Seaweed
Seaweed or macroalgae refers to several species of macroscopic, multicellular, marine algae. The term includes some types of red, brown, and green macroalgae. Marine algae species such as kelps provide essential nursery habitat for fisheries and other marine species and thus protect food sources; ocean algae species from seaweeds to planktons play a vital role in carbon capture, producing up to 90 percent of the planet's oxygen. Understanding these roles provides guiding principles for conservation and sustainable use of seaweeds to take precedence over industrial exploitation. Mechanical dredging of kelp, for instance, destroys the resource and dependent fisheries. Certain species of seaweed are valuable for nutrition, biomedicine, bioremediation, and other uses.
Harmful algal bloom
The other types of algae are diatoms and dinoflagellates, found primarily in marine environments, such as ocean coastlines or bays, where they can also form algal blooms, commonly called red tides. Red tides, however, may be a natural phenomenon, although when they form close to coastlines or in estuaries. They can occur when warmer water, salinity, and nutrients reach certain levels, which then stimulates their growth. Most red tide algae are dinoflagellates. They are visible in water at a concentration of 1,000 algae cells per milliliter, while in dense blooms they can measure over 200,000 per milliliter.