Spiny seaweed
Acanthophora spicifera
Acanthophora spicifera is a marine red alga known for its highly branched, bushy structure and characteristic spine-like projections. It preferentially inhabits shallow, warm coastal waters, reef flats, and lagoons, growing on hard substrates or as an epiphyte. The coloration of the alga is highly variable, ranging from light green and yellowish to deep dark red, depending on light intensity and nutrient levels. In some regions, most notably Hawaii, it is considered an invasive species due to its rapid growth rate and ability to displace native ecosystems.
Details
Oxygen production
Significant oxygen release during the light phase as a byproduct of photosynthesis.
Habitat function
Forms complex three-dimensional structures that serve as nurseries for marine microorganisms.
Nutrient uptake
High efficiency in taking up dissolved nitrogen (ammonium/nitrate) and phosphate from the water column.
Food source for
Food source for numerous herbivorous marine inhabitants, including the Green Sea Turtle.
Human use
Used in some cultures (e.g., Philippines) as a salad ingredient or studied for the extraction of agar-like substances.
Ecology
Ecological role
Important primary producer in benthic systems; provides habitat and hiding places for various small crustaceans, polychaetes, and juvenile fish.
Natural predators
Herbivorous fish such as surgeonfish (Acanthuridae) and rabbitfish (Siganidae), as well as sea turtles and sea urchins.
Competitor species
Other macroalgae (e.g., Dictyota, Sargassum) and reef-building corals, which can be overgrown during nutrient surplus.
Ecosystem service
Nutrient sequestration, oxygen production, and provision of biomass for the food web.
Threats
Herbicide pollution near coasts and extreme ocean acidification; however, locally often more of a threat as a non-native species.
Scientific profile
Profile
Reproduction
Triphasic life cycle (Polysiphonia type): alternation between haploid gametophytes, diploid carposporophytes, and diploid tetrasporophytes. Very effective vegetative reproduction through fragmentation, where broken parts quickly form new colonies.
Protection & threats
Status not on standard scale
Main threats
No immediate threats known; the species benefits from anthropogenic eutrophication and ocean warming.