PT14 Toxicity of Mixtures
Exhibit Hall
8:00 AM - Tuesday
(PT233A) Assessing reproductive effects of final bleached kraft pulp mill effluent using pair-breeding fathead minnow (Pimephales promelas).
Rickwood, C1, 2, Dube, M2, MacLatchy, D3, Hewitt, L4, Parrott, J4, 1 University of Saskatchewan, Saskatoon, SK, Canada2 National Water Research Institute, Saskatoon, SK, Canada3 University of New Brunswick, Saint John, NB, Canada4 National Water Research Institute, Burlington, ON, Canada
ABSTRACT- Reproductive effects (e.g., reduced gonad size and altered hormone levels) have been recorded in wild fish in waters receiving pulp mill effluent (PME) since the mid to late 1980’s. Observations from laboratory studies assessing egg production of fathead minnow (FHM) after exposure to PME have been variable and a lack of consistency in response has made confirmation of cause difficult. The lack of environmental relevance in these lab studies may have contributed to the variability observed. The objectives of this study were to 1) increase the environmental relevance of a FHM lab-based bioassay by conducting an in situ test in a field-based artificial stream system and 2) identify a consistent endpoint that could be used for an investigation of cause study. A mobile bioassay trailer was situated on-site at a bleached kraft mill for 60d allowing supply of both ambient water (Lake Superior, Canada) and final PME. The reproductive output of FHM breeding pairs was initially assessed to obtain baseline data. At the end of the pre-exposure period, selected breeding pairs were exposed to final PME (100% & 1% v/v) for a further 21 days. Significant time and treatment interactions were observed for both spawning events and egg production (RM ANOVA, p= 0.007 and p=0.000 respectively). Spawning events, egg production, testosterone levels and ovipositor development in females were identified as sensitive and consistent endpoints. Obtaining pre-exposure data and the use of pair-breeding FHM in this assay gave a sensitive indication of effluent effects and allowed accurate endpoint comparisons to be made.
Key words: reproduction, fathead minnow, pulp mill effluent, breeding pairs