Chemical and zooplankton studies of lentic habitats in north-eastern New South Wales

Abstract

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 triarticulata (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.