The Australian and New Zealand Guidelines for Fresh and Marine Water Quality are a key document in the Australian National Water Quality Management Strategy. These guidelines released in 2000 are currently being reviewed and updated. The revision is being co-ordinated by the Australian Department of Sustainability, Environment, Water, Population and Communities, while technical matters are dealt with by a series of Working Groups. The revision will be evolutionary in nature reflecting the latest scientific developments and a range of stakeholder desires. Key changes will be: changing the guidelines to an electronic format; increasing the types and sources of data that can be used; working collaboratively with industry to permit the use of commercial-in-confidence data; increasing the minimum data requirements; including a measure of the uncertainty of the trigger value; improving the software used to calculate trigger values; increasing the rigour of site-specific trigger values; improving the method for assessing the reliability of the trigger values; providing guidance of measures of toxicity and toxicological endpoints that may, in the near future, be appropriate for trigger value derivation. These changes will markedly improve the number and quality of the trigger values that can be derived and will increase end-users' ability to understand and implement the Guidelines in a scientifically rigorous manner.

Benthic macroinvertebrates were sampled (seven Surber samples per site) in 88 rivers throughout New Zealand in "runs" (velocity 0.4-0.8 m s" 1 , depth = 0.3-0.6 m), under autumn baseflow conditions (Q < median). Medians and 10-90 percentiles for the following community level characteristics were: taxa richness, 14 and 7-20(0.7 m -2 ); Shannon Diversity (H'), 1.33and 0.80-1.90; total density, 1900 and 230-6700 nr 2 ; and total biomass, 0.608 and 0.112-2.932 g AFDW nr 2 . Invertebrate abundance and taxonomic richness were lowest in rivers with beds of silt or sand, or cobbles overlain with sand deposits. Comparisons of environmental factors between sites grouped by TWINSPAN indicated that the degree of catchment development to improved pasture, water temperature, and level of enrichment (indicated by increased nutrients and periphyton biomass) are important factors affecting invertebrate community structure in New Zealand rivers. Mayflies, stoneflies, and predatory caddisflies were associated with cooler, less enriched, steeper, and more elevated sites than snails, crustaceans, chironomids, and worms. Stonefly biomass was minimal at sites having mean annual temperatures >13°C. The following community characteristics emerged as useful indicators of the level of water enrichment: the Macroinvertebrate Community Index (MCI) and its quantitative analog (QMCI); the presence of some species (e.g., Zelandoperla decorata and Bereoptera roria), and the densities of some widely distributed taxa (e.g., M90014Received 5 March 1990; accepted 23 May 1990 Deleatidium spp. and Psilochorema spp.); percentage predator biomass; and the number of ephemeropteran, plecopteran, and trichopteran taxa (EPT). Sites did not separate out clearly into ecoregions, although rivers with "clean-water" faunas were more predominant in the South Island than in the North Island. This is thought to reflect the greater degree of development of the North Island catchments.

(1991) Microhabitat preferences of benthic invertebrates and the development of generalised Deleatidium spp. habitat suitability curves, applied to four New Zealand rivers, New Zealand Journal of Marine and Freshwater Research, 25:2, 187-199, DOI: 10.1080/00288330.1991 Marine and Freshwater Research, 1991, Vol. 25: 187-199 0028-8330/2502- velocities, Potamopyrgus antipodarum and Chironomidae low to moderate velocities (0.0-0.75 m s -1 ), and all three were associated with a broad range of substrates. Deleatidium spp., Olingaferedayi, Hydrobiosidae, and Aphrophila neozelandica were found in a wide range of habitats. Velocity, depth, and substrate suitability curves developed for Deleatidium in each of the four rivers also demonstrated the broad habitat tolerances of this genus. Generalised suitability curves formed by enveloping, rather than averaging, curves from each of the rivers performed favourably when compared to models based on suitability curves developed for each river individually. Correlations between Deleatidium abundance and the joint suitability function, calculated from the generalised velocity, depth, and substrate curves, were significant but poor (r = 0.44-0.69) in each of the four rivers. The intercepts of the linear relationships between Deleatidium abundance and the joint preference factor were not significantly different from zero for three of the four rivers, suggesting that the preference functions are applicable to in-stream flow assessments.

