating the excess accumulation of nutrients in aquatic and marine environments have been well studied and shown to be driving factors in eutrophication.

There are methods to process and greatly reduce arsenic from this genus of seaweed, potentially making it a nearly inexhaustible food supply for animals or people.