Biology of the Blood Crayfish, Euastacus gumar Morgan 1997, a small freshwater crayfish from the Richmond Range, northeastern New South Wales

Abstract

The biology of Euastacus gumar, a poorly known species of crayfish from northeastern New South Wales, is recorded for the first time. The distribution of the species was compiled following a major regional survey, and micro- and macro-habitat information was recorded at each site. Long-term monitoring was carried out at one site in Culmaran Creek to gather data on growth, moulting, maturity and reproductive activity, and berried females were retained in aquaria to study egg and juvenile development. The species is slow-growing and likely long-lived. Moulting occurs during the warmer months, and growth increments are small (0.8-2.3 mm OCL). A small proportion (< 50%) of mature females breed during the cooler months, carrying 20-150 eggs for a relatively short gestation period (2 months). Although the species does not rely on flowing or standing water, it is restricted to the rainforested headwater reaches of each of the nine streams it inhabits, and large areas of cleared, agricultural land separate the species into three disjunct areas on the Richmond Range and the Yabbra Spur. Euastacus gumar is a narrow range taxon with a fragmented, highland distribution (overall extent of occurrence = 985 km2). The species is uncommon across its range, and under IUCN criteria should be considered 'Endangered' due to its restricted and fragmented distribution and an anticipated decline in the quality and amount of habitat due to climate change.