Euastacus robertsi

Euastacus robertsi is a large freshwater crayfish belonging to the family Parastacidae, a group of decapod crustaceans endemic to Australian waterways. Like other members of its genus, it possesses a hard calcified exoskeleton, robust claws used for defense and foraging, and a long lifespan typical of spiny mountain crayfish. It is largely nocturnal, sheltering in burrows and under submerged debris by day, and feeds opportunistically on plant matter, detritus, and small invertebrates.

As a benthic omnivore, it plays a role in nutrient cycling and organic matter breakdown within its stream ecosystem, and its presence is often considered an indicator of water quality.

The species is restricted to a small range in the subtropical/tropical moist lowland forests of Australia, where it inhabits cool, well-oxygenated freshwater streams and rivers. Its distribution is highly localized, making it especially vulnerable to environmental disturbance.

Threats include predation and competition from invasive species, alteration of stream habitat through logging and land clearing, encroachment of annual and perennial cropping into catchment areas, and continued harvesting by fishers. Habitat shifting linked to broader environmental change compounds pressure on the limited watercourses this species depends on, as sedimentation and altered flow regimes degrade burrow sites and water quality.

Conservation measures specific to this species remain limited, though it benefits indirectly from general protections afforded to freshwater habitats and forested catchments in parts of its range, along with broader research attention given to threatened Euastacus crayfish as a genus.

Population trends are currently unknown due to a lack of systematic monitoring. Given its narrow range and multiple ongoing threats, the species' conservation outlook remains precarious without targeted habitat protection and monitoring efforts.