Science & Mathematics

The littoral macroinvertebrate assemblages of Lakes Albina, Blue, Club andCootapatamba in the Mt. Kosciuszko region were sampled by two methods: sweeps and cobble picks. Thirty-six species were collected with total abundance and species richness greatest in Lake Albina. Common species included themolluscs Pisidium kosciusko and Glacidorbis hedleyi, the crustaceans Metaphreatoicus australis and Neoniphragus n. sp., and an unidentified limnephidtrichoperan. Community structure was influenced by the nature of the substrate, with cobble sites having greater richness and abundance than boulder sites. The importance of the major taxonomic groups (crustaceans, insects and molluscs) varied with sampling method and among lakes. Crustaceans (isopods and amphipods) usually dominated in sweeps, with molluscs and insects varying in importance among lakes, while insects mostly dominated in cobble pick samples. Oligotrophic lakes are typically thought to be dominated by insects, however this study shows such lakes may appear to be dominated by insects or crustaceans depending on the sampling method used and the presence of fish.

Before 2003, unique assemblages of aquatic invertebrates in Lake Cootapatamba and Lake Albina lived in a fishless environment. A sequence of events in 2003 following a large-scale bushfire in the area allowed the native Mountain Galaxias Galaxias olidus to enter Lake Cootapatamba. This study determines the extent of any temporal changes in the invertebrate assemblages of each lake and whether the introduction of fish into Lake Cootapatamba affected these assemblages. The littoral and benthic fauna of both lakes were found to have changed since the earliest studies of these lakes in 1997/1998 and 1976, respectively. In particular, there has been a large decrease in the abundance of the isopod Metaphreatoicus australis and planarians, and the gastropod Glacidorbis hedleyi and amphipod Neoniphargus sp. have apparently disappeared. The effect is greatest in the benthos and in Lake Cootapatamba, so while fish seemed to have affected some invertebrates in some habitats, other factors may be acting. Sometime since 1976, the exotic worm Lumbriculus variegatus arrived into Lake Albina. Shifts in the representation of other taxa, such as ephemeropterans, plecopterans, tricopterans, dipterans and coleopterans, are thought to reflect natural year-to-year fluctuations but more data are needed.

Part of the apparent variation in community structure and abundance of macrobenthos between lakes is attributable to the different sampling strategies used. A comparison of 7 sampling options in Lake Pearson, Canterbury, New Zealand, shows that spot samples and line transects are inadequate but that an augmented line transect is almost as good as stratified random sampling. Winter/early spring and summer samples are needed to account for seasonal variations in species richness and community biomass. Much less effort is required for an augmented line transect, therefore it is recommended for lake survey and management studies.

In a study of four species of centropagid copepods, particularly Boeckella minuta S ars, occurring in south-east Queensland, Australia, body length was found to correlate with the rate of water renewal in the reservoir. R avera & T onolli's explanation for interpopulational differences in lengths of copepods has thus been confirmed. There was also a positive correlation between body length and egg number in ovigerous females. Sex ratio (females/males) increased with the rate of water renewal, this providing for relatively more females to be present when population numbers were smaller. © 1968 Dr. W. Junk Publishers.

Forty‐four species of aquatic Coleoptera are recorded, many for the first time, from coastal northeastern N.S.W. Only four (Hyphydrus elegans (Montrouzier), Megaporus nativigi Mouchamps, Rhantus suturalis (Macleay) and Gyrinus convexiusculus Macleay) are relatively common, most of the remainder being recorded only once or twice. Few species show any preference for the ecological type of dune lake/pond inhabited. The number of species per locality is apparently independent of the presence of possible fish predators, but is at least partly related to habitat heterogeneity. Copyright © 1981, Wiley Blackwell. All rights reserved.

In twelve reservoirs in south-east Queensland, the limnetic planktonic crustacean community is made up, on the average, of 2.3 copepodian and 2.0 cladoceran species. Of these, one copepodian and one cladoceran species usually dominate the plankton to the extent of comprising 78% and 80% of the total, respectively. Two congeneric occurrences are reported. © 1968 Dr. W. Junk Publishers.

Chemical and zooplankton data for 103 reservoirs and lakes on the northern tablelands and the central and north coast regions of New South Wales are presented and discussed. Twenty-three of the localities are natural, occur in five distinct regions, and are variable in their modes of origin. All the waters are fresh, and most have less than 200 p.p.m. total dissolved solids. In general, waters on the coastal plain are dominated by sodium and chloride ions, while those on the highlands are dominated by bicarbonate and sodium, magnesium, or calcium. A total of 43 species of Entomostraca inhabit the lentic environments of the area, though many of these cannot be considered to be eulimnetic species. Only a few species (2.2 copepods and 1.1 cladocerans, on the average) occur in any one locality, this number being influenced by site size and age. The distribution pattern of the major species are depicted and discussed in terms of four factors. Altitudinal-related factors are important for many species, particularly calanoid copepods; water chemistry influences the distribution of at least two species-Boeckella triavticulata (Thomson) and Calamoecia tasmanica (Smith); turbidity has a subsidiary effect on the occurrence of species in the genera Daphnia and Ceriodaphnia; and the locality age is important for most species. The relative dispersal powers of the more common species are assessed from their tendency to be present or absent in new reservoirs. © 1969, CSIRO. All rights reserved.

The summer benthos of 24 lakes ranging from 1-204 g l-1 salinity contained 27 species of macroinvertebrates. The worm Antipodrilus timmsi, the ostracod Mytilocypris splendida, the amphipod Austrochiltonia subtenuis, the chironomids Procladius spp. and Chironomus duplex aand the snail Coxiella striata were common at lower salinities (3-ca. 30 g l-1) while the crustaceans Australocypris robusta and Haloniscus searlei, the chironomid Tanytarsus barbitarsis and a ceratopogonid larva dominated in salinities ca. 20-100 g l-1. Small ostracods were common from 40-150 g l-1. Diversity changed little with salinity. Mean dry biomass ranged from 0-3.94 g m-2; distribution between lakes was negatively skewed with a peak around 7 g l-1 salinity. Within many lakes, there was considerable spatial heterogeneity which in some cases seemed to result from different bottom characteristics or to point source enrichment. Many groups contributed to the standing crop at low to moderate salinities, and at high salinities crustaceans were important. The lakes were grouped into two low salinity associations, an association which comprised the Red Rock Lakes and a cluster of highly saline lakes. This reflects the grouping of species into halobiont, halophilic and salt-tolerant freshwater species. © 1983 Dr W. Junk Publishers.

Cyclestheria hislopi was first described as Estheria hislopi by Baird (1859), from Nagpur, India and has since been found circumtropically. There are only two records for Australia (Saars, 1887; Timms, 1979) suggesting a limited distribution there, but this conchostracan occurred commonly in collections made recently in tropical Australia to study cladocerans. The purpose of this note is to report on the taxonomic characteristics of these specimens and to document the distribution and habitat preferences of C. hislopi in Australia.