An assemblage of cyanobacteria (blue-green algae) or other photosynthetic microorganisms forming a dense flat mass, especially on or within the surface layer of an aquatic sediment.
Origin
Early 20th century.
Definition of algal mat in US English:
algal mat
noun
An assemblage of cyanobacteria (blue-green algae) or other photosynthetic microorganisms forming a dense flat mass, especially on or within the surface layer of an aquatic sediment.