Inland Waters of the Pilbara, Western Australia - Environmental ...

Because of the remoteness of the Pilbara, use was made of a 4-wheel drive vehicle equipped
with long-range fuel tanks, spare parts and a HF radio so that repairs could be carried out
and contact made with Port Hedland Royal Flying Doctor Base if emergencies arose.
Sufficient provisions and fuel were carried for several weeks work away from sources of
supplies. As only a small amount of space was available for collecting gear and specimens,
sampling of the fauna was limited. Appropriate licences to collect plants and animals were
obtained from the Department of Fisheries and Wildlife
During the course of the study 76 sites were surveyed. Observations were made on a number
of physical and biological characteristics at each site visited. Land tenure was ascertained
from cadastral maps. Field observations were recorded on an amended version of
Paijmans' (1978) proforma. This proforma was subsequently revised on the basis of field
experience and from reference to a report on a field study of African wetlands (Morgan and
Boy, 1982). The revised proforma (see Appendix 1) is recommended for recording field data
on subsequent field studies of Pilbara inland waters.
The system of springs and pools at Millstream is the best lrnown body of inland water in the
Pilbara. Because it has been studied in some detail (Dames and Moore, 1975). and because
the importance of Millstream is recognized by its National Park status, it was not
intensively sampled in the course of this study.
The methods used for measuring and observing parameters are briefly outlined below.
2.2 PHYSICAL CHARACTERISTICS
Water temperature, conductivity, dissolved oxygen, pH and turbidity of surface waters (0-10
cm depth unless stated otherwise) were recorded with a thermometer and a Horiba U. 7 Water
Checker, Horiba Ltd Japan. Surface water permanency, water source and the relationship
to groundwater were assessed where possible by direct observation and by reference to
anecdotal data from local people familiar with the site. Observations of substrate types and
bed gradients were also made.
The area and depth of each water body were estimated and recorded for the time of sampling.
Estimates were made of prior maximum flood levels from flood debris along levee banks
and caught in trees.
2.3 BIOLOGICAL CHARACTERISTICS
The dominant floral and characteristic fauna! associations of different wetland types were
examined to obtain base-line data useful in the formulation of a suitable classification
system for the surface waters of the Pilbara region.
(i) Fringing vegetation - The fringing vegetation was sampled along a transect from the
land/water interface to a point designated as the limit ofwetland influence (eg top of a levee
bank) and recording apparent zonation patterns. Plant specimens were collected, pressed
and dried in the field, and mounted on herbarium sheets (often more than one specim~n per
sheet due to space limitations) for later identification.
Preliminary identifications were made in the field and at Karratha with the assistance of W
Edgecombe and P Ryan from the Forests Department. Identifications were verified by M E
Trudgen using the facilities of the W A Herbarium. Specimens will be mounted and used as
aids for plant identification during future studies in the region.
(11) Aquatic vegetation - The emergent and submerged aquatic macrophytes were
sampled and zonations recorded. Specimens were collected and treated similarly to those of
fringing vegetation. The more delicate submerged plants were preserved in 10% formalin.
(iii) Phytoplankton - Phytoplankton was sampled to determine concentration and
major genera present. A known quantity of sample water, up to I L, was filtered through a
Whatman 2.5 cm D GF /C filter. The filter was airdried and stored in the dark for subsequent
determination of the major chlorophyll concentrations by the trichromatic method
(Strickland and Parsons, 1972). A 5 ml water sample was also passed through a Metrical
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