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1. Benthic invertebrates were sampled over a matrix of about eighty combinations of mean velodty (10-150cms~^) and depth (10-150cm) in two rivers that differed in substrate size variability. Vertical velodty profiles were measured at each sample site and substratum roughness was measured and estimated from percentage cover by stone size classes. The influence of depth on periphyton biomass was also measured. 2. The hydraulic and substrate data were used to investigate the correlations between conventional (mean velodty, depth, subsfrate size) and complex hydraulic variables (Froude number, shear velodty, and water column and boundary Reynolds number) that were either calculated from direct measurements or inferred from mean velodty, depth, kinematic viscosity and substrate roughness. The ecological relevance of these hydraulic variables was investigated by comparing their degree of correlation with invertebrate densities and community metrics. 3. The invertebrate variables had similar correlations with mean velodty and the complex near-bed hydraulic variables in the river with uniform cobble subsfrates. In the river with diverse subsfrates, however, average correlations with Froude number, and inferred shear velodty and boundary Reynolds number were 25-45% higher than with velodty. Of all the individual hydraulic parameters, the boundary Reynolds number, calculated from simple measures, was most sfrongly correlated with benthic invertebrate distributions and taxa richness. However, invertebrate distributions were more sfrongly correlated with predictions of multiple regression models, incorporating substrate size, depth and mean velodty, than with any single hydraulic variable. 4. Hydraulic influences on food availability and oxygen concentration in the benthos are likely mechanisms affecting the hydraulic preferences of several taxa. Lower periphyton biomass with depth, partly attributable to light attenuation, appeared to have a nonhydraulic influence on a collector-browser spedes.

A set of near-stream flowpaths in pasture, native forest and exotic pine plantations in New Zealand was sampled to describe differences in dissolved organic carbon (DOC). The quantity and bioavailability of DOC varied among flowpaths in different land uses, with higher concentrations of DOC in near-stream flow paths than the parent groundwater emerging from the hillslope. Tiles incubated in these waters did not consistently yield higher bacterial growth rates than tiles incubated in groundwaters. DOC composition, measured as fluorescence and absorbance properties and extracellular enzyme fingerprints, differed significantly among land uses and position along flowpath.Differences in riparian vegetation can indirectly affect DOC by altering exposure to ultraviolet radiation. A 2-h exposure of water from subsurface flowpaths to full sunlight caused marked changes in fluorescence characteristics of water from the pasture catchment but only small changes in water from the native forest catchment. There were up to fivefold differences in extracellular enzyme activities on tiles incubated in light-exposed water for the native forest site, but not for the pasture site. Bacterial growth and respiration were higher on tiles incubated in native forest water exposed to sunlight, but there was no light effect on growth for tiles incubated in water from the pasture flowpath. These results indicate that riparian flowpaths will affect the quantity and character of DOC delivered to streams and ultraviolet exposure may, at least in some cases, alter DOC bioavailability.

Australian freshwaters have relatively low water hardness and different calcium (Ca) to magnesium (Mg) ratios compared with those in Europe. The hardness values of a substantial proportion of Australian freshwaters fall below the application boundary of the existing European nickel biotic ligand models (Ni BLMs) of 2 mg Ca/L. Toxicity testing was undertaken using Hydra viridissima to assess the predictive ability of the existing Ni BLM for this species in extremely soft waters. This testing revealed an increased competitive effect of Ca and Mg with Ni for binding to the biotic ligand in soft water (<10 mg CaCO /L) than at higher water hardness. Modifications were made to the Ni BLM by increasing the binding constants for Ca and Mg at the biotic ligand to account for softer waters encountered in Australia and the more important competitive effect of Ca and Mg on Ni toxicity. To validate the modified Ni BLM, ecotoxicity testing was performed on 5 Australian test species in 5 different natural Australian waters. Overall, no single water chemistry parameter was able to indicate the trends in toxicity to all of the test species. The modified Ni BLMs were able to predict the toxicity of Ni to the test species in the validation studies in natural waters better than the existing Ni BLMs. The present study suggests that the overarching mechanisms defining Ni bioavailability to freshwater species are globally similar and that Ni BLMs can be used in all freshwater systems with minor modifications. Environ Toxicol Chem 2018;37:2566-2574. © 2018 SETAC.