Habitat Changes, Growth and Abundance of Juvenile Giant Spiny Crayfish, Euastacus hystricosus (Decapoda: Parastacidae), in the Conondale Ranges, South-east Queensland Geoffrey Clifford Smith 1 , Adrian Borsboom 1 , Rina Lloyd 2 , Nadya Lees 1 and John Kehl 3 (Communicated by J.R. Merrick) 'Resource Sciences Centre, Department of Natural Resources (DNR), RO. Box 631. Indooroopilly, Q. 4068; department of Environment, Brisbane, Q. 4000 and 'Forest Allocation and Use, DNR, Mineral House, Brisbane, Q. 4000 Smith, G.C., Borsboom, A., Lloyd, R., Lees, N. and Kehl, J. (1998). Habitat changes, growth and abundance of juvenile giant spiny crayfish, Euastacus hystricosus (Decapoda: Parastacidae), in the Conondale Ranges, south-east Queensland. Proceedings of the Linnean Society of New South Wales 119, 71-86. As part of broader investigations of the impacts of catchment activities on water quali-ty and stream faunas, aspects of habitat, growth and abundance of the giant spiny cray, Euastacus hystricosus, have been studied (1984-1994) in two creek catchments in the Conondale Ranges. E. hystricosus juveniles grew during their first summer and autumn; most ceased growing in winter, then resumed growth as water temperature rose again in spring. Slope coefficients of linear regression lines fitted to the growth data for the first growth period to May did not differ significantly between catchments or years. Juveniles were generally larger in Bundaroo Creek in any month, with significant differences in May of 1987 and in 1994. Individuals were also significantly larger in Bundaroo Creek in October of 1993 and 1994. While population fluctuations within each stream were similar, densities of crayfish along the Bundaroo Creek survey transect were slightly lower than the transect on North Booloumba Creek. Turbidity was usually higher in North Booloumba Creek which may, in part, explain differences in growth rate; however, uneven precipitation in the Conondale area and short-term effects of rain events on stream turbidity would contribute to poor correlation of rainfall records with growth or abundance. Manuscript received 6 September 1997, accepted for publication 15 January 1998. KEYWORDS: Juveniles, growth, population size, Euastacus hystricosus, paired catchment, habitat, environmental conditions. INTRODUCTION The Giant Spiny Crayfish Euastacus hystricosus (Morgan 1988; Riek 1951) is restricted to upland streams surrounded by rainforest or wet sclerophyll forest in the Conondale and Blackall Ranges of south-eastern Queensland (Morgan 1991). Females mate and spawn in autumn (March to April) and incubate eggs, attached to their pleiopods, from May to September (Kehl, unpublished data; Turvey and Merrick 1997a). However there is little published information on other aspects of the biology or ecology of this species. This situation reflects a general lack of baseline data on the Australian freshwater crayfishes (Merrick 1993, 1995). This is somewhat surprising, given their bio-geographic status, and their potential as indicators of environmental health. Freshwater macro-inverte-brates in general are considered indicators of environmental health (Faith and Norris 1989; Proc. Linn. Soc. n.s.w., 119. 1998
Habitat changes, growth and abundance of juvenile giant spiny crayfish, Euastacus hystricosus (Decapoda: Parastacidae), in the Conondale Ranges, south-east Queensland
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