Studies on the ecology of some temporary freshwater pools in Victoria with special reference to microcrustaceans

Abstract

Fifty-three temporary freshwater pools (mean depth 23 cm) located mainly in eastern Victoria were studied from February to September 1973. Chemical parameters determined were pH (range 5.7-8.2, mean 6.9), conductivity (K18, range 55-5500, mean 340 �S/cm), dissolved oxygen (range 23-170, mean 72% saturation) and turbidity (range 2-310, mean 50 Formazin turbidity units). A total of 60 microcrustacean species was recorded. The Australasian endemic cladoceran, Saycia cooki (King), was of common occurrence from June through to August. The fact that it tends to reach peak numbers early in the life of a pool is probably related to the production of large numbers of ephippial eggs. In contrast, cladocera which produce only one or two ephippial eggs, such as Chydorus, Moina and Simocephalus, tend to appear later in succession. Simocephalus expinosus (benthic) and Daphnia carinata, s.l. (planktonic) had mutually exclusive distributions and are apparently unable to coexist in shallow waters. Endemic cyclopoid copepods encountered included three new species of Microcyclops, M. arnaudi (Sars), Acanthocyclops australis Sars, and Acanthocyclops, sp. nov. Like Saycia, Microcyclops varicans and Acanthocyclops bisetosus exhibited maximal numbers early in succession. Several new combinations of coexisting calanoid copepod species belonging to the genera Boeckella and Hemiboeckella are reported. Computer analysis showed that the following four groups of species had a high probability of co-occurrence: (1) Cypretta sp., Attheyella australica, Ilyodromus sp., Saycia cooki; (2) Cyprinotus leanus, Acanthocyclops bisetosus, Moina tenuicornis; (3) Boeckella major, B. pseudochelae, Cypris sp., Daphnia carinata, s.l. ; (4) Simocephalus exspinosus, Microcyclops varicans.

Invertebrates, macroalgae, and chemical features in morainic ponds near Lakes Tekapo and Ohau, including new distribution records of Crustacea

“…The conductivities of the ponds at Ohau and Tekapo were low compared with those of temporary freshwater ponds in southeast Australia (Morton & Bayly 1977) and southwest Australia (Bayly 1982), but were near the low end of the range of conductivities reported by Stout (1975) for Canterbury high-country lakes. Sodium and chloride contributed proportionally more to the total salinity than is characteristic of fresh waters of the same conductivity on continents (Hutchinson 1957).…”

“…In their study of 53 temporary pools in southeast Australia, Morton & Bayly (1977) noted that D. carinata and Simocephalus exspinosus never cooccurred and suggested that this may imply that if these 2 species are brought together in shallow pools only 1 is capable of survival. Although we found that these 2 species generally did not co-occur, we recorded them together in Pond 20 at Ohau.…”

“…The succession of species through time is a welldocumented feature of temporary ponds (e.g., Stout 1964;Barclay 1966;Morton & Bayly 1977;Bayly 1982) and the absence of some crustacean species from all sites in 1 area and their presence at several sites in the other area (e.g., Bosmina meridionalis, Simocephalus vetulus, Monospilus dispar, Ephemeroporus barroisi, Ilyodwmus smaragdinus, and 3 species of Cypretta-see Table 1) may merely be a consequence of our sampling the ponds only once. An alternative hypothesis is that the differences in distributions reflect differences in the proportion of permanent and temporary ponds in the 2 areas and in the ability of species to survive drought.…”

“…Although Byars (1960) has described the biology of a permanent pond in coastal Otago, and Stout (1964) and Barclay (1966) have studied temporary ponds in Canterbury and Auckland, respectively, the emphasis in these studies was on the changes which occurred seasonally in the ponds. There have been no general surveys of the water chemistry or of the invertebrates of ponds in New Zealand of the kind, for example, done by Hartland-Rowe (1966) for approximately 300 pools in western Canada, by Morton & Bayly (1977) for 53 temporary freshwater pools in Victoria, Australia, or by Bayly (1982) for 19 temporary freshwater pools on granite outcrops in southwestern Australia.…”

A new species of Boeckella (Copepoda: Calanoida) from arid Western Australia, an updated key, and aspects of claypan ecology

“…B. major Searle matures rapidly, typically within a few weeks after a wetland fills, produces resting eggs and then disappears (Green et al 1999). B. pseudochelae Searle reaches maximum numbers later, more towards the middle of a pool's hydroperiod (Morton and Bayly 1977). At this stage more information is needed to determine the life-history of B. pilkililli.…”