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DNA sequence data from for histone H3 (34 species), U2 snRNA (34 species) and two segments (D1 and D9–10 expansion regions) of 28S rDNA (28 and 26 species, respectively) have been collected to investigate the relationships of polychaetes. Representatives of all of the major morphologically identified clades were used, as well as members of the Sipuncula, Echiura, Turbellaria, Clitellata and Siboglinidae (formerly the phyla Pogonophora and Vestimentifera). Maximum parsimony analyses of the separate data sets gave conflicting results and none conformed closely to previous results based on morphology. Instead each data set provided corroboration of a few of the morphological groupings, usually pairing, though inconsistently, members of the same family. Higher groupings proposed on morphological grounds were rarely recovered. Maximum parsimony analysis of the combined data, excluding areas of uncertain alignment, recovered some morphological groupings such as Cirratulidae, Terebellidae, scale worms and eunicimorphs, and did not significantly contradict others. However, some expected groupings were not recovered. Surprisingly, the fanworms (Sabellidae and Serpulidae) were not shown as sister taxa, and monophyly of Phyllodocida, a morphologically well corroborated clade, required four more steps than most parsimonious trees. Aciculata was not seen in our analyses, although it was the most strongly supported large clade in Rouse and Fauchald (1997, Cladistics and polychaetes. Zoologica Scripta 26, 138–204). Trees constrained to show Aciculata as monophyletic were 18 steps longer than the most parsimonious trees. If trees are rooted on sipunculans rather than the nematode, Aciculata is nearly recovered, being rendered paraphyletic by the inclusion of the sister-pair of Oweniidae and Chaetopteridae. As suggested by some recent morphological and molecular analyses, Siboglinidae and Clitellata may well have sister groups among polychaetes. The morphologically aberrant Sternaspidae are closest to members of Terebellida in the present analyses, supporting the placement of Rouse and Fauchald. Interesting results deserving further assessment concern the placement of Chaetopteridae, Oweniidae and Sipuncula.

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This ecological study of the Myall Lakes, a lagoon system on the New South Wales central coast, presents the physical setting and characteristics of the Lakes' catchments and relates these characteristics to the hydrochemical features of surface and subsurface waters. In turn these hydrochemical features have been related to the aquatic communities.It is suggested that the predominance of forest vegetation and stable soils in the Lakes' catchment has assisted in retaining these lakes in a generally undisturbed state.Fluctuations of salinity, turbidity and ionic concentrations in the lower part of the system are controlled by natural inputs of rainfall, run-off and tidal flushings. However, Boolambayte Lake and particularly Myall Lake, the upper part of the system, appear to be isolated from these influences. The aquatic communities reflect these hydrochemical differences.The lack of flushing of waters in this upper part of the system, in Dirty Creek and to a lesser extent in the Myall River immediately upstream of the Broadwater, makes these areas particularly susceptible to pollution and eutrophication associated with increased development.

A series of replicate samples of dead coral reef habitats was collected across Yonge Reef on the outer and inner reef (back reef) and on fringing reefs around Lizard Island. Five categories of habitats were selected, branching, thin plates, high percentage of live coral, solid reef, rock with either a small surface area or a large surface area, and easily broken up. The surface area, volume, percentage cover of epifauna and flora, and biomass of cryptofauna were determined for each habitat. An estimate of the percentage of cavity space (i.e. available living space for cryptofauna) occurring in each habitat was made. The cryptofauna is dominated by polychaetes, molluscs, and sipunculans. Habitats on inner Yonge have a larger biomass of cryptofauna than similar habitats found on outer Yonge or on fringing reefs around Lizard Island. Differences in physical attributes of the habitat together with exposure and surrounding species of coral and sponges may be responsible for these differences.