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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