Journal of the Royal Society of Western Australia, 90: 137-142, 2007 
A contribution on the biodiversity and conservation of the freshwater 
fauna of rocky outcrops in the central Wheatbelt of Western Australia 
M Jocque’, B V Timms^ & L Brendonck' 
' K.U.Leuven, Laboratory of Aquatic Ecology, 
De Beriotstraat 32, B-3000 Leuven, Belgium. 
^School of Environmental and Life Science, 
University of Newcastle, Callaghan, 2308, Australia. 
Correspondence to: Brian Timms 
S Brian.timmscfl'newcastle.edu.au 
Manuscript received jammry 2007; accepted June 2007 
Abstract 
Rock pools on top of inselbergs are probably the only freshwater biotopes in the Wheatbelt of 
southwest Western Australia not threatened by salinisation. Their invertebrate fauna is highly 
diverse, but variation on and between outcrops raises serious difficulties in setting minimum 
conservation goals to protect the rock pool fauna in the central Wheatbelt. We intensively sampled 
the invertebrate communities in a large number of pools on Wave Rock (57 pools) and King Rocks 
(35 pools) near Hyden. To help establish the conservation value of these habitats we present a 
comprehensive list of species. Overall 66 taxa were found. Sampling of 10 pools on an outcrop is 
enough to establish the most common species, but even after sampling 57 pools, new species were 
still being added to the list. We argue for the conservation of several rocky outcrops in different 
precipitation zones. Outcrops should bo selected on the criteria of (a) degree of isolation from the 
other outcrops, (b) the presence of large and deep pools and (c) whether amphibians breed in the 
rock pools. 
Keywords: conservation, rock pool, gnamma, granitic inselberg, freshwater fauna, biogeography. 
Introduction 
Freshwater habitats in the Wheatbelt of WA are scarce 
and disappearing through salinisation (Halse et al. 2003; 
Finder et al. 2004). Probably the single habitat 
independent from this problem are rock pools on granitic 
inselbergs, locally known as "gnammas". These 
"freshwater havens", as Ian Bayly (1992) describes them, 
are completely rain dependent, support a diverse fauna 
and flora, and in many cases provide water for humans 
as well (Laing & Hauck 1997; Bayly 2002). The people of 
Hyden, a town in the central Wheatbelt in Western 
Australia, still use the w'ater collected from Wave Rock 
for drinking and stock water. Two recent symposia 
(Hopper & Withers 1997; Withers & Hopper 2000) have 
drawn attention to rocky outcrops, but nonetheless the 
rock pools in Western Australia remain a poorly studied 
habitat. Some ecological, but mostly systematic studies, 
presenting the results of surveys at the community level 
have been completed (Bayly 1982 1997; Finder et al. 
2000). These studies found strong differences in species 
richness in pools on and between rocky outcrops. 
Differences in species richness between outcrops in WA 
are related to regional precipitation patterns, affecting the 
length of the inundation period (joeque et al. 
unpublished data). The length of the inundation period 
in temporary waters is probably the single most 
important factor determining the structure and richness 
of a community (Wellborn et al. 1996). The heterogeneous 
environment (I'.e., variation in depth, size, sediments. 
© Royal Society of Western Australia 2007 
vegetation, in-pool boulders) of the pools further results 
in a diverse group of species occurring on a single 
outcrop (Finder et al. 2000). The rich and diverse aquatic 
invertebrate fauna combined with the large proportions 
of endemic inhabitants in these rock pools (Frey 1998) 
and the vulnerability of temporary (freshwater) habitats 
in arid Australia (Roshier et al. 2001) urge the protection 
and conservation of these rock pool habitat systems. The 
high diversity on and between outcrops poses serious 
difficulties in setting minimum conservation goals to 
protect the rock pool fauna in this region and Finder et 
al. (2000) made a plea for more intensive studies of 
Wheatbelt outcrops to obtain a better idea of the 
distribution of rock pool inhabitants. To help establish 
the conservation value of these habitats we present a 
species list from an intensive survey of 57 pools on Wave 
Rock and an extensive survey of 35 pools on King Rocks. 
A more detailed analysis of the data will be published 
elsewhere. 
Material and Methods 
Study site 
The rock pools sampled were situated on Wave Rock 
(57 pools) near the town of Hyden and King Rocks (35 
pools) approximately 50 km northeast of Wave Rock (Fig. 
1) We sampled the pools in the winter of 2004 from 8"' of 
July to 29* of August. 
Sampling protocol 
Two sampling methods were used to collect the 
137 
