Journal of the Royal Society of Western Australia, 90(3), September 2007 
Figure 1. Map with the exact location of Hyden, the inselbergs 
Wave Rock (WR) and King Rocks (KR) in Western Australia. 
The lines indicate the major roads in the area. The scale 
indicates 5 km. 
organisms, the first procedure aimed at the smaller 
benthic organisms and the second procedure was 
performed to collect the larger macro-invertebrates 
missed by the first sampling method. Benthos samples 
were taken by placing a plastic rectangular frame 
enclosing a surface of 0.5m^ randomly in the pool. Tlie 
water was stirred thoroughly to lift all the benthic 
organisms. The calculated volume of the enclosed water 
was subsequently removed with a plastic one litre 
measuring aip and poured through a 64pm filter. The 
filtered content was then preserved in 70% ethanol. This 
was done once for small pools, twice for medium sized 
pools and three times for large pools and aimed at 
sampling roughly 10% of the surface of the pools. On 
King Rocks there was time to sample only nine of the 35 
pools by this method. 
The second sampling method was done with a 500- 
pm kicksampler. Between 5 and 30 kicks were executed 
with the same speed and covering the same distance, 
aiming at covering the whole surface of the pool once. 
Macroinvertebrates were partly picked out in the field 
and the sample residuals were preserved in 70 % ethanol 
and double checked for presence of animals in the lab. 
Samples were screened in the lab for macroscopic 
organisms and identified as far as possible under an 
OLYMPUS SZ-X 12 stereo-microscope. All studied pools 
on both outcrops were sampled by this method. 
In this study, the species list (Table 1) is compiled 
simply on a presence/absence basis and the cumulative 
richness curve (Fig. 2) is based on 999 permutations of 
the Wave Rock data. Due to identification uncertainties, 
Chironomidae (at least five taxa) as well as AJon.i (2), 
Ephemeroporus (2), Paroster (2), Limnocythere (3) and 
Macrotrix (2) are each treated as a single taxon in the 
graph. 
Results 
We found 58 and 43 taxa in the rock pools on Wave 
Rock and King Rocks, respectively, and 66 taxa overall 
(Table 1). The most speciose groups in our study were 
Coleoptera (15), Cladocera (13), Ostracoda (12) and 
Diptera (10). The most common organisms were the 
ostracod Cypretta baylyi and the endemic cladoceran 
Neothrix armata, both occurring in 51 of the sampled 
pools. Although not identified to species level, 
Chironomidae and Turbellaria were present in 55 and 48 
of the sampled pools and are also a major component of 
the rock pool communities. The rare taxa in these systems 
occurring in only one, or two pools were all Insecta 
(Necterosoma penicillatus, Tipulidae, Rhantus sp., 
Limnoxenus zelandicus, Micronecta gracilis) as well as a 
gastropod (Glyptophysa sp.) and a cladoceran 
(Planicirclus alticarinatus). 
On average we found 18.7 ± 5.0 taxa in the rock pools 
on Wave Rock. Most of the common species occurring on 
Wave Rock were found after the sampling of 10 rock 
pools. Although the slope of the Cumulative Species 
Richness curve (Fig. 2) decreased with increasing number 
of pools, the curve did not plateau. 
Discussion 
More species were found on Wave Rock than King 
Rocks (57 as against 43), probably because of the lower 
sampling effort on King Rocks. In fact King Rocks has 
more pools and bigger pools (see later) than Wave Rock, 
so it is likely it has more species. Our figures for species 
richness compare with the average 48.9 taxa in the study 
by Finder et at. (2000). Their highest taxon richness (77 at 
Wanara Rock), was much higher than ours, but this rock 
was advantaged by having a deep (50cm) artificially 
dammed pool with macrophytes that is normally wet for 
much of the year (B. Turner pers. comm.). A long 
inundation cycle in temporary pools is one of the most 
important factors determining the composition and 
structure of communities (Wellborn et al. 1996). A longer 
inundation cycle, removes the developmental constraints 
which could prevent some organisms occurring in the 
most temporary pools (e.g., Odonata), allows for a 
transition of taxa (succession) and also provides a refuge 
for actively dispersing insects with an adult aquatic 
phase such as several Hemiptera. The richness values for 
Figure 2. Cumulative species richness curve for 57 rock pools 
sampled on Wave Rock. 
138 
