Sargassum is a tannish-brown species of macroalgae, also known as seaweed.

What’s going on?

When it dies, it sinks to the sea floor, providing nutrients to deep-sea ecosystems. Sargassum also provides extremely important refuge and habitat for species like sea turtles, fish, crabs, shrimp and more. In fact, in 2003, Sargassum was designated as Essential Fish Habitat within the U.S. Exclusive Economic Zone off the southern Atlantic states, which gives these habitats special protection.

However, nutrient inputs by humans can cause it to bloom out of control and form massive mats that cause issues for natural ecosystems and humans alike.

Why it matters.

In 2018, 20 million tons of sargassum bloomed, nearly spanning from Africa to the Atlantic Ocean. This impacted the Florida Keys and Florida’s marine coasts. 2021 has been another record year, with the macroalgae blooming in significant amounts

Sargassum can deprive coastal waters from oxygen, limiting animal movement. This species is also a problem for humans, as it can wash up on beaches in enormous quantities, decomposing, releasing noxious gases, and causing skin irritation.

What you can do.

Featured image from iNaturalist user kruskaya_024 (CC-BY-NC 4.0).