Detoxification Enzyme Assays for Biomonitoring Pulp and Paper Effluents in a New Zealand Recipient: UDP-GT Activities in Goldfish, 1993 Environmental Conference Proceedings

Due to legislative developments and an expanding wood processing sector in New Zealand there is an increasing need to use effective monitoring systems for assessing biological impacts attributable to effluent discharges. Two critical components are the development of assessment techniques for effective early detection of irreversible biological change, and accurate prediction that ecological harm is occurring or about to occur.

An approach being applied in New Zealand is the use of detoxification enzyme responses in fish, including both conjugating and mixed function

oxidase systems. Initial investigations have focusedon the measurement of uridine diphosphate glucuronyl transferase (UDP-GT) activities in a feral population of goldfish (Carassius auratus) taken from a recipient of a bleached kraft mill effluent.

The UDP-GT activity levels (measured using para-nitrophenol. p-NP, as a substrate) were found to be very low or absent, and no relationship occurred between enzyme activities and distance from the discharge. Goldfish at the upstream site, separated by a hydroelectric dam, also showed limited UDP-GT response. A number of experimental procedures were used to verify that the low response levels were not due to inappropriate assay conditions. Factors considered included the use of pure enzyme, use of hatchery reared rainbow trout (Oncorhynchus mykiss), comparison of liver homogenate and microsome activities, use of surfactants, and effect of reaction temperature, time and enzyme concentration.

Following these various treatments, the UDP-GT response in the gold fish liver tissue was still found to be negligible. The results suggest that the UDP-GT assay in goldfish is inappropriate for biomonitoring. As goldfish were expected to have UDP-GT activity, based on published information, it is considered that the fish population could be genetically different in the study area, and the goldfish were using other conjugating pathways. Before detoxification enzymes systems can be used for biomonitoring more information on their fundamental control and response mechanisms for different species is required.