Verh. Internat. Verein. Limnol. 28 1–8 Stuttgart, October 2002 Halophile aquatic invertebrates in the wheatbelt region of south-western Australia Adrian M. Pinder, Stuart A. Halse, Russell J. Shiel, David J. Cale and Jane M. McRae Introduction spread across the study area as possible and covered the full salinity range, from fresh (approx. 40% of In the wheatbelt region of inland south-western Aus- sites) to extremely saline, and included both natu- tralia, extensive clearing of native vegetation for dry- rally and secondarily saline sites. Most sites were len- land agriculture has reduced evapotranspiration tic but 15 lotic sites were included. Two samples which, in turn, has caused ground water to rise. This were collected at each site: one benthic sample using has resulted in widespread secondary salinisation and a 250-µm mesh net and one plankton sample using a waterlogging of aquatic and terrestrial environments 50-µm mesh net. Each sample involved sweeping for (GEORGE et al. 1995). Despite the severity and extent a total of 50 m (not necessarily contiguous) and of salinisation, the area still has significant conserva- included all macrohabitats (major vegetation types, tion value. This was recognised in the State Salinity organic matter, etc.) within wadeable depth. Samples Strategy (ANONYMOUS 1996), which included a sur- were sorted in the laboratory and the identities of vey of the region’s biodiversity to provide informa- vouchers were verified by taxonomists. Total dis- tion for regional conservation planning. Aquatic solved solids (APHA method 2540C, APHA 1995) invertebrates and waterbirds were censused at 230 was used as a measure of salinity and is presented as wetlands. The survey is nearing completion and parts per thousand (‰), and pH was measured in there are sufficient data to summarise some compo- the field using a WTW Multiline P4 meter and nents of the biota, such as the aquatic invertebrates probe. Some sorting and identification is still taking of granite outcrops (PINDER et al. 2000) and, in this place and data were not available from all 230 sites study, the aquatic invertebrates that show a distinct for the present study. Macroinvertebrate data were optimisation under saline conditions. available for 199 sites (lacking only for some of the Although salinity has negative connotations in a northern wheatbelt sites), copepod data for 172 sites region severely affected by secondary salinisation, (mostly in the central and southern wheatbelt) and naturally saline playas, in extensive palaeodrainage ostracod, rotifer and cladoceran data for 95 sites flats, are a prominent feature of the wheatbelt land- (mostly in the central wheatbelt). In the present scape. Many of the rivers along the south coast are study, saline water is defined as water with a salinity also naturally saline. There have been few studies of of more than 3‰, following recent convention the fauna of these saline wetlands. Forty-two saline reviewed by HAMMER (1986), and water with salinity lakes from two areas of the wheatbelt were sampled between 3 and 10‰ is termed subsaline. A halophile by GEDDES et al. (1981), but only a limited suite of is defined as a species occurring mostly or entirely in crustaceans was identified to species level. BROCK & saline water. No attempt is made to separate halo- SHIEL (1983) also included several wheatbelt sites in biont species, as variously defined in the literature a study of saline lake plants and invertebrates of the (e.g. TIMMS 1983, WILLIAMS 1985). south-west but the identification effort was concen- trated on some microinvertebrate groups. A more intensive study of aquatic invertebrates, but from a Study area smaller number of saline wetlands in the northern wheatbelt, was carried out by HALSE (1981), and two The wheatbelt is an area of mostly dryland agricul- wetlands affected by secondary salinisation were ture approximately bounded by the 600-mm rainfall studied by HALSE et al. (2000a). isohyet to the west and the extent of clearing to the east (Fig. 1), occupying a plateau of low relief, poor Methods soils and poor drainage. This region has been exten- sively cleared of native vegetation, which was mostly The 230 wetlands surveyed (Fig. 1) were as evenly eucalypt woodlands, grading to mallee inland and 0368-0770/02/0028-1 $ 2.00 ©2002 E. Schweizerbart’sche Verlagsbuchhandlung, D-70176 Stuttgart 2 Verh. Internat. Verein. Limnol. 28 (2002) Fig. 1. Map of south-western Australia showing the saline and freshwater survey sites in the wheatbelt region. scrub-heath to the south and west coasts. As already they were collected. Some invertebrates (such as mentioned, this clearing has resulted in dryland nematodes and most dipteran families) could salinity, which currently affects about 10% of the not be identified to species level, but are wheatbelt but is expected to affect up to 30% included in Table 1 because they contain halo- (ANONYMOUS 1996). The extensive inland catch- ments of the largest rivers (such as the Avon, Black- philic species. wood and Moore Rivers) are broad, low-gradient Of the new species in Table 1, Australocypris palaeodrainage flats which rarely flow. These palae- odrainage flats largely consist of hundreds of natu- sp. nov. has been recorded in previous studies rally saline playa lakes, most of which dry seasonally. (unpublished data) but several others were col- By contrast, most coastal salt lakes have a marine ori- lected for the first time in this survey. The gin. Freshwater wetlands include shallow seasonal sabellid polychaete Manayunkia sp. nov. claypans and more substantial lakes in upland areas appears to be widespread but uncommon, or in areas with fresh ground water or higher rainfall. occurring in seasonal, naturally saline playas except for one record in a broad saline drainage Results line. The new copepods and ostracods were also Approximately 730 invertebrate taxa have been restricted to seasonal, naturally saline playa identified in the survey to date, of which 680 lakes but there are only single records of these have been identified to species or morphospe- and little can be said about their habitat prefer- cies level. Of the latter, 311 species were ences and distribution in the absence of further recorded only from fresh water, leaving 369 data. The new Paroster is notable, within an species that occurred at least once at or above otherwise freshwater genus, for occurring in 3‰. Of these, 84 could be considered halo- two secondarily saline lakes in the southern philic and the rest were halotolerant freshwater wheatbelt. All of the new Parartemia were col- species. The halophile species are listed in Table lected from seasonal playas, but one also 1, along with the salinity range within which occurred in a semi-permanent lake. Parartemia A. M. Pinder et al., Assessment of halophile aquatic invertebrates 3 Table 1. List of halophilic invertebrates collected during the biological survey of wheatbelt wetlands. Taxon Salinity range (outliers) ‰ Number of records Cnidaria Australomedusa ?baylii (Russel) 21.0 1 Rotifera Ptygura ?melicerta (Ehrenberg) 55.7 1 Hexarthra ?oxyuris Sernov 6.4–45.7 3 Hexarthra fennica (Levander) 4.2–81.2 (240.2) 10 Brachionus plicatilis (Müller) 4.2–53.0 6 Brachionus quadridentatus cluniorbicularis (Skorikov) 0.4–4.9 (40.5) 5 Brachionus rotundiformis Tschugunoff 5.3–10.9 4 Mollusca Coxiella exsposita (Iredale) 3.1–31.0 (126.9) 5 Coxiella glabra Macpherson 6.0–126.9 11 Coxiella glauerti Macpherson 88.0 1 Coxiella striatula (Reeve) 3.4–27.0 (120.0) 9 Coxiella gilesi (Angas) 22.0–60.0 3 Coxiella sp. 1 49.0–88.0 2 Coxiella sp. 2 25.0 1 Oligochaeta Tubificidae sp. WA10 5.5 1 Paranais litoralis (Muller) 3.8–7.6 8 Polychaeta Manayunkia sp. nov. 20.0–49.0 (120.0) 6 Anostraca Artemia parthenogenetica 104.8–218.5 3 Parartemia contracta 84.0–240.2 3 Parartemia serventii 60.0–74.0 3 Parartemia cylindifera 20.0–49.0 2 Parartemia informis Linder 52.0–88.0 2 Parartemia sp. nov. 1 226.2 1 Parartemia sp. nov. 2 49.0 1 Parartemia sp. nov. 3 41.0–130.0 2 Parartemia sp. nov. 4 33.0 1 Parartemia sp. nov. 5 110.0 1 Parartemia sp. nov. 6 92.0–300.0 6 Cladocera Daphniopsis pusilla Serventy 40.9–81.2 5 Daphniopsis queenslandensis Sergeev (1.4) 10.7–24.1 (68.0) 6 Daphniopsis australis Sergeev and Williams 21.0 1 Ostracoda Cyprideis australiensis Hartmann 6.7–37.1 2 Australocypris insularis (Chapman) 21.0–126.9 16 Australocypris sp. nov. 33.0–240.2 6 Cyprinotus edwardi McKenzie 4.2–40.5 12 Diacypris dictyote De Deckker 30.0–81.2 4 Diacypris spinosa De Deckker 1.4–45.7 (126.9) 14 Diacypris compacta (Herbst) 20.6–146.8 11 Diacypris whitei (Herbst) 92.0–146.8 2 Diacypris sp. nov. 523 55.7 1 Diacypris sp. nov. 562 21.0 1 Mytilocypris ambiguosa 1.4–24.2 8 Mytilocypris tasmanica chapmani 4.9–60.0 (126.9) 20 Reticypris clava De Dekker (1.4) 6.7–63.0 6 Reticypris sp. nov. 556 60.0–240.2 4 Reticypris sp. nov. 640 33.0 1 Platycypris baueri Herbst 15.0–120.0 12 4 Verh. Internat. Verein. Limnol. 28 (2002) Table 1 contd. Taxon Salinity range (outliers) ‰ Number of records Leptocythere lacustris De Dekker 6.7–37.1 3 Copepoda Calamoecia clitellata Bayly (o.4, 1.6) 3.2–126.9 26 Calamoecia salina (Nicholls) 37.0–110.0 2 Calamoecia trilobata Halse & McRae 33.0–240.2 6 Gladioferens imparipes Thomson 5.5–21.0 8 Sulcanus conflictus Nicholls 3.9–10.9 3 Metacyclops arnaudi (sensu Kieffer) 6.0–240.2 26 Metacyclops sp.