Brown algae

Brown seaweeds contain the brown pigment, fucoxanthin, as well as chlorophyll and vary in form from small filaments to tubes to large leathery kelps several metres in length. Large brown algae form complex communities on rocky coasts worldwide including Sargassum communities which are found locally.


Ectocarpus fasciculatus

common name: none
features: thalli usually small to 5 cm long, growing to 50 cm long during blooms; main filaments well developed, sparsely branched near the base and much branched in the upper thallus with the lateral branches arising in series from one side of the main filament; filaments 25-40 µm in diameter.
habitat: epiphytic on larger macroalgae or seagrasses growing in sheltered to wave swept habitats.
blooms: in winter and spring in Pumicestone Passage and Moreton Bay

Hincksia mitchelliae

common name: none
features: thallus medium to dark brown, usually to 10 cm long but longer in nutrient rich habitats, with much branched filaments. Filaments 30-60 µm near thallus base tapering 20-30 µm towards the thallus apex.
habitat: sheltered to wave swept rocky shores.
blooms: recorded once, during winter in Pumicestone Passage.

Hincksia sordida

common name: none
features: small to large thalli to 100 cm long forming loose tangled masses, composed of sparsely-branched filaments 30-50 µm in diameter.
habitat: epiphytic on larger macroalgae or seagrasses in calm sheltered estuaries and bays.
blooms: small fragments ~ 5 cm long occurred in spring and early summer of 2002-2005 at Main Beach, Noosa and north to Fraser Island, with wave action depositing large masses along the beaches. Large thalli of this species grow during winter at Cleveland, Victoria Point and possibly at other localities in southern Moreton Bay.

Colpomenia sinuosa

common name: oyster thief
features: thalli appear as globular, convoluted, hollow, thin sacs 2-25 cm in diameter broadly attached to rocks. Known in other countries to grow attached to oysters, with detached large air-filled thalli floating away with the oyster.
habitat: sheltered to wave exposed rocks.
blooms: in Gold Coast estuaries, periodically washed out and fragmented by the surf into brown flakes commonly referred to as 'cornflakes' by swimmers.

Sargassum spp.

common name: none
features: thallus leathery, to 50 cm or more high, composed of one to several thick (0.5-1 cm) main axes ('stems') bearing lateral branches, leaf-like structures, vesicles (floats) and receptacles (reproductive structures).
habitat: lower intertidal and subtidal zones on wave exposed and sheltered rocky shores; common species in drifts and indicator of low nutrient waters.