Marine brown alga

Marine Brown Algae (Photo: L. Mamo)

Scientific name

Nereia lophocladia

Status in NSW

Critically endangered.


The Marine Brown Alga is one of four species in the genus Nereia. It has seasonal alternating life history stages, in which it goes through a microscopic stage as well as a macroscopic (visible) stage.


It is a small species, typically growing to less than 15 cm long, but may grow as large as 30 cm.

A Marine Brown Alga (Photo: B. Kelaher)


In NSW, the Marine Brown Alga has only been found on the north coast, from Sawtell to Woolgoolga Headland.


Marine Brown Alga is found on hard substrate at the sand/reef interface on the seabed in about 3 - 12 m depth of water. Knowledge of the species’ biology and ecology is only just emerging due to very few sightings prior to 2015.

Why is the Marine Brown Alga threatened?

  • Physical disturbance
  • Sand inundation
  • Climate change
  • Extreme weather events, such as large storms

A diver surveying Marine Brown Alga (Photo: B. Kelaher)

